A Blog Devoted to my Many Hobbies

Archive for the ‘Repair’ Category

Hendey Lathe Assembly: Part 2

Posted by davidjbod on August 22, 2014

Work continues on the lathe….

I used my woodworking lathe to clean up the lower cone pulley and the back gears shaft.  I made an arbor out of wood to mount the pieces and then worked on them at my lathe’s lowest speed.  It made the work much easier.  You can see the difference in the clean and rusty sections below.

H80

I cleaned the gear box gears one by one with a wire wheel.  Overall the gears appeared to be in great shape as there were no missing or deformed teeth.

H81

I cleaned up the smooth bars using a wire wheel but the lead screw was a lot more trouble.  I capped off the end of a 1-1/4″ PVC pipe to soak the lead screw in parts cleaner solution.  It dried out the grease on the lead screw but I still had to clean every thread with a Dremel wire wheel.  But once it was done I was able to reinstall the gears and lead screw into the gear box.  The gear box and bars were then reinstalled on the machine.  Somehow I managed to miss the end of the reverse rod but I cleaned it up after the pic.

H82

Next up was putting all the gears back on.  This went pretty smoothly since I’d numbered everything and took plenty of pics.H83

The carriage was dunked in the parts cleaner and then hit with the wire wheel.  This was followed up with a little bit of paint.

H84

I reassembled the apron and carriage next in preparation of reinstalling them.  After that was finished, I put the carriage back on the lathe, installed the plates which keep it from lifting, and put the apron back on.H86

It’s beginning to look like a lathe again!

H85

One of the things I broke when the lathe fell was a threaded rod in the taper attachment.  I’m not 100% sure what the rod does but it has to be replaced.   I ended up drilling through the rod and using a square ease out to remove the broken section.H87

I figured I’d clean up the chuck while I was cleaning everything else up.  The inside of the chuck is pretty well sealed and was clean inside.  It went to the regualr cleaning progress.  Once everything was clean I oiled, greased, and reassembled the chuck.

H88

Brass plates look nice but are time consuming to clean up. Best I can tell there’s no easy way of cleaning them.  I soaked the plate and the scrubbed it with a soft bristled brush.  Judicious scrubbing cleaned most of it up but some of the corners required the use of a dental pic.  Eventually I got it cleaned up and then used some some Brasso on it.  Much better.

H89

I got the back brass ring on the head stock fixed (it’s threads were messed up in a spot) and then reinstalled the spindle.  With it in place, the back gears and the rest of the gear train was reinstalled.  After that, covers were reinstalled.

H91

The last touch on the “main” part of the lathe was reinstalling the brass plate. Big difference from when I originally got it.

H92

At this point I could do some turning if I had an overhead line shaft.   Since I don’t, next will come repairing and cleaning up the motor arm components and tailstock.

Posted in Repair, Restoration, Tools | Tagged: , , , | Leave a Comment »

Hendy Lathe Assembly: Part 1

Posted by davidjbod on August 3, 2014

In my last Hendey post I’d finally reached the point where I’d taken the lathe completely apart with the exception of the tail stock.  Now comes the repetitive task of cleaning and painting.

The handles, knobs, and dials were originally polished steel or brass.  I cleaned them up with a Dremel and buffing wheel.  One of the handles below has had its pin replaced with a bolt and nut.  Once I get the lathe up and running I’ll fix this.

H60

I picked up a parts washer off of Craigslist and it has been great for cleaning the smaller parts.  The parts were tossed in and left overnight.  After they’d dried, the grease was converted to a chalky gray substance that was easier to remove than trying to wipe off all the grease.  I used a variety of wire brushes for cleaning.  Where I could, I used a wire cup on an angle grinder.  Any spots I couldn’t reach with the grinder were cleaned using a 3/4″ wire brush on a pneumatic die grinder and if needed a wire wheel on the Dremel.  I ordered a large lot of wire wheels for my Dremel off of eBay for much less than you find them in the store.  They seem to shed a little more than the name brand ones but at the cost I was ok with it.  Below is a picture of the compound in the middle of being cleaned with the wire cup.  It works well and is fast.

H61

Once the parts were cleaned, I wiped them down with paint thinner until the rag didn’t pick up any dirt (or close to it). Next, most of the parts were primed but some of the gears were left bare and then painted.   I hand painted some parts but spray painted what I could.  The brackets could be easily masked but the gears were easier to hand paint.

H62

The body casting of the lathe is held on to the intermediate legs by six bolts.  With them removed, the casting can be separated for cleaning.  I tried pressure washing it but it wasn’t very effective.  After a bit of time with the grinders I was able to get it ready to paint.  No more straps here.  The lifting setup has a significantly higher working load limit than the engine crane.

H63

The main legs and pan were cleaned and primed with self etching primer.

H64

The pan required a little bit of masking off with tape.

H65The body casting required significantly more masking.

H68

For the most part I didn’t worry about filling imperfections.  I don’t mind mold texture on the castings or the occasional flaws.  It is a tool not a Corvette.  That being said, it looked like someone had taken a grinding wheel to the outer gearbox cover.  So, I used a little filler here and there.  I should mention that I used some dental picks in cleaning as well.  They’re great for scraping crud out if tight corners.  I got a large amount of them from my father in law.  Check to see if your dentist is tossing some out and you may luck out.

H67

The brass plate with the gear chart on it was held on with brass nails that had been peened over.  I drilled them out to remove the plate.

H69

Here’s the completed compound.  I polished up the dial and handle and adjusted it as best I could.

H66

The apron has a bunch of parts but most of them don’t require paint.  I painted the inside of the apron because it was there.  I doubt anyone would notice if they saw the machine.

H70

For the most part the apron didn’t have any issues.  The first was that someone had replaced the set screw on the half nut lever with a bolt that they ground flush.  I drilled it out and taped it for a 1/4″ set screw.  The second issue was a pain.  Show below is the longitudinal feed mechanism.  The shaft on the bottom goes inside of the assembly with the gears.  The large wheel fits on the assembly and a knob screws onto the end of the shaft on the bottom.  Tightening the knob causes the carriage to be driven longitudinally by the lead screw.  In the past someone had hit the hand wheel bending the entire thing.  The end of the hollow shaft was egg shaped which required a little bit of hammering and drilling to fix.  The shaft for the knob required a little filing, polishing, and numerous test fits to correct.  Finally, the knob tightened and loosened with a light constant drag.  H71

I discovered that modeling clay can be used to cover small holes and the Gits oil cups.  It hardens after a day and pops off cleanly.  I used if several times to help mask off the head stock.H72

The legs and pan were primed and hand painted by brush separately before being reassembled.  I primed the body casting and then dropped it back on the stand as it held it well for painting.  H73

More later!

Posted in Repair, Restoration, Tools | Tagged: , , , | Leave a Comment »

David White 8300 Transit: Part 2

Posted by davidjbod on May 19, 2014

My previous post covered disassembling the David White 8300 transit and this one will cover rebuilding and calibrating it.

Some of the brass hardware would not be removed no matter what I tried.  Eventually, they would break or get damaged enough to warrant replacing.  The two assemblies that put friction into the altitude movement wouldn’t come out.  I had to drill them out.  I’m not exactly sure what made up these assemblies though I do know there was a brass plug on the bottom, spring in between, and a nut on the top.  I gather turning the nut increased the friction.  I drilled everything out and came up with a plan to fix it.  Here’s a picture of me drilling out one of the assemblies.

T24

The altitude fine adjustment screw/knob had also corroded itself to the aluminum frame.  While trying to remove it, the knob started spinning on the shaft.  I removed the knob and worked on drilling out the rest of the screw.  It wasn’t perpendicular to the base so I had to elevate one side of the frame before drilling.

 

T25

The cross hairs on my transit had long since vanished.  There was a thick black disk with a hole in it (see below) that had very fine groves in it that held the cross hairs.  I looked around for what to replace the cross hairs with and found that tungsten wire or Kevlar filaments would work.  Some said the cross hairs used to be made of spider web silk.  Specifically, the Black Widow spider was mentioned.  I felt it’d be safer to go with the Kevlar.  Chris from One Tool at a Time was able to get me enough Kevlar thread to do a million cross hairs.  To make cross hairs out of Kevlar you pull a piece of thread apart until you get to the filaments that make it up.  The Kevlar filaments are very fine and strong.  I supported the cross hair ring and laid the filament across it.  To keep the filament from sagging I weighted the ends with a couple paper clips.  Once it was in place I put a few drops of super glue down to hold the filament in place.  I repeated the process for the other hair.

T51

Once the cross hair had dried I reassembled the telescope portion of the transit.

T52

To clean up the other upper parts of the transit, I media blasted them with glass beads and gave them a cost of paint.  The paint doesn’t match the paint of the telescope but it works well with it.

T53

To repair the vertical axis friction assemblies I taped the holes for a 5/16″ bolt which I had hoped to find made out of brass.  I was unable to and used some grade 8 bolts instead since they’re golden in color.  For the rest of the friction mechanism I used a couple pieces of nylon and some springs.  This works well and gives me the ability to adjust the friction.

T54

The small screws that held the vertical vernier scale also had to be drilled out and tapped to a 4-40 thread.  I found some small brass hardware to hold it on.  I’m had to use one of the washers elsewhere but picked up another later.

T55

I lightly polished some of the brass and chromed pieces before putting the altitude locks back on.

T56

The vertical lock knob survived the disassembly and was reused.

T57

I needed to replace two of the brass screws and knobs.  They were both 10-32 size thread but the screws I bought were too tight to turn by hand.  To fix this, I ordered an adjustable die that I used to trim down the screws.  I didn’t have a die stock in the appropriate size so I had to use my vise.  Its slight overkill I know.

T58

The azimuth fine adjustment screw was missing its knob when I purchased the transit.  I stumbled upon a brass piece that would work as a replacement knob at Ace.  It doesn’t match the style of the other knobs but it is better than a black plastic knob.  If (when) I get a metal lathe I’ll see about making some replacement knobs.  Opposite of the fine adjustment screw is the part which is supposed to put pressure on the tab on the frame to hold the transit in place while you adjust it.  This was also broken when I picked it up.  I settled on a small spring (not pictured here) to pull the tab up against the adjustment screw.

T59

Since the transit is permanently stuck to the tripod base I welded some wing nuts and all thread together so I can get the legs on and off quickly.  The welds weren’t pretty but they’ll work.

T60

And here’s the final product…T61 T62

At some point I will probably clean up the tripod.

T63

Even though I’ve fixed and reassembled the transit it isn’t useful until it is calibrated.  In the real surveying world instruments can be taken in to a shop and calibrated.  I’m not sure I’d be able to find someone to calibrate my transit even if I had tried.  It might have been funny.  So, I needed to do it myself.  Calibrating it proved to be a little tricky but I eventually worked out a way to do it without specialized equipment.  As an overview, when a transit is set up it needs to be level in all directions when you swing it around in azimuth.  To help with this, there is a level built into the transit.  Normally, you plop the transit down, position the level over a pair of leveling knobs, and turn them until the bubble is centered.  You’d then turn the transit 90 degrees over the other set of leveling knobs and center the bubble. (My transit has four leveling knobs.  Some have three.  Adjust procedure as needed.)  You repeat this until the bubble doesn’t move  as you swing the transit is azimuth.

As you may recall, I took the level off when I disassembled it meaning that the axis of the level is no longer parallel to the optical axis of the telescope.  When they aren’t aligned the transit will give incorrect readings.  After thinking about it for a bit I figured out how to solve this problem using the “Two Peg Test”.  This test is/was used to gauge the accuracy of your  surveying instrument. I’m going to use it to calibrate and then test mine.

My process was this:

1) Adjust the level so that it looks parallel to the telescope optical axis. It won’t be at this point but get it as close as you can.

2)  Set up the tripod and do your best to get the top of the tripod level by looking at it.  The leveling knobs can only adjust so much.

3)  Adjust the altitude locks so that the telescope is held level compared to the rest of the transit.  This is just a guess at this point.   Engage the locks.

4)  Level the transit using the four adjustment screws on the base of the transit.  Since the level isn’t parallel to the transit base you can’t just center the bubble using the adjustment screws.  Instead seek to have the bubble displaced by the same amount of marks on the level when you compare the transit facing at 0 and 180 degrees (I’ll call this front and back).  If you can’t get the bubble to do this you may need to adjust the altitude locks.  Eventually, you’ll reach a point where the bubble is displaced an equal amount when you rotate the transit to face front and back.

5) Now, rotate the transit 90 degrees and adjust the other set of leveling knobs to get a bubble that is displaced equally when you compare it facing this way and opposite 180 degress (I’ll call this left and right).

6) Check front and back and side to side to make sure you still get equal bubble displacement.  If not repeat steps 4 and 5.  With steps 4 and 5 completed the base of the transit will be level and we can start the “Two Peg Test”.

7) The test has two parts and we’ll now do the first part.  Mark out 100 or 200 ft (I used 100) and put pegs in the ground at both ends with your transit at the middle.   Have someone hold up your surveying rod at the first peg (call it A) and take a reading with the transit.  Move the rod to the other peg (call it B) and take another reading.  Subtracting these two readings will give you the elevation difference between the two pegs.

8) Step two of the “Two Peg Test” required moving the transit and taking another reading.  So, move your transit to peg B and repeat the leveling process covered in steps 4 and 5.

9) Measure the height of the transit’s eyepiece.  You can now use your previous elevation difference between peg A and B to calculate what you should see when you take a reading of peg A from peg B.

10) Send your helper down to peg B and take a reading.  Unless you’re really lucky, what you see and what you calculated won’t match.  Thats ok.  Unlock the altitude holds and rotate the telescope to get the reading you calculated.  Now holding the telescope steady adjust the level to center the bubble.  I tightened down the altitude friction bolts so the telescope wouldn’t move.  With the bubble level adjusted you’ve now made the bubble level axis parallel to the telescope’s optical axis.

11)  Now readjust the vertical locks to hold the transit horizontal (bubble centered) when they are engaged.

12) Repeat the “Two Peg Test” to test the transit.  This time you’ll want to try to center the bubble when leveling the base of the transit.  If you can’t, run through all the steps above again.

13) Repeat step 12 until the difference between the elevation in step 1 and step two of the test is very small.

 

I realize thats a bunch of instructions so I’ll use the numbers from my testing as an example. I may add some drawings at a later point to clarify things.

I marked out 100 ft with my transit in the middle.  I leveled the base as best I could as covered in steps 4 and 5.  I took a reading at peg A of 4′ 9-1/2″ and turned the transit 180 degrees.  At peg B I got a reading of 4′ 7-5/8″.  Subtracting these tells me that Peg A is 1-7/8″ higher than Peg B.  (Technically, my pegs were garden pavers.)

I moved the transit to Peg B and leveled the base of the transit.  My eyepiece height was 4′ 2-1/2″ and I measured 5′ 1″ at Peg A.  This shows an elevation difference of 10-1/2″.  Clearly, this is horribly off as expected.  Instead,  I expected to see 4′ 4-3/8″ (4 2-1/2″+ 1-7/8″). I then adjusted the transit as covered in step 10 and 11 to read this value.

Now I need to repeat the test.  I placed the transit back in the middle and leveled it.  This time I got a reading of 3′ 11-1/8″ at peg A and 3′ 8-7/8″ at peg B.  Doing the math shows an elevation difference of 2-1/4″ with peg A being higher.  (Yes, this is different than last time.  The first time the rod was on top of the paver and the second time it was on the ground next to it.  My helper left and I had to pinch the rod between two stones to hold it up.  In the end it doesn’t matter because values from one “Two Peg Test” don’t carry over.

I then moved my transit down to peg B and leveled it.  This time I got an eyepiece height of 4′ 2-1/4″ and read a value of 4′ 4-1/4″ at peg A.  Subtracting the values shows an elevation difference of 2″.  Comparing the elevations readings of 2-1/4″ and 2″ shows a difference of 1/4″ at 100 ft.  At this point I was happy with the results.  I did a test and determined each mark on the transit’s level corresponds to 1/2″ at 100 ft.  So, measuring half a mark is probably about the best I can do by eye.  For the record 0.25″ elevation 100 ft forms a triangle with 0.012 degrees at one of the corners.  So, a little error goes a long way.   Doing this gives you an appreciation for those who did this back in the day and who continue to do it today.

I now feel I have a transit calibrated well enough to do the work I need to do in my backyard.  I think I almost go in over my head on this one but managed to pull it out.  It’s not completely returned to original like I normally prefer but it beats it rotting away in a land fill somewhere.

T64

Rambling on the “Two Peg Test”…  The two peg test is pretty ingenious and simple trig shows it.  When you take readings at equal distances in step 1, any error due to altitude misalignment cancels out (because both errors are the same) if the base of the transit is level.  If it is, then you’re given the actual difference in elevation between the two pegs.  When you head to one of the pegs and take a reading of the other peg you now can see the error in a higher or lower value than expected.  Since you’re taking a reading at twice the distance the error would be twice that in step 1.  If the base wasn’t level in step 1 then you have some error in your elevation calculation which messes up the test.  So, level carefully!

Posted in Repair, Use | Tagged: , , | Leave a Comment »

David White 8300 Transit

Posted by davidjbod on May 11, 2014

It’s been raining a lot here recently.  During the heavier rains my back yard turns into a lake with most of it being under 3 to 4″ of water.  It was 7″ deep in one spot during the last rain.  I’ve decided I want to fix this by installing some kind of drain.  I can tell from the way the yard dries out that my yard isn’t flat and there a several high and low spots.  There are drainage ditches around my house that I might be able to run the water into.  To see what was possible I decided I should survey my yard to see what could be done.  The first step in doing this was to acquire a surveyor’s transit.  I could have bought a level but I liked the idea of being able to rotate the scope vertically.  To that end, after a little research, I decided that I’d like to get a David White 8300 transit.  It seemed like a good one and after watching Ebay for a bit I found one on Craigslist with a tripod for less than I’d seen on Ebay.  Of course this one wasn’t in the best shape but I can fix that without much trouble.  Or at least that’s what I thought.

I’ll jump to right now…this project bit me both figuratively and literally.  Figuratively, I quickly learned that when aluminum and brass corrode they stick together really really well.  Most of this transit is aluminum and all the the screws and knobs are brass.  I tried penetrant, heat, tapping with a hammer, anything I could think of and the pieces have stayed stuck together or the brass broke.  There’s a large nut that holds the transit to the tripod.  I have tried everything I know of and it will not budge.  I finally, threw in the towel and decided they’ll be together permanently.  Literally, I got hurt working on this project.  I was drilling out a broke bolt in the bottom of the tripod in the drill press.  This part of the tripod head was still attached to the heavy bottom of the transit.  It was going smoothly until it didn’t.  The bit aught, torqued the piece around, and then tossed it at my chest.   The chunk bounced off me harmlessly but along the way, one of the wings of the tripod head, slashed my palm in two places.  After bleeding for a short time, I took a trip to the ER where I got to watch the doc skillfully sew four stitches into my palm.  In a week or two I’ll be fine but I should have had the piece clamped down.  So, do what we all know to do and clamp down the piece you’re drilling.

I’ve watched a few more transits go by on Ebay in much better condition than this one and for cheaper than I paid for mine.  I like to think it’s the universe laughing at me.  In retrospect I should have passed on this corroded transit but hind sight is 20/20 and if I had you wouldn’t be about to learn how to disassemble a David White 8300 transit.  I hope this info will be useful to someone else out there cause there’s not much out there on these things from what I found.

Here’s the sad subject.  Not much would move on this thing.  It would rotate up and down and the leveling studs moved but everything else was frozen.  I checked the optics out and they looked clear but the crosshairs were gone.

T1 T2

 

I’m sure there is a correct order to taking this thing apart but this is the way I did it.  First, I removed what I’ll call the eyepiece.  It’s more of a microscope that focuses on the cross hair.  After light prying the assembly popped out.  It was frozen and wouldn’t adjust so I needed to free that up first.  The retaining ring at the end can be removed to get access to a circlip. T3T4

With the circlip removed I could slide the pieces apart and get to the corrosion.  Once it was removed a bit of oil smoothed out the operation and I was able to put it back together.

T5

The objective lens and its housing screws into the other end of the telescope.  After a little bit of persuasion it came out too.T6

The knob at the top of the picture focuses the scope.  To remove the knob, the screw opposite of it needs to be removed.  T7

With the screw out, the knot can be removed.  It has a helical gear cut into it so twisting as you pull up will help to remove it.  T8

With the focus knob removed the focusing assembly can be removed out of the front of the scope.  It’s basically a brass tube with a couple lenses at one end.T9

Next, I wanted to remove the insert that held the eyepiece in place.  I removed the two small screws at the end of the scope which actually hold it in place. It was, unsurprisingly, stuck.  The four screws before the raised potion of the scope body hold in a brass ring that I assume is some kind of field stop.  Further up the body, on the other side of the raised portion, are four screws that have been crossdrilled.  These hold a thick ring which holds the cross hair.  They can be worked in unison to position the cross hair.  I used a small drill bit to remove all four.

T10

 

On the bottom of the scope tube is a level.  It’s held in place by four circular nuts with holes in it.  Removing two allows the level to be removed.  The level can be removed at any time.  I randomly decided to do it here.T11

 

Back to the optics… Here’s the piece that holds the cross hairs (top) and the brass ring (bottom) form inside the scope.T12

At this point I had clear access to the other end of the brass piece that held the eyepiece.  I rammed it out with a wooden dowel.  The little winged piece sit into a hole and helps keep the whole thing centered I think.  T13

I started removing more knobs at this point.  The one prominently shown locks the scope to the alitude tangent arm to allow for fine movement via the blurry knob in the back of this picture.

T14

The altitude tangent knob was well stuck and I tried everything to get it out.  Below I’ve wrapped an old bike inner tube around the knob. I am also using older channellocks with worn teeth covered in electrical tape to minimize damage to the soft brass.  It didn’t work well.  More on this in a bit.T15

 

At this point I decided to separate the transit into what I’ll call the upper part (scope and vertical movement) from the lower part (horizontal movement and leveling).  Four screws hold these parts together.  Here I am removing one.T16

With the top half off we get access to the azimuth vernier.  The wide rimmed casting has the azimuth scale on it even though it can’t be seen in this picture.  There is a central assembly here that is held in place by a wide flat brass ring that is threaded at the bottom with two opposing slots cut into it.  It can be unscrewed allowing removal of the assembly. T17

The assembly has a bearing on the bottom of it that fits into the casting.  It’s tight but wasn’t pressed in.T18

 

With the assembly out of the way the large azimuth indicator piece and azimuth lock ring can be removed.  They were very tight and require a lot of delicate work to remove.  The azimuth indicator piece is pretty solid.  The lock ring is very fragile though and I broke part of it trying to get one of the brass knobs out.  It was later JB Welded back together.T19

 

Back on the upper half…  The two lock tabs can be removed by taking off the split nut and then the top screw.  The pieces that the tabs fit into can also be removed at this time by unscrewing the screws that hold it on.  They’re better shown in the seventh and eighth pictures.T20

There is a flat brass piece that acts a spring for the fine altitude adjustment that is held on by two screws.  The brass cap on the end with two holes can be removed to allow removal of the altitude tangent arm.

T21

As best I can tell there are two mechanisms centered over the altitude axis.  They can be adjusted to change the altitude movement resistance.  On mine they were completely and utterly frozen solid.  Attempting to remove the brass nut on one sheared off the post that it attached to and reveled a spring.  My best guess is the nut puts pressure on the spring which puts pressure on a brass plug that increases the friction in the movement.  They put pressure on two brass cylinders that support the scope.  One of the brass cylinders has the altitude scale piece on it.  The scale piece is held onto the brass cylinder by a clamp that can be loosened by removing the screw in it.  On the bottom of the scope centered over each brass cylinder is a  set screw that keep the brass pieces in.  After removal of the adjustment mechanism and set screws I imagine it’d come apart easily.  Not on mine though.  I drove one of the brass pieces out with wedges and then used a punch through that side to drive the other brass piece out.  Now the scope can be separated from its supports.T22

The head on this knob just spun in place.  I pulled it off and tried to get the stud out.  It was well stuck.T23

 

Here’s most of it in pieces.  The bottom of the transit with the leveling studs and large nut that attaches to the tripod aren’t shown.    T26

Posted in Repair | Tagged: , | 2 Comments »

Froe Fixup

Posted by davidjbod on December 14, 2013

I picked up an old froe from a auction store last week.  A froe is a woodworking tool for splitting wood along the grain.  It was rusty and had no handle…but not for long.  Here it is as found.  I threw the ruler in for scale.  As you can see it is pretty large.

F1

I picked one of the branches that I had left over from the ash tree I cut down.  It is larger than the eye in the froe and had a budge near the bottom I thought would work well to keep the froe in place.

F2

I bandawed off the knots and limbs before taking it to the shaving horse.

F3

Next came a lot of working with the draw knife.  I haven’t found a way to work the knots with the draw knife without getting really bad tear out.  To avoid them I worked around the knots and then hit most of the wood with a rasp. F4

When it came to shaping the part of the handle that would go into the froe’s eye, I slowly removed material and checked my progress.  After a little bit I had a good fit.

F5

To keep the froe from flying off the handle I cut the end to insert a wooden wedge.  I also bandsawed a small wedge to fit.F6

The edge of the froe was pretty dull.  A few minutes with a white stone on the grinder resulted in a serviceable edge.  It could still use some touch up with a file though.

F7

Next comes the joining of the pieces.  I tapped the froe into position and then flipped it over so I could hammer on the end of the handle.  This drove the froe head tightly onto the handle.  After that I tapped the wedge into place and oiled the handle.  The handle is longer than usually seen so I may cut it down after using it a bit.F8

Posted in Modification, Repair, Tools, Woodworking | Tagged: , , | Leave a Comment »

Orion Laser Collimator Collimation

Posted by davidjbod on November 3, 2013

On telescopes, all of the optical pieces need to be aligned.  Whether it is a mirror or lens, if they’re not pointing in the right direction the image will suffer.  A Newtonian reflector has two mirrors and they must be aligned to each other and the focuser.  There are a number of tools that can be used to accomplish this.  One of them is the “laser collimator.”  This device sits in the focuser like an eyepiece and shoots a laser out of the front of it.  The laser beam is reflected by the secondary mirror towards the primary mirror.  The secondary mirror is then adjusted until the laser strikes the exact center of the primary mirror.  Some laser collimator have a cutout with a screen built into them allowing the return beam from the primary mirror to be seen.  The primary mirror can be adjusted using the return beam.

All of this is a waste of time if your laser collimator not collimated.  Ideally, the laser should be emitted so that it is perfectly parallel to the body of the collimator.  If for some reason it is not, it must be fixed before it can be used.  I manged to pick up an Orion brand “Deluxe Laser Collimator” for cheap because it was out of collimation.  To fix it required some minor adjustments.  Here’s the steps I took to fix it.

The easiest way to check the alignment of the laser with respect to the body of the collimator is to spin it.  If the laser is not aligned to the body and the collimator is spun about the axis the laser should be on the laser beam will trace out a circle on a surface in front of it.  The further away the collimator is from the surface, the larger the circle will be.

To hold the collimator, I made a set of V blocks out of wood.  First, I ripped a V into a piece of 2×4 and cut it into pieces.

LC1

 

Next, I made a spacer block large enough to fit the central bulge of the collimator.

LC2

 

I attached it all to a base that I could use to clamp the block down to a fixed surface.

LC3

 

The laser emitter inside of the collimator is pointed via three set screws.  These set screws require a 2mm Allen wrench to be adjusted.  These set screws can be found under the label sticker on this collimator which should be removed during the procedure.  (Aside: The set screws are under the label on the regular Orion laser collimator too.)  The set screws are located in the little holes in the body.  Mine had some kind of RTV in the holes that had to be scraped away first.  LC4

 

The collimator was then placed into the V blocks and pressed against the front block to check the alignment.

LC4a

 

On a wall across my living room, I put up a sheet of paper and marked out the circle traced by the laser.

LC5

 

Now the set screws are adjusted and the collimator is rotated to check the of the size circle it creates.  This is repeated over and over again until no movement in the spot can be noticed.  At this point, I marked where the laser point hit the paper to use as my new reference point.  As before you’ll iteratively adjust and check.  But now, since the movement is so small, you have to walk back and forth between the paper and collimator to see how the spot has moved.  Note that the set screws seem to push on some springs inside of the collimator which means you don’t have to turn one set screw in and reverse the other two at the same time.

LC6

 

Once the spot doesn’t move anymore when you rotate the collimator you’re finally ready to use it on the scope.  Once the scope is collimated correctly, the return laser spot should fall in the hole in the middle of the collimator.  This is the most accuracy the stock collimator can give and you’ll need to use different tools to improve upon the collimation.

LC7

Now to go look at Jupiter!

 

Posted in Astronomy, Repair | Leave a Comment »

Collins Axe

Posted by davidjbod on September 8, 2013

I found a Collins axe head at the flea market yesterday.  For some reason I like axes so I bought it for $5.  In my minimal experience with axes it seems the older ones are better than the modern day ones.

Here’s the axe head as I found it.  It is sitting next to a nice set of Allen ball end drivers I found at the flea market as well.

Ax1

 

There’s two things wrong in this picture.  The first, is that someone tried to tighten the head by pounding a bunch of nails into the eye.  Bad idea.  The second issue, is that the bottom of the axe head is up in this picture.  Yup it was mounted upside down.  There’s a taper in the eye of an axe head that is smaller at the bottom to mechanically lock the handle in.  Mounting the head upside down guarantees it would never be tight.

Ax2

 

That junk was hammered out.Ax3

 

The back of the head is called the poll.  It is not for hammering on with a steel hammer.  Doing so just mushrooms the back of the axe head and makes it look like crap.

Ax4

 

I took it to the grinder and removed all of the mushrooming and lips where the head had been hammered on. I’d like it if the color was even on the head but I’m not sure what I could do to achieve that other and paint.  I’m sure it’ll even out over time though.

Ax5

 

I ground a 25 degree angle on the edge and then refined it with a machinist’s file.  Then I put a small primary bevel on the cutting edge and honed it.

Ax6

 

When I was trying to insert the handle into the head it wouldn’t go.  Inspection showed that hammering by the previous owner had also formed a lip inside of the eye.  I used a Dremel with a stone to remove this lip.

Ax7

I used a store bought handle that I had around the garage.  This handle has a mix of heartwood and sapwood which isn’t ideal as it can cause the handle to fail earlier than it should.  I also prefer the curved handles but figured I should do something with this one.  Most store brought handles come with a varnish on them.  I like to scrape or sand the varnish off and then oil the handle with Boiled Linseed Oil.  The oil is better for the wood and isn’t as slippery as the varnish.  I sanded the handle with 120 and then used 220 everywhere except for the lower parts of the handle where the stationary hand is placed.  This helps with grip.  After a little fitting, I cut a wedge out and then attached the head.

Ax7a

 

Once I’d oiled and waxed the head it was out to give it a try.  The head remained attached and it chopped wood without wedging.  Success!

Ax8

Posted in Repair, Restoration, Tools | Tagged: , , | Leave a Comment »

Small Backsaw: Part 2

Posted by davidjbod on August 24, 2013

In the previous post I’d cleaned up my small backsaw but there were still a couple problems to address before the saw could be used.  First, the saw was dull.  Second, the handle rocked on the saw plate.

In order to find out how to sharpen I went to Google.  Eventually, I came two good pages on saws: The Norse Woodsmith and Vintage Saws. The Norse Woodsmith is a fan of saws and even went to the trouble of making a backsaw from scratch in his garage just to show it could be done.  On those pages, I found the Norse Woodsmith Sharpening page and Vintage Saw’s Sharpening page where there’s a lot of information on sharpening.  Both have good coverage of the topic but in slightly different ways.  I read over the pages a few times and decided to give it a try.  On the pages they say you need a triangular file and a saw vise.  While I have a triangular file, I didn’t have one small enough.  So, I picked up a 6″ double extra slim triangular file.  A saw vise clamps on the saw panel to hold it steady while you file the teeth.  I don’t own one, but I do have a 6″ Wilton vise which, with a couple of pieces of wood, held the saw suitably.  The first step in sharpening saw teeth is the joint the teeth.  To do this, you run a file across the top of the teeth points to bring them all to the same level.  Once most all of the teeth have small flat spots where the points used to be, it is time to file.

BS2_1

To create identical saw teeth the triangular file needs to be consistently held at the same angle.  To help the user hold the file at the correct angle, the pages recommend using a block with a line on it to make orienting the file easier.  The block has a hole drilled in it to stick the file’s tang in.  The angle of the line is determined by the amount of rake you want on the teeth.  Rake is the term that describes the angle between the front of the tooth and vertical.  A larger rake angle makes the saw more aggressive but harder to start.  The pages recommended 8 degrees which is what I went with.  The file is inserted in the block with a face of the file parallel to one side of the block.  Then while filing the block and file are held so that the line on the block is vertical.  This results in the file being rotated 8 degrees like we want.

BS2_2

Sharpening requires filing each tooth individually but it is recommended that you sharpen every other tooth from one side and then all the others from the opposite side.  This should balance any errors the sharpener has created while sharpening.  As this was my first saw sharpening, I took it slow and focused on the task.  I could describe how to sharpen more in depth, but I suggest you check out one of the pages linked above as they have much more experience than I.  After filing, I examined each tooth and found that a few required touching up.  When I was done, I noted that I have no inherent gift for sharpening as the teeth all seemed to be slightly different.  I tried it out on a piece of pine and was amazed.  The saw flew through the wood like a hot knife through butter.  Three cuts with the saw and I was 3/4″ into end grain.  So, while my saw teeth may not all be perfect, they seem to work very well.  Now about that handle rocking…

 

I started looking into the handle rocking and identified a few possible causes.  The first, seen below, is that one of the holes in the saw plate, where the barrel bolt goes through, was misshapen allowing the barrel bolt to move up and down.  The second cause is that one of the barrel bolts was stripped and wouldn’t tighten down.  The last possible cause, is that the barrel bolts could move freely around in the wood as the holes seemed to be slightly oversized.  I think the first issue was the main cause, because I tried some regular bolts which did tighten down but the handle still rocked.  Of course having a stripped barrel bolt is problematic too.  To solve all the problems I drilled the holes progressively larger until both holes were circular.  The final size ended up being 1/4″.

BS2_3

I drilled the handle to 1/4″ as well and temporarily used some regular bolts and nuts to see if the problem was solved.  Happily, it was and resulted in the handle being solidly attached to the saw plate.  I could leave this hardware in the saw, but you know I won’t.

BS2_4

There’s another style of hardware used to hold a handle on called a split nut.  It’s similar to a regular hex nut but is circular on the outside with a slot cut into the face of the nut to tighten it.  I found a page on the Norse Woodsmith where he made some and thought I could come up with something a little simpler for my saw.  I ran to Ace Hardware to find some brass 1/4″ hardware to use.  While there, I found some barrel nuts and bolts that were for a 1/4″ hole.  They fit a 1/4″ hole loosely and were no good.  On to the brass hardware I bought.  As you can see below, this is better than the zinc plated steel but still doesn’t fit the saw ascetically.

BS2_5

 

The first step to make my split nuts, is to cut the slot into the brass hex nut with a hacksaw.  I threaded the nut onto a bolt along with another nut and clamped it into the vise so I could cut it.

BS2_6

To make the hex nut round, I used my drill press and a flat file.  I cut the top off of a regular bolt to create an arbor to hold the brass nut in the drill press.  The shoulder of the unthreaded portion of the bolt holds the nut in place.

BS2_7

 

The drill press was turned on at a low speed and multiple light passes were made with my file.  Note to use a handle on the file so that the pointy tang doesn’t go through your palm if there is a catch.  Here’s a setup shot with the drill press off to show you what I’m talking about.

BS2_8

 

Once the nut was circular, I installed it on the saw to see what it’d look like.  That’s an improvement but I’d like to make the hardware not stick out so much.

BS2_9

Reducing the length of the brass machine screw is done easily enough with the belt sander.  While I was at it, I decided to flatten the dome on the other side of the machine screw which made it look a lot better.

BS2_10

 

To reduce the thickness of my split nuts, I threaded them onto a bolt along with another nut to hold things in place.  Back to the belt sander….

BS2_11

 

Here’s how the trimmed down nut looks compared to one at the original height.  The nuts are round but the irregular bevel on to the hex bolts still makes them appear slightly hex shaped.

BS2_12

 

Here’s my close to finished set of hardware.  I hit all the edges I created with some 2000 grit sand paper after this picture to remove some of the scratches.  Yes, I have a way to put a tool on each part to tighten it.  Typically, only one part of the hardware set on a saw allowed you to use a tool to tighten it.  I like it better my way.  The razor blade, which occasionally made it into some of the pictures, fits the slot in my split nuts perfectly.

BS2_13

 

Here’s how it turned out.  BS2_14 BS2_15 BS2_16 BS2_17

 

I’m happy with it.  The hardware holds the handle solidly to the saw plate and looks like it is supposed to go with the saw.

BS2_18

All in all, this project would have been easier with a metal lathe.  It’s on my list….

 

Posted in Repair, Restoration, Tools | Leave a Comment »

Fire Extingusher

Posted by davidjbod on April 27, 2013

I ran across a pressurized water fire extinguisher in an antique store the other day for cheap.  I didn’t know if it worked or not so I gambled that I could fix it.  I already have one of these but it wouldn’t hurt to have another.  I gave it once over in the store and it looked good.  There was no rust that I could see and all of the parts were there.

This type of extinguisher is filled with water and then pressurized through a Schrader valve like you have on a tire up to 100psi.  I put water in mine and then put about 10 psi.  It started leaking around the collar nut (the big nut in the pic below) which didn’t surprise me that much.  It was made in 1980 and rubber O-rings have a limited life.

F1

 

I took the valve assembly back off and replaced the big O-ring with one from the hardware store.

F2

 

The surface inside the neck of the water tank, called a cylinder, had some corrosion on it that I cleaned up using a little Brasso.  Anything other than a clean smooth surface can result in leaks.

F3

 

That’s a little better.  I smeared some Plumber’s silocon on this surface and reassembled the extinguisher.

F4

 

I put 10 psi back on it and heard some faint hissing from the nozzle and the Schrader valve.  I removed the Schrader valve, blew it out, and put some silicone on the rubber surface.  The main valve inside of the extinguisher is held closed with a spring under the brass nut seen in the second picture.  I removed all of this, cleaned up the mating surfaces and reassembled it.

F5

 

I put 10 psi back on it and listened.  No leaks this time.  I slowly increased the pressure up about 50 psi when I heard a “tink” and saw water leaking out of the bottom.  That’s not good.

F6

 

I took off the bottom plastic foot and was greeted with a small pinhole in the bottom of the cylinder.  It looks like a little bit of rust had built up around here and weakened the cylinder.  It also looks like there are a couple more bad spots near the hole.

F7

 

At this point I threw in the towel on the extinguisher.  Maybe I’ll run across a good cylinder in the future or find someone who can weld stainless.  But for now I’ve just put it aside.  You can’t win them all I suppose.

Posted in Repair | Leave a Comment »

Microwave Repair

Posted by davidjbod on March 9, 2013

My microwave decided to stop working last week.  Everything seemed normal but it didn’t warm anything up.  It is a GE Space Saver model JVM1631.

M1

I’ve never worked on microwaves before so I did some research on the internet and found out they’re pretty simple devices.  The Sci.Electronics.Repair FAQ has some excellent information in it and I highly suggest you check it out if you’re repairing any appliances.  Youtube also had some good videos on the topic.  I couldn’t find a schematic for my microwave but was able to find one for a JVM1450 which seems pretty similar.  I didn’t want to repost the entire picture but did hack out the important bits out which I’ve posted in the picture below.  The top is the plug that goes into the wall and receives 120VAC.  The two gaps on either side is where I’ve cut stuff out of the diagram.  In the gap, there are thermal cutouts, switches, fan motors, the control panel, etc.  All of this stuff can be ruled out though with a simple test that I’ll cover below.  The High Voltage transformer (marked H.V. Trans) bumps the line voltage up to around ~2000V.  The capacitor (marked H.V. Capacitor) stores energy during one half of  the 60Hz cycle and dumps it during the other half.   This is controlled by the High Voltage diode (marked H.V. Diode).  When the capacitor discharges, its voltage is combined with the transformers to send ~4000V-5000V to the magnetron.  The magnetron uses these high voltage pulses to generate microwaves and cook your food.   I edited the resistance and capacitance values to what I’d measured.

schematicSafety time.  Microwaves contain high voltages that will ruin your day quickly.  Be careful if you decide to work on yours.

I don’t show it in the schematic above but microwaves also contain a fuse.  The way the fuse is wired in mine, if it blew, the microwave wouldn’t do anything.  This indicates that the fuse wasn’t the problem on my microwave but I showed it here anyway.

M2

 

I mentioned above that I’d cut part of the pieces out in my schematic above.  I can do this because the functions of all the thermal cut outs and switches are to keep line voltage from reaching the transformer.  If I run the microwave and check the voltage going to the transformer I can quickly rule out everything upstream of the plug.  Shown below is the side of my microwave.  The silver box in the middle top of the picture is the magnetron.  Below it is the transformer.  The black and blue/white wires supply 120V to the transformer.  To the top left, out of the picture is where the capacitor and diode are.

M2a

 

To see if voltage is present at the transformer, disconnect the plug and test for voltage when the microwave is running.   With the transformer disconnected, there is no high voltage being generated.  If you have line voltage here everything above it in the schematic is good.  I had 120VAC here as I should.

M3

 

The next item to test is the transformer.  Transformers are simple loops of wire that are near each other.  This means you can test each loop for continuity.  If you have continuity through all the loops the transformer is probably good.  My transformer has three loops.  The loop that hooks up to the 120VAC is called the primary.  The  other two loops are secondary loops. On the schematic, the primary loop is on top and the two secondaries are on the bottom of the symbol.  The secondary winding on the left provides a low voltage to the magnetron all the time while the one on the right, combined with the capacitor, pulses the magnetron with high voltage.  With the transformer disconnected each of the loops can be checked fro continuity with a DMM.  I did this to my transformer and had continuity through each loop.  It appears the transformer is good.  Transformers are more complicated in practice and you can read more here.

The next item to test is the capacitor.  My DMM has a capacitance mode that allows me to test it.  The capacitor can shock you with high voltage if charged.  Be sure it is discharged before trying to measure it.  Disconnect the wires connected to it and test.  My DMM showed a value close to what the capacitor’s label said indicating it too was good.

M4

 

The last item I can test is the high voltage diode.  Diodes are a one way valve for electricity.  So, they pass current in one direction but not in the other.  High voltage diodes are slightly different from regular diodes.  They have a higher “cut-in” voltage.  This is the voltage that is required before the diode will pass current.  As such, a regular DMM cannot provide enough voltage to “turn-on” the diode. If you try to test it with your DMM, the diode while block current in both directions leading you to falsely think it is bad.  The diode is hiding under the capacitor and must be removed to test.

M4a

 

To test the high voltage diode requires more voltage.  A simple 9V battery can provide this voltage.  To test the diode, create a circuit loop that has a battery, resistor, DMM, and the diode in it.  The resistor adds some resistance to the circuit to reduce the current.  Set the DMM to measure voltage and then connect everything.  When the diode is functioning with current in the correct direction, the meter will read the voltage minus the “cut-in” voltage.  Shown below is the test on the diode when current is flowing in the correct direction.  If you look at the diode carefully, you’ll see a little arrow on it that indicates the direction current flows through it.

M5

 

If I reverse the direction of the diode in the circuit loop, it should not pass current.  You can see below that this is what happens.  So, this indicates that the diode is good.

M6

 

This only leaves the magnetron, which I cannot really test.  I found some instructions saying you could test both prongs in the connector for continuity and then check each prong of the connector against the casing for continuity.  It should have continuity between the two prongs but net between a prong and case.  I did this and the magnetron appeared good, but I wondered about the validity of this test.  The inside of the magnetron is evacuated (under vacuum) and if that were no longer true it would still pass the test above but not work.  To really test the magnetron correctly, requires specialized equipment I don’t own.  After thinking about it some and talking with my father, we decided it had to be the magnetron.  Everything else tested fine and I couldn’t really test it correctly.  So, my dad ordered a new magnetron and it arrived here yesterday.  In the picture below is the new (left) and old (right) magnetrons.  Note the little black thing on the front, a thermal cut out, needs to be switched as the new one doesn’t come with one.

M7

 

To remove the old magnetron requires removing four nuts and lowering the shelf the transformer sits on.  After this the magnetron can just barely be removed.  Then you swap the new one back in place and connect everything back up.  To see if it worked I grabbed a cup of water and put it in the microwave for a minute.  As you can see the microwave is working once more!  Hurray!

M7a

 

That’s the end of the section on microwave repair.  Now it is time to dig into the magnetron.  I’d noticed that there were a couple of large magnets in it and I was also curious what was inside of it.  Wikipedia has an entry on magnetrons that shows how they work and what the insides look like.  I decided to check it out for myself though.  The first thing to do is remove the metal casing off the top of it.

M8

 

I thought I’d also see what was on the bottom.  They’d crimped the cap on pretty well but the grinder took care of it.  Nothing interesting here.  I clipped the two wired that allowed me to separate the magnetron from the metal casing. With it apart I could take off the two magnets (pictured at the bottom of this post).

M9

 

Back to the top of the Magnetron.  Hmm I wonder what is in here?

M10

 

That looks like the cavities they were talking about on Wikipedia.

M11

 

A little work with a hacksaw shows the cavities.

M12

 

Anyways, here’s the two magnets I was after.  They’re stacked on a 3/4″ dowel.

M13

 

That concludes my post on microwave repair.  I’m happy to say I was never shocked while working on it and now have a couple more magnets stuck to my toolbox.

Posted in Repair | Tagged: , , | Leave a Comment »

 
Follow

Get every new post delivered to your Inbox.

Join 74 other followers