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Archive for the ‘Repair’ Category

Making a T-Bolt for the Hendey Lathe

Posted by davidjbod on December 6, 2014

In the process of grinding the jaws on my lathe, I tightened down one of the compound bolts…but it never got tight.  Hmm.  I looked at it carefully and noticed the nut and stud were both turning.  Not good.  I disassembled the compound and found one of the T bolts had broken.  I pulled the bolts out and found one had sheared apart.  It turns out that this wasn’t an original bolt.  Someone had made it by welding a stud to a small plate.

HT1

As you can imagine, I need a replacement T bolt and you can’t just pick up a replacement part.  Luckily, Gill offered the use of his lovely Monarch 10EE to make a new one.  I ordered some 1″ 1144 steel to make the bolt and headed down to his house once the steel had arrived.  I cut off a piece to use and mounted it to the lathe to being work which first involved facing the piece.

HT2

The T bolt uses a 7/16″ – 14 tpi thread.  To cut the thread on the new bolt the diameter of the piece was brought down to the major diameter of the thread.  behind the section to be threaded, the bolt was brought down to the minor diameter so that the tool would have a place to stop after making a pass to cut the threads.  Without this area, the cutter would cut a V shaped groove into the part when the carriage stopped moving.

HT3

Cutting the threads required making several passes advancing the compound each time.  After demoing how it worked, Gill turned the threading operation over to me.  After a small error at the beginning of the first pass, cutting the threads went well.  In the picture below you can see the results of the threading operation.  In this pic, I’m about to reduce the diameter of the T, which explains the cutter.

HT4

Once I was happy with the part, it was parted off and rechucked to clean up the opposite side of the T bolt.

HT5

Here’s a pic of the new bolt fresh off the lathe compared to the original T bolt.  The original T bolt has a kidney bean shaped head.  So, there’s a little more work to do.

HT6

To shape the head, I painted the bottom of the bolt, held both bolts back to back, and scribed the correct shape on my new bolt.  I set to work using a file to shape the bolt after putting it in my vise with Aluminum jaws in place.  I used couple coarse files to remove most of the material and then finished the edges with some smooth files.

HT7

Here’s the final part compared to the original.

HT8

With the new bolt in place, it’s time to make chips again.  I’ve added a green arrow to show where the bolt goes.  They’re loosened and tightened to rotate the compound.

HT9

Making the T bolt I learned a couple things.  First, 1144 steel machines very nicely on Gill’s lathe with carbide and on mine with HSS.  I even got a good surface finish with a regular cutting tool profile.  Second,  you have to be quick when threading. Threading involves the carriage moving pretty quickly.  When the tool exits the area you’re threading you’ve got to disengage the carriage feed before the tool hit the work piece.  Third, quick change tool posts are wonderful.  Being able to just drop the tool in place and go without setting the height is great.  Finally,  Gill’s lathe is very nice.  Well, that last one was just reaffirmed.

 

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Hendey Finishing Touches: Jaw Grinding

Posted by davidjbod on November 28, 2014

I decided to address another problem with my Hendey lathe.  This time I turned my attention to my three jaw chuck.  My chuck had two issues I wanted to address.  The first is that it would not hold a part perfectly centered which is known as runout.  Runout is measured by holding a ground bar in the chuck and placing a dial indicator to measure the surface.  The spindle is turned through a complete revolution and the maximum and minimum values noted.  The difference of these values is the runout.  It’s easier to set the dial indicator to zero at the low point and then find the high spot.  I measured 0.008″ runout with a 1.25″ diameter ground rod.

JG2

The second issue with the chuck was that the jaws were wider at the front of the chuck than the back.  I’ve seen this referred to as being “bell mouthed”.  This is easy to see because you can see light between the part and the jaws.  To illustrate this I’ve slipped a 0.006″ feeler gauge between one of the jaws and the part.  It goes in about 0.25″ and thinner gauges went in further.

JG1

To fix these problems the jaws are ground on the lathe.  As there is slack in the jaws, they must be forced outward to take out this slack.  I used a method I came across on Home Metal Shop Club‘s website.  The author of the article suggested using shims to push the jaws apart as opposed to the more commonly seen ring.  Using my friend Gill’s Bridgeport, I made a set of 1.25″ shims.  In the picture below, you can see I’ve also marked the jaw faces with Dykem to monitor progress on the jaws.

JG3

Professional machine shops and well equipped hobbyists use tool post grinder for grinding the jaws.  It is setup to be mounted in the tool post to easily attach it to the lathe.  I lack such a tool and instead used the arrangement you see in the picture below.  It’s a pneumatic die grinder that I’ve “attached” to the tool post.  Though it looks rather shoddy it held the grinder tightly enough for what needed to be done.

JG4

I don’t have any pictures of the actual grinding because I wanted to focus on that.  First, I covered my lathe as best I could to keep out grinding dust.  Grinding is done with both the lathe and grinder spinning.  I ran my lathe at ~100 rpm during grinding after trying several slower speeds first.  To start the actual grinding, I advanced the grinding wheel to the back of the jaw until it contacted to locate my zero.  I dialed out 0.002″ with the cross slide and slowly moved the grinder out with the feed wheel.  From here I kept advancing the grinder out and making passes checking my progress frequently.  At first I was only contacting one jaw but eventually all three were being ground.  As expected, in the beginning the area ground was in the back of the jaws.  As work progressed the ground area moved outward.  Once I was happy with the results, I moved the grinder in, dialed out another thousandth, and made a pass out of the jaws.  I figured that this would impart a slight taper into the jaws which would be wider at the back since the grinding stone wears as the pass is made.

Seen below is a picture of the results.  Note that my shims now have a concave edge on them.  Before I started grinding I noticed they would get hit first by the grinder.  I pulled them off and ground them on my bench grinder.  The jaws all showed an evenly ground area everywhere except at the very tips.  The tips were banged up and I didn’t want to remove the material required to get the last little bit ground.

JG5

While I was set up for grinding, I figured I’d touch up the front face of my jaws.  As you can see below, the front faces of my jaws near the middle are a little dinged up.

JG6

I made passes with the grinder taking a couple thousandths off each time until most of the front face was cleaned up.

JG7

Once I was done grinding, I wiped all the surfaces of the lathe down to remove any grinding dust.  I also removed my chuck, disassembled it, and gave it a cleaning as well.  I put it back on the lathe and proceeded to take another measurement of the runout to see if there was improvement.  I was rewarded with a runout a small bit over 0.003″.  I’ve seen this runout specified on some new chucks.  So, I was pleased with my results.

JG9

The “bell mouth” was also gone.  I couldn’t see any light between the chuck jaws and the part.

JG8

If you’re wondering why I don’t have zero runout, there are a few reasons.  The first is that inside of the chuck is a large scroll which also wears some over time during operation.  The jaws ride different portions of the scroll depending on how wide open the jaws are.  Thus, the area the jaws were pressed against on the scroll when I ground the jaws is not the same as when the jaws are at some other position.  Since the scroll has probably worn unevenly, even if my jaws were perfectly ground in one position you can’t say that they would be perfect in another position.  This also means, that my ~0.003″ runout measurement is only at that one diameter.  I measured runout with a ground 0.25″ rod and had less than 0.001″ runout.  Another reason would be my grinding set up.

I’m happy with the improvements I’ve seen in my chuck.  I’m not sure how old the chuck is but I imagine it is quite old.  I’m glad to keep running it with the lathe.  Even if my runout had not decreased the removal of the “bell mouthing” will result in a better grip on the work piece.  I’m hoping this will translate into an easier time parting off on the lathe.

Unfortunately, while tightening down one of the locking nuts on the compound, I broke one of the T bolts.  It looks like someone had fabricated it from a stud by welding a piece of steel on top of it.  So, I will be fabricating a replacement T bolt in a future post.  For that, I’ll be taking a field trip to Gill’s.

 

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Jack Repair

Posted by davidjbod on November 15, 2014

I was doing some automotive work last weekend when the release mechanism on my jack broke.  I had jacked the car up and placed jack stands under it.  When I went to lower the jack, which requires twisting the handle, there was a little bit of resistance and then the handle spun freely.  Hmm, not good.  I used another jack to free my broke jack and was able to get the car safely back on jack stands.  I inspected my jack and found that the universal joint had broken.  My jack is an aluminum Craftsman jack and they felt like saving an ounce by making the U joint out of aluminum as well.  This doesn’t seem like the best decision in my mind.  Anyways, seen below is my broken universal joint.  The square end on the left fits inside of the jack handle and rotates the valve on the right side of the pic.  The U joint has two pins of different sizes and the body piece that the larger pin went through broke.  I looked online but Craftsman didn’t offer a replacement part that didn’t involve buying the cylinder.  Guess I’ll make a replacement part.

JR1

To start I chucked up a piece of 3/4″ steel rod into the lathe to drill a hole through it.  Before drilling, I used a center point to start the hole.

JR2

Next, I drilled to an appropriate depth with the lathe.

JR3

I cleaned up the surface with a few light cuts to eliminate the mill scale.  The original part was 3/4″ diameter.  So, my part will be a little smaller but made of a stronger material.

JR4

Here’s my piece once I’d parted it off the lathe.

JR5

From this point, making the part will require drilling three holes through the part.  Two holes are for pins and the other hole is to remove a large amount of material to form the U.  I used my height gauge (Thanks Gill!) and some Dykem to scribe the location of the holes.  I also used a small machinist square to scribe a vertical line to align the two pin holes.  Finally, I lightly punched the hole locations to keep my drill bit from wandering.

JR6

Here’s the point I’d use a mill…if I had one.  Since I don’t, it was off to the drill press that did a good job.  I oriented the part as best I could under the drill bit and proceeded to drill the two pin holes.  JR7

I rotated the pin 90 degrees and drilled out what would be the bottom of the U shape.  After drilling I noticed that this hole wasn’t exactly 90 deg from the two pin holes.  This was unfortunate, but not bad enough to trash the piece.

JR8

I held the piece in the vise and used a hack saw to remove the material between the large drilled hole and the end.  Then, I used a file to round over the edges and clean up the inside of the part so that the cross journal block would fit.

JR9

I dressed the ends of the pins I’d removed and then reassembled the universal joint with my arbor press.  Once I was satisfied with how everything fit I peened the ends of the pins to keep them in place.

JR10

I reinstalled the part back into the jack, bled it, and gave it a couple test releases.  Success!

JR11

Now back to putting the transmission back in the car.

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Hendey Finishing Touches: Part 1

Posted by davidjbod on November 10, 2014

As expected, as I’ve been using my lathe, I’ve run into some issues.  The first issue I mentioned in my last post.  During drilling with the tail stock, the spindle would seize in the conical bearings.  My Hendey employs two conical bearings for the spindle to run on.  The face of the front bearing runs against a spacer that presses against a flange on the spindle.  Over time this spacer and the bearings will wear.  As a result the spindle can contact the bearings instead of riding on a cushion of oil.  Shims can be added to the spacer (or a new spacer made) to maintain the correct spacing between the bearing and spindle.  Thanks to the folks at Practical Machinist I knew why I was having this issue and expected to run into it.

The first thing I had to do was get the back plate off the threaded nose of the spindle.  To do this I removed the chuck from the adapter plate.  The adapter plate is held on with three screws with recessed hexes.  Unfortunately, the screws had somehow been damaged to the point where I couldn’t remove them with a hex key.  I ended up drilling out the heads enough to where I could remove them with a screw extractor.

H140

With the adapter plate removed, I had access to the back plate.  Though I’d tried to get this off before, I was able to finally.  After seeing the idea in a post on Practical Machinist, I wedged a tapered piece of wood under the bull gear to immobilize the spindle.  Then, with a piece of mild steel and a hammer, I struck the shoulder of the cut outs on the back plate.  After a hand full of moderate blows the back plate broke loose and I breathed a sigh of relief.

H141

Here’s the nose of the spindle.  It looks to be in great shape.

H142

From posts on Practical Machinist, I was able to determine what size shim for the spindle was required.  The method to determine the proper spacing first requires you to remove the spindle, wipe the oil from the spindle and bearings.  Then, remove the stock spacer and reinsert the spindle using firm hand pressure to seat it.  Next, measure the spacing between the front of the bearing and the inside of the spindle’s flange.  For my lathe the space was 0.129″.

H143

Next, you need to measure your spacer, as I’m doing in the picture below, and subtract this from the gap size. Then add about 0.006″.  I say about because there was a small range I saw discussed and this was in the middle.   The 0.006″ provides the correct spacing for the bearings.  Doing the math says I needed a 0.011″ shim.

H144

I ordered some 0.012″ shim stock from McMaster and went to visit my friend Gill to cut it out on his Bridgeport.  Try as we might, we were not successful.  In the end, I picked up a piece of 0.01″ thick brass locally which we were able to successfully cut.  I didn’t get a picture of the shim because my camera was dead but you can see it installed in the picture below.  Brass will probably wear faster than if I’d used steel but I think it will last a long while under the light use it’ll see from me.

H145

Once I had the shim taken care of, I reinstalled the chuck.  To replace the screws I had to drill out, I bought some from the store and then turned the heads down to fit on Gill’s superb Monarch lathe.

Next up, is the issue of the rear bearing leaking oil profusely.  As the machine is running oil is picked up by a ring and carried onto the spindle.  It then runs out both ends of the bearing into a flanged section of the bearing and then back into the reservoir via a small hole.  As you can see below, a piece of the flange was broken before I got the machine which lets the oil leak out.

H146

To take this back to factory would require making a new bearing which is something I’d like to avoid right now.  Instead, I cut a piece of flashing and formed it to the shape required.  It is held in place with a metal band clamp.  The back side of the flashing was covered with a thin coating of RTV sealant before putting it on to keep it from leaking at the edges.

H147

With the guards back in place the bandage on the rear bearing doesn’t stand out that much.

H148

The last thing I did was to replace the key in the tail stock.  The original one had been worn and allowed the tail stock spindle to rotate slightly under load.  This key fit tightly into the tail stock and took some filing to fit correctly.

H149

Once the lathe was back together, I tried drilling steel with a 1/2″ drill bit like I’d done previously.  This time the drilling went well and produced some nice chips.  Yay!

H150

Now I can get back to making stuff on the lathe.

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Hendey Assembly: Part 5

Posted by davidjbod on October 15, 2014

In my previous post on the lathe, I’d reached the point where the lathe was running.  I still had a few more things to do though.  When I’d started on the lathe I set the tail stock aside since it is pretty much a separate item.  It came apart easily as it was covered in gunk like the rest of the lathe.

H130

I ran all the parts through the parts washer and then hit them with a wire wheel/cup.  The parts were cleaned and then painted.   I hit all of the shiny parts with a buffing wheel and they cleaned up nicely.  I reassembled the tail stock and noticed that the spindle didn’t move in and out easily.  I removed the main screw and mounted it between centers on my woodworking lathe.  Using a dial indicated I determined that there was about 0.03″ run out on the shaft.  To fix this, I took the screw over to my arbor press and straightened it.  After one iteration the screw showed 0.005″ of run out which allowed the tail stock spindle to move freely.

H131

Here it is back on the lathe.  Luckily, the tail stock spindle has a #3 Morse taper instead of the hybrid Morse-Hendey taper I feared it might have.  The #3 Morse taper is a standard size and arbors can easily be purchased today.H132

I removed the motor and the motor mount I fabbed up.  I added a simple metal electrical box to cover the cord to motor wire connection.  I then used double sided tape to hold the box in place in case I decide to remove it later.   I also painted the motor mount black to match the rest of the lathe.

H133

While I had the motor off I replaced the motor pulley.  The old motor pulley is poorly made and allowed the belt to slip excessively.  I replaced it with the gray pulley which works much better.  Shown below, are both pulleys for comparison.  I removed the old pulley before reinstalling the motor.

H134

With the combination of V belt pulleys, the countershaft turns at 266 rpm.  After taking measurements of the cone pulley diameters I should have spindle speeds of approximately 93, 193, 368, and 761 rpm.   I measured the actual spindle rpm unloaded at 97, 193, 351, and 678 rpm.  There seems to be a little slippage on the upper two speed values.  I’m not sure what it slipping but I’d place my money on the V belt.  Additional tension may solve this but I think the slippage can be attributed to the combination of really large and small pulleys.  The belt doesn’t get a lot of contact with the small pulley since the wrap angle is small.

The first project I completed on my lathe was to turn some plugs for the two spindle oil holes in the head stock.  I patterned my replacement plugs after the original ones on Chris’ lathe.  They have a ball on top which flares out to a rim and then reduces to a cylinder.  You can see them in the picture below the front and back tie bar contact points.

H135

Here’s a few pictures of the finished lathe.

H136 H137 H138

Overall, I feel the lathe works pretty well.  There’s some backlash in the movements but that’s probably not surprising given that the lathe is around 100 years old.  The nuts for the cross slide and compound are brass and I imagine they have worn instead of the screws.  As such, I could probably make new nuts in the future.  I may also make new half nuts as the threads show a lot of wear as well.  There’s also some tightening in the cross slide as I move it in and out due to wear but so far it isn’t problematic.  One of the gears on the side of the late is made of brass and seems a little loose on its shaft.  When running it tends to make a ringing noise.  At some point, I’d like to bore this gear out some and make a new shaft for it to run up.

Here are a couple videos of the lathe in operation. In the first video, I’m taking a light cut on some hot rolled 3/4″ steel. I’m also showing the automatic stop feature.

In this video I’m taking a little heavier cut.

 

 

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Hendey Assembly: Part 3

Posted by davidjbod on September 21, 2014

After weekends of traveling and retrieving Chris’ lathe, I was finally able to get back to working on my own lathe.  While I was visiting my parents, my dad and I took a trip over to a friend of his who owns Goode Machine Works.  They were able to fix the motor support arm that was cracked.  I also got a tour of the facility where I was able to drool over the numerous cool machines they have!  A 400 ton shear is an impressive machine.  Here’s a couple pics of their handiwork.  Best I can tell they heated it up and used Nickel rod to make the repair.

H100 H101

I proceeded to grind down the welds and prime the arm in preparation of painting it.  I left the serial on it so someone can be confused about it like I am in the future.

H102

The chain drive “tank” took a trip through the parts washer and was then painted as well.  On my machine, it only supports one end of the countershaft as it had been gutted previously.

H103

The support arm, bracket, and tensioning mechanism received the same treatment.  They were hung to dry on my fancy drying rack.

H104

When the lathe fell, the lid on top of the chain drive “tank” took damage.   A chunk popped out of the side and the lid was cracked from there, through the hole, and almost to the other edge.  I decided to see if I could weld it up.  I’m happy to say it turned out successfully!  Since the lid is cast iron, which is tricky to weld, I was concerned.  I ground the crack out with a carbide burr and then welded it with some Nomacast rods since I didn’t need to do any machining on it.  I ran short beads and peened them with a needle scaler while it was cooling as I’d read to do online.  I don’t think anyone would mistake it for the work of a skilled welder, but after a little filler I don’t think anyone will notice.

H105

I turned my attention to the counter shaft which held the upper cone pulley.  Once I got it apart, I discovered that the pulley shown in the center of the picture below is wooden.  There were also several broken screws and a drill bit in it for some reason.

H106

This is the other half of the cone pulley.  As expected it is cast iron.  For several reasons, I don’t think this is the factory setup on the lathe.

H107

I reattached the arm and brush painted it in place.  It was simpler than trying to hang it some place and spray it.  The cylindrical bar at the top of the arm is actually backwards in this pic.

H108

I turned the bar around and started adding parts back on.  The folks at Goode said that it wasn’t worth fixing the broken motor mount given how badly it was broken.  I also realized that it was broken and missing some parts before I got the lathe.  I’m going to fab something up to support the motor later on.

H109

I used the wood lathe to clean up the upper cone pulley.  This section has a fair amount scoring and the smaller pulley shown below has an odd wear pattern on it.

H110

 

Here’s the wooden pulley.  It also has some scoring but cleaned up well.  I re-profiled it a little bit to put a slight hump in the middle of the pulley.

 

H111

I’m currently waiting on paint to dry on some parts but it is definitely getting closer to running.

 

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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.

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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!

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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!

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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

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