Roughing Bowls

I took some video while I was roughing out one of the bowls.  I finally got it sped up and pushed up to Youtube.  Enjoy!

 

More Bowls

My dad gave me a couple pieces of wood from some trees he had cut down out of his yard.  I roughed a couple bowls out of them this weekend.  My dad said the pinkish wood is Pear and the other is Elm.  They’re all about 10 inches in diameter and 3 to 4 inches in height.  I put them all in paper bags to dry over the next couple of months as I’ve had success with this simple method.   I don’t have much to say about them.  So, it’s on to the pics.

 

 

 

Arcadia Mill

I went to Arcadia Mill the other day.  It is a historical site of the “largest 19-th century water-powered industrial complex in Northwest Florida” according to the website.  It’s maintained by a local college.  I didn’t really know what to expect and figured there’s be some ruins of machinery or buildings.  Here’s the sign from the site to tell you some more about it.  A lot more info about the site can be found here.

 

This a drawing of the complex from the visitor’s center showing how it was laid out back in the day.  At it’s peak the site generated 900,000 ft of lumber a year which seems like quite a lot.  Pine, Juniper, and Cypress was processed here.

 

Most of the area is overgrown with trees but they have an elevated boardwalk around some of the ruins.  There’s signs to be read around the loop pointing out types of trees and what used to be there.  One of the signs indicated that we were standing right next to where the lumber mill used to be.  I looked around for a bit for anything and finally found these rocks which were the foundation of the building.  There were a couple other similar areas and that was about it.

 

Luckily, there were a few recreations.  The mill had a small animal powered railroad for moving timber and there was car and track on display.  Log flumes were also used to move the timber around the area.

 

The mill made use of a water will to run a series of saws to cut the lumber.  They had a little recreation that runs off of electricity to show how it would have worked.  Unfortunately, it wasn’t running at the time.

 

It was a pretty simple setup though.  The water wheel would have turned a shaft that was probably geared using belts and wheels which would have been connected to various machines.  Fro the saws, a crankshaft would have moved the frame holding the saw blades up and down cutting the lumber.

 

To move logs felled in the area, a carriage like the one shown below would have been used.  Chains and hooks hung from the platform between the two large wheels and were used to lift the log to move it.

Fire Extingusher

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.

 

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

 

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.

 

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

 

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.

 

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.

 

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.

 

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.

Turned Spatula

I happened upon a website called aroundthewoods.com that showed how to make a kitchen spatula on the lathe.  I thought it looked interesting and decided to give it a try.  For wood, I decided to use some Magnolia that I had sitting in the firewood pile.  I brought a wedge of wood in and ran it through the band saw a couple of times to turn it into a block.  Next, I made a couple of templates out of card stock and traced them onto the wood.  Below you can see the piece I started out with.

 

Before I can get to the lathe, I need to make a couple passes through the band saw.  The first pass cuts out the spatula as viewed from the top.  For the next pass, the spatula is flipped on its side to remove material from on top and under the blade (the flat part).  Now its off to the lathe.

 

I put the blade end into the small jaws on my chuck and held the other end with my tail stock.  Unfortunately, the only tail stock I have is a cup style so I’m not able to easily put a rounded end on the handle.  I might have to pick up a cone style tail stock soon.  I roughed the handle out with a roughing gouge and then cleaned the surface up with the skew chisel.  I’m really liking the skew.  The surface it leaves is great which means less sanding.   I then put a few grooves in it to add some detail.

 

At this point the lathe portion of the project is over and it is time for sanding.  I used a combination of belt sander, random orbit sander, and hand sanding to get the spatula smoothed out.  Here’s a picture of it after the belt sander.

 

After some random orbit and hand sanding to 320 grit here’s the final shape.

 

Now all that is left is to dab on some mineral oil.  I also made another, smaller, spatula out of some Soft Maple I had laying around.  The larger one has a 3″ wide blade and the smaller one has a 1.5″ blade.  While the Magnolia one looks more interesting I prefer the Maple one.  But I could be biased because Maple is one of my favorite woods.

Overall, this is a fun project that is finished relatively quickly.  Most of it isn’t done on the lathe but I think it still counts as a turned project.  Give it a try!

Saturn V: F-1 Engines

I started on the engines for the first stage of my wooden Saturn V.  I think I may have also figured out how to turn the fairings as well.  I’ll need to do some testing first though.

I made the engines out of the same 1-3/8″ Poplar dowel that I made the Apollo CSM out of.  So far I’ve got three of them done.  There’s diamond shaped support structure on the actual engine that I’ve added to my wooden version to add a little detail.  So far I only have three completed.

As opposed to describing what I did, I decided to record a video of making one.  I think some additional lighting would help but you can see what I’m doing.  I’ve sped it up by 15x so it’s only a couple of minutes long. I tried to keep my head out of the shot.  I make use of mostly skew chisels but a flat nosed scraper also makes an appearance.  I use a card stock template that I reference frequently in the video.  There’s also two outside calipers that I use to check the sizes of various parts.

Saturn V: Interstage Ring

I got back to working on my Saturn V model tonight.  This time I worked on the ring between the first and second stages that I’m calling the Interstage Ring.  All in all, it’s a pretty simple piece.

Here’s the picture showing where the piece is located on the real rocket.

 

As always, I start with a block of laminated pine.

 

I roughed it into a cylinder and brought it down to a slightly oversized.  I made a tenon at one end to go into the chuck.  I then used the skew chisel for some finishing passes.  It worked great and left a smooth surface.  I’m still a little apprehensive using the the skew but didn’t have any issues.

 

The ring needs to be pretty thin near the top to fit onto the second stage and the entire ring must be hollow to clear the nozzles of the second stage.  To do this required turning the part around several times on the lathe.  First, I drilled the largest hole I could using a Forstner bit to about three quarters depth of the piece.

 

Next, I hogged the inside out and focused on getting the right thickness at the end of the piece to snuggly fit the second stage.  To get the size correct, I used some calipers.

 

I cleaned up the inside a little more and then flipped the part over.  I used the Forstner bit again to drill through the piece.

 

Here’s the piece after drilling.  The inside dimension of this end isn’t critical but does need to be large enough to clear the nozzles.

 

 

I flipped the part over a final time and made some passes to clean up the inside.  After that I did some light sanding.

 

Looks like it fits pretty well.

 

Here it is in the stack with the rest of the rocket.  It doesn’t add much to the height.

 

Up next is the first stage.  I’ve been putting it off some because I’m not sure how I’m going to make the four conical fairings that are on the bottom of the stage.  They’ll have to be made as separate pieces and then glued on.  Ideally I’d like to make them out of wood.  I just haven’t figured out a way to make the inside surface of the conical pieces fit the diameter of the stage body.  If anyone has thoughts, please comment.

DVD Review: The Skew Chisel by Alan Lacer

Making my Saturn V requires making a bunch of cylinders.  The smoother the surfaces on the cylinders, the less sanding I have to do.  To this end I’ve been using my skew chisels.  They’re able to work the wood and leave a great surface that doesn’t really need sanding.  The downside to the skew is that when something goes wrong, it can really go wrong.  You can create gouges and spirals that may trash your workpiece.  Because of this, and my lack of experience with the skew, I wanted to find an instructional DVD on the skew.  After a little bit of searching I found that “The Skew Chisel” by Alan Lacer was highly recommended.   I checked SmartFlix to see if they had it and sure enough they did.  If you’ve never heard of SmarFlix, you may want to hit up their site.  They’re an online DVD rental store, much like Netflix is, but they carry instructional videos on just about everything.

The DVD is 90 minutes long and is what you’d expect out of a wood turning DVD.  There’s someone standing at a lathe narrating while doing certain things on the late.  They illustrate, effortlessly, things that don’t go so well for you.  The picture and sound quality are pretty good.  The camera work is nice and every so often you’ll be treated to an additional view in the main shot to show another perspective.  He talks about both the straight and curved edge skew during the sharpening section but only uses the curved skew on the lathe.  He covers ten different types of cut including the planing cut I’m illustrating below.  The planing cut is a finishing cut that leaves behind a smooth surface.

He also covers V cuts for starting details and then shows how to use Rolling and Coving cuts to get the shape you want.  He also covers the Saucer cut which leaves a concave surface.  Using this cut, he creates a captured ring which I haven’t yet been able to duplicate.  Below, I’m showing some of the shapes you can create using the skew and the great surface it leaves behind.

Another cut covered is the shoulder cut.  He shows how to use the chisel to cleanly cut endgrain.  Shown below on the left, is the surface left behind using a parting tool.  On the right, is the surface that is the result of a skew chisel.   The surface on the left would take a long time to clean up with sandpaper.  The more sanding I can avoid the better.

While the skew chisel cuts cleanly and leaves a great surface it can be unforgiving.  If you drop the tip into the surface or don’t support the cutting edge properly it’ll gouge a spiral on your workpiece in the or remove a big chunk blink of an eye. Shown below is the kind of damage the skew can cause.  He covers what causes these issues and how to avoid them.   He also suggests using a dead center in the headstock instead of a spur.  This way, if there is a catch, the wood will stop spinning which reduces the shock and impact of a catch.

There are also some sections on cutting pommels, the pealing cut, working with knots and twisted grain, and end scraping.  He wraps the whole video up by using a very large skew to turn an teeny tiny top.

Nothing will replace actual experience at the lathe but the DVD will greatly reduce the slope of the learning curve with the skew.  My method of watching instructional videos is to watch it once through and then come back and watch specific sections on what I’m interested in or having trouble with.  The chapters on the DVD make this easy to do.  Overall, the video is very good and worth checking out if you’re interested in learning more about the skew.

Saturn V: S-II Stage

I worked on my Saturn V replica some more.  Up next, moving down the rocket, is the S-II stage.  This stage was responsible for moving the rocket through the upper atmosphere.  At 1/112the scale this stage, from top to the bottom of the nozzles, is about 8.75″ long.  It is 3.5″ in diameter.

Here’s the NASA pic to show where this section is located on the rocket.

As before, this stage will be turned out of some laminated pieces of southern yellow pine.

I roughed it into shape with a gouge and then brought it close to the final size with a skew chisel. I put a tenon on the left (top) side of the stage to fit into the ring I made previously.

I took the stage on and off several times to make sure the fit was good with the ring.  Here’s a pic of a test fit.  Unfortunately, after additional sanding later the diameters no longer match as well.

Once I was happy with the size of the tenon and outside diameter, I started work on the nozzle end of the stage.  There’s no way I can turn the five nozzles in place.  The plan was to finish the stage off leaving an area to put the nozzles.  I used a cutoff tool to define the end of the stage and mark the depth of the bottom of the stage.

From the previous step I connected the two cuts with a flat surface and trimmed off the extra.  I really couldn’t run the stage in the lathe held like this.  Any pressure would cause the stage to start to wobble.  Holding it by hand at low speed, I was able to get the little nub trimmed off though.  Still, a steady rest would be a great aide here.

In order to give the J-2 nozzle on the end of the S-IVB stage a place to go I drilled a shallow hole into the top of the stage on the drill press.

Next, comes making the five J-2 engines.  I started with pieces of Poplar dowel I had laying around.

First, I turned the top end of the nozzle and left it a little long to fit inside the stage.

Again, I used the cutoff tool to mark the end of the nozzle and the correct diameter.  With these two locations defined, I started to create the bell shape of the nozzle.

I made a template to use on the nozzles to get them all close to the same shape.  To create the template, I printed a line drawing of the stage and then glued the nozzle drawing to a piece of hard board.  A little cutting and sanding left me with a good template.  I’d turn some and then check it against the template.  After a few iterations I had a well shaped nozzle.

After repeating the above four more times I finally had five little nozzles.  They’re close to being the same.

To give the nozzles a place to rest, I marked off points to drill using the line drawing referenced above.  Seen below, I used the drill press to drill the holes.

After some fitting, all of the nozzles were inserted to the correct height.  I need to get some thin super glue to hold them all in place.  The glue I had was too thick to wick into the joint.

Finally, here’s all the pieces together. 

Microwave Repair

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.

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.

Safety 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.

 

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.

 

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.

 

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.

 

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.

 

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.

 

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.

 

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.

 

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!

 

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.

 

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).

 

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

 

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

 

A little work with a hacksaw shows the cavities.

 

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

 

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.