Tuesday, January 10, 2017

Wire Dispenser for Wrapping Cable Splices

 I wanted a way to hold the loose coil of 22 gauge wire while wrapping the splice so that I didn't need to cut a piece of wire and risk getting my eyeball scratched again.  The end of a piece of safety wire got around my safety glasses when I was in the Air Force.  I still have a scratch.  I wanted a spool but couldn't figure out how to wind it.  I also liked the packaging of the 20 gauge wire with it's slit on the side to dispense the wire as the coil spins inside.  I figured I could duplicate their idea.

 At the hardware store I bought a 2" PVC cap and a 1/2" coupler.   The coupler has a ledge in the middle so you don't push either pipe in too far.  This made a perfect ledge to set some washers on for a nut on the bolt to hold the coupler in the middle of the cap.  This post helps keep the coil from getting tangled.
 I want the wire to feed out at the edge of the cap so I ground off the raised lettering with the belt sander.  Spin it on the table while holding it lightly against the belt.

 This all leaves a nice square edge.  A few turns of the de-burring tool put a smooth radius on the inside, wire feed, corner.

 A 1/4" diameter hole was located in the center of the cap.

 Some guide lines helped for filing a nice square hole to pocket the carriage bolt which hold everything together.  The carriage bolt assures The cover nut is easy to get off and makes it all a little smoother in the hand.

 You can see how the washers and nut work to hold the center post in place.  I started with a short bolt so I can grind the post to length.  We need a gap of no more than the thickness of the wire.

 I used a thin ruler to use as a thickness gauge drawing a guide line for grinding.

Hold the cap on the table of the belt sander while gently rolling the cap and grinding down the post.  This keeps the top end parallel to the edge of the cap so the cover will have an even gap for the wire.

 I used a hole saw to gently cut out a cover.  The hole saw has a 1/4" drill in the center which is why I used a 1/4" bolt.

To clean up the edge I held the cover on the table with a piece of 1/4" rod and spun it to keep it nice and round.  A little clean up on the edge with a file removed the last burrs and left a smooth edge.

 You need to make sure you have the end where they started winding on the inside and the end where they finished winding coming out the gap under the cover.

I'll look for a nice knob to replace the nut to make loading even easier.  It fits my hand perfectly.

Time to wind some more splices.

Monday, January 9, 2017

Improved Thumb Wheel for the Cable Splicing Clamp

After using the Splicing Clamp to make about 10 cables, for my Fly Baby, I decided I needed to stop and make a larger, easier to grip, tightening wheel.  I originally made the wheel from the same 1/4" x 1" bar stock used for some of the parts.  It seemed clever and would work fine with flexible cable.  With the non-flexible 1x19 cable it was just too hard to get the cable tightened against the thimble.  You could do it but it took a lot of wiggling the cable while turning the wheel.

I decided I needed a wheel closer to 2" in diameter with nice big knurls for a good grip.  I also wanted to keep it 1/4" thick to have a reasonable number of threads.  If it wears out I may need to make one from 3/8" thick steel.
 The only piece of 1/4" steel I had was on some tools for making wire ferrules for the WACO internal bracing wires.  I decided it would be fine with a 2" hole in the base since I just clamp the base to my work bench.

I located a pilot hole for the 2" hole saw then used the saw to draw a centerline to layout a pattern of holes for the knurls.  It certainly took the guesswork out of where the center of the holes should be.

 I center punched a pattern of 12 holes, pilot drilled them with a 3/16" drill and finished them with a 5/16" drill.

 To round the edges of the holes, it makes more comfortable knurls, I countersunk the holes with a 1/2" center drill, steeper flutes.  Then I lightly countersunk then with a 1/2" twist drill.  It really makes a nicely rounded edge to the holes.

 Back to the 2" hole saw to cut out the wheel. I cut half way from each side and when it got close just pounded it out with a light hammer blow.  I didn't want to risk this 1/4" slug flying around.

It's looking like a thumb wheel.

 I cleaned up the outside radius with the belt sander and the chamfered the edge at 2 angles, sort of like with the hole edges.

 The remaining burs were cleaned up with the small sanding drum on the Dremel tool.  It needs to feel good in your hand and no sharp edges.
 The hole was tapped with a 3/8" fine thread to spin on the center bolt.
I had a little trouble getting the 3 bolts apart since I had put Loctite on the threads and cut off the head of the 3/8" both after tightening it in the clamping bar.  A little heat took care of the Loctite.  I greased the threads and the pivot with Molykote to keep the friction low.

I'm ready to make some more cables.  Much nicer wheel.

I'll go back and add this to the original posting.

Saturday, January 7, 2017

First Wire Wrapped and Soldered Bracing Cable Terminal

 All of the external bracing cables on the wings and tail of my WACO were made from 1x19 galvanized wire rope (cable).  At some point in 1927 they changed to the more expensive, solid, streamlined wires as used on the WACO TEN and later WACO planes.  The ends of the non-flexible cables were formed using the Wire Wrapped and Soldered Cable Splice.

 Today we use either a fitting swaged to the end of the cable or a Nicopress sleeve to form the splice.  I plan to use the original wrapped and soldered method for all the bracing cables.  Flexible control cable used a woven method like is used for the ends of ropes.  I'll get to those later.

On our Fly Baby we made all the 1x19 bracing cables ends using Nicopress sleeves.  The problem is it leaves one end sticking out to snag skin, clothes, or anything else that gets close. The Nicopress sleeve makes a splice which has the full strength of the ecable.  The wire wrapped terminal only has 90% of the strength of the cable so I couldn't use it on the Fly Baby without a lot of engineering work.

To give the Fly Baby that old time look I decided to make the loose end of the cable (sticking out of the sleeve) a little longer and wrap it with wire to look like a wrapped splice.  This would also let me practice doing the winding and soldering in a way that would not risk cable failure while learning how to make the cables for the WACO.  I also used a zinc plated sleeve so it would be less obvious what I had done.

I found some 22 gauge galvanized wire at the last real hardware store in Charlottesville.  They had packs of 100 feet so I bought the three they had.  It takes about 5 feet per splice.  I had previously bought 20 gauge wire.  The WACO Drawing Room Manual (D.R.M) page II-4 Shows 0.035" (20 gauge) wire for 1/8" cable as does WACO drawing 3800, per the Army-Navy Standard.  The D.R.M references WACO Spec. No. 25513 which I do not have.  I'll need to find a copy of it.  The cables on my WACO clearly use 0.025" (22 gauge) wire as shown in CAM 18 which is what I will use unless I can find proof the heavier wire makes a stronger joint.

For the Fly Baby I installed the Nicopress sleeve, trimmed the loose end of the cable at the point where it would have been for a wrapped splice, and then wrapped it with the 22 gauge serving wire.
 I have a soldering pot I made but I did the soldering with just my big iron and it came out great.  I was able to use the soldering iron to get right up to the Nicopress sleeve without making a mess on the sleeve.

 Since my earlier post, I've learned there is an easy cheap source of rosin.  Dancers use it to dust their shoes.  They sell it in quantities up to 50 pound buckets.  I ordered a pound of it, about $20, to make a new batch of flux.  I believe the old batch got overheated and does not work as well.  In the future I will only re-heat with a double boiler well below boiling to avoid damaging the flux.  This batch works so much better.
 This rosin is a mix of chunks and powder.  The dancers use it as a powder to coat the bottom of their shoes.  For our purposes it doesn't matter since we're melting it.  I like seeing it as chunks so I'm more confident I'm really using rosin.

 I cut some of the candle shaped tallow into chunks to help melt it.  I'm making a mix with 40% tallow (stearic acid) so I've measured out 4 ounces of tallow.

This time I was very careful to heat it slowly to avoid any chance of damaging it with heat.  I set the hot plate at it's lowest setting and let it heat very slowly.  Again, in the future only re-heat with a double boiler.

The tallow was fully melted at about 170 degrees F.

 Once it was melted I added 6 ounces (60%) of rosin, stirred it in, and let it slowly melt.

It was a gooey mess as it slowly heated and melted.  This took about an hour.

As it got to 200 degrees the rosin was fully melted.

The old batch had turned a very brown color.  This batch looks like you would expect with the yellow resin and white tallow mixed.  I made application sticks as with the old batch and did some soldering.  This batch is like magic.  I'm discarding the old batch.  The new flows faster and only takes one application of flux.

I made my first wire wrapped terminal to tryout the process.  I'll write up a detailed explanation of the process once I've had some more practice.  I soldered the Fly Baby terminals with the soldering iron to keep solder off the Nicopress sleeve.  I dipped this whole terminal in the solder pot.  The one thing I noticed doing that was that it is hard to get the gap under the wire wrap to stay full of hot solder.  It all wants to run out because everything is so hot.  With the soldering iron you can control the heat a little better.  We'll see what works best with some practice.  CAM 18 requires the gap under the wrap wire be filled with solder.  CAM 18 also prefers you to use a solder pot.  One of the old text books I have prefers you use a soldering iron, go figure.