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Hank.... Search for broaching tool. Best be sitting when you see the cost. Maybe a square file would be better. Drill round hole, clean out corners with file.
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Mike Wood
Montgomery, TX
'46 BC12D
N44085 #9885
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Unfortunately it is a blind hole with only a small center hole for the screw. Couldn't use a file (my first choice, a LOT less expensive than a broaching tool!!! I ended up using a tiny chisel and being VERY careful not to punch through or crack the part. I shouldn't have worried. The resin was a LOT stronger than I thought when I started. I had to clean up some other parts and they are real blade dullers! I think if I do another one the square balsa insert is a great idea.
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You might also be able to find a piece of square aluminum or brass tubing. Fill the ID with wax, cast the piece, the melt the wax. Instant lined hole with very little work.Comment
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Lathe and rotary broach, mount on faceplate, make in aluminum if you want, hey Hank when you get your gingerly foundry going, let me know!N29787
'41 BC12-65Comment
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Never used a Gingerly foundry but when I was at University of Kansas a buddy and I built a charcoal fired foundry and made lots of castings with our secret alloy called "Pistalloy". We made all kinds of things and lots of guys wanted to know what our secret alloy was that worked so well. I will let the secret out now. We were getting old VW pistons at the salvage yard and melting them down. Made really nice castings for everything from car parts to small metal trinkets. We also did a lot of lead soldier castings. Weren't happy with the detail from straight pours so we built a centrifugal caster and a second story drop caster. Imagine what a spinning mold holder will do as hot lead is slung into it with no way to maintain balance of the spinning parts. Yep, made a real mess with molten lead slinging all over the garage barn, but NOTHING like the time the drop cast mold blew apart! When it worked the detail in the castings was BEAUTIFUL, but when the mold box failed there was liquid metal flying everywhere. We were lucky we were up top doing the pour and not down with the mold. Got it all cleaned up before his dad ever saw the mess. Gas was easier to use than charcoal and we didn't need that much heat for the lead.
I thought it was really stupid when KU ended their foundry program. Engineering schools have been ending classes on things like machine tool use, foundries and welding and increasing the math and science classes. Good engineers should be able to DO what they specify,at least at a beginners level. Most new graduates have no idea how what they specify is done. It is a huge loss.Comment
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Are the original inserts and glove box doors wood or metal with wood veneer?Comment
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Metal, but I don't think it was a veneer. I'm pretty sure it was painted or printed.Comment
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All were hand painted in Faux finish. I had never done it before and the photos are of my first attempt at Faux finishing. Get a piece of metal and he Faux finish materials from an art store and just give it a try (NOT on your plane for your first time like I did.) I did it on my planes' panel because I had made my panel myself and didn't feel any personal threat I would be ruining an irreplaceable antique part. Since I made it I knew I could strip it back to bare metal and do it again. If is NOT hard, it is NOT skill. It is just patience. I got a really nice piece of wood I liked the grain pattern in (like I would have made he doors and insert from if they were really wood) and copied the grain. I used a few techniques from a Home Depot free class but a few feathers and some wadded paper made for some realistic grain. What i had NO luck with was the curved wood graining tools they sell. All I could get with that was a mess. Grab a chunk of sheet metal and give it a try.Comment
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I bet they at least used some kind of roller for the grain pattern. Yes, one off pieces can be done by hand. I have done it before with descent results. I learned from an expert car restorer.Comment
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I have seen some really nice graining done with the curved grain tool but it isn't a roller. It has a raised pattern in the curved surface that you drag acro0ss the surface and you rock the applicator back and forth. The Home Depot lady who did the class was pretty good at it but I could never get the technique down and just did it by hand. I even used an old paint dried brush on the edges to simulate end grain on the doors by stippling the paint with the stiff bristles. Looked just like end grain. I guess it is really whatever works. Different people will be drawn to different techniques. The thing is to not be afraid of it. just get teh materials, watch a couple of videos and jump in. You really can't hurt the part. When it is wet the coatings will just wipe right off if you mess up.
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Hank
that is impressive, very very realistic. is the dimpling at the guages original or an added touch? i really like it. the one i have does not have the dimpling, only flat metal, maybe mine is an old reproduction? i will be checking with max and dave wenglarz to see about the glove box door
thanksComment
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Face book is doing it's normal thing. When I type my text first it puts in the photos randomly in different places around the text. Hope it works this time. The left photo is of what the mag switch marking were in 1941. the RH photo is my first shot at a lever and face of the switch that would be behind the insert. I have the graphics corrected now but need to get them engraved and move the Grimes Mag switch in the sub panel so teh lever can turn through the hole smoothly. The printing on the right is for a POST war mag switch and has L and R instead of MAG 1 and MAG 2. I will get there yet. The later stock A-7 with the works removes and replaced with a Grimes Mag switch is a bit easier. I will post photos when I get it working reliably. The later replacement version should be able to be directly replace an A-7 with a keyed lever and look just like original.
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Just a few of the parts I have been working on. That is the post war A-7 back plate in the middle and one of the levers on a mold top right. The door handle came out GREAT (right before Jim brought me an original!)and the inside lever will be sent off next week (the one that was such a BUGGER to cut the square hole in). That is a Cabin Heat knob I made and will be casting more of them with a BIG project coming to make wheel pant mounts with a welded steel core and replica exterior to make them look just like original cast ones but they won't have the cracking problem of stock ones. That is an original glove box handle and it was "interesting" making a copy and bending it straight as the resin cured so I could make a second mold that produced STRAIGHT handles!
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Hank,
Do you ever think about making a number of these hard-to-get parts and selling them to T-craft owners? Or, is it just not worth the trouble? I would buy all the knobs if they were available.Comment
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Problem right now is I had my own company a couple years ago and if I sell things the IRS wants me to file as a business. I trade a LOT for parts and give some away. I know a LOT of guys would like a set of matching knobs and am trying to figure out how to do it. When I start making welded aileron hinges I think we will HAVE TO get something working. I can't think of a single thing more important than getting corroded cast aileron hardware OFF of our planes and replaced with welded ones! We are eventually going to have a failure and the FAA will step in and require taking them all off for inspection. I have a box full of cast fittings that are cracked or corroded. I'm good. Both of my planes already have welded hinges and bell crank supports. I just hope when the next one fails someone doesn't loose control and get killed. It will make the wing strut mess look like a walk in the park. CHECK YOUR AILERON HARDWARE!!!!
Sorry to preach.Comment
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