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Help drilling hole

Av8torTom

Well Known Member
Hey all,

Well, I have my 9A center section all assembled and I realized I forgot to enlarge the tooling holes in the ribs to 5/8" (bottom rib in illustration below). Too tight to get a regular drill in there now. I have a 90deg angle drill but it takes threaded bits. Does anyone know where/if I can get a 5/8" threaded bit? Also a 5/8 chassis knockout punch would work but I can't find one that small. Any other thoughts?

Thanks,

Tom

 
Maybe one of these??

image_11761.jpg
 
Threaded bit

My set has a threaded check that screws into the right angle adapter. Unfortunately it won't hold a step drill bit but I'll bet you could buy a HF step drill and grind down the shank till it fit in one. Just an idea. YMMV.
 
Weld ?

A friend welded the step drill on to a threaded portion for the 90degree drill. Comes in handy later for conduit also.
 
need a threaded bit

Thanks all - a stubby unibit would be great, but I need it to have a threaded end to attach to the drill since it doesn't have a chuck.

Keep the ideas coming... :D
 
Step drills, very similar to the ones Mike posted above, are available pretty cheaply at Harbor Freight. They have 1/4" hex shanks.

http://www.harborfreight.com/3-piece-titanium-nitride-coated-high-speed-steel-step-drills-91616.html

Also pick one of these up from your local Lowes:

http://www.lowes.com/pd_143440-54602-RW9273_0__?productId=3654042

I used this setup a lot in my build.

Kurt, what sort of chuck does that Lowes drill have? Looks like it also takes threaded bits
 
My angle drill has a small chuck adapter. I got a cheap Harbor Freight step drill and had to grind down the end to fit.

IMG_2044-M.jpg


I ended up drilling these tooling holes out, but I don't think I used any of them for wiring. The brackets that hold the control stick interfere with this location. You are better off drilling holes farther back and down low near the bottom skin (eg, near the "F" in the F-916 on the drawing picture).

See this photo for the location.
IMG_3753-M.jpg
 
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I might suggest a flexible drive shaft and the step drill bits. Of course a step drill bit and a socket and drive will work if you only have one hole to drill.

Don
 
Kurt, what sort of chuck does that Lowes drill have? Looks like it also takes threaded bits

The Lowes right angle drill has a 1/4" hex chuck. Fits perfectly with the 1/4" hex shank step drills that HF sells. It will not accept threaded bits.

From the product description on the Lowes link above:
"Accepts standard 1/4 inch hex shank bits"

Actually the one I bought at Lowes is red. Exactly like this one:
http://www.amazon.com/Milescraft-1302-Drilling-Attachment-Magnetic/dp/B000KICSGQ
 
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Drilling hole

I remember a previous post here on VAF showing a 1/4-28 threaded piloted countersink bit with a 5/8" dia body being used in conjunction with a 90 degree drill motor or adapter to create the hole. I have not tried this technique. Piloted countersink bits with 5/8" dia bodies do exist.
 
I bought a bunch of different sized threaded bits from, IIRC, McMaster-Carr (I think). Be advised that you definitely need to back up the part with a block of wood, something about the larger sized bits plus the 90 degree angle makes it want to "grab" and twist, deforming the hole/part. And definitely, definitely start smaller and work your way up in drill size.

Just FYI.
 
... Also a 5/8 chassis knockout punch would work but I can't find one that small. Any other thoughts? ...

A Greenlee socket punch for a 7-pin miniature tube socket makes a 5/8" hole. That's what I used. Perhaps an nearby older ham (who remembers the vacuum tube days) has one. I would ask at a ham club meeting.

--
Joe
 
Rotobroach?

Check Avery catalog. I don't know how long old posts are saved, but I may have posted years ago when I drilled those holes in a QB wing. I threaded a metal rod and used a jam nut to lock the rotobroach. The rod was 36" long so I was able to drill through every rib.

Larry Tompkins
544WB -6A
W52 Battle Ground WA
 
Do you really need/want the snap bushing there?

I built a 7A and put the snap bushings in, but never needed/wanted to run wire there.

I put holes in a different locations in the rib when I was wiring the plane. These new locations made better sense for my wiring layout.

I would wait until your in your wiring phase and you might not want or need to put holes there.

Food for thought
 
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