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Drilling pushrod woes ..

bkervaski

Hellloooooooo!
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I'm down to installing pushrods into my wings and then I get to close them up, take them to the hangar, and final assembly!

This weekend, drilling pushrods and subsequently getting a rivet in them straight proved to be quite a challenge.

Here is a pic of my .. ahem .. practice piece. I can't keep the bits from roaming from one side to the other. I've tried short and tall bits and have tried scoring the location with a punch, etc. No luck, every other attempt to drill wonders off to one side or the other.

There has to be a better way to drill these things .. hoping I'm missing something simple.

I have the press set to its lowest rpm.

Any advice appreciated!

ouP.jpg
 
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One thing I have found is to use a bit that is as short as possible, and insert it fully into the chuck ... that looks like a 12” bit, and those things will wander all over, especially in #30 and #40...
 
One thing I have found is to use a bit that is as short as possible, and insert it fully into the chuck ... that looks like a 12? bit, and those things will wander all over, especially in #30 and #40...

Yep, I tried the short bits too.

You can get a usable set from Harbor Freight; fine for drilling aluminum.

These rods are steel .. but I don't mind tearing a couple bits up if I can get them drilled properly.
 
I just take my hand drill and very carefully drill a #40 pilot hole on one side. Then put it in the jig and drill it through to the other side with the drill press. It's always worked for me.
 
Yep, I tried the short bits too.



These rods are steel .. but I don't mind tearing a couple bits up if I can get them drilled properly.

I've used mine on steel quite a few times without noticeable issues. Don't expect them to last like hi-$ stuff, but you're not going to use something like this for production work.
 
V-block

I center punch. Then use a tiny bit like #50 to drill a hole and move up incrementally. Tiny bit is less likely to wander from a punch mark. A V-block helps but not necessary.
 
I just take my hand drill and very carefully drill a #40 pilot hole on one side. Then put it in the jig and drill it through to the other side with the drill press. It's always worked for me.

Plus 1 for this method. All you need is a small pilot hole and light pressure on your drill press, throttle the arm of your drill press.

If this is the aileron push rod, the more challenging part is the riveting part. Go really slow with the rivet squeezer or better yet use your vice on the table (if you have one) to get the rivet set and then the rivet squeezer to finish it.
 
You could try this

http://www.aircraftspruce.com/catalog/topages/drillrite.php

although I seem to recall that the advice here, all taken together, was all I needed...short bit fully stuffed up into the arbor, start small, go VERY slowly, and make sure your workpiece is firmly clamped so it doesn't move. It's key to get the desired location dead nuts under the bit *and* at the very top of the tube...any off-to-the-side positioning will start the bit wandering.
 
I just take my hand drill and very carefully drill a #40 pilot hole on one side. Then put it in the jig and drill it through to the other side with the drill press. It's always worked for me.

Yep, and look through the end to visually align through the center, the curve will do the rest.

It is the location on the opposite side that makes it a diametrical hole.
 
gave up on rivets

I gave up on the rivets and welded mine. For my 9, the rivets touched the rear spar at the extreme ends of travel and I didn't like that. YMMV
 
Drilling hole in round tube

Might try a "center drill" into punch mark to get hole started. Or I often use a small end cutting end mill instead of drill bit.

Set up will need to be as rigid as possible for the milling cutter and with a slow feed rate into material. Not something you can "hand hold."

A milling machine is preferred, but small end cutters will work in a drill press as long as there isn't much play in the spindle.

Can probably get the above bits at a local machine tool supply store (if you have one in your area) or Amazon or MSC on line.
 
I would use this: https://youtu.be/n7HLfHZlKL4

Instead of clamping, firmly duck tape the v guide to the tube and use a hand drill. I used that on the tip-up release mechanism tubes and those are even smaller diameter than the aileron push rids. .
 
I got them done by carefully drilling a tiny pilot hole with a hand drill and then using the drill press to finish. The fully drilled through pilot hole was enough to keep everything on track.

I like the welding idea lol :D :D
 
Center drills work wonders for stuff like this. And don't buy the cheap China crappy ones!
 
Holes on tube

I have had luck drilling holes on tube by filing a flat into it first, then center punch the flat, and drill. Just keep the flat area smaller then the hole so that when you upsize the hole, the flat disappears.
 
If you are still having trouble drilling those i have two suggestions you can try
Make sure the v block is in exactly the right place by putting the drill bit down all the way to verify it is touching the center of the v to insure it is perpendicular.
Also, You can make a saddle out of a piece of scrap tubing with a drilled hole in it. Place the saddle on the tube with the hole over the spot you want to drill and it will keep your bit from wandering. You can clamp the saddle on or make it big enough to just hold it in place till you get the bit started
 
I got mine drilled using a pilot hole instead of a punch .. but keep the suggestions coming this is all great stuff!!!
 
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