90 degree drill adapters

niblettda · #1 02-21-2010, 02:30 PM

So I brought a nice new 90 degree drill adapter to work on my fuselage. I got most of the holes without an issue, I started with the smallest bit and worked my way up every few sizes until I got to final size. Seemed reasonable to me, maybe I shouldn't have done it that way, but I didn't want to put too much stress on the fine tooth gears in the drill.

On my last hole, I stripped out the gears. I don't think I was going to fast, trying to take out too much material, etc. A few other builder friends said it's common.

What I would like to know is
a) Is one 90 degree adapter better than another? (Economy, Avery tools, Brown tools, etc). I bring up Avery and Brown because Avery seems to have a very different head design than Brown, which is more common among other sites.)

b) Should I just a few economy and accept that I shall destroy them?

c) What's the best technique to drill with one of these things and not end up destroying the gears.

Thankfully I don't need to drill many holes with this thing, but it might best to learn how to do it right with the next one I buy.

TIA

lrfrey · #2 02-21-2010, 02:41 PM

David I can't really answer your question, I guess it just depends.

I have an economy angle drill adapter from Avery and I built my entire 7A with it, still works OK. I must admit, that whenever possible I used a 12 inch drill bit instead, I got better results that way. I always had trouble with the angle drill giving me elongated holes or walking off center.

For what it's worth starting with a small drill and enlarging as you said is the best way. Don't apply too much pressure let the drill do it's job, it's slow but works OK

Larry

jsharkey · #3 02-21-2010, 03:43 PM

With thin sheet especially I noticed that on break through the drill bit can stall on the "barbs" formed before it breaks through cleanly. Feeling that this is about to happen I pull back and "peck" at the hole with a high rpm. It seems to work and keeps the torque down.

As for walking with the 90 deg attachment you need to hold the body of the attachment very rigidly otherwise the torque from the drill wants to rotate it and move the drill bit sideways. It's because the body of the attachment isn't connected to the body of the drill - although regular right angle drills want to do this too but you tend to naturally hold them more rigidly.

Jim Sharkey
RV-6 Phase 1

Mel · #4 02-21-2010, 05:02 PM

I have probably one of the cheapest 90 degree adapters available and it's been through a lot of years building, rebuilding, and repairing. If you are having trouble with the drill "grabbing" as it goes through, maybe you are using too much pressure. For aluminum and other soft metals you should use high speed and low pressure.

niblettda · #5 02-21-2010, 05:40 PM

Thanks for all the tips. I'll grab another cheap adapter version and attempt to refine my technique some more. I tried to use as little pressure as possible, but I did tend to run into having the bit grab right as it tries to exit the hole. I'm working on the fuel tank attach brackets and with all the build up of material, the bit always seems to want to grab that last sheet of aluminum upon exit.

Sometimes tools are the price of education.

flion · #6 02-21-2010, 07:40 PM

You might want to disassemble your adapter, too, and see if you really stripped the gears. The one I got from Avery (don't have the make/model in front of me right now) has a shear pin inside. Turned out I had stripped the shear pin and when I disassembled it the gear dropped right off the shaft into my hand. An email to the company resulted in a package of 10 or so being mailed to me, gratis.

JanRV6UK · #7 02-22-2010, 04:52 AM

buy a second hand angle drill on ebay ....

az_gila · #8 02-22-2010, 10:14 AM

...and the failure mode looked like the gears stripping - but it was actually looseness in the plastic that held the two gears. The bevel gears just got out of mesh under load, and not really fixable

If I were to buy another one, I would make sure that the structure that holds the two bevel gears is metal and not plastic.

However, like Jan said, I managed to find 3 right angle drills on E-Bay for about $100, thinking I could at least make one whole one.

All three were quite useable...

-- and since they are a major US brand, spare parts are available if needed in the future.

Added

This is the cheap one with the plastic housing for the bevel gears...

Noah · #9 02-22-2010, 10:23 AM

I have one of the "Economy" angle drill adapters. Every time I use it, instead of thinking "Wow, I saved $80 buying this tool", I lament "What a waste of money this tool was". It is so sloppy and the quality of the holes it produces are marginal. I usually buy tools to last a long time, and this was an exception. Spend the extra $80 and get the ball bearing version.

If thats too much money then plan to sell it when you finish your plane. You probably wouldn't even be able to sell the economy model, but I would think there would be plenty of buyers for the well made version.

flytoboat · #10 02-22-2010, 10:55 AM

Quote:

Originally Posted by JanRV6UK

buy a second hand angle drill on ebay ....

An angle drill is very handy and can be sold easily after the project is completed. I lucked out and found a small Souix angle drill with a very nice teasing trigger in a pawn shop for $29.00. I had already purchased a used DOTCO on here for $100.00 but re-sold it here in 5 hours for the same amount.