drilling aileron counterweight

prkaye · #1 08-02-2007, 04:52 PM

I've had a lot of problems trying to drill the holes for the aileron LE skin to the aileron counterweight pipe. First I tried drilling through both simultaneously. The holes in the pipe came out OK, but hte holes in the sking became severely elongated. Then I tried adding some new holes in the skin, marking and using a center-punch to mark the holes in the pipe. Then I tried drilling the holes in the water pipe separately. When I put it back together I found the holes in the water pipe didn't line-up with the holes in the skin. I think the drill bit keeps slipping on the surface of the pipe getting hte holes out of position.
Even using my drill press, the drill bit itself flexes causing the hole to move.
Any suggestions?? I've already written-off at least one aileron LE skin.

Mel · #2 08-02-2007, 04:55 PM

The pipes have to be "punched" pretty good. It takes several punches. Then use a VERY sharp and small drill to drill first. Then enlarge to final size.

prkaye · #3 08-02-2007, 05:14 PM

small drill? how small? is my black and decker cordless small enough?
I thought of cutting the bit shorter to prevent it from flexing.

Question - the plan say to drill these holes (LE skin through water pipe) while the whole thing is assembled and weighted down. It seems to me it would be better to drill these holes with it disassembled, so I could clamp the water pipe into the drill press. What do you guys think?

Mel · #4 08-02-2007, 05:34 PM

Quote:

Originally Posted by prkaye

small drill? how small?

.040 or smaller.

prkaye · #5 08-02-2007, 07:05 PM

.04? so you're talking about the drill bit size? i don't udnerstand... the holes have to be drilled #30 for the blind rivets...

Brockster · #6 08-02-2007, 07:30 PM

Cleco the aileron together and weight it down. Use a fine point sharpie pen and trace each hole. Disassemble and as Mel said put a heavy center punch directly in the middle of the traced hole. Drill by hand using slow speed with #40 drill making absolutely sure you stay within the confines of the traced hole. When all the holes are drilled with #40 reassemble and weight aileron. Use 40 size clecos to hold temporarly. Now use #32 drill to drill through skin and counter weight and install #30 size clecos. When done, go back and final size to #30. Maybe overkill but it worked. That counterweight material is pretty tough.

prkaye · #7 08-02-2007, 08:32 PM

Should i use a cutting oil when doing this? Is Kerosene good for that?

WSBuilder · #8 08-03-2007, 07:30 AM

[quote=prkaye]small drill? how small? is my black and decker cordless small enough?
QUOTE]
That was funny.

I'm told the CW on the -9 is stainless, which is hard stuff. The best way to drill IMO is to mark or center punch the hole site then use a small CENTER DRILL in your drillpress. A center drill (GOOGLE them) is a short, beefy, hole-starting drill bit (more like an end mill). They are extremely tough and won't wobble or drift. They come as a set usually and are indispensible. Make sure to put your pipe in a drill press vise and clamp the vise to the drill press table. For hard steel like stainless, use slower RPM's, say 400, good pressure and cutting oil. Almost anything other than good Canadian beer is better than nothing, but kerosene is fine. The center drill has a cutting tip and then increases in diameter with another cutting step. Just use the small tip to start your hole, about 1/8" deep, then use your first small-size drill bit. Make sure you set your table height such that you can go from the center drill to your longest drill bit without moving the table so that you keep the hole/drill press alignment. Cobalt tipped drillbits, rather than cheapy high speed steel, will last longer and can stand higher heat.
Hope this helps.

prkaye · #9 08-03-2007, 07:54 AM

Do you have any recommendations on where I can get one of these center drills? They don't come up in searches at any of the main aircraft tool suppliers online...

WSBuilder · #10 08-03-2007, 08:52 AM

Quote:

Originally Posted by prkaye

Do you have any recommendations on where I can get one of these center drills? They don't come up in searches at any of the main aircraft tool suppliers online...

Anyplace that has machining tools. Here's one with a good picture.
http://www.littlemachineshop.com/pro...ProductID=1230