Deburring between sheets?

DCat22 · #1 10-08-2010, 02:02 PM

So, apologies again if I failed to find the answer during a search.

When working on my "control surface" practice kit, I came across an area to debur I wasn't sure how to accomplish.

You rivet the ribs to the spar in an earlier step, and then later cleco the skins to the skeleton and match drill. This creates brand new holes in the spar.

The problem is the very front hole in the rip is already sandwiched under the spar (and riveted on), but now there is a bur between it and the spar. Seemed like too small of an area to use a "chip chaser" type arrangement too, but I could be wrong as I don't yet have one to test. (And there is a notable bur there pushing the metal apart.)

I figured I could just make a "mini chip chaser" out of scrap aluminum... but was curious what the proper/usual solution might be, by all those that have come before me?

Thanks!

LuisR · #2 10-08-2010, 02:34 PM

Any chance in posting a picture?

flion · #3 10-08-2010, 02:45 PM

There are two general ways of handling this. First is to take the instructions as a guideline and hold off riveting until all the parts are drilled. Then you can deburr completely before riveting. However, that is not always possible (I've run into areas where the skeleton cannot be held together with clecos and still allow a skin to be drilled), so you just have to drill the mated parts. In many cases, those parts will be held together with 'keeper' rivets (the 'J' stringers in my -6A have a rivet offset at each bulkhead to hold the skeleton together). The final holes through the skin were treated as if the bulkhead/stringer were a single part and any slight burr between the stringer and the bulkhead was crushed flat by the riveting process. Of course, this is easier when the parts are held tightly together, such as with the keeper rivets. If you have to drill through multiple thicknesses, use sharp bits and little pressure; don't force your way through the material. Drilling undersize and finishing with a reamer may also help.

DCat22 · #4 10-08-2010, 03:10 PM

Manny, I'll grab a pic tonight.

Quote:

Originally Posted by flion

There are two general ways of handling this. First is to take the instructions as a guideline and hold off riveting until all the parts are drilled. Then you can deburr completely before riveting. However, that is not always possible (I've run into areas where the skeleton cannot be held together with clecos and still allow a skin to be drilled), so you just have to drill the mated parts. In many cases, those parts will be held together with 'keeper' rivets (the 'J' stringers in my -6A have a rivet offset at each bulkhead to hold the skeleton together). The final holes through the skin were treated as if the bulkhead/stringer were a single part and any slight burr between the stringer and the bulkhead was crushed flat by the riveting process. Of course, this is easier when the parts are held tightly together, such as with the keeper rivets. If you have to drill through multiple thicknesses, use sharp bits and little pressure; don't force your way through the material. Drilling undersize and finishing with a reamer may also help.

Thank Patrick...that makes sense. And a side clamp keeping the metal firmly together would have indeed probably helped...didn't think of that ahead of time. That little flange is off on its own, so to speak, so probably separated quite a bit when drilling.

This little training kit does manage to expose you to quite a variety of work.

scard · #5 10-08-2010, 04:06 PM

Believe it or not, I built about 1/3 of the little airfoil training kit, learned a lot. I ended up stomping it into the trash can for fear that anyone would see it. Ended up building a pretty nice airplane.
Oh, and you should take the question mark off of the sig: "RV-7 ...TW Tipper?"

DCat22 · #6 10-08-2010, 04:18 PM

Quote:

Originally Posted by scard

Oh, and you should take the question mark off of the sig: "RV-7 ...TW Tipper?"

....done!

smiller · #7 10-09-2010, 06:49 AM

This WW-II era video, a little over 2 minutes in, says it's not necessary to disassemble for deburring if the parts are clamped tight together when drilled. I don't know if that advice has changed from a scientific standpoint since then or not. As you can see from the video, not much else has changed! I could be made to believe that two parts clamped firmly together when drilled become "one in tune with the other" vs. "one poking the other or having high stress focal points." So deburring just the top of the top piece and bottom of the bottom piece might be all that's really needed? At least it was good enough to win the war!

http://www.youtube.com/watch?v=5DVPG8go4Jk

rapid_ascent · #8 10-09-2010, 09:50 PM

Rick,

I went with the mickey mouse solution. I clampled those together with my cleco clamp. I think in general as long as they are clampled you shouldn't get much of a burr. On mine that part of the rib is a separate tab. After you drill you can remove the clamp, bend it down slightly, sand lightly and bend back.

By the way my first practice kit would never fly.It will go into the recycle bin at some point.

I got an EAA kit as the second kit. I primed the EAA kit just to see how much work it was. Not too bad. All in all it looks pretty good.

I think I'll try one more Vans Practice kit before the real deal.

Good luck.

Ray

Ray