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Countersinking E-606 and E607

chris mitchell

Well Known Member
Well, we had a great session last night and made huge progress, but tonight depression has set in again. I have to countersink the upper edges of the E-606 and E-607 trim tab spars to suit the dimples in the upper surfaces of the elevator and trim-tab. Experiments on a discarded section of spar that "a friend gave me" suggest that it is very difficult to do the countersinking without having the countersink go all the way throughthe material and begin to enlarge the hole. What have I not understood, got wrog etc anddoes it matter if thee holes get oversized because the hinge strip will be acting as a doubler? BA (building assistant) says its fine, "build on" but it doesn't seem right to me.

Thanks

Chris
 
IIRC, your right, the hole will be enlarged becase the material is so thin. Its not a problem, as you pointed out, because it is sandwitched between the skin and hinge. The issue to be carefull with is when you countersink them, they need to remain centered around the original hole. As soon as the hole that the pilot is riding in is cut away, the countersink can start cutting to the side. Your countersinks will no longer line up with the dimples if this happens. My solution was to clamp a strip of wood under the holes, drill the hole into the wood, so now your countersink has a pilot hole to ride in.
 
Its been a while, but to prevent this and other holes from drifting as the hole gets enlarged, I took a scrap of .125 and drilled a #40 on one end and a #30 on the other. I use it to back up countersinking to prevent the drifting.
 
Very useful advice, thanks. I drilled through into a piece of wood, cleco the ends in place and then did the counersinking. THe holes got a little enlarged but when its all sandwiched up everythihg is fine.

I was sopleased with this that I went on and completed the trim tab, bends and all, first go. Much happier to night!! :) :) :)

Chris
 
I'm not looking at the diagram but from what you've said it sounds like you could cleco to the hinge strip and countersink both pieces at the same time (so that the hinge strip ends up slightly countersunk and perfenctly matched to the layer above). My understanding is that when there is a sandwiched piece that is on the thin side for countersinking that this is a preferred method of construction.

Yes, No, thoughts :confused:
 
I realise I'm resurrecting an old topic, probably for a stupid question. I had scrapped an E-606 due to the enlarging issues mentioned above. But I ordered a new one and have successfully countersunk the holes that match to the hinge.

My question is what to do with the four outer holes that are not matched to a hinge. The instructions say to countersink, I'd you read them literally. But I think they can be dimpled.

Thoughts?
 
Slow and steady wins the race.

One thing that helps delicate countersinks is to ditch the high speed air drill, and carefully use your cordless drill. Go slowly. It's not a race. With a receiving hold behind the material being countersunk and a slow drill, it's much easier.
 
I realise I'm resurrecting an old topic, probably for a stupid question. I had scrapped an E-606 due to the enlarging issues mentioned above. But I ordered a new one and have successfully countersunk the holes that match to the hinge.

My question is what to do with the four outer holes that are not matched to a hinge. The instructions say to countersink, I'd you read them literally. But I think they can be dimpled.

Thoughts?

That's what I did. I dimpled the ones where the E-606 meet the elevator skin and only countersunk the ones associated with the hinge.
 
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If I may, anytime dimpling on any skins throughout build, do not match drill at final size,i.e. #30/#40 etc. until after dimpling. Use 2 size drill bits smaller if needed before dimpling and then drill hole to final size. This will help not to enlarge hole and keep rivets from tipping when being bucked.
A bit off topic of aligning countersunk and dimpled holes. But I feel along same topic of improving bucked rivet result.
 
The dimpling process naturally stretches out the hole. You just would prefer it stretch out a slightly undersized hole into a perfect #30/40 dimpled hole that a rivet snugly fits into vs a slightly oversized dimpled hole that a rivet fits loosely into.
If that makes sense.
 
The dimpling process naturally stretches out the hole. You just would prefer it stretch out a slightly undersized hole into a perfect #30/40 dimpled hole that a rivet snugly fits into vs a slightly oversized dimpled hole that a rivet fits loosely into.
If that makes sense.

I see what you're getting at but what size dimple dies are you using in these cases?? #42 instead of a #40 for example??

I don't even recall what size the holes come pre-punched at.
 
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