I've read several posts on the topic of countersinking (or dimpling) the tank skins at the baffle. The debate has to do with being able to seal it properly if you've got all those pesky dimples where the baffle needs to slide in. Based on my own experience and what I've read, I'd much rather dimple than countersink these holes. And I've read that dimpling has been done successfully. What I'd like to know, however, is if anyone has dimpled these holes on their RV10 tanks and then succesfully got them sealed?
Van's Air Force
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tank/baffle countersink or dimple?
- Thread starter jwilbur
- Start date
rleffler
Well Known Member
Just get the tank dimple dies. They are slightly deeper than the standard dimple.
Already got 'em. Did you dimple the aft line of rivets on your tank and baffle? Did you have any real trouble getting the baffle in and sealed?
I countersunk
like the plans said. I fought with the baffle the entire install trying to maintain alignment. If others have dimpled successfully, that is what I would do. The holes become essentially self aligning with dimples.
If you countersink you might think about touching up each hole in the baffle after you countersink the skin and baffle in assembly. The skin is .032 so the counter sink will take the skin to a knife edge condition. If you countersink the skin a few thousands deep for the proseal you will in theory be into the baffle a few thousands if the clecos have the assembly completely tight.
My baffle rivets wanted to sit a little proud. I'm not sure whether it was alignment or the rivets bottoming out on the baffle. I'm thinking touching up the baffle holes with a countersink will give the rivet a little more real estate.
like the plans said. I fought with the baffle the entire install trying to maintain alignment. If others have dimpled successfully, that is what I would do. The holes become essentially self aligning with dimples.
If you countersink you might think about touching up each hole in the baffle after you countersink the skin and baffle in assembly. The skin is .032 so the counter sink will take the skin to a knife edge condition. If you countersink the skin a few thousands deep for the proseal you will in theory be into the baffle a few thousands if the clecos have the assembly completely tight.
My baffle rivets wanted to sit a little proud. I'm not sure whether it was alignment or the rivets bottoming out on the baffle. I'm thinking touching up the baffle holes with a countersink will give the rivet a little more real estate.
Wayne Gillispie
Well Known Member
Followed plans
And used almost 1 can of proseal per tank. Lots in that area. 30+ hrs and no leaks.
And used almost 1 can of proseal per tank. Lots in that area. 30+ hrs and no leaks.
rleffler
Well Known Member
I don't recall the details. I followed the plans.
Like Wayne mentioned, use ample proseal.
Dimpled successfully
Just a followup here. I have successfully finished my tanks and have no leaks. I dimpled the rear baffle and the associated skin-to-baffle rivet holes. The plans call for countersinking. I opted to dimple. I had NO trouble whatsoever sealing. I Just layed down a bead of proseal along the bottom of each hole and slid the baffle down. The alignment was trivial. In fact, I worried about this task for the entire process and in the end it turned out to be about the easiest thing of the entire tank job.
Given the issues others have described with alignment and countersinking, I highly recommend dimpling the baffle.
Build log entry:
http://airplane.athomeinthewilburness.com/2012/08/02/rear-baffles/
Just a followup here. I have successfully finished my tanks and have no leaks. I dimpled the rear baffle and the associated skin-to-baffle rivet holes. The plans call for countersinking. I opted to dimple. I had NO trouble whatsoever sealing. I Just layed down a bead of proseal along the bottom of each hole and slid the baffle down. The alignment was trivial. In fact, I worried about this task for the entire process and in the end it turned out to be about the easiest thing of the entire tank job.
Given the issues others have described with alignment and countersinking, I highly recommend dimpling the baffle.
Build log entry:
http://airplane.athomeinthewilburness.com/2012/08/02/rear-baffles/
My recommendation would be to use caution. I believe (but might be wrong) that standard diameter dimple dies will crash in the bend radius of the baffle.
An alternate method (which I think has been written into some of the build manuals, it will be in the RV-14 manual), is to leave every 10th or so hole un-countersunk. This will help assure good alignment when the baffle is final installed. After installing rivets in all of the countersunk holes, you can countersink and rivet the remainder.
sstellarv10
Well Known Member
I countersunk with no issues but I made a slight mistake which in hindsight solved any kind of alignment problem. I dimpled one hole on each side( like I said by mistake
) and it accually helped me align them easily when it came to sliding the baffle between the skins.
) and it accually helped me align them easily when it came to sliding the baffle between the skins.This is an excellent point. I used small diameter dimple dies to dimple the baffle. They prevent the issue you describe. Or you could grind a standard dimple die to fit. Here's a link.
http://www.cleavelandtool.com/prodinfo.asp?number=DIE4263S
CharlieWaffles
Well Known Member
I dimpled without any problems and the baffle slid in very easily. I was surprised that Van's would even recommend countersinking as it's not as tight as they would lead you to believe. Definitely easy to dimple.
The recommendation of machine countersinking, is not because it would be too tight to insert the baffle between the skins.
AltonD
Well Known Member
I counter sunk mine, If I ever build another one, they will be dimpled with a normal dimple die. I will and did use the tank dimple dies on the rest of the skins.
ppilotmike
Well Known Member
What's the reason then...?
I countersunk like the plans say, leaving every 10th hole alone so that it can aid in aligning the baffle. Why is countersinking (vs. dimpling) called for exactly?
I countersunk like the plans say, leaving every 10th hole alone so that it can aid in aligning the baffle. Why is countersinking (vs. dimpling) called for exactly?
CharlieWaffles
Well Known Member
Current thinking is that Vans thought if you dimpled the holes the rear baffle would be too difficult to move into place. But there is enough flex that it's easy enough to slide the baffle in.
Actually the reason (partially), is to make sure the skin doesn't have to flex when the baffle is being inserted. The sealing of the baffle is entirely dependent on a pre-applied bead being wiped on the skin by the corner of the baffle as it inserts. The goal is to leave this area as smooth as possible, to give builders as big of a chance of success as possible.
Maybe some builders with rear baffle leaks, never make the association of them dimpling the baffle, to a factor in their leak???
Side comment....
Many builders over compensate with tank sealant during the baffle install to help assure a good seal. This often cause another problem.
To minimize water entrapment in each rib bay, the intent is that the seal bead along the corner of the baffle, not be so large that it fully closes up the bottom aft corner of the rib. If it does, you will likely be trapping water in the tank that can not be drained during preflight.
ppilotmike
Well Known Member
Thanks Scott. I actually found that countersinking wasn't too bad when you have it all clecoed together in the cradle. Helps to have a sharp countersink bit and nice holes to prevent chatter.
