Why Every Tenth One? Tank Baffle Countersinking

Tank Baffle Countersinks--why do the plans recommend leaving every tenth hole un-countersunk until after sealing?

I know the plans say that the purpose is to improve alignment during baffle installation, but I can't wrap my head around why alignment would be difficult, nor in what way having some holes un-countersunk would help.

Can someone help me out of my confusion?

Please note that I have considered dimpling and decided to just go ahead with the countersinking and already have a few done, so that ship has sailed.

Possibly due to likelihood of dimples/countersinking engarging the holes? More likely in a dimple situation.

I think the reason is to ensure the baffle is seated properly all the way down the rivet line. CSKing enlarges the holes allowing for some lateral play with the clecos. By leaving a few holes unCSKed, you eliminate that issue. That's my guess anyway.

Auburntsts said:

I think the reason is to ensure the baffle is seated properly all the way down the rivet line. CSKing enlarges the holes allowing for some lateral play with the clecos. By leaving a few holes unCSKed, you eliminate that issue. That's my guess anyway.

Click to expand...

OK, I think this makes sense to me: to prevent the baffle from being shifted due to the enlarged countersunk holes.

I was seriously considering not doing the "skip every tenth" thing, but once again I see the wisdom in the plans.

Thanks!

I was taught, (and teach in my sheet metal seminars) by men who'd learned their trade in the WW-II factories in So Cal that if you're matching parts, you drill holes with a 1/8" or .125 drill, at, for example, opposite corners and use -4 rivets as locators.

mjb