Tank skin countersinks...

I was just reading a thread about the 'tank dimple dies' and how they are deeper to allow for the proseal under the rivet.

So I'm wondering if I should countersink the holes in the skin (for the baffle) a little deeper than normal to allow for proseal under the rivet?

I already have them countersunk, but it wouldn't be difficult to go back over them with the countersinker set a click or two deeper.

Thoughts??

I used the regular dimple dies, did not countersink anything (except what was called for, I believe the rear baffle) and mine came out fine, and lots of proseal.. no leaks.. lots of pics in my picasa site of the tank building.

my view is it would not help sealing

Mark,

If I am not mistaken (not looking at the prints) the countersink rivet line you are referring to is not really a sealing area. The rear baffle to tank skin proseal fillet that you will apply around the perimeter of the baffle is the key to sealing the rear of the tank.

The rivet line that you are referring to does secure the baffle but these rivets do not go through the proseal fillet around the baffle. It's different than the tank skin to rib rivet line interface.

If you Counterink these rivets deeper, you will have to contend with a rivet head "minus" situation on the finish of your wings. If you get too crazy with the C/S cutter it will be a weaker joint.

hopefully the rivets you are referring to never see fuel. well, unless you are clumsy like me and spill it all over the wing during refilling once in a while....

s10sakota said:

I was just reading a thread about the 'tank dimple dies' and how they are deeper to allow for the proseal under the rivet.
So I'm wondering if I should countersink the holes in the skin (for the baffle) a little deeper than normal to allow for proseal under the rivet?

Click to expand...

No, you should not.

Put more proseal

Off topic but tank baffle related anyway Mark put more "black death" along that rear baffle. In the corners Vans manual specifically mentions. Two of my top corner rivets are "breathing".

Thanks that all makes sense. How much proseal should I order from Van's to complete two tanks?

s10sakota said:

Thanks that all makes sense. How much proseal should I order from Van's to complete two tanks?

Click to expand...

Opinions and experience vary, but I ordered one can. It did both tanks leak-free and I still had some left over. I didn't use it sparingly, just as neatly as I could so I wouldn't waste much. Don't mix up too much at a time and you'll throw less of it away. Van's instructions have you mix up way too much, if you follow them exactly.

Another thing to keep in mind is that it has a shelf life. You can always order more later if you need to. If you run out and need to order more, you'll get a fresh batch the second time.

I used 1.5 qts on two 30 gallon tanks. I sealed under rib flanges, both sides of ribs got a fillet, all shop heads and all rivets were dipped. Anywhere I could seal I did. I went over all prosealed areas with buna-n from ACS. Pressure tested to 1 psi with electronic manometer. No leaks after 80 hrs and no paint blisters. For the little extra weight and cost, I would not skimp.

If you use the tank dimple dies, just simple a piece of scrap and countersink accordingly.
As for the pro-seal, I would recommend a quart kit for each tank and remember to keep it in the fridge when not using it. You can always get one quart kit and do a tank and figure out how much you used and then order another if you need it.