Dimple Info

[Anitech]

Hi,

I have been on here for quite a while but seldom post. I am at the dimple stage of the VS and have a few questions for the experienced ones here...

1. I have a DRDT2 and want to know how to set the dimple depth. I know its suppose to be flush with the skin but I have read so many posts I am not sure if there is an objective way to set it or is it all subjective and when it looks right you will know it. Any suggestions would be welcome...

2. Relative to #1 above, using the pneumatic squeezer for the rib dimples again how do you know its deep enough but not over dimpled?

3. I have also read about a pneumatic squeezer that can be attached to the DRT2 frame. Does anyone have experience with it and is it still available?

Thanks in advance....
Steve

 

[paul330]

Basically, the "depth" is set by the die - it's not possible to over-dimple so to speak. It is, however, possible to under-dimple if you don't use enough pressure (or whacking effort if you use a C-frame).

In my experience, you only have to worry about using too much pressure if you are dimpling a very thin skin where you can end up with a bit of a ripple. The only other thing to worry about is making sure you get it square.

I suggest you practice on some scrap. The rivet should sit nicely in the dimple just below flush.

 

[rzbill]

As Paul said, you can't over dimple but you can under dimple.

Set the DRDT2 such that the overcenter toggle does go overcenter on the closing stroke. It should do so with enough force to spread the throat of the DRDT2. That is what builds the "spring" pressure to form the dimple. It should "pop" when the linkage goes in and out of the down locked position.

Put a rivet in the finished dimple and feel it for flushness. Adjust the ram up or down, make a few dimples and you should quickly learn the "spot" to set it. Set it for minimum force required to fully form the dimple. Again, it should pop but not overly so. During my build I don't think I ever tightened the adjustment nut with anything other than my fingers. That allowed easy adjustment for different dies and sheet gages.

 

[Dan Langhout]

DRDT-2 and squeezer

In my experience, I set the DRDT-2 up with one full turn of preload. Basically, with the handle all the way down (and no metal in between), turn the adjustment screw by hand until the two die halves touch (where you can't turn it by hand any more). Then raise the handle and turn the adjustment screw one additional turn. Tighten the lock nut and you are ready to go.

I use a similar technique to set a preload on my pneumatic squeezer when using it for dimpling - although with the squeezer I only use about 1/4 turn of preload.

I have never had any problem with "over dimpling". The DRDT-2 will definitely "under dimple" if you don't set it up with some preload though.

My experience and advice - worth what you paid for it!

 

[BillL]

The dimple nesting is not perfect and there are dimple dies for the underlying rib dimple that are dimensionally different. I am not recommending them, but certainly make a test piece with skin thickness with a dimple and test against all the ribs to see that you don't have a little rocking. I did not know this for a long time and found recently the need to pay attention to this detail.

If the underlying (your rib dimple) is not adequate, I just take a deburring tool and make a couple to three rounds (depending on force) to ensure a good nest.

Happy riveting.

 

[maniago]

For 426 3 series rivets, you can get what are called "tank dies" and "substructure dies" for nesting from Cleaveland Tool. I use the substructure die pretty much everywhere, and use both when I have a 3 piece nested stack - the tank die in the middle skin and the substructure on the farthest from the mfg head. Makes the skins rest nice and flat on each other. Highly recommended.