Are screw dimples special?

[N73JE]

I'm getting my tools assembled and was looking over the tool list on Van's website.

I see the usual 3/32" Rivet Dimple Die and 1/8" Rivet Dimple Die. I also see #8 Screw Dimple Die. And in the forums I have read that a #10 Screw Dimple Die will be required as well.

Is there something different about a "screw" vs "rivet" die? Are the screw heads not at 100 degrees or something?

I was looking at buying the dies at "The Yard":
http://www.yardstore.com/browse.cfm/2,405.html

They are all 100 degree "spring back" dies and seem well priced.

Also, are 3/16" Rivet Dimple Dies the same as #10 Screw Dimple Dies?

Inputs?

Thanks!

[noelf]

The dimple dies produce a 100deg dimple, some special dimples dies are for 110deg blind rivets.

If you drill the proper sized hole for an AN-xxx screw, and try to use a rivet dimple die, there is no real way to get the dilple die centered in the hole for a "centered" flush-head screw. The same goes with trying to use a #6 dimple die for a #10 screw.

[Mel]

Originally Posted by noelf

The dimple dies produce a 100deg dimple, some special dimples dies are for 110deg blind rivets.

Actually, pulled rivet heads are 120°.

[N73JE]

Okay... so I got figured that both the solid rivets and screws we're using have a 100 degree head. The blind rivets have 120 degree heads. Cool.

Please correct my understandings below:

Universal (button) head rivets and Flush head rivets (countersunk surface):
-3 rivets use a #40 drill bit
-4 rivets use a #30 drill bit

Flush head rivets (dimpled surface):
-3 rivets use a #41 drill bit and 3/32" dimple die
-4 rivets use a 1/8" drill bit and 1/8" dimple die

Flush screws (countersunk surface):
#8 screws use a #19 drill bit
#10 screws use a #11 drill bit

Flush screws (dimpled surface):
#8 screws use a #20 drill bit and a #8 screw dimple die
#10 screws use a #12 drill bit and a 3/16" dimple die

Or am I not understanding correctly?

[Bob Kuykendall]

Originally Posted by N73JE

...Or am I not understanding correctly?

Sounds about right. But don't forget #6 screws, you've probably got a handful of them to do as well.

[N73JE]

Originally Posted by Bob Kuykendall

Sounds about right. But don't forget #6 screws, you've probably got a handful of them to do as well.

Ok, adding the #6 screw to my table gives me...

Universal (button) head rivets and Flush head rivets (countersunk surface):
-3 rivets use a #40 drill bit
-4 rivets use a #30 drill bit

Flush head rivets (dimpled surface):
-3 rivets use a #41 drill bit and 3/32" dimple die
-4 rivets use a 1/8" drill bit and 1/8" dimple die

Flush screws (countersunk surface):
#6 screws use a #28 drill bit
#8 screws use a #19 drill bit
#10 screws use a #11 drill bit

Flush screws (dimpled surface):
#6 screws use a #29 drill bit and a #6 screw dimple die (no substitute)
#8 screws use a #20 drill bit and a #8 screw dimple die (5/32" dimple die is a close substitute)
#10 screws use a #12 drill bit and a #10 screw dimple die (3/16" dimple die is a close substitute)

Still looking good?

[terrye]

Yep, pretty much what I am doing except I use #40 and #30 drills for both universal head (AN470) and flush head (AN426) rivets.

[fehdxl]

FWIW, I have to make a #18 hole to dimple for a #8 screw...might just be my dimple die though. I too use #30/40 holes for -3/4 rivets irrespective of flush or not.

Also, please note that you really want to make sure those #8 and and #10 screw holes are smooth and de-burred well before dimpling. Don't over-do it...but just get it right. There's a lot of bending and stretching going on and the chances for cracks around the dimple edge is higher than the smaller holes.

Just my observations.

Best to you,

-Jim

[N73JE]

Originally Posted by fehdxl

FWIW, I have to make a #18 hole to dimple for a #8 screw...might just be my dimple die though. I too use #30/40 holes for -3/4 rivets irrespective of flush or not.

Also, please note that you really want to make sure those #8 and and #10 screw holes are smooth and de-burred well before dimpling. Don't over-do it...but just get it right. There's a lot of bending and stretching going on and the chances for cracks around the dimple edge is higher than the smaller holes.

Just my observations.

Best to you,

-Jim

Thanks for the advice. I actually didn't think about that. Perhaps a light deburr before dimpling and another just after? Just in case a stress point is made?

[Auburntsts]

IMO you're making this more complicated than it needs to be. You don't need seperate sizes for dimples vs. CSKs (unless the pilots on your dimples and CSKs aren't fitting through the holes). Here's what I use with no problems whatsoever:

#40 drill bit for all -3 rivets (426 and 470)
#30 Drill bit for all -4 rivets (426 and 470)
#28 drill bit for #6 screws
#19 drill bit for #8 screws
#12 drill bit for#10 screws

The advice to ensure the #8 and #10 holes are well deburred before dimpling is spot on.

YMMV...