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Picatinny Rails

A place to ask general spud cannon related questions.
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Picatinny Rails

Unread postAuthor: dewey-1 » Mon Jun 01, 2009 12:20 pm

I am making a 3D CAD model of Picatinny Rails.

I cannot locate the following dimensions:

1) Mounting holes diameter

2) Mounting holes center to center

Could some one please measure with a calipers and help me out.

I have a rough "guesstimate", but I would prefer an accurate measurement.

Handguard Picatinny Rails
Short rail is 1-3/8 inches with 2 mounting holes.

http://www.valhallaarmory.com/Picatinny ... ctar02.htm

long rail is 3.5 inches with 3 mounting holes.

http://www.valhallaarmory.com/Picatinny ... ctar03.htm
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Unread postAuthor: jackssmirkingrevenge » Mon Jun 01, 2009 12:33 pm

I'd love to help out but what I have is these dovetail adapters (and they're Weaver, not Picatinny) without mounting holes.

It doesn't seem like there's a standard size for these holes either though, have a look.
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Unread postAuthor: dewey-1 » Mon Jun 01, 2009 1:17 pm

JSR

I used that Mil spec drawing to create the rail profile.

I am guessing the hole centers are on a multiple of 10mm (.394 inches)because that is the center spacing of the "posts".

Can you give a hole size on your rails? Also screw size, 3mm or 6-32 American

I am thinking around 3.5 mm or maybe .140".

Center to center probably varies depending on application.

Some rails have slots for various centers.
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Unread postAuthor: jackssmirkingrevenge » Mon Jun 01, 2009 1:59 pm

dewey-1 wrote:Can you give a hole size on your rails? Also screw size, 3mm or 6-32 American


If you're referring to the holes at the top of the rails, there are none in my adapters:
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Unread postAuthor: dewey-1 » Mon Jun 01, 2009 2:15 pm

JSR

Yes, I see what you mean now!

You are mounting to an existing dovetail on the "launcher".

I was thinking the rail was screwed to a flat surface.

I maybe SOL and have to make a wild a$$ guess.

Thanks!
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Unread postAuthor: Demon » Mon Jun 01, 2009 3:17 pm

http://www.hawkeoptics.com/us/chairgun/index.php

Could this be used for spudding?

(off topic)
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Unread postAuthor: jagerbond » Mon Jun 01, 2009 3:19 pm

Dewey,
What is this going on?
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Unread postAuthor: jackssmirkingrevenge » Mon Jun 01, 2009 3:21 pm



It's very useful for airgunners who fire consistent professionally made projectiles through consistent professionally made rifles, but in our realm of relatively amateur fabrication, GGDT is a much more useful tool ;)
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Unread postAuthor: USGF » Mon Jun 01, 2009 3:22 pm

dewey-1 wrote:JSR

Yes, I see what you mean now!

You are mounting to an existing dovetail on the "launcher".

I was thinking the rail was screwed to a flat surface.

I maybe SOL and have to make a wild a$$ guess.

Thanks!


Dewey,
Yep we often buy them blank and machine our own specific hole patterns to mate up with whatever we are affixing this to. #6, 8, 10 and 1/4 SHCS, LHCS, FHCS are most often used. I don't know if you have run into this. We have lying around about 10 different brands or rails. When measured against so called Mil Spec drawings, NONE match. We tried looking at Weaver specs and the same thing. Seems most rails are a hybrid of the two combined? BTW, a lot of rails makers do not stick to the 10mm spacing.
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Unread postAuthor: dewey-1 » Mon Jun 01, 2009 4:07 pm

So much for a so called "mil standard".

Guess I will just use what fits the application.

I will use M3x.5 SHCS and go with multiples of 10mm spacing.

That way the holes are between posts.

Image


edit: add rendering
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Unread postAuthor: jackssmirkingrevenge » Tue Jun 02, 2009 12:00 am

beautiful as always :)
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