I'd like to try and cut my own rails, just for fun - So I need a dovetail cutter or have to set up an adjustable jig, but that might not be as repeatable.

Dovetail cutter would be best. What is the angle of the underside edge that the rings clamp on to?

Like this?





I used a 60 degree cutter. Width of rail .840. Slots .156

You have to measure over the functional surfaces of the angles. You cannot make the bar a particular width and then try to machine the angle surfaces until the "V" is "sharp". You must have "v" blocks to measure over and a target dimension based on calculations and the 1913 Picatinny specifications.
Or just guess and make the rail fit a particular set of rings or attachment that you have.
Opinion of one,

Express, this should help you.

http://www.brownells.com/aspx/NS/GunTech/NewsletterArchive.aspx?p=0&t=1&i=558

The complete Mil STD 1913 document is is available for down load at the government's web site.
Search google for

assist quick search

then in the little box put 1913 and hit search

The PDF will appear for down load.
Save it to your computer.


If you can design and make a good 45° fixture or tilt your mill head, or mill vise 45° you can cut the angles with a standard end mill.
The measurement requires datums set .108 apart.
Easy to design and make with your mill if you think about the measurement process a few minutes.

Thanks guys, but I was not able to get a result from the assist website, Best I could find was a link to a Currycomb 1913 but it was "cancelled"...I'll keep trying.

Westpac, nice work, what angles did you use on those rails?

Thanks. This customer requested a particular height and length for the rail. If I could have located a blank rail that was tall and long enough, I would much rather have used it instead of having to machine this particular piece from scratch. Very time consuming.

The "original" MIL-STD-1013 profile calls for 45 degrees for both top and bottom, but on the above rail, I used a 60 degree cutter for the bottom and 45 on top. The 60 degree bottom worked just fine for this project.

You couldn't access the link to Brownells?

No it didn't but I just tried it now and it came up, with some errors on the page, not all of it downloaded properly. Must be a temporary glitch. Thanks for your info, I might try making one from scratch, just for fun. How did you get the underside radius right? Multiple passes or did you get a round nose end with the correct radius?

quote:

Originally posted by EXPRESS:
No it didn't but I just tried it now and it came up, with some errors on the page, not all of it downloaded properly. Must be a temporary glitch. Thanks for your info, I might try making one from scratch, just for fun. How did you get the underside radius right? Multiple passes or did you get a round nose end with the correct radius?

That particular rail is flat on the bottom. But, when I make ribs, sights and scope bases, I use my lathe to cut the radius.

Express,
At the Assist Quick Search page put the number

1913
into the document number box and hit submit.
It will bring up several 1913 documents just pick the one for the rail.