MilStd 1913 rails

[NesikaChad]

Here's the latest.

Machined from 300 series bar stock stainless steel.

These are fairly labor intensive little bastages.

1st op is contouring the bottom to provide a qualified edge. I machine these as a surface model so that I can use off the shelf tooling instead of having to buy form tools. Better finish too I think as there's less tool pressure doing it this way. Also gives the advantage of being able to control the contour a little more. Adding included minutes of angle are a snap, you just rotate the contour in the drawing and it updates the code for you.

2nd op is whackin off the excess and then just making the passes with the angle cutters to get the overall profile. then buzzing through the stuff with a little bugger to make the slots. That's what takes the longest since you can't go blazing away for fear of snapping the endmill.

I guess I could fixture and put the part on edge but I think surface finish would look like crap as I'd have to have a key cutter with a long reach shank to get all of them without the spindle smacking the part. Long reach tooling generally doesn't cut near as nice since it's so far out there unsupported.

Then a little engraving to mark the part and off to the rock tumbler to knock off the burrs and rub all the sharp edges nice and smooth.

I'm leaving the holes out so I can fit them to a wider variety of actions.

cheers,

C

 

[Chas1]

Thought I saw a similar post just the other day with these pics, they sure look good, nice work. Are you making them to be commercially available or just for your own needs?

 

[NesikaChad]

They are for sale also. I don't have them listed on the site yet.

$180.00 for all the Standard lengths. the Magnums will be a little more due to material

These are all 0 MOA. Next batch will have some elevation included.

I'll have to write code for a Remmy to deal with the offset height on the rear bridge. All in good time.

Cheers,

Chad

 

[Chas1]

Chad, any rough guess and timeframe for 20 moa and whether they'll be for custom actions such as BAT?

 

[NesikaChad]

I can have one ready early next week. Just need to know the length and the hole spacing.

Give me the model of BAT receiver you have and I'll make it happen.

 

[Chas1]

Chad, sending a PM on the BAT action.

 

[GNERGY]

Good write up. It's nice to learn how you go about making custom parts and the plus's and minus's of machining them. And how sometimes they change shape when you take them out of the vice.
I took a weaver one piece base and went to machine a different radius in the bottom to fit a .813 dia. T/C barrel. I put it in the vice on some parallels and angled the head on the bridgeport to get the radius from the 13/16th's end mill. The radius turned out great, till I opened the vice, then I ended up with this 'U' lookin thing Took a little while to get it flat again.

Keep the Show and Tells coming.
Tarey

 

[Chas1]

GNERGY, what's at play that causes the piece to change shape on it's own and how does one avoid it?

 

[NesikaChad]

Anytime you put a tool to a piece of material you run the risk of it distorting. It's a natural by product of machining. You relieve stress inside a chunk of steel by cutting on it.

Another way of course is to have the pieces normalized prior to working on them. This is a process where the parent material is heated/cooled at a specific rate to allow things to settle down a bit.

Basically it's like this: If you are making a 1913 rail expect the piece to "sway it's back" when you cut the little slots. It'll tend to want to bow up on the ends and rock like a chair. Just part of the deal. If you were to flip it over and cut the bottom the same way it'd probably bend back to almost straight again.

Not a big deal, just stick em in a press and bend them back straight.

Alot of aluminum rails are made as an extrusion meaning they have a die made and then "poop them out" in the general shape. From there you just zip the slots, drill some holes and maybe contour the corners and your done. Because it's an extrusion the grain of the material is a little different and they behave a little differently.

 

[vintec]

I made some rails the otherday and they bowed almost .040 up in the middle. It seems to me that SS tends to move more than carbon steel. I know that during faberication of SS parts you have to really pay attention where you put your tacks. Heat from machining and stress relieving from machining, I am surprised that mine did not form a circle