What is the correct end mill

[DPittman]

I don't have any ball end mill cutters but I suspect that is the right tool to cut this rounded profile? Is there something else that could be used successfully in aluminum?

 

[Dabbler]

Don, you show 2 round profiles in the picture; the one on the top looks like 1/8" radius, and the one on the bottom looks like an .800 radius. which profile are you referring to?

 

[DPittman]

Don, you show 2 round profiles in the picture; the one on the top looks like 1/8" radius, and the one on the bottom looks like an .800 radius. which profile are you referring to?

Oops my bad. The top smaller profile.

 

[YYCHM]

Is that a one piece or two piece weaver scope base? If it's a two piece I would just file it in.

 

[DPittman]

Its a one piece picatinny style. I am milling it and want to do it more precise than what I can file. Its a project.

 

[YYCHM]

Ya, trying to file a one piece base length wise wouldn't work very well at all. I think you're going have to source a ball end mill for that project.

 

[Dabbler]

There are 2 ways to machine this. A ball end mill is the conventional approach. The other way is to get a 1/4" slitting saw, and reprofile the cutters and mount the rail 90 degrees offset, and profile the slot using the slitting saw.

I guess the honorable mention is to use one of those ubiquitous horizontal milling machines. I think I have a 1" arbour 1/4" radius milling cutter for a horizontal mill, buried somewhere.

 

[Dabbler]

BTW why the slot? None of my picatinny rails have it...

 

[DPittman]

I might end up just making a flat with a plain old end mill. Not that it should really matter anyhow but I was thinking I should try to copy for learning sake

 

[YYCHM]

Shaper?

 

[DPittman]

BTW why the slot? None of my picatinny rails have it...

Yes i don't see much reason for the slot on the original rail that I am sort of copying but in my odd ball application I am thinking it will allow me to still use the iron sights ( air gun pistol) with the mount.

 

[Tom Kitta]

A small ball end mill is cheap - even carbide.

 

[DPittman]

Yes i don't see much reason for the slot on the original rail that I am sort of copying but in my odd ball application I am thinking it will allow me to still use the iron sights ( air gun pistol) with the mount.

Come to think of it...I think the original design was probably for the same purpose....that particular rail was designed to be used on a particular shotgun and I think the radius slot on top would have allowed the use of the bead sights along with the scope mount.

 

[PeterT]

Part of my head profiling required a longitudinal cut with ball end mill just to give you a feel for that kind of operation. No drama, just find the happy speed & DOC for the material and away you go. I eventually found some (metric) carbides on Aliexpress that were very reasonably priced, but the whole shipping situation is out of whack.

If your profile is critical to match, it almost looks yo my eye like you may have a smaller radii so would be offsetting passes on either side of center?

 

[Dabbler]

If it isn't that critical, how about a 1/4" square slot with a regular end mill? Or better yet, a vee slot...

 

[DPittman]

If it isn't that critical, how about a 1/4" square slot with a regular end mill? Or better yet, a vee slot...

Yes i think i will probably use just a 1/4" endmill for a square slot.
One other way I think i might be able to do it if I had too is to make a horizontal boring/flycutter for use in the lathe and mount the rail on the compound/tool post or milling attachment.

 

[Johnwa]

It could be done by grinding a round nose HHS cutter. Use it in a boring bar to make a single point milling cutter. Mount the base on an angle block or jig held in your vise so the face being cut is vertical.