T slot cutter for shellholder

[Jmp50]

Its the .562 t slot that the shellholder slides into. It's normally machined into the top of a ram on smaller presses. The big max uses a screw in ram attachment with this, These are HD presses designed for loading 50 cal, swageing bullets, extensive case forming...ect. 1.250 vs 1.00 ram Here's another attachment with a spring loaded claw extractor that covers a wide variety of case head sizes. IMO not as desirable as one which uses interchangeable shellholders. Neat design.

 

[pontiac428]

I would think that the critical dimension is the diameter just above the rim.

You are 100% correct. The rim needs to fit deep enough to engage the extractor groove or case body (auto or rimmed, respectively), but if it is an oversize cut for the base it's not an issue. The oblonged pocket was a problem for me because it didn't allow the lips to engage the rim enough, so it was the pocket that caused the problem, but the most critical thing is a solid fit around the rim/body, as you point out. I stand corrected.

I have 25 different shell holders, and all those divisions fit within maybe a 3/16" range, so thousandths matter. I measured a bunch of mine at one point where I was having problems, and the sizes were within .002-.003 of SAAMI nominal on the rim pockets.

Edit again:
My Lyman Ram-Prime (TM Lyman) Has a fairly loose tolerance on the primer body to shell plate slot to accommodate varying manufacturer's shell plates. When it is under compression, it's locked up solid, but the seat of the shell holder has room to swim in the priming die body.

 

[benmychree]

I looked through my Woodruff cutter selection, and found a 1/8 X 9/16 cutter, checked MHB listing and it is not standard, I suspect that I modified one when I made new rams for a couple of Herter's reloading presses that I use that were made for their dies and holders, which are completely unlike the RCBS dies and holders available. It was likely made from a 1/8 X 5/8 cutter, reground on the OD and resharpened for clearance.

 

[Jmp50]

I looked through my Woodruff cutter selection, and found a 1/8 X 9/16 cutter, checked MHB listing and it is not standard, I suspect that I modified one when I made new rams for a couple of Herter's reloading presses that I use that were made for their dies and holders, which are completely unlike the RCBS dies and holders available. It was likely made from a 1/8 X 5/8 cutter, reground on the OD and resharpened for clearance.

Interested in selling it?

 

[benmychree]

Interested in selling it?

Make me an offer.

 

[mickri]

Thanks for the explanation. I think that I understand it now. We are talking about the pocket the shell holder slides into. I can see where that needs to be a precise fit.

 

[pontiac428]

Thanks for the explanation. I think that I understand it now. We are talking about the pocket the shell holder slides into. I can see where that needs to be a precise fit.

Now that I'm clear that you're cutting the slot in the prime die body for the shellholder, I'm a bit anxious to get home (next week) and see if Lyman did anything crafty like draft taper the bottom of the die slot cutout in order to force concentric alignment under compression and eliminate shellholder float. That's the sort of engineering I'd expect in modern computer-designed CNC parts from long-lived manufacturers in a competitive industry. That's a random thought, but little things like that can make all the difference in this sort of application.

 

[Chewy]

Just an idea. Jo Pi made a small T-slot cutter by taking an endmill and grinding the flutes away above the desired depth. Found cheap 9/16" endmills for $7 and up. You could rough out the slot with a 1/2 X 1/8 Woodruff cutter and finish with the 9/16" endmill.