Help: Reaming the last few thousand of an inch

[CFCA1237]

I have a Grizzly G0709 and have been building rifles for personal use. The lathe is fantastic and the results have been absolutely incredible.

I find the only difficult part -- the only part still giving me any anxiety -- is reaming the last few .001's to get to final headspace. I use a Kiff reamer stop which is a great tool but it is very hard to see when you have engaged the shoulder and it feels like you can push it an extra .001-.002.

At the same time, its almost impossible to get back to the exact depth of cut, after moving out the headstock to clean the reamer, clean the chamber and and remeasure headspace. The lock the tailstock, move the reamer in until it stops seems to only get within a few .001's. Just doesn't feel accurate.

Does anyone have any technique that is more obvious? Duel dial indicators - one on the bed to the base of the tailstock (to reset the exact location) and one on the tailstock spindle possibly to get it to exactly where the last cut left off? Other? Or just keep doing what i'm doing - bump the reamer stop as lightly as possible - check, check, check again.

Half of me wishes i could use the carriage and a micrometer mounted on the V ways (i probably could but).

I haven't botched one yet but am always somewhat uncomfortable. Tricks?

Thanks!

 

[Terry]

Are you using the reamer micrometer? It has .001 adjustments. Once firmly against the barrel it stops if set up correctly. Your consistency applying pressure does matter.

Best Wishes!

 

[Doug Beach]

Use your carriage as a tailstock stop. Lock it in place, and return your tailstock to it.
The reamer stop should be pretty positive, no need to turn the wheel any further, once you feel it make contact.

 

[Stan Taylor]

I'm probably going to be a smart ass but chamber deep set the headspace by setting shoulder back I'm old school sorry.

 

[Terry]

I'm probably going to be a smart ass but chamber deep set the headspace by setting shoulder back I'm old school sorry.

That's what I do when I miss!

 

[Dusty Stevens]

If your stop is set up correctly it cannot physically go too deep. Youll push the barrel into the headstock first. Dial it in with the markings on the stop and have confidence

 

[ridgeway]

I put a simple DRO scale on tailstock. Before DRO... Clamp on tailstock quill and a 2" travel dial on a mighty mag.

 

[Butch Bradshaw]

 

[tobnpr]

What Dusty said.

No different than a micrometer saddle stop on the v-way. I can run the saddle into the stop (pretty damn hard if I want to), and the DRO readout at that point is 100% repeatable, every time. But you can't run the reamer in to "x", take a measurement, then put on the stop, set it to what you think you need, and push it to the breech and call it good. Couple of passes needed (for me anyway) to confirm it's precisely "calibrated" at the point where material is being removed.
As mentioned until you get it set pressure matters.

JMO

 

[tac284]

What I use, very repeatable.

 

[Dusty Stevens]

 

[GenePoole]

I can't find a more recent photo, but I dug this one up. My setup has changed a bit. I built a new longer plate for the quill so that I can clear the dial indicator with my custom splash shield. You can just make out the set-screw that holds it tight to the quill. Even though the pictured setup would have some (undoubtedly small) cosine error, It is very repeatable as long as I don't bump anything. Future plans: a more rigid dedicated indicator holder instead of the mag base pictured. Bumping it would mess everything up.

Picture was culled from this video:

 

[hogpatrol]

I use the same setup as this ^^^^^^ but the indicator is on the tail stock. The Clausing's is larger and flat but the plate is still fastened as shown here but on the operator side. When I get close, machine off, I run the reamer in until it stops, set the indicator, back off the reamer, start the machine and go from there. As in most machining, there's a hundred ways to skin a cat, and a lot of good ones posted here.

 

[RGRobinett]

Being paranoid, except for the reamer "stop", I've done most of this . . . now, after watching pal, Mike, do it, I use a modified Stan Taylor method: turn the tenon LONG; face off tenon to head-space; cut the thread; cut the cone/recess as needed.
This has worked great . . . but, I do work for myself only, so, don't get too much criticism . . . and, my rifles seem to shoot Ok.RG

P.S. Ooops - it seems obvious, but, as others stated, but i omitted, ya gotta run the reamer in far enough to accommodate this - hey, nobody picked on me!

 

[Will Henry]

For the last 43 years or so, I have simply pushed the tailstock in until contact, locked the tailstock, and fed the reamer to the appropriate depth. I let the reamer dwell for 1 second at the end, then withdraw. Now and then, I'll miss by a thou but not very often. I use a dial indicator when cutting a coned breech. WH

 

[Stan Taylor]

They make these 2 tool's for a specific reason.LOL
If you notice on the tail stock I have a dial indicator to do the final plunge with the reamer after take measurements an set headspace off of shoulder.

 

[Bamban]

I'm probably going to be a smart ass but chamber deep set the headspace by setting shoulder back I'm old school sorry.

This^^^

Run deep, finish the tenon, set headspace, thread, cut cone. My story, I am sticking to it.

Just a rookie learning this machining thing.

Nez

 

[Shrek]

View attachment 1164488 They make these 2 tool's for a specific reason.LOL
If you notice on the tail stock I have a dial indicator to do the final plunge with the reamer after take measurements an set headspace off of shoulder.

That Old Graziano SAG is beautiful ! What model is it ?

 

[DaveTooley]

I have a Grizzly G0709 and have been building rifles for personal use. The lathe is fantastic and the results have been absolutely incredible.

I find the only difficult part -- the only part still giving me any anxiety -- is reaming the last few .001's to get to final headspace. I use a Kiff reamer stop which is a great tool but it is very hard to see when you have engaged the shoulder and it feels like you can push it an extra .001-.002.

At the same time, its almost impossible to get back to the exact depth of cut, after moving out the headstock to clean the reamer, clean the chamber and and remeasure headspace. The lock the tailstock, move the reamer in until it stops seems to only get within a few .001's. Just doesn't feel accurate.

Does anyone have any technique that is more obvious? Duel dial indicators - one on the bed to the base of the tailstock (to reset the exact location) and one on the tailstock spindle possibly to get it to exactly where the last cut left off? Other? Or just keep doing what i'm doing - bump the reamer stop as lightly as possible - check, check, check again.

Half of me wishes i could use the carriage and a micrometer mounted on the V ways (i probably could but).

I haven't botched one yet but am always somewhat uncomfortable. Tricks?

Thanks!

Who's reamers are you using? Some bottom out with a distinct clank. Others stop with a dull thud. The later does not instill confidence on the last pass.

 

[Stan Taylor]

That Old Graziano SAG is beautiful ! What model is it ?

I will make post when I go to work in the morning an give you the model number, It's been there since I started 30 years ago very nice machine.