Help: Reaming the last few thousand of an inch

[hogpatrol]

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!

Make sure your uncut bore is clean, the pilot is clean and spinning freely and isn't binding when you push the reamer back in. If everything is clean and the pilot has clearance, it should feel solid instead of mushy when it hits. How much smaller is your pilot than the bore. I assume you have a selection of pilots.

 

[CFCA1237]

Thank you all... What an amazing resource.

Gene - I like your concept of running the dial indicator on the front, vs off the tailstock for the last few .001. Seems very smart. Doing that in conjunction with my micrometer stop, i think will be my winning combination.

The locking of the carriage and bumping the tailstock against it to reset "zero" is also an interesting thought.

Dave - PTG piloted reamers. They seem to really cut well for me.

You are all amazing... Thank you!

 

[kendog]

I made a hook to attach the tail stock to the carriage, and feed the reamer with the carriage hand wheel, with the tail stock snugged to no side movement on the ways. MUCH better feeling than using the tail stock quill. Seems most tail stocks are too low geared for good reamer feed. Also put a dial indicator in front of the carriage to judge depth.

 

[gunsandgunsmithing]

I made a hook to attach the tail stock to the carriage, and feed the reamer with the carriage hand wheel, with the tail stock snugged to no side movement on the ways. MUCH better feeling than using the tail stock quill. Seems most tail stocks are too low geared for good reamer feed. Also put a dial indicator in front of the carriage to judge depth.

That's pretty smart! Got any pics of your setup?

 

[CFCA1237]

I made a hook to attach the tail stock to the carriage, and feed the reamer with the carriage hand wheel, with the tail stock snugged to no side movement on the ways. MUCH better feeling than using the tail stock quill. Seems most tail stocks are too low geared for good reamer feed. Also put a dial indicator in front of the carriage to judge depth.

This makes two of us... Would love to see a picture!

 

[kendog]

That's pretty smart! Got any pics of your setup?

I would love to take the credit, but I learned it from my mentor, the late Jack Davis. A lot of his rifles wound up in the winners circle at CA state championships, as well as Camp Perry. I'll get a pic later today.

 

[kendog]

 

[GNERGY]

I get within .010 and I use a tap handle and turn it in by hand for the last couple thousandth's. It is too much trouble to set the shoulder of the barrel back.
I use my right hand to push the base of the reamer in the T handle and turn it with my left hand, ( I do it with the lathe off ) Works every time.
Tarey

 

[DaveTooley]

Thank you all... What an amazing resource.

Gene - I like your concept of running the dial indicator on the front, vs off the tailstock for the last few .001. Seems very smart. Doing that in conjunction with my micrometer stop, i think will be my winning combination.

The locking of the carriage and bumping the tailstock against it to reset "zero" is also an interesting thought.

Dave - PTG piloted reamers. They seem to really cut well for me.

You are all amazing... Thank you!

I have never had good luck with getting a repeatable zero with PT&G reamers. I always watch either the indicator and/or the feel of the hand wheel when I turn the lathe back on. Many times there's a bit of a jump before the reamer starts cutting. You can see and feel it. I chamber on a Haas TL-1 these days. I have a cut down tailstock I mounted in a tool holder that has a graduated hand wheel. I have no problem holding Go+.000"-.001".
Of course you have to be able to accurately measure the HS of the chamber.

 

[CFCA1237]

I have never had good luck with getting a repeatable zero with PT&G reamers. I always watch either the indicator and/or the feel of the hand wheel when I turn the lathe back on. Many times there's a bit of a jump before the reamer starts cutting. You can see and feel it.

Dave exactly. Nailed it. For me that "band" on engagement seems to be a few thousands. You can feel engagement and see engagement on the dial indicator but its never "crisp" - its almost mushy. If it was, this would be so simple. Maybe i should try a different brand reamer brand/type. That said, these seems to cut well for me.

 

[Will Henry]

I have also run into this issue with PT&G reamers. The clearance is non-existent or the margins too wide. I have had a few which would not cut until considerable pressure was put on them whereupon they would grab. I have not had these issues with any other reamer. I have had some Clymer reamers which had a real tendency to chatter but never one which wouldn't cut.
I have been able to stone the PT&G reamers and get them to work but one shouldn't have to do that. Understand, this doesn't apply to every one of their reamers but a significant percentage. I just quit buying them. WH

 

[Dusty Stevens]

Those inconsistencies in the cutting start is why i went to an adjustable reamer stop

 

[DaveTooley]

That problem never stopped me from using a particular reamer but you do need to develop methods to cope. That's easy for us that do it for a living. We have a bag of tricks, many of which, we don't realize we have. We just work and deal with the world as it's presented to us. It's a lot tougher for the guy that chambers a few barrels a year. My advice to those guys is as you come close to the finished chamber length try and hit a couple of numbers. Say .050" short then .025" short. You'll have more confidence in that last pass.

 

[kendog]

When I am a few thou short of my number, say less than .005, I bring the reamer back to the last position on the dial indicator and stop and let it dwell there for a second or two. Sure nuff will cut a little whether I feel it or not.

 

[CFCA1237]

Those inconsistencies in the cutting start is why i went to an adjustable reamer stop

Hard part is seeing if / when it is fully touching. Thus how hard do you touch the shoulder with the reamer stop?

Dave i like the idea of hitting random numbers on your way down to zero. Very smart.

 

[DaveTooley]

On cantankerous reamers i'll put a good deal of pressure on the reamer in an attempt to get it to the bottom. I'll bump it several times. Set my travel indicator to zero then back off and turn the lathe on. Doesn't always work but just part of the bag of tricks.

 

[rgc54]

I use a dro on my tailstock to set my headspace. I do not have a problem going to .001 on go gauge

 

[Doug Beach]

Hard part is seeing if / when it is fully touching. Thus how hard do you touch the shoulder with the reamer stop?

Dave i like the idea of hitting random numbers on your way down to zero. Very smart.

You don’t need to see if it’s touching. Your clue will be the handwheel on your tailstock. It will turn, and then it won’t. When it stops turning, don’t force it, and you’ve arrived.

 

[DR_2297]

This works well and has proven to be very repeatable.

 

[Rich S]

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.

I use the carrage as a stop also. That with a indicator on the tailstock has worked well for me. I found developing a routine so I know how far the reamer is backed off helps me. I back the tail stock out 0.020 every time I remove the reamer. When I reinsert the reamer I move it in 0.015 so that it is 0.005 off. This also ensures no backlash in the tailstock. This gives me a consistent feel and start. I only do a hanfull of barrells a year but haven't had an issue achieving consistent head space. I try to make my last cut 0.003 to 0.005 deep but have made 0.001 without issue.