Movement of reamer in chamber and die

[Will Henry]

I have re-aligned headstocks with adjustments, when such were available, by scraping and shimming when they were not. I have rebuilt carriages, compound slides, tailstocks. I once had to repair a 22x120 lathe which had a piece which was parted off get between the chuck jaws and the ways. It twisted the countershaft in two. Made and heat treated the new shaft. That was twenty five years ago and it is still in service, so I guess it worked out.
About twenty years ago I had a 28 inch CNC lathe which had an accumulation of chips pile up in front of the tailstock. The result was, when the turning operation finished, the carriage went back to zero, pushed the tailstock back, disengaging the center. This resulted in a 12 inch shaft, five feet long, falling onto the carriage and climbing over the toolpost. The machinist (it was I) was lucky to have survived that one. If the cabinet had not held, I'd have been squashed like a bug. Near scared me to death! After that, I became fanatic about keeping chips blown clear. It took me two days to repair the lathe. I was happy I was able to do so.
I have yet to see a floating toolholder which does not cut to center (its own center mind you) under load. The exceptions are the ones which will get stuck offset under load. Mike Bryant's pusher system can work well. A solid holder can work very well providing alignment is perfect. Tool post holders are the same. If perfectly aligned, they control the reamer perfectly. I support the reamer on the center, as a rule. I have made mistakes. in nearly fifty years of cutting chambers, it happens. I always cover any remedial work and parts. Most gunsmiths are more than capable of troubleshooting these problems, if they just take the time to think. Many, perhaps the majority, certainly know more than I. WH

 

[linebaugh]

Interested enough to buy the reamers?

Water capacity for this one is nearly 69gr for Peterson and a bit over 70 for Lapua, so a couple of few gr more than standard 30-284.

https://forum.accurateshooter.com/threads/for-sale-30-284ai-manson-reamer-set.4129554/#post-38998362

I'm thinking I'm exiting this cartridge and going back to my factory barrels. I've been burned a couple times now on less than desirable smith work trying to get a 30-284 going and just want to prioritize my limited funds elsewhere. If I can't find a buyer it may just sit until sometime in the future.

I am not interested, but again appreciate the info you shared. I'm winding down on the gun builds and do not need another caliber nor gun. Time to start going the other direction on ownership. I will read that article. Thanks again for sharing.

Seems like that case capacity in 30 cal could yield some good groups.

 

[gunsandgunsmithing]

Interested enough to buy the reamers?

Water capacity for this one is nearly 69gr for Peterson and a bit over 70 for Lapua, so a couple of few gr more than standard 30-284.

https://forum.accurateshooter.com/threads/for-sale-30-284ai-manson-reamer-set.4129554/#post-38998362

I'm thinking I'm exiting this cartridge and going back to my factory barrels. I've been burned a couple times now on less than desirable smith work trying to get a 30-284 going and just want to prioritize my limited funds elsewhere. If I can't find a buyer it may just sit until sometime in the future.

Have you considered a 284 walker or shebang? Similar and dies might be more available

 

[DShortt]

Will, I have been doing CNC maintenance professionally for the last 11 years. Lathe adjustment can be a bit of a dark art. A tailstock alignment is simple, anyone who runs a lathe better know how to do that. Beyond that, there is an entire universe of ways that a lathe can be messed up. Almost all of them are hard to wrap your head around without classroom time and plenty of chicken scratches on the whiteboard.

I'd add that if the reamer is not ground correctly or is dull/damaged it really doesn't matter what setup you use. Can't make a round hole using an oblong peg.

You can test this yourself. Buy a cheap reamer and intentionally sabotage your set-up and the reamer condition. Measure the results. Intentionally throw your setup out on all 3 axis and see if that floating reamer holder you bought really works.

I believe none of what I hear and half of what I see. So I experiment.

 

[gunsandgunsmithing]

I'd add that if the reamer is not ground correctly or is dull/damaged it really doesn't matter what setup you use. Can't make a round hole using an oblong peg.

You can test this yourself. Buy a cheap reamer and intentionally sabotage your set-up and the reamer condition. Measure the results. Intentionally throw your setup out on all 3 axis and see if that floating reamer holder you bought really works.

I believe none of what I hear and half of what I see. So I experiment.

How does that explain a boring bar? I'm with ya on testing, for sure and on the floating holders. You can't count on them to be dead on at all. I do think they help once dialed in close but at that point, why not just dial everything dead nutz and cut rigid? The floater can only hurt then, imho.

 

[Ccrider]

How does that explain a boring bar? I'm with ya on testing, for sure and on the floating holders. You can't count on them to be dead on at all. I do think they help once dialed in close but at that point, why not just dial everything dead nutz and cut rigid? The floater can only hurt then, imho.

What are you saying about using a boring bar? Or not saying?

 

[gunsandgunsmithing]

What are you saying about using a boring bar? Or not saying?

I'm saying that a boring bar isn't round, even sorta oblong, but makes a very round hole. The rules are different than drilling a hole when the part is the one that's being spun vs the cutter, ie a drill bit.

 

[LVLAaron]

Things get wonky when you have a reamer with a tall flute.

 

[gunsandgunsmithing]

Things get wonky when you have a reamer with a tall flute.

I've not experienced any issues in nearly 40 years of machining. There are reamer designs based on that kinda thing actually. Why would it create an issue and what issue have you seen?

 

[DShortt]

I've not experienced any issues in nearly 40 years of machining. There are reamer designs based on that kinda thing actually. Why would it create an issue and what issue have you seen?

If you've cut a chamber on size with a straight reamer with a tall flute then your experience has been completely different from mine.

They might cut a concentric chamber, but it'll be oversize. Perhaps not enough to cause a problem, but I don't perceive the current discussion to be about problems that can't be managed.

Either it's on spec, or it isn't. Only measurement will tell that tale.

 

[DShortt]

I'm saying that a boring bar isn't round, even sorta oblong, but makes a very round hole. The rules are different than drilling a hole when the part is the one that's being spun vs the cutter, ie a drill bit.

Difficult at best to finish cut a chamber with a boring bar though. And I'd dispute the idea that it matters if the cutter or the material (barrel) is being spun. Again, based.on my personal observations/experiments.

 

[gunsandgunsmithing]

Difficult at best to finish cut a chamber with a boring bar though.

That, I agree with. Reamers are the right tool for the job...cnc or not.

 

[gunsandgunsmithing]

If you've cut a chamber on size with a straight reamer with a tall flute then your experience has been completely different from mine.

I'm a big believer that there is no such thing as perfect, particularly in machining. This means literally, that there will always be a tall flute. Then there are reamers with different numbers of flutes, opposing or not, different staggers, etc.

 

[Alex Wheeler]

Sometimes a tall flute might teach you something.

 

[DShortt]

Sometimes a tall flute might teach you something.

Might not be.happy about it, either.

 

[DShortt]

I'm a big believer that there is no such thing as perfect, particularly in machining. This means literally, that there will always be a tall flute. Then there are reamers with different numbers of flutes, opposing or not, different staggers, etc.

Agreed. It's impossible to be absolutely perfect. But if we're gonna venture down the rabbit hole I figure we might as well mention the most obvious things.

Kinda like a former President stated. 'It depends on what the meaning of is is'.

For the record, I never cared for that guy. He could sell ice to Eskimos.

 

[gunsandgunsmithing]

Sometimes a tall flute might teach you something.

More prone to poor finish or gouging, yes. The "low" flute has room to pick up swarf.

 

[gunsandgunsmithing]

Gun drills are a pretty good example of a single flute "reamer". Like barrels, honing is the next step to a precision hole diameter beyond reaming. Several bbl makers have figured this out in the last few years and are honing after reaming. Lube is more of a factor because of the surface finish. Smoother actually creates more force to pull a button through, on buttoned bbls...fwiw. No place for oil retention.

 

[DShortt]

So can we agree that reaming isn't the best option for precision?

That question will upset a few folks, I expect.

 

[gunsandgunsmithing]

So can we agree that reaming isn't the best option for precision?

That question will upset a few folks, I expect.

Yessir, but it's close. Drill, bore, ream and hone...then lap, I suppose but honing sure gets ya almost to there, too. I'd say lapping a honed hole is more about finish now or possible teeny tiny post mfg, last step imperfections. I have no edm experience so not sure where that would fall today. True precision takes true time!