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Sophomore Questions as Shop gets Busy

INTJ

So things are going well and word is getting out that we build quality rifles. We are getting a lot of rifle builds. That is generating sophomore level questions:

1. How long will a HSS reamer last with a flush system?

2. How do I know when a reamer needs resharpened?

3. We have a PM 1440GT at the shop. We will soon need a second lathe. We are thinking perhaps one setup up for tenons and chambering and the other set up for threading muzzles. I don't think a larger lathe is the right answer since I want to keep the headstock short. I do have a PM 1340GT at home.

What should I be looking at for a second lathe? We don't know that we really need a CNC lathe, unless there is a significant advantage. We want to keep the quality which means an old guy (me) being fussy with dial in and chambering. I know there is a step above the Precision Matthews Taiwan built lathes, not sure if that is an advantage. Thoughts?
 
I have a very special BRA reamer. It became very obvious the vast majority of records were coming from that specific reamer. I sent it out to be measured so I could duplicate it. It was actually quite different from the print. At the point I sent it in, there were hundreds of chambers cut with it. There was a couple tenths of taper in the straight sections but everything looked good and there was no need to sharpen it. I still use it but have a certified copy as well to try to spread out the wear. Point is, I have still not worn one out yet so I don't know. But JGS did say they have seen worse from reamers used 3 times. So obviously you can abuse them.
 
I rough in chambers with a core drill. I take reamers out of service earlier than most. As soon as I can see wear on the leade and junction of the FB cylinder section I retire them. I do a lot of work for folks that go in harm's way so they get only the best. That's usually 60-80 chambers on a reamer. Carbide 300+ and counting. YMMV

TL-1 | Toolroom Lathes | 8" Chuck | 10" Chuck | Lathes – Haas CNC Machines

www.haascnc.com www.haascnc.com
 
^^^
Dave's take is mostly common-sense, though it eluded me for longer than I like to admit...
As he notes, the leade is the most critical area- and also the most subject to wear as that section is cutting from the get-go.

I pre-bore (quick/dirty, nothing crazy, no taper), then use a rougher or previously retired finisher if I have one-for the bulk of it, and the "finisher" cuts the final bit consisting of the neck/FB/leade and final chamber. Just minimizing cutting and wear to the most important area.

I have a smaller SB with collets that I use for miscellaneous ops and leave the primary machine set up with the spiders for barrel work. Because muzzles need to be dialed in same as chambers (though I don't get as in-depth into tenths), that's also done in the spider setup. Crown, thread, time and ream the brake in place, in the same setup.

JMO
 
Below is the reamer I was talking about. I dont know how many chambers its cut. 2-300 is my guess. It was made in 2017. I also have not kept count but Id say over 20 records easy have been on this one ( IBS NBRSA and Williamsport) and the majority of current 1k IBS records are on this reamer. I wouldnt sell it or let anyone sharpen it, LOL. You can see the most wear is in section C. Thats the lead cutting the rifling away. Section D is under bore diamter and has never cut steel. Section B is the freebore diameter. Its not worn much, theres .0002" taper in it now and the back half doesnt do any cutting since its straight. Same goes for the neck, section A. If there is no taper the front part is all that cuts. I think a lot goes into how long you can make one last. But if you get a good one you want it to last, you cant replace them. I agree with Dave and Dusty. If your seeing wear or smaller throats, its time to replace it. You will get a hang of what to look for in the bore scope. You will know when that freebore starts to get small.



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When I got the job chambering test barrels five years ago, I knew my old Sheldon was not up to the task. I looked at a bunch of machines and settled on the Acra clone of the Hardinge toolroom lathe. One reason was that it was immediately available. It has a belt driven VFD spindle, making it very smooth and quiet. The digital readout is reads in 0.0001 increments and the machine is very capable of holding it. The electronic threading is very easy and fast to use.
If I was to buy one today, I would start looking at Babin Machine Tool. https://www.babinmachine.com
They take original Hardinge lathes and rebuild them. They even upgrade some with CNC controls.
Is there a downside to these? Yes. They are expensive - but worth it if you need repeatable precision that is easy to use. They are short. You will still need a longer lathe for some operations. They have a 5C collet ready spindle. So 1.250 is the max to go through. I order 1.245 diameter straigh blanks and have no problem.
As far as reamers, I too use JGS piloted core drills to rough the chambers like Dave Tooley. That greatly reduces wear on the finisher. I spent 25 years running a wire EDM. A lot of that time was spent straightening out reamed holes. So, I don't buy the line that a reamer will follow the existing hole without a pilot. YMMV. I mainly use steel reamers. I have several carbide reamers - some cut great, some not so much. Using the core drills has let my steel reamers last well over 50 chambers.
 
DaveTooley said:
Section C is what I pay close attention to. In reamers that are +.0005" over in the FB, when that starts to wear the phone starts to ring. That's why I'm not a fan of overly tight FB's. But that's another discussion. ;)
Click to expand...
Neither am I. Section B is the freebore diameter. C and D are the 1.5 degree lead. Confusing how I broke it into two sections. I just wanted to explain that the front part never gets used. If B gets tight we have trouble for sure! I never order them .0005 over. Not since the PTG days when they were spec'd .0005 over but always ran bigger. It saved us from our selves.
 
Alex Wheeler said:
Neither am I. Section B is the freebore diameter. C and D are the 1.5 degree lead. Confusing how I broke it into two sections. I just wanted to explain that the front part never gets used. If B gets tight we have trouble for sure! I never order them .0005 over. Not since the PTG days when they were spec'd .0005 over but always ran bigger. It saved us from our selves.
Click to expand...
A double like.
 
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