Sophomore Questions as Shop gets Busy

[dnellans]

You can dial anything in radially at a single point and with a drill, bore, ream process the chamber should be both radially centered and axially aligned with the spindle. Runout in the chamber shouldn’t be affected by that choice, you can get no runout bushing or spider.. If the chamber has runout something else is wrong.

With the bushing however, you only get a single point of radial runout to align, you have no control over the axial alignment of the bore ahead of that single point to make sure that your nice chamber isn’t pointed cockeyed to the bore axis.

Runout isn’t really the metric to consider, it should be nil either way.

 

[Dusty Stevens]

You can dial anything in radially at a single point and with a drill, bore, ream process the chamber should be both radially centered and axially aligned with the spindle. Runout in the chamber shouldn’t be affected by that choice, you can get no runout bushing or spider.. If the chamber has runout something else is wrong.

With the bushing however, you only get a single point of radial runout to align, you have no control over the axial alignment of the bore ahead of that single point to make sure that your nice chamber isn’t pointed cockeyed to the bore axis.

Runout isn’t really the metric to consider, it should be nil either way.

Thats what i was trying to say. You can bore a hole in a barrel running out half an inch and stick an indicator in there and get zero runout. Its not about checking your work, its about knowing how to check it

 

[std7mag]

I wonder about having a lathe with a "tail stock" on the other side of the chuck where the spiders would be.
Run the ways under the chuck, or a frame work that could lay the ways "behind" the chuck.
Would be simple to indicate the bore at the chamber end then.

 

[dnellans]

A second tail stock on the outboard side doesn’t give you the adjustability of a spider to jack the muzzle end around to create a bore that is in alignment with the spindle at case neck plus first inch of bore.

If all bores were perfectly straight, then a perfectly aligned tailstock there would work, but…

 

[std7mag]

As far as CNC vs manual lathe.

For chambering & putting the threads on for mating the barrel to the receiver, i'd op for manual lathe.

CNC is great if your starting from a raw piece & making hundreds/thousands of identical parts. Only way to go for mass production.

But....

From what i've observed from running CNC doing mass production.
1) Preventive maintenance is non existent! Run it till it breaks. Then bandaide it to keep it running doing something till an outside firm that specializes in fixing CNCs shows up.

2) You WILL crash a CNC machine!
Time is money! That second less that it takes moving in the rapid counts.
And on some machines 100% rapid is scary fast! Often without the benefit of real estate to react.
And when it does crash, then the turret, or the chuck, or both chucks are out of whack.

 

[Judd]

Y’all tip toed in the taboo subject around here. Here’s my take after indicating a barrel both ways, talking to lots of old and younger guys and shooting against both methods. If it’s straight and the barrel is good, they both work and I’ve never seen the advantage on a target.

The hypothesis is solid but to make theory it’s got to be proven and it’s almost impossible with the variations in barrels to prove one over the other. My 2 cents worth even less…

 

[INTJ]

Y’all tip toed in the taboo subject around here. Here’s my take after indicating a barrel both ways, talking to lots of old and younger guys and shooting against both methods. If it’s straight and the barrel is good, they both work and I’ve never seen the advantage on a target.

The hypothesis is solid but to make theory it’s got to be proven and it’s almost impossible with the variations in barrels to prove one over the other. My 2 cents worth even less…

It may not be on this thread, but in other threads we have discussed many times that many different methods work, and to do what you think is best.

I know without question that an outboard spider provides the best way to get a barrel as straight as possible. I don't know if that shows up on target vs other methods. Regardless, it's the way I like to dial in and will continue to do so.

 

[Dusty Stevens]

It may not be on this thread, but in other threads we have discussed many times that many different methods work, and to do what you think is best.

I know without question that an outboard spider provides the best way to get a barrel as straight as possible. I don't know if that shows up on target vs other methods. Regardless, it's the way I like to dial in and will continue to do so.

I think the main thing it does is make the leade even and cuts the freebore diameter perfect all the way around. Thats where youll see the differences in setups. Most are straight enough youll never see a bad setup but those wandering bores will tell on you every time

 

[FireMedic]

I almost bought a trubore chuck. But decided not to. I want one of the places I dial to be directly under a jacking screw. Dialing away from one makes you chase it and the less parts involved the better. I just couldn't see how it would improve my work or speed. You can actually chamber a barrel pretty quickly if your brain is thinking of the next step before you get to it and no one is interupting you.

If you have a lathe big enough for the true bore system, it’s hard to beat. I had one on my pm1440tv which is about 2200lbs and I would get some chatter with parting or threading with just the crosslide.

My current acra 1440cvs weighs 2800lbs and handles it nicely.

I’ve chambered holding barrels every way that’s commonly done today. One thing I can say, I never have barrels move when locked down in the 6 jaw chuck. I can’t say that about the other methods I’ve used.

I chambered a 30-338 lmi today, I set a timer to see how long it took me to dial in. It was 14 minutes from tightening the chuck on the barrel until it was .0000 runout at 1/2” in and 2.750 in.

 

[INTJ]

If you have a lathe big enough for the true bore system, it’s hard to beat. I had one on my pm1440tv which is about 2200lbs and I would get some chatter with parting or threading with just the crosslide.

My current acra 1440cvs weighs 2800lbs and handles it nicely.

I’ve chambered holding barrels every way that’s commonly done today. One thing I can say, I never have barrels move when locked down in the 6 jaw chuck. I can’t say that about the other methods I’ve used.

I chambered a 30-338 lmi today, I set a timer to see how long it took me to dial in. It was 14 minutes from tightening the chuck on the barrel until it was .0000 runout at 1/2” in and 2.750 in.

View attachment 1389555

Do you have an outboard spider?

 

[FireMedic]

I do but it’s not necessary. I’ve chambered without a spider before I went to the flush system. The end your working on will not move. But I don’t get crazy with rpm’s either. I turn at 600, thread at 150-200 depending on TPI, and chamber at 100-200 depending on what the reamer likes

I thread the muzzle first and then use an extension to to hook the flush to. The spider is there to just hold it in place.

I think the biggest thing is matching your work holding to the machine you have. The Precision Mathews I had before had too much deflection in the bearings to support the mass of that 6 jaw that far away from the spindle.

I wouldn’t run the tbas on a 1440gt class of machine personally.


My prior lathe, about the bare minimum size I’d recommend for the tbas

 

[hoz53]

It's not the dial in. I usually take 5-10 minutes to dial in. I can't remember if I posted on this thread or my other recent thread, buts it's all the double checking and hand-fitting I do. If I were to make fewer passes and cut to the numbers, it would speed me up. I will start incorporating that, but I am not sacrificing quality for speed. The owner is very onboard with that.

I am not shooting up at 2 AM. We are expanding our space again, and talking about walling off the area where we have the lathes. I don't think people who don't machine understand how much it slows you down when you keep getting interrupted.

Adding the second lathe and lathe operator will double our production. We will have one setup my way--dual spiders--and the other likely set up with the bushings.

The guys that use the bushings get the same chamber runout as the outboard spider guys.

i hope youre not shooting up at all

 

[INTJ]

i hope youre not shooting up at all

The range isn't open any more at 2AM.........

 

[dnellans]

I do but it’s not necessary. I’ve chambered without a spider before I went to the flush system. The end your working on will not move. But I don’t get crazy with rpm’s either. I turn at 600, thread at 150-200 depending on TPI, and chamber at 100-200 depending on what the reamer likes

I thread the muzzle first and then use an extension to to hook the flush to. The spider is there to just hold it in place.

I think the biggest thing is matching your work holding to the machine you have. The Precision Mathews I had before had too much deflection in the bearings to support the mass of that 6 jaw that far away from the spindle.

I wouldn’t run the tbas on a 1440gt class of machine personally.

View attachment 1389569
My prior lathe, about the bare minimum size I’d recommend for the tbas

Tell me more about that aluminum t-track with insert holder setup you've got there. Thats one of the slicker ones I've seen as you can adjust it to any spacing you want it looks like. Is that much mass hanging on the chip shield dicey or ok?

 

[FireMedic]

I picked it up off eBay several years back. I don’t have any info on it other then that.

I don’t have a rack on my current lathes. Heck I don’t use but 3 tools for an entire barrel job. I went through a bunch of them before I found those 3 tools and the inserts that work for my methods.

 

[LVLAaron]

I do but it’s not necessary. I’ve chambered without a spider before I went to the flush system. The end your working on will not move. But I don’t get crazy with rpm’s either. I turn at 600, thread at 150-200 depending on TPI, and chamber at 100-200 depending on what the reamer likes

I thread the muzzle first and then use an extension to to hook the flush to. The spider is there to just hold it in place.

I think the biggest thing is matching your work holding to the machine you have. The Precision Mathews I had before had too much deflection in the bearings to support the mass of that 6 jaw that far away from the spindle.

I wouldn’t run the tbas on a 1440gt class of machine personally.

View attachment 1389569
My prior lathe, about the bare minimum size I’d recommend for the tbas

Is the chip tray.... on the back side?

 

[FireMedic]

no chip tray on that one….cast iron base. It’s like a 1440gt on steroids but still not 1/2 the machine of the Kent or acra 1440 trl/ERl class of lathes.

It was a special order through pm when I bought it.

 

[Dusty Stevens]

no chip tray on that one….cast iron base. It’s like a 1440gt on steroids but still not 1/2 the machine of the Kent or acra 1440 trl/ERl class of lathes.

It was a special order through pm when I bought it.

No chip tray seems like a bad idea

 

[tobnpr]

Seems to me that the TBAS is just fine for chambering where you have a straight cylinder in the chuck jaws.
Then, it's another machine for the muzzle end (or change setup) to deal with the barrel taper.

Still the best system I've seen for bringing "through the spindle" method to machines where the spindle's too long to accommodate typical barrel lengths.

 

[Tucker65]

I chambered a 30-338 lmi today, I set a timer to see how long it took me to dial in. It was 14 minutes from tightening the chuck on the barrel until it was .0000 runout at 1/2” in and 2.750 in.

View attachment 1389555

By the looks of your lathe I bet it took longer to clean the lathe than it did to chamber the barrel.