Lathe Purchase--Have Requirements Now

[INTJ]

Your only delays are threading (the electronic threading on the acra will let you thread at a higher rpm) and your double checking your work. With a flush you can go in all at once- no need to stop and patch out just to take a peek. Use a reamer stop and set it about .025 short, one shot reaming, measure once and dial it in. If you cant talk somebody out of a 1.350 barrel just do it on the other lathe. Most barrels i do are 1.200- i can go way bigger but nobody really cares between a 1.2 or a 1.250. Imagine threading at 1000+ rpm and taking deeper cuts like .025 on the first pass? Imagine reaming a whole ultramag chamber without stopping because you have confidence in your setup? Thats where youll be soon.

All good stuff except our BAT Vesper Action does better with a 1.25" barrel. The tenon is 1.121. also we do need a larger spindle on the second machine. The 1.35 barrel was on a 375 CheyTac on a BAT CT.

That smart lathe looks very interesting.

 

[Ksracer]

I take .050" for the first 2-3 passes on the tenon, and I like my last past to be within .010". That minimizes deflection and keeps the diameter consistent. When threading I use the compound only. I make .005" cuts until .030, then .003 to .048, the .002 or .001 after that. I clean the chips off after each pass.

If I need to take an 1.250 barrel down to 1.060, my first cut is ~.040 (.020 per side), then I measure and set the dro. I take two more .050 passes, measure again and tweak my final .050 cut by a thou if I need to. If you take a "heavy" cut followed by a light cut, your light cut will most likely not be accurate due to less deflection.

I think your first threading cut can be deeper also. I do a scratch pass to verify pitch, then a .015, (on the compound, so per side) dropping to .010's, and .005's and I try to set my last one up for a .003 with a second pass at the same setting.

I've found that if I try to take a .001 cut, I don't remove any material so I dial in another thou and end up taking .002.

I prebore to .100 or less. I usually don't pull the reamer out until the shoulder has cut .050. I take a rough measurement and aim for .030-.040 left. Clean, measure, and ream to .010. Clean, final measurement, and aim for my number. I use a dial indicator fixture to measure and a tailstock DRO and can usually hit it plus or minus .0005.

That's with a 17" machine, but I don't really consider these heavy cuts and I can't imagine that a 10 or 14" machine would have any issues.

That's just the way I do it, but I'm not the quickest and it's certainly not a production environment.

 

[INTJ]

If you take a "heavy" cut followed by a light cut, your light cut will most likely not be accurate due to less deflection.

I must be missing something here. I have seen the opposite many times. When my final cut is a light cut, the diameter is more accurate and consistent due to less deflection. The light cut clean us up whatever taper there was because of the heavy cut.

 

[Dusty Stevens]

I must be missing something here. I have seen the opposite many times. When my final cut is a light cut, the diameter is more accurate and consistent due to less deflection. The light cut clean us up whatever taper there was because of the heavy cut.

I always take a spring cut at the same as the last pass and itll always clean up a little. Youre going right. Then you can be perfect on your last cut dialing it in

 

[Walt Krafft]

I do a lot of barrels for Rem 700 actions. Most are 1.245 diameter straight blanks. This is what I do after indicating it in. Face off the end setting Z to 0. Touch off X setting to 1.245. Move X to 1.150 and take a cut to my Z finish. Check X and adjust the readout to match to the tenth. Move X to 1.060 and finish turn the tenon. Usually it is within +/-0.0003. Cut the threads using the crosslide at 600 to 650 rpm. 10 passes includes 3 spring passes. Easypeasy. My Acra is very rigid for its size. Larger shanks fit no problem as long as the contour goes to 1.250 within abought 6 inches of the breech.

 

[Ksracer]

I must be missing something here. I have seen the opposite many times. When my final cut is a light cut, the diameter is more accurate and consistent due to less deflection. The light cut clean us up whatever taper there was because of the heavy cut.

If you follow a light cut with a measurement and an adjustment, another light cut will be to size and vise versa

If you follow a heavy cut with a measurement and adjustment, a light cut most likely will not come out where you want it to be cause the cutting forces changed.

If you're getting taper in a 1" long part, then that is a completely different deal, and light cuts might be the answer.

 

[INTJ]

If you follow a light cut with a measurement and an adjustment, another light cut will be to size and vise versa

If you follow a heavy cut with a measurement and adjustment, a light cut most likely will not come out where you want it to be cause the cutting forces changed.

If you're getting taper in a 1" long part, then that is a completely different deal, and light cuts might be the answer.

It was over 4" but only with heavy cuts. The final light cuts solved it.

 

[LVLAaron]

It was over 4" but only with heavy cuts. The final light cuts solved it.

Part deflection.

 

[INTJ]

Part deflection.

Absolutely

 

[Ksracer]

It was over 4" but only with heavy cuts. The final light cuts solved it.

My bad, I thought you were talking about a tenon.

Definitely part deflection like Aaron said. If you can't move the work closer to the chuck or use the tailstock, light cuts and sharp tools are the fix then.

 

[INTJ]

My bad, I thought you were talking about a tenon.

Definitely part deflection like Aaron said. If you can't move the work closer to the chuck or use the tailstock, light cuts and sharp tools are the fix then.

I should have mentioned that I had to turn down about a 4" section of the barrel shank on six barrel nut barrels. On a sub 1" tenon that's within a couple inches of the chuck it doesn't seem to be much of an issue.

 

[Ksracer]

I should have mentioned that I had to turn down about a 4" section of the barrel shank on six barrel nut barrels. On a sub 1" tenon that's within a couple inches of the chuck it doesn't seem to be much of an issue.

I've done that before with blanks also. Why didn't you use the tailstock to support it?

I was using a brass tipped set screw fixture in the chuck at the time. I stuck the factory center of the big end against a live center in the tailstock and grabbed the taper with the set screws and inch past where I had to machine. Then I dialed out on the OD by the setscrews, double checked for runout along the length, and had support on both ends.

 

[ronsatspokane]

Automated turning/threading cycles. Might even be a way to set up to ream the chamber as well...
All servo controlled with the "feel" of a manual machine (supposedly...)

Manual Lathe (Smart) For Sale | Edmonton Alberta Canada

We have a new & used lathe for sale in our machine shop in Edmonton Alberta Canada. Smart Lathe is our new line of manual lathes that are made to simplify work with programmable threading without G-Code (CNC) required. Variable speed and touch screen settings so you don't need to crank a lot of...

stancanada.com

Want! I might consider doing barrels as a business with one of those. As it is, I do mine like INTJ does only slower.

 

[INTJ]

I've done that before with blanks also. Why didn't you use the tailstock to support it?

I was using a brass tipped set screw fixture in the chuck at the time. I stuck the factory center of the big end against a live center in the tailstock and grabbed the taper with the set screws and inch past where I had to machine. Then I dialed out on the OD by the setscrews, double checked for runout along the length, and had support on both ends.

I did use a live center in the tailstock. Still a little deflection until cuts were light.

 

[DaveTooley]

Want! I might consider doing barrels as a business with one of those. As it is, I do mine like INTJ does only slower.

all that and it costs more than a Haas. At least when I call Haas they speak English and are in the same state. And the way I chamber I have the same feel as on a manual machine.

 

[INTJ]

A new TL-1 starts at $31k. The Smart Lathe as configured is around $33k. That's pretty much the same price. Besides, our third lathe with likely be a TL-1

 

[ronsatspokane]

all that and it costs more than a Haas. At least when I call Haas they speak English and are in the same state. And the way I chamber I have the same feel as on a manual machine.

I'd like to see it in operation. It sounds like you could turn them out fairly quickly. When I said that I do mine like INTJ does only slower, I should have said, much slower than INTJ does.

 

[LVLAaron]

Starting a new thread since I have more specifics. Boss told me we will be ordering a second lathe this month. We are still deciding which one.

Requirements:

1. Will be used for chambering barrels at a higher volume than I can do on the PM 1440GT

2. Will be a manual lathe. A CNC lathe will be added as a third lathe some time in the future

3. Need to be able to change between SAE and Metric threads without swapping gears inside the lathe

4. Want variable speed

PM has a "PM-1640-TL" in stock...

 

[INTJ]

PM has a "PM-1640-TL" in stock...

Don't think the boss is going that way. Most likely it will be a Kingston HJ 1100. We are going tomorrow to a local shop that uses one to be shown how barrels can be chambered and finished in an hour.

If it were me I would probably get the smart lathe or a TL-1. Doesn't really matter for me as I will likely stay on the 1440GT and be stuck doing all the weird stuff, since the Kingston will be very specialized.

 

[Dusty Stevens]

Thats a huge lathe. 7.5hp and 17” swing.