new lathe

J

Jim Mc

New member
First I would like to say hello as this is my first post on this forum. I have enjoyed reading a lot of topics here for a while. I live in NC and shoot 600 and 1000 yd. br and am open to any type of trigger pullin.

I purchased a small Grizzly G4003G lathe for turning my own barrels and my question(s) or concerns are what tolerances do you set the lathe up to?
I first installed the stands and removed any soft foot, then mounted the lathe. When I shot the ways for level there was a 0.024" rack. I shimmed out the rack under the feet 0.001" then found a 0.004" belly in the bed ways. I think I can get most of that out at the feet on top of the stand under the head stock. Do I have to?
I can think of what may be a series of issues if the tail stock doesn't remain coincident through the travel. Is there a better way than another to chamber to not have to worry about this? Wouldn't this be a concern if I chamber between centers or through the head stock?

Notes, I did a quick check of the head stock to tail stock with a rotalign and adjusted it close for square but ran out of time, did not get it for level. I think it said I need to make a 0.008" change in the back for level, but there's no adjustment for that. I can drill and thread for an adjusting piece if necessary. How close do you have your tail stock in line to your head stock (and through out its travel)?
When I return home I will try to finish it with optics because my company has our rotalign on another job.

I bought the book John Hinnant writes for barrel fitting and so far, half way through the book, he shows everything between centers.
I know this is a potentially pompous post but I could use some help.
More questions to come, my machining experience is little, my machine installation experience is fairly large, mostly gear boxes and bearings.
Thanks, Jim
 
Jim,
If you chamber in the headstock, don't worry about the rest for chambering. You will only travel about 1" approx on the ways cutting the tenon and threading. If you drill, taper bore, and ream with the proper reamer pusher your tailstock alignment is not important. When you are doing a lot of turning of stock your alignment is important then.
Butch
 
Could you tell me a little more about reamer pushers? A friend said he would sell me a Manson floating reamer holder, not sure how that works. Is it what your talking about?
Some of my questions may be premature, but I am enthusiastic at the moment. I will look for pictures, as they say = 1000 words.
Thanks, Jim
 
Thanks Don, that about sums it up for me. I know, I should use the search option first.
Reading that thread covered a lot of what I was thinking about. At work, we use tapered pins to hold against shear that require drilling and tapering. Sometimes done with a mag drill. Crude compared to a lathe, but same principles.
I wonder about a round end reamer of sorts with some type of fixed (or not) dished pusher. Just thinking.
I'm still curious of what others lathes are set to. I heard some are buying these and just setting them on the floor. I guess it depends on what your going to use em for.
Jim
 
Jim Mc said:
I'm still curious of what others lathes are set to. I heard some are buying these and just setting them on the floor. I guess it depends on what your going to use em for.
Jim
Click to expand...
On setting a small lathe to do barrel fitting, all you need to do is to get the twist out of the ways. The lathe can be out of level from end to end but the side to side needs to be in the same plane.

i.e. put a good machinist level across the bedways just below the chuck and note where the bubble is. Then put the level across the bedways just ahead of the tailstock. If the bubble is in the same location as above you are good to go.

It is nice to have the lathe level from end to end especially if you have a coolant system and the bed pan is the catch pan for the coolant. This end to end leveling allows the coolant to flow back to the coolant sump. Otherwise, just getting the twist out is good enough.

If you have twist in the bed, as you move the tailstock, its relationship to the headstocks rotational center will constantly be changing.
 
Jim Mc said:
I wonder about a round end reamer of sorts with some type of fixed (or not) dished pusher. Just thinking.Jim
Click to expand...

Jim, You want your pusher to be flat so the back of the reamer can "float". This will give you the most accurate chambers if you do everything else correctly. Your method would require perfect alignment of the tailstock which is often difficult to acheive. Joel
 
one thing not mentioned so far is letting the lathe settle on the floor.
no idea how stable your foundation is. go turn the lathe on and let it run for a half hour or so...every day for 6 or 7 days...more time if you can.

vary the speed it runs at........

just let it all find a new home....


mike in co
(my bed was twisted in movement to my house. this resulted in an installation that lasted about 9 months while the bed "settled".)
 
Jim Mc,

That 'rotalign' sounds like a nifty setup tool. I wonder if you could describe a bit how it works and what kind of accuracy is routinely achievable.

Your comments regarding the discovery of some 'belly' along the ways reminds me that a touted feature of the Grizzly G4003G lathe is an ability to tweak the vertical position of the tailstock 'barrel' centerline over a range of about .006" by adjusting the torque on the tailstock lock stud, using a torque wrench to avoid exceeding 40 ft-lbs. When you again have the use of the 'rotalign' it could be interesting to see how well that feature works and to generate a calibration curve of required centering torque vs tailstock position along the ways as one means of compensating for any 'belly' in the ways.

Keeping in mind that North Carolina subsoil is largely made up of old clay sea bed, checking periodically to see if alignments shift over time seems like a good idea. Do you find this to be so in your industrial setup work ?

David Merrill
 
Joel, did you get Garret squared away with his AR?
I was just thinking about a device that could possibly combat the effects of a misaligned tail stock or bed ways. I'll get me some time on the machine before I go trying to solve the problems of the world with it. I'll stick to a bought pusher for now.

Mike, yeah, settling is a HUGE problem for some of the paper mills I go into all over the US. I just inspected a machine that had settled on the drive side by 0.300" over about 4 yrs.
I decided to anchor mine to the floor which has about 4" of unreinforced concrete. I don't think it'll need more than that.
It's not as bad of shape as I was expecting coming from oversees.
That's a good idea though, I'll check it again in 6 mos. As in my first post, I removed 0.024" twist out of the ways during the initial install. I took the time then to level it end to end to a couple a thou. in case as, Jerry said, I go with a coolant system.

Jerry, what do you recommend for a coolant system. I even had a gander thought about a sine bar and some high pressure gundrills. :). Now I'm getting off track again.

David, the rotalign is from a company called Pruftechnik, it is darn nifty.
We use it when ever possible for shaft alignment. I forget what all the tolerances are, but it is more accurate then the theodolites/TTS's we use.
I just plug in a little higher rpm and that increases the tolerances. Here check it out, www.pruftechnik.com. We as in OASIS use one of the older ones. Click on the products page, then click on the Ex-High end model. That should answer the questions better then I. I can attest, it works very well, even on the turbines as they promote.

Thanks all, throw in what ever you think I need to know.
Jim
 
Jim Mc said:
Jerry, what do you recommend for a coolant system. I even had a gander thought about a sine bar and some high pressure gundrills. :). Now I'm getting off track again.


Thanks all, throw in what ever you think I need to know.
Jim
Click to expand...
Jim, IMO, unless you are trying to do several barrels per day, a coolant system is more trouble than it is worth. For just a few barrels, get a good squirt can and some good cutting oil.

Retract the reamer, clean it and the bore and chamber about every 0.150 for the first 25% of depth, then go to 0.100 for the next 50% then about 0.025 for each succeeding step, checking headspace each time during the last 3-4 cuts.

Each time before reinserting the reamer, give the chamber neck area a squirt of oil and a few drops of oil the reamer concentrating on the neck area. It doesn't take much oil but oil must be present on all the reamer all the time.

All the above is for a predrilled chamber in the PPC/BR size range. Other chamberings may vary the above as will different barrels and their machinabillities.

Always listen to the lathe, the reamer, and the feel if you are holding a pusher handle. Loud music and BS don't mix when cutting a chamber.

Like the old barber shop sign "No Loud or Bolsterous Talking"!!!
 
Jim Mc said:
I purchased a small Grizzly G4003G lathe for turning my own barrels .Thanks, Jim
Click to expand...

If you really mean turning the exterior contour I have some advice:

Buy the bbl in the contour you want.

Turning a thick long chunk of steel into a thinner long piece of steel is a chore. No pleasure involved.

If you actually mean turning the tenon threads and chambering then have some fun !!
 
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