What's new
What's new

Lathe Spindle Bore, Does Size really Matter ??

15mules

Aluminum
Joined
Aug 3, 2011
Location
Mtn. View Arkansas
I have searched the old post and seen the debates over import or American, or working between centers or through the headstock and which is better. There is no doubt there are strong feelings on each side of these debates. If you have read some of my other post, then you know I am in the process of outfitting my shop to make the move from hand tool work on guns to more machine work in order to gain a few new customers and maybe save some time also. I have a small Rockwell 36" lathe and I am seriously considering adding a larger lathe for barrel work. I am a mamber of the FCSA, so yes I can see that I would likely want to do some chambering etc. on a 50BMG in the future. It seems to me most things can be upgraded or added to a lathe with the exception of one thing, spindle bore size. The size is the size, and it will never expand. So how important is it? How many times have you said, "I wish I had bought a lathe with a bigger bore". How many jobs have you not been able to do, because the bore was just to small. From reading old post, it seems unanoumous amoung most, that for gunsmith work the 1 3/8" bore of the SB Heavy 10 is about the minimum size. In the same price range there are other lathes with 1 9/16" bore and for a bit more 2" bores. What gun jobs are there,that just can't be done with any of these bore sizes? Just how important is bore size and is there such a thing as "Too Big" ??
 
Some 50BMG barrels are up to 1 3/4", so for your future needs, it looks like you would want close to a 2" bore.
 
You'll find that as you get into larger bore diameters, the length through the headstock increases and the swing of the lathe increases, meaning the overall size and weight of the lathe increases as well. So there are those issues as potential downsides...
 
Learn how to turn between centers and use a 4 jaw with a steady. I have sold a few lathes thru eBay and craigslist and the first question I recieve (from novices) is always, "whats the spindle bore".
 
Learn how to turn between centers and use a 4 jaw with a steady. I have sold a few lathes thru eBay and craigslist and the first question I recieve (from novices) is always, "whats the spindle bore".

If you can't do this then you have no business putting someone's barrel in your lathe.

Buy a bigger bore lathe for other reasons like threading hydraulic cylinder rods or something else that has swivellish ends and that isn't going to matter at MOA.
 
It seems the aspiring gunsmith with zero machining experience is intimidated by creating or acquiring a proper steady rest/cat head, and the coward's route is a larger spindle bore.

Just because the Grizzly catalog doesn't have it, doesn't mean the device is useless :)

Which means he is competing for the same limited number of used machines, and intending to do his work at the same place that much lathe work gets performed: just outside of the headstock, i.e. the location of most of the wear on a lathe.

If these newcomers would just carefully pay attention to the advice given, they would realize "that too long lathe with a small spindle bore" on craigslist would most likely not go for a premium, and have little wear 2-3 foot away from the headstock.

Buy THAT lathe, and use the money saved to either create or acquire a suitable steady rest/cat head.

I have never seen torque wind-up mentioned as a problem with working with steady rest/cat head, so I assume the torque required in barrel work is minimal.
 
I have a steady rest, and I use it when I HAVE to. But, if there is any other way around it, I would never use a steady to chamber a barrel. I also think comments that are derogatory towards someones capabilities just because they don't want to use a steady is wrong. If you want to use a steady and chamber barrels, then fine, help yourself. But don't criticize someone who doesn't want to use a steady.

In my opinion, there is just absolutely no way you can indicate in a barrel in a steady better than you can through the headstock using a spider on the left side. It just can't happen. I'm talking down to within .0002" or better. Plus, for those that let a barrel run loose, have at it. I guarantee you'll never see a barrel chambered that way wining benchrest matches.
 
I simply do not understand why there are some on these forums who find it necessary to chime in on threads, which they have no interest in, only to criticise or add in a derogatory comment, while doing there best to avoid actually answering the question. " Have you found a gunsmithing job that you simply could not do, because of the headstock size"? I know you can turn a barrel between centers, and chamber a barrel with a steady rest. I plainly stated that in my original post. I know there are those who simply visit these forums for entertainment purposes and have no interest in seeking any useful information, or offering any, and I can understand that. I know there are also knowledgable people here who are interested in a meaningful dicsussion of a subject and I look forward to hearing from them.
 
It seems the aspiring gunsmith with zero machining experience is intimidated by creating or acquiring a proper steady rest/cat head, and the coward's route is a larger spindle bore.

Just because the Grizzly catalog doesn't have it, doesn't mean the device is useless :)

Which means he is competing for the same limited number of used machines, and intending to do his work at the same place that much lathe work gets performed: just outside of the headstock, i.e. the location of most of the wear on a lathe.

If these newcomers would just carefully pay attention to the advice given, they would realize "that too long lathe with a small spindle bore" on craigslist would most likely not go for a premium, and have little wear 2-3 foot away from the headstock.

Buy THAT lathe, and use the money saved to either create or acquire a suitable steady rest/cat head.

I have never seen torque wind-up mentioned as a problem with working with steady rest/cat head, so I assume the torque required in barrel work is minimal.


cowards route? really?

personally, if i were buying a piece of equipment, i'd make sure it could do what i wanted to do with it instead of buying the wrong machine and having to build a steady rest/cathead to compinsate.
 
Learn how to turn between centers and use a 4 jaw with a steady. I have sold a few lathes thru eBay and craigslist and the first question I recieve (from novices) is always, "whats the spindle bore".

so chambering through the spindle with a spider on each end is a novice thing? people are doing it because they don't know how to use a steady rest, not because they feel it offers an advantage when the absolute best accuracy of the finish product is the goal?
 
I simply do not understand why there are some on these forums who find it necessary to chime in on threads, which they have no interest in, only to criticise or add in a derogatory comment, while doing there best to avoid actually answering the question. " Have you found a gunsmithing job that you simply could not do, because of the headstock size"? I know you can turn a barrel between centers, and chamber a barrel with a steady rest. I plainly stated that in my original post. I know there are those who simply visit these forums for entertainment purposes and have no interest in seeking any useful information, or offering any, and I can understand that. I know there are also knowledgable people here who are interested in a meaningful dicsussion of a subject and I look forward to hearing from them.


mules, if you are planning on working though the spindle, you want to make sure you have a large enough bore to pass your largest barrel though with room for adjustment but also short enough that you can reach both sides of the shortest barrel you will work with. it may be tough to find a perfect match for both large 50 cal barrels and smaller rifle barrels. something that may be of interest is the "true bore alignment system" by straight shot gunsmithing: Straight Shot Gunsmithing. with this, you can use a larger bore and not have to worry about reaching the back side of the barrel. if i were making money doing this, i'd be purchasing one of these in a heartbeat. since it's just a hobby for me, i can't justify it right now. but as soon as some spare scratch comes my way....

edit: is it just me or is this site a major pain in the ass to post replies now after the site change?
 
Another thing to think about. Small chucks have small thru holes.
Sometimes the big thru hole is like extending your bed length immensly.
Sure, you can rig up some way to do it without a four jaw but I wouldn't if i didn't have to.
I could also do a barrel with mittens on, but I would be a lot slower.
I use a steady only if there is no other way but I don't care if you do. Kenny
 
I have a Clausing 6300 that is excellent for most gunwork. Two weeks ago I took a job that I thought would be a piece of cake, which I envisioned chucking a 1911 Colt barrel in the 4 jaw with the chamber end into the spindle bore. My machine has a 1-3/8" bore and with the lug on a 1911 barrel you would need a 1-5/8" bore minimum to chuck it the way I had first thought. Wound up making a fixture much like a LaBounty bolt jig to do the job.

300 It's a little more pain with the "new and improved" website. I like to preview my message before I post and now have to go through extra steps.
 
Well for gun work a hole through the spindle is not really needed at all. I know a lot of guys that chamber and do all facets of gunsmithing with old Southbend, Myford and Altas machines that you couldn't jam a pencil through. In days gone by they were considered the BEST machines for gun work. The problem is that lathes never end with gun work. Odds are your going to find yourself making jack shafts for the farmer down the road or trying to Micky Mouse some other thing for some one else that's longer than your bed and your going to want to run it through the headstock. Despite what the hobbyists and kids may tell you, there is no such thing as a big enough machine. It comes down to what you can afford. Bigger is ALWAYS better. There is no replacement for massive displacement. Mind you, if you are just doing gun work, make sure you can cut a thread and have 40 inches between centers and you can do it all. If in the end, if you do choose to buy a small machine, despite what some of the children might tell you, is that with proper care and machining practices, what you turn out on the little can opener machines will be just as accurate as the stuff they are turning out on their Gildemeisers and Mazaks.
 
Thanks to everyone for your opinion on the subject. I found a used SB 16" , with the riser blocks making it a 21", and a 12' bed, within driving distance, at a price I could afford, so for now my decision is made. I think between my little Rockwell and the South Bend I will have the lathe end covered for a while. But short of running out of space, can you really ever have to many machines??? I think I will keep looking, just in case!!
 
As Spearchucker said bigger is always better. I have a Clausing lathe 14"X40". I still run into jobs that are hard to do. Usually they are because of things like sights, recoil lugs, or locking lugs that stick out that cause the problem.
 
i completely disagree with "bigger is ALWAYS better". if you intend on working thought the spindle with a spider/catheat on each end, getting a lathe with a 30"+ long spindle isn't going to do you any good. i feel you should pick out the machine that is right for what you intend to do. buying the lathe that was used to turn propeller shafts for the titanic isn't going to work well if your intended use is cutting 8-32 threads.
 
Last edited:
Just a couple of practical points based on having four lathes in the shop ranging from a SB Heavy Ten to a Colchester 15x48 with 2 inch bore spindle.

I find no time benefit from using a 4-jaw chuck versus the steady-rest for an individual job. On the other hand I use a specially constructed steady rest. If all you are going to do is bang the barrel in a 3-jaw and cross your fingers then through the spindle is quicker I suppose (better have some idea about how you are going to secure the other end of the barrel at the left end of the spindle).

I like to work around the tail-stock end of the lathe, it gets me away from all those nasty snagging rotating parts while I concentrate on the job.

A smaller lathe lets me get closer to the work to see what I am doing. My small Clausing and the SB have relatively narrow chip pans at about waist height or below so I can get in close to examine progress. I can even move around to the back of the lathe to check the work from that side. The Colchester bed is quite high and the chip pan is quite wide and it wraps around the back of the lathe near the tail-stock so it has nowhere near to the convenience of the smaller lathes for examining fine work.
 
i completely disagree with "bigger is ALWAYS better". if you intend on working thought the spindle with a spider/catheat on each end, getting a lathe with a 30"+ long spindle isn't going to do you any good. i feel you should pick out the machine that is right for what you intend to do. buying the lathe that was used to turn propeller shafts for the titanic isn't going to work well if your intended use is cutting 8-32 threads.

There is no need to Micky Mouse around with cats heads, dial indicators, range rods or precision ground plugs if you know what you are doing and have enough machine. Bigger is ALWAYS BETTER! Of course if you DON'T have enough machine then you are forever FORCED to Micky Mouse stuff around and waste time.

I think if you try it you will find that you can cut 8x32 threads just as quick and just as well on a 24 inch x 15 foot engine lathe as you can on a Unimat. Providing both machines have that threading option. I can do it. You should be able to as well.
 
I always advise to get the biggest heaviest machine you have room and budget for... Bigger is better unless it's too big for the task at hand! A little common sense goes a long way, and most often the budget/space is the limiting factor.

For those short barrels I made up a little cat head to tweak the bore axis into alignment with the spindle bore. This allows getting the crown cut to a tenth or so.

Finished.jpg
 








 
Back
Top