9x30 lathe imperial threading questions

[Road_Clam]

I'm interested in purchasing this lathe:

Upgraded 8.7"x 29.5" Mini Metal Lathe 1100W Metal Gear Digital Display 5 Tools 729270372692 | eBay

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Ideally i'm looking for a 8-9" swing with a 1.5" dia through hole primarily for gunsmith imperial threading of barrels and receivers. Would like to keep the cost <$1700 . I really need the weight to be below 450 lbs. as I will need to get this lathe down into my basement and up onto a workbench. Lastly would like the minimum rpm capability either 50 or 100 rpms. I'm having a hard time finding the ideal lathe. This lathe looks like a close match but it looks like it can't be configured to cut 16 and 24 TPI thread pitches. Does anyone know if there is gear combos available (or gears that can be 3D printed) to achieve 16 and 24 imperial pitches ? Thanks is advance !

 

[mickri]

Little Machine Shop has an online calculator that will tell you what gears you need to cut different threads. https://littlemachineshop.com/reference/change_gears.php
Here are two more gear calculators. http://www.imagesalad.com/lathenovice/lathegears/lathegears.html and https://www.k10y.com/gear-calculator-for-a-mini-lathe/
There is also a program that has been shared on the forum called Lathe Gears. Do a search and you should find it.

I wish my lathe had a 1.5" spindle bore. My craftsman 12x36 has a 3/4 bore so I will be doing my gunsmithing between centers.

 

[Road_Clam]

Thanks mickri for all the helpfull info. Looks like you can come up with most any imperial pitch if you can fab some optional gears.

 

[mickri]

You can probably buy the gears you need. A lot of these lathes use the same gears. I would ask the seller what other gears are available for the lathe. And what the specs are on the gears. The specs will give you the info you need to go shopping for the right gears.

 

[matthewsx]

Before you pull the trigger on that eBay lathe you may want to read through this thread.

First things first with a new lathe?

Been using a little Emco-Maier Compact 5 for the odd times I needed a lathe to do something, which honestly was small work and the Compact 5 did all I needed to do. I guess I have had it maybe 15 years or so, most of the time of which it has just been getting dusty. But recently I wanted to do a...

www.hobby-machinist.com

Forum sponsor Precision Matthews has a very good reputation around here with lots of users to ask questions of.

And no, even though we share a name I have no connection to them, nor do I own any of their products. Just hate to see another forum member go through what @Tired&Retired went through.


John

 

[Road_Clam]

Thanks for the heads up on the quality issues from that forum member comments duly noted. Believe my ive been researching lathes from PM and LMS ( i actually have the LMS 4198 dlx mill and totally happy with it). Lms lathes only have a .82 spindle bore, i need a bare minimum 1". Im looking at the pm1030 but now im far over budget as im not going to be using this lathe daily but more just an ocassuonal fix it lathe focusing on imperial threading. I do cnc machining for work so i have access to a Trak lathe anyways.

 

[mickri]

My guess is that you are wanting to thread and chamber through the headstock. This seems to be the current in vogue method for making very accurate rifles. There is a lot to be said for chambering and threading between centers. I have not seem any real test data comparing the two methods as it relates to the accuracy or lack there of in rifles. If you are going to be using already profiled barrels most profiled barrels will fit in a .82 spindle bore. If you are planning to profile the barrels you can do that between centers and then do the chambering through the headstock.

If you are willing to consider older lathes the South Bend heavy 10 has a 1 3/8" spindle bore. You should be able to find one of these within your budget. There are probably other makes that will also meet your requirements. Look for 12" to 14" lathes.

 

[Road_Clam]

My guess is that you are wanting to thread and chamber through the headstock. This seems to be the current in vogue method for making very accurate rifles. There is a lot to be said for chambering and threading between centers. I have not seem any real test data comparing the two methods as it relates to the accuracy or lack there of in rifles. If you are going to be using already profiled barrels most profiled barrels will fit in a .82 spindle bore. If you are planning to profile the barrels you can do that between centers and then do the chambering through the headstock.

If you are willing to consider older lathes the South Bend heavy 10 has a 1 3/8" spindle bore. You should be able to find one of these within your budget. There are probably other makes that will also meet your requirements. Look for 12" to 14" lathes.

My primary goal is to learn barrel and action threading. Its getting very difficult to find gunsmiths as its a dying master trade. Ive learned many tricks to accurize an inaccurate lathe. I ultimately want to modify my lathe to utilize an outboard spindle spider. I wish i had the situation to house a quality older lathe but my situation is i need this lathe no greater than 500# as i need to wrestle it down my bulkhead stairs down into my basement workshop, then get it off the floor and lifted on to a steel workbench.

 

[mickri]

What type of shooting do you do? Unless you are at the very top echelon of competitive shooting threading and chambering between centers should be more than adequate. It wasn't that many years ago that all barrel work was done between centers. South Bend 9" lathes and similar small lathes have been used by many gunsmiths for threading and chambering for decades. Gunsmithing does not require a monster lathe.

Getting a lathe down into a basement is a chore. Taking the lathe apart really helps. When I got my Craftsman 12x36 I took everything off that I could. I did not have the any type of lift to help moving the lathe. All I had was a HF furniture dolly and several boxes of varying heights. Working by myself and lifting one end at a time I was able to get the bed and headstock out of my truck and onto the dolly. Did the same to get the bed and headstock from the dolly up to the bench. Then I reassembled the lathe. I did not have to go down any stairs. If I had to do this I would use a 4 part block and tackle with a cam cleat to control the descent of the lathe down the stairs. Sheets of plywood for the lathe to slide on would help.

I would not focus on getting the lathe down to your basement. I would focus on getting the best quality lathe within your budget and then figure out how to get that lathe into the basement.

 

[Road_Clam]

What type of shooting do you do? Unless you are at the very top echelon of competitive shooting threading and chambering between centers should be more than adequate. It wasn't that many years ago that all barrel work was done between centers. South Bend 9" lathes and similar small lathes have been used by many gunsmiths for threading and chambering for decades. Gunsmithing does not require a monster lathe.

Getting a lathe down into a basement is a chore. Taking the lathe apart really helps. When I got my Craftsman 12x36 I took everything off that I could. I did not have the any type of lift to help moving the lathe. All I had was a HF furniture dolly and several boxes of varying heights. Working by myself and lifting one end at a time I was able to get the bed and headstock out of my truck and onto the dolly. Did the same to get the bed and headstock from the dolly up to the bench. Then I reassembled the lathe. I did not have to go down any stairs. If I had to do this I would use a 4 part block and tackle with a cam cleat to control the descent of the lathe down the stairs. Sheets of plywood for the lathe to slide on would help.

I would not focus on getting the lathe down to your basement. I would focus on getting the best quality lathe within your budget and then figure out how to get that lathe into the basement.

I belong to a gun club and I shoot High Power, vintage sniper, and some mid range F Class. Nothing super competitive, and my rigs are mostly oem stock precision rifles. I do have a couple aftermarket precision barrels, but they came with finished chambers. I would like to have the ability to thread muzzles as I have a few direct thread silencers. I guess i'm just concerned that if my asian lathe has the centers off vertically, that could be a challenging situation to correct. With a independent 4 jaw chuck, and a spindle spider you can easily adjust for runout. Just trying to visualize the worst concentricity scenario. The other issue is a lot of the gearbox lathes have a minimum speed of 100 - 150 rpm's. That's kinda fast for threading short distances utilizing a center. I would probably custom grind the centers to a tip dia that is slightly under my major dia so as to allow some runoff space. I have lathe experience but i'm no expert, i'm more of a milling guy. I don't have a lot of experience threading on a lathe.