Theading away from the head stock.

[Ernest]

I have an older Taiwanese made lathe with screw on chucks. I really want to start doing threading away from the head stock to lower stress and to be able to thread ant higher speeds for smoother threads.

Every thing I study about this says you risk unscrewing the chuck while running the machine in reverse as is needed to thread away from the head stock. I certainly do not want to risk damaging my lathe but is there any way to pin or otherwise make it impossible for the chuck to unscrew. ?

thanks in advance for your advice.
Ernest

[BLAHUT]

A friend had one of these lathes and did his threading like you are talking about> what ever he did to the maching i do not know> he was a tool grinder, he is no longer with us>>

[M-Tecs]

With light cuts like threading and a properly seated chuck I have never seen one come loose. By properly seated I mean snapped in with the spindle lock engaged or if it doesn't have spindle lock engage the back gear on the lowest speed setting. Make sure everything in clean and install the chuck. Spin it on till it hits the shoulder. Back it off about a 1/3 turn and use the chuck wrench to rapidly spin it on. I have seen people turn the spindle on and let the chuck spin itself on. That does work but the chuck can get overly tight and it can be difficult to remove.

You running HSS threading tools or carbide? The Taiwanese lathes tend to better than the Chinese versions in the same class but some of the models are not overly rigid so HSS or some of the freer cutting carbides will give you the best results.

[john.k]

Even if the chuck does begin to unwind,alls will happen is your thread you are cutting will be damaged .....provided you are reasonably quick on the stop button ,and brake if it has one,no damage to the lathe will happen.........as a precaution ,put a piece of plywood ,rubber,etc on the bed under the chuck,so if the chuck should fall ,the bed wont be marked.

[Jeff Michel]

You might try insert tooling to improve finish/decrease depth of cut/ more or better lubricant/ cut a relief groove/ practice. I have a Myford Super Seven and a 12" Enco, both threaded spindles. Though I've been temped to try, I just laid down until the urge passed. Good luck.

[yovinny]

So.... your wanting to right hand thread running away from headstock ?
Running in reverse with the tool on the back side of your work and out of sight dosent really sound like fun or a viable solution...or am I missing something..?

[Rat-Man]

My chuck screws on and has this arrangement to keep the chuck from unscrewing in reverse. Don’t know if such a thing would be possible with your lathe, but thought I would throw it out as an idea!

[country gent]

Set the lathe up as normal for the right hand thread but mount the tool in upside down to normal and run in reverse.This allows cutting on the front side easily. Benifits are better coolant flow due to tool relief and chips dont block view.

Getting the chuck tight is important a good thread fit is important also. A couple heavy passes taken before threading will seat the chuck also. Another little trick is to turn a false center on the part and use a live center this provides stop and wont let the chuck back off.

[yovinny]

Set the lathe up as normal for the right hand thread but mount the tool in upside down to normal and run in reverse.This allows cutting on the front side easily. Benifits are better coolant flow due to tool relief and chips dont block view.

Getting the chuck tight is important a good thread fit is important also. A couple heavy passes taken before threading will seat the chuck also. Another little trick is to turn a false center on the part and use a live center this provides stop and wont let the chuck back off.

So putting upward pressure on apron, cross slide, compound slide and tool holder,, four things all designed to rigidly support downward pressure only,, dosent cause chatter like crazy ?

[Idz]

I made an adapter to lock into the headstock through tube and attach a hand crank for threading projects. The small lathes don't have a slow speed back gear so the momentum of the chuck makes precise stopping impossible.

[country gent]

Ever see the old turret lathes with the back cut toff post ( some had turrets even) tools were upside down and ran fine I think the cut offs ran even better than in the front position. When the gibs are properly adjusted there is little to no chatter.

I have a block of steel set aside to make a rear tool holder for my Nardinni lathe as it already has the mounting slots in the cross slide for one. ( its a 14/18 X 40 ). My smaller lathe dosnt have the slots id Im leaving it as is. Since I dont want to disassemble the cross slide and machine them in to it.

[elmacgyver0]

I made an adapter to lock into the headstock through tube and attach a hand crank for threading projects. The small lathes don't have a slow speed back gear so the momentum of the chuck makes precise stopping impossible.

I did this for my HF 9X20 lathe, it works really well and not as tedious as it would seem. I didn't lock the head stock or thread away from the chuck though.
The HF 9X20 is supposed to thread in SAE and METRIC, well it does in metric, but not so much in SAE.
The threads are close but not really SAE, don't know if this is an issue for other Chinese lathes, but it is for the HF 9X20.
I now do most of my work on a vintage 1947 Southbend 9-inch swing lathe with a long bed, a deal I fell into for $100.00
I love the Southbend it has a full transmission and back gearing; I still can't believe what I paid for it. The previous owner said he wanted it to go to someone who would appreciate it and actually use it and not rust away somewhere in some barn. Part of the reason it was so cheap was the back gearing was frozen due to the step pulley frozen to the spindle.
The step pulley has a 1/4" screw that is labeled "Oil", I removed it and sprayed some WD-40 into the hole then threaded a 1/4" bolt in the hole and tapped on the side of the bolt, first on direction then the other until the bolt was about to snap. I then removed the bolt and spray more WD-40 and put in a new bolt and repeated.
After ruining about 5 bolts, it finally broke loose.
I oiled it and it has worked ever since.
I guess it had seized up to just sitting.

[Alasgun]

Im surprised that no one’s mentioned when you thread away from the chuck; you are cutting LEFT hand threads! I’d agree with others saying; light cuts, no concerns; and the proper methods of “setting the chuck”. I especially agree with the one saying “practice”.

As a hobbyist, experience and confidence may come slower but you can get good results with a little effort. Regarding higher speed for a better finish, dont buy it. In a lot of cases you can improve finish with speed but high speed threading takes a lot more of everything you dont have, which adds to the stress immensely.
Many years ago i made thread gages for companies cutting oil field connections, Rotary Shouldered connections. You could spend big money for ground thread gages, or you could use high speed steel (Rex95) and “water polish” the final passes which gave you a brilliant finish. With threading tools properly ground and aligned we’d run at the slowest speed the lathe would produce, usually under 5 rpm and the cuts were in tenths of thousandths; many times running thru again and again at the same setting. Using a good lube at this slow rpm you end up somewhere between a cut and a burnished thread. These connections were up to 10 inch diameter, 3,4 or 5 thread per inch and tapered at 2-3 inch per ft. And threading against a shoulder.
Enough rumination from me; dont give up on forward threading, if it wasn’t the most efficient method all those machine tool manufacturers would have went a different direction all those years ago.

Heres a link with visual aids showing what you get threading away fromt he chuck.

https://www.wisc-online.com/Learning...2/MLT12302.htm

[Ford SD]

[JSnover]

So putting upward pressure on apron, cross slide, compound slide and tool holder,, four things all designed to rigidly support downward pressure only,, dosent cause chatter like crazy ?

Nope. Set it up tight and short. I didn't do it often but I never had a problem with it. One benefit is that nothing but coolant flows into the cut; you won't have a pile of chips sitting on top, trying to foul things up.

[M-Tecs]

Im surprised that no one’s mentioned when you thread away from the chuck; you are cutting LEFT hand threads! I’d agree with others saying; light cuts, no concerns; and the proper methods of “setting the chuck”. I especially agree with the one saying “practice”.

That would be because the OP stated he wanted to run the spindle in reverse. That dictates the tool has to be upside-down. In industry this is a very common technique on manual machines to do just what the OP wants. That is cutting right hand threads while cutting away from a shoulder.

years ago.

Heres a link with visual aids showing what you get threading away fromt he chuck.

https://www.wisc-online.com/Learning...2/MLT12302.htm

That is correct when the spindle is rotating forward and the tool is mounted in the normal manor. When the spindle is ran in reverse and the tool is upside-down (inverted) not so much.

Some more insight here

https://www.practicalmachinist.com/f...pindle.398664/

https://bbs.homeshopmachinist.net/fo...ing-in-reverse

[uscra112]

So putting upward pressure on apron, cross slide, compound slide and tool holder,, four things all designed to rigidly support downward pressure only, doesnt cause chatter like crazy ?

BINGO! Even if it doesn't chatter, you can't expect the lathe to run as accurately.

Running the tool upside down, the chips won't block your view, but the tool will.

[kenton]

Has no one single pointed an internal thread? Why would you worry about seeing the tool? Especially if you are cutting away from the head stock. I have used an ID threading tool on the backside of the part with the spindle running backwards to thread away from the chuck the few times I felt the need to. Seeing was not an issue since every lathe under 20 inch swing that I have run you look mostly down from the top, not from the side.

[Ernest]

As usual the wonderful folks on this site have been very generous with their knowledge and I appreciate it a great deal ! Primarily what I am concerned about is threading barrels. I only get to do this every once in a while so it is pretty easy to be a little slow on disengaging at just the right time. I finished my 4th barrel yesterday and on almost the last pass I was slow on disengaging and the threading tool went across the relief groove not by much but enough to cause some anguish on my part.

The you tube by Joe Pie got me thinking about doing it away from the head stock. I am going to take precautions and small cuts and try it in reverse with my next project.
Thank you again.
Ernest

[country gent]

Another little thing that helps, is a 1 inch dial indicator on the bed. Set it so that 0 is the start and .800 is the stop point then watch that and when it touches you can count down to disengage point.
I do this milling to a shoulder with the readout I watch the readout counting down the .1 then the last .01 the stop with in .010 easily.

You want a bed stop that clamps to the bed vee solid, You also will find this useful for turning shoulders and facing to length.