Amateur with tenon threading question-

Mram10 said:
I had NO idea a 3 phase had anything to do with finish on threads! I always touch mine with a thread file or emery cloth to pretty them up. Great info.
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It didn’t really make a lot of sense to me and I’m an electrician ? I’d think 1800 rpm is 1800 rpm but the more and more I researched it It’s fairly common with single phase equipment the sign wave on single phase is more spread out than 3 phase and guess that mean something. I can attest that the surface finish is much better now that I’m on 3 phase. If I were the one paying for all the up grades (motor, VFD and switching) I’d prolly have just lived with it.
 
Rubicon Prec. said:
I don’t use a thread relief, but I do make a tool nose radius relief at the shoulder. This isn’t required if the lug opening or receiver face is chamfered sufficiently.
On integral lug receivers I thread at 750 rpm and pull out .005” before the edge of the insert crashes into the shoulder. With a separate lug, I thread one thread pitch under the lug.
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Are using CNC? Carriage stop? I’m pretty ing good like 200rmp with a tool width relief cut good I don’t even wanna think how fast that carriage is traveling at 750 RPM.
 
killswitch505 said:
Are using CNC? Carriage stop? I’m pretty ing good like 200rmp with a tool width relief cut good I don’t even wanna think how fast that carriage is traveling at 750 RPM.
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Yeah, CNC. I was threading tenons at 1100 rpm but for some reason one barrel manufacturer would chatter. Rather than changing the speed based on barrel maker, I just slowed them all down.

I’ve been wanting to video it but there isn’t much to see with the coolant spraying on the window.
 
Butch, I don't own

Butch Lambert said:
I do it a little different. I thread to the shoulder watching my Trav a Dial and then disengage the half nut. I then casually retract the cross slide. It leaves a thread relief that you can't see unless you look very close. Everybody has their own method and we do what we prefer. One of my buddies and a forum member made up a proximity sensor tied into his DRO and VFD on his old oriental lathe. When he gets to his programmed point on his DRO his VFD, with braking resistors, instantly stops the spindle. He retracts the spindle, does not disengage his half nuts and reverses the feed. Know you crank in your cross slide to "0" and crank in your compound and turn it on as the half nut is still engaged.
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a trav-a dial and have only seen one and never in use.
I know some thread straight in with the cross slide but I don't. Does the tool compensate for the movement of the compound? Or do you stay away from the shoulder to begin with?

Richard
 
killswitch505 said:
I was having a similar issues as you with a similar lathe. I know this may not be an issue your having but I’ll get to that..... I was having problems with my threads looking like . I did a ton of research and found that single phase lathes leave an awful finish on parts. I changed my belts that helped. I still wasn’t getting the finish I was seeing everyone else getting so I did a 3 phase upgrade using a vfd. Boom problem solved I could even go down to 1 RPM to thread if I wanted. I then tied the brake option to a micro switch now I can stop on a dime.

https://youtu.be/Ncc72aKgzVY
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I would like to hear more about your “brake option and micro switch”. I have an Okuma LK with a metric lead screw and would like to use a setup similar to yours. Thank you.
 
coontz74 said:
I would like to hear more about your “brake option and micro switch”. I have an Okuma LK with a metric lead screw and would like to use a setup similar to yours. Thank you.
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What would you like to know? I can post a parts list of what I used and take some better pictures and video tomorrow I’ll be chambering a 300NM for my father.

Drive
https://www.automationdirect.com/ad...ts_(115_-z-_230_-z-_460_-z-_575_vac)/gs2-23p0

Brake resistor
https://www.automationdirect.com/ad..._-_gs3_braking_units_-a-_resistors/gs-23p0-br

Limit switch
https://www.automationdirect.com/ad...ion_touch_(5_micron_repeat_accuracy)/cs067b-l
 
killswitch505 said:
What would you like to know? I can post a parts list of what I used and take some better pictures and video tomorrow I’ll be chambering a 300NM for my father.

Drive
https://www.automationdirect.com/ad...ts_(115_-z-_230_-z-_460_-z-_575_vac)/gs2-23p0

Brake resistor
https://www.automationdirect.com/ad..._-_gs3_braking_units_-a-_resistors/gs-23p0-br

Limit switch
https://www.automationdirect.com/ad...ion_touch_(5_micron_repeat_accuracy)/cs067b-l
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That’s perfect!! Thanks!! If you could take a video and more pictures would also help. Thank you very much.
 
Last edited:
Treading to the tenon with no chicken groove

HERE IS THE EASY WAY TO TREAD TO THE TENON WITHOUT STRESS. i ADOPTED THIS WAY AND NEVER LOOKED BACK.:eek:
https://www.youtube.com/watch?v=Z-dqOi_z5bk[/url]
 
Engrbill said:
HERE IS THE EASY WAY TO TREAD TO THE TENON WITHOUT STRESS. i ADOPTED THIS WAY AND NEVER LOOKED BACK.:eek:
https://www.youtube.com/watch?v=Z-dqOi_z5bk[/url]
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I agree...that’s a very good way to thread worry free....but, my situation is trying to thread towards the chuck and having to keep the half nuts engaged.
I have a metric lead screw and am cutting regular threads with no factory brake, hence why I’m looking for braking ideas...or any ideas really...

I can cut some nice threads with one hand on the power lever and one on the cross slide wheel to keep carriage out of the chuck but it can be stressful at times...

Thanks for the link. Much appreciated.
 
Pete are you saying your Central Machine didn't come equiped with a back gear? What is the slowest speed that you can select on your machine.
 
rvander1 said:
Hi,
I have a Grizzly gunsmithing lathe, and am chambering a Krieger heavy varmint barrel blank for my Nesika Bay single shot 6.5-284, F-Class type gun.

I have cut the thread and the tolerances are good-- action screws on etc.-- At the shoulder end of the threading I had cut a threading relief cut just behind the recoil lug area with a cutoff tool to avoid problems at the shoulder end of the threading operation. The barrel I took off the gun (shot out after 1400 rounds) was chambered by a professional gunsmith, and he did not cut a relief cut at the shoulder end of the threaded portion of the tenon-- his threads just taper up and end very nicely.

While both methods seem to work-- I am curious as to how the professional gunsmith managed to thread that tenon and have the threads end so beautifully without a threading relief cut.

Thanks in advance for any responses.
Bob
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There are a number of attachments for lathes than can automatically withdraw the tool very quickly.
We had a dedicated threading lathe at work that mechanically withdrew the cutter when it hit a preset stop.

This allowed for faster work and did not rely on the skill of the operator as much.
They did have to set the 'stop trip' rod though.
Simple disk with a set screw.
The entire rod was moved in a another clamp to position the stop disk.
The tool pivoted upward clear of the cut.

Some retract the tool (and not by the feed screw).


The other way is to simply cut slowly enough to withdraw the cutter by hand reliably and consistently.
This often takes a final 'clean up' to make a smooth end.
 
Thinking aloud...

If your lathe is 3-phase, you could get a VFD and slow it down. If it's single-phase, you might be able to implement a planetary pulley to reduce speed. I've also seen people attach a crank to the outboard end of the spindle and thread by hand. (Sorry, don't know any of the particulars of your machine.) I'd also dig in and see if there's anything you can do about the half-nut. No telling, but until you try...

GsT
 
Richard said:
a trav-a dial and have only seen one and never in use.
I know some thread straight in with the cross slide but I don't. Does the tool compensate for the movement of the compound? Or do you stay away from the shoulder to begin with?

Richard
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Sorry I didn't see your post earlier, but I use the compound. If you watch what you are doing, you can end up close to the shoulder and not hit. The relief in the receiver allows for the small amount of unthreaded on the tenon.
 
Not back gear as such

Louis.J said:
Pete are you saying your Central Machine didn't come equiped with a back gear? What is the slowest speed that you can select on your machine.
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It's a gear head lathe with speed selections by three levers. Yes, it will go slow. What i don't remember is if the speed selection is a part of the selection for thread pitch. My memory told me it was but after not seeing it since November, I can't say right now. Prolly fretting over nothing like old people tend to do.:)

Pete
 
Ive done much of what you suggest

GeneT said:
If your lathe is 3-phase, you could get a VFD and slow it down. If it's single-phase, you might be able to implement a planetary pulley to reduce speed. I've also seen people attach a crank to the outboard end of the spindle and thread by hand. (Sorry, don't know any of the particulars of your machine.) I'd also dig in and see if there's anything you can do about the half-nut. No telling, but until you try...

GsT
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It runs on 220 single phase. I have considered going to a 3 phase motor with a bit more umph and a VFD so I can get the breaking action. Wouldn't cost a whole lot and I'm still playing with House Money, considering what I paid for this one and what I got for the 10L.

I've had the half nuts out and adjusted them or, they look new and really didn't need adjusting that I could tell. This lathe wouldn't really lend itself to a crank. We'll ess. If indeed I can slow the spindle speed down I think my troubles will be minimized.

Pete
 
My guess, Pete, is that that thread pitch and feed rate are connected (same gears with different purposes ) and the speed selection is a different set of levers. It would have to be otherwise you would be threading 8 tpi at 1200 rpms, and 32 tpi at 50 or something like that. You should be able to thread at whatever rpm you choose. The same levers that allow you to choose thread pitch also would be used to set the feed independent of speed (essentially both are just a measured movement of the carriage over time).
Methinks when you get back up north it will all fall into place.
Mike
 
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