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Threading on a Lathe

Rauce said:
Just gotta get yourself a toolroom lathe like a Hendey that doesn’t have or need a thread dial ;)
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Can you or @Darren explain how it does that? If it's too complicated, a link to a user manual would be fine. But please no youtube - I'd rather not know than go crazy o_O
 
The leadscrew has a fwd/neutral/reverse lever. To setup for threading, you can engage the half nuts with the leadscrew in neutral, the half nuts remain engaged until the thread is completed. To begin threading, you put leadscrew in fwd, make a pass, kick it to neutral, back out the tool, throw leadscrew in reverse, got back to thread start, etc. You never stop/reverse the spindle or release the half nuts. Its just a really smooth way of doing it. No thread dial to look at, theres no timing to worry about as the half nuts are always engaged while threading.
 
Susquatch said:
Nice project.

Did you document that on the forum? If so, I either missed it or a few neurons passed away and I forgot it.

I'm really curious, how does an ELS avoid the 29.5 degree cut?
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It feeds straight in, like the Europeans do threading all the time on manual lathes as do CNC lathes. The depth varies depending on the pass, essentially constant chip load. Tool cuts on both sides, esp. suited to inserts. For the thread pitches hobby users are doing the 29dg isn't necessary. This table is from the excellent Sandvik Metal Cutting Training Manual.

1654774282488.webp
 
The ELS I built is similar to this one, but with more uptodate code. Commonly known as RELS, the original is from https://chipmaker.ru where development and discussion continues. Mine is viewable here (I have since sorted out the ramp up/down sequencies, they were overly long due to incorrect backlash settings)
I added BA threads to the internal table, for my Synchronome clock build.

Gerrit
 
Darren said:
The leadscrew has a fwd/neutral/reverse lever. To setup for threading, you can engage the half nuts with the leadscrew in neutral, the half nuts remain engaged until the thread is completed. To begin threading, you put leadscrew in fwd, make a pass, kick it to neutral, back out the tool, throw leadscrew in reverse, got back to thread start, etc. You never stop/reverse the spindle or release the half nuts. Its just a really smooth way of doing it. No thread dial to look at, theres no timing to worry about as the half nuts are always engaged while threading.
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Hmmmmm.... My lathe has a forward and reverse on the leadscrew. But I don't know if it has a neutral. I've never tried it. I will have to look at it more closely. And even if it doesn't have one marked, it prolly must have a neutral zone of some sort. If so, this will be really cool discovery for me. After I get over the embarrassment of not know knowing about this, I will owe you two guys a case of beer each.

That said, I'm still struggling a bit here. How does disengaging the lead screw maintain the timing between the spindle and the lead screw? Throwing the lead screw into neutral stops the leadscrew from turning, but it doesn't stop the spindle from turning. Can't the spindle and leadscrew get out of sync by doing that? If the spindle turned a half turn extra, the threads would be messed up by a half thread. Isn't the whole idea of threading the concept of having x turns of the lead screw per y turns of the spindle? And isn't that ratio determined by the thread gearing?

I assume that there is a simple explanation for the above, so the obvious next question for me is - do I stop the lathe before I reverse the leade screw to avoid gear clash? Or is this done on the fly kinda feeling for it like on the half nut?
 
Susquatch said:
Hmmmmm.... My lathe has a forward and reverse on the leadscrew. But I don't know if it has a neutral. I've never tried it. I will have to look at it more closely. And even if it doesn't have one marked, it prolly must have a neutral zone of some sort. If so, this will be really cool discovery for me. After I get over the embarrassment of not know knowing about this, I will owe you two guys a case of beer each.

That said, I'm still struggling a bit here. How does disengaging the lead screw maintain the timing between the spindle and the lead screw? Throwing the lead screw into neutral stops the leadscrew from turning, but it doesn't stop the spindle from turning. Can't the spindle and leadscrew get out of sync by doing that? If the spindle turned a half turn extra, the threads would be messed up by a half thread. Isn't the whole idea of threading the concept of having x turns of the lead screw per y turns of the spindle? And isn't that ratio determined by the thread gearing?

I assume that there is a simple explanation for the above, so the obvious next question for me is - do I stop the lathe before I reverse the leade screw to avoid gear clash? Or is this done on the fly kinda feeling for it like on the half nut?
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Tumbler will not work, you will lose sync, and no clutch

on the SM, it just knows....you can let the spindle run for 10 mins, stop it, reverse it, and it will maintain sync. Clearly black magic built into the single dog clutch (the dog clutch is between the spindle and the beginning of the geartrain.)
 
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Darren said:
Tumbler will not work, you will lose sync, and no clutch

on the SM, it just knows....you can let the spindle run for 10 mins, stop it, reverse it, and it will maintain sync. Clearly black magic built into the single dog clutch (the dog clutch is between the spindle and the beginning of the geartrain.)
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I see..... Black magic eh...... LOL!

No tumbler on my lathe. Its a fully enclosed oil bath gear head. Mind you, I suppose there could be a small reversing tumbler inside there. But it feels more like a fork shifter.

It also turns out my leadscrew direction lever does have a neutral. In fact, it even has what sounds and feels like a ball detent. A detent for forward, a detent for reverse, and a detent for neutral - all with a fair bit of dead space between them.

But, no way is it syncronized in any way that I can detect. There are a lot of gear engagement positions between each rotation of the spindle.

Anyway, I am not complaining. I love my lathe and I love threading on it just the way it is. In fact, I even think that a system like you guys have might take some of the joy out of using it...... That's my story anyway...... ;)
 
Susquatch said:
Can you or @Darren explain how it does that? If it's too complicated, a link to a user manual would be fine. But please no youtube - I'd rather not know than go crazy o_O
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You asked for a written explanation, they are in the 2 links I provided. Step away from the keyboard for a second and read one or both :-) So much typing, so little reading :-) No black magic involved in the design.

Gerrit
 
gerritv said:
You asked for a written explanation, they are in the 2 links I provided. Step away from the keyboard for a second and read one or both :) So much typing, so little reading :) No black magic involved in the design.

Gerrit
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Sorry Gerrit. I was replying to Darren's post first, then I got some orders from my SWMBO.

I am not the sort who replies before reading what others provide. You took the time to write a reply, you didn't link me to YouTube, and you gave me some great info in your links. I appreciate the info you provided very much. I'm not gunna just throw that info to the wind. It is too bad that the boss lady got in the way of getting a timely reply to you. Or maybe it's too bad I didn't reply to your note before @Darren s.

Regardless, I have reviewed both links to understand how that works, and I also read the references you provided for an ELS. I can see how that all works. My reference to black magic was a direct reply to @Darren s comment calling it black magic.

I do love the ELS. Although, it's not likely going to be something I will actually do, it is something I appreciate knowing about. I spent a career designing and making things like that in the Auto industry. Now that I am retired and farming, I prefer to keep my finger on the pulse but put my energy into improving farm equipment. With a few exceptions (VFD system, DRO, Accessories, etc) my lathe and mill will still be mostly mechanical devices as they go to new homes after I pass on. That's not a indictment of how I feel about such things but rather a direct result of the priorities I choose as my life unfolds. I'd rather be making other things than automating my existing machines. That also applies to financial commitments. Nonetheless, my biggest priority of all is learning. The advancement of knowledge itself is one of my most important goals - it always was. And that's what drove me ask the questions.

A single tooth dog clutch certainly explains how that system maintains synchronization between the lead screw and spindle. But it doesn't explain how @Darren s lathe works - unless of course it has an internal single tooth engagement system too.......

In the meantime, and at the risk of repetition, I am not complaining. I love my lathe and I love threading on it just the way it is. In fact, I even think that a system like you guys have might take some of the joy out of using it......

Like @thestelster, I'm not running out and buying a new Hardinge any day real soon!

Thank you so much for teaching me something new.
 
Sorry, I get frustrated sometimes with ppl doing too much typing. Apologies for the snarkiness, and I am now summoned by Hers Indoors to find hole punches for fabric :)

I think I recall that the lathes having the feture Darren describes all have some implementation of the dog clutch. At one time I spent far too much time reading patents about lathes and gear hob tooth relieving, this threading method got in the mix somewhere.
When I got my lathe the Graham Meek solution came to mind, however my milling capabilites were not up to it. Now that I have a CNC gantry mill, I have the capability but instead I built the ELS. Because besides threading it also does tapers (excellent MT2) and turning to a diameter with multiple passes. All time savers after the initial implementation.
 
The single tooth dog clutch is at the spindle, before the gearing. Therefore the chuck is always in the same place relative to the geartrain/leadscrew.
 
In the hendey there’s an intermediate gearbox of sorts but the principle is the same.

The intermediate gearbox allows for isolating the spindle from any gears for best surface finish, driving the QCGB with a belt. The single tooth dog clutch is between the intermediate gearbox and the QCGB.

Some lathes like Monarch and Hardinge put the lever for the feed reverse on the apron and have stops that can be set to kick it into neutral at the end of a thread.
 
Susquatch said:
Here you go @thestelster. Affordable and plenty accurate enough for any threading job I do. Free shipping too!

Accusize Industrial Tools 0-1'' by 0.001'' Screw Thread Micrometer with 5 Anvil in Fitted Box, S916-C750 https://www.amazon.ca/dp/B0189RHDWS/ref=cm_sw_r_apan_i_KY35B39PGXBA8QFZP8G7?_encoding=UTF8&psc=1

Turns out that's what I have. But I got mine in a two micrometer set about 5 years ago - maybe more..... Mine are also only 1 thou mics. But that's plenty for the threading I do.
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I have multiple ones. They are not that expensive used, usually same price a regular mic is - and used mics are cheap.
 
Susquatch said:
As for his threading wire advice, he can go fly a kite. Those things are a fiasco and I hate them. Give me a good threading Micrometer all day every day. Well worth the investment. And just skip right over those dumb wires and all the fancy gizmos out there to hold them. All junk in my humble opinion.
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Over the years I've been fortunate to collect thread mics up to 4", all like new mitutoyos....fancy stuff and they are handy.

But I wouldn't be without thread wires. 1) they're only a few dollars until you luck out and trip over a pile of Mit thread mics, but 2), and most importantly you can use them to measure any thread. I've used them for acme, buttress, BA and Whitworth - they save the day over and over. Armed with the formulas below you can measure about any thread

Handling them can be a pain, but you can use a bit of plastercine, inner tube with a slit or grease. All work....and I just happen to have some pics!


thread-wire-formulas-threadcheck-1300x1536.jpg



DSC_5185-large.JPG


DSC_9729-large.JPG


DSC_9731-large.JPG
 
gerritv said:
Sorry, I get frustrated sometimes with ppl doing too much typing. Apologies for the snarkiness, and I am now summoned by Hers Indoors to find hole punches for fabric :)
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No sweat Gerrit. I know the feeling....... No offense taken at all. I hope the tone of my reply conveyed that well.

Again, thank you!

Prolly no cnc or els for me. But never say never..... ;)
 
Darren said:
The single tooth dog clutch is at the spindle, before the gearing. Therefore the chuck is always in the same place relative to the geartrain/leadscrew.
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Got it!

Wish I could convey thought so quickly and suscinctly as you do......
 
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