Tips/Techniques ELS discussion. Options. Experiences.

[Susquatch]

Perhaps formulae could be employed to calculate the feed force?

Here is an article that delves into the subject of lathe power required. They do calculate the feed force as well.

Thanks @RobinHood! Looks like I have some reading to do tomorrow.....

 

[Dabbler]

I have read - and I have no experience here - that typical socket type torque wrenches are inaccurate at rotation rates above a very low minimum. Something very well emphasized by the guys that make wireless torque devices for higher RPM applications.

I'm not partisan here, I'll check both methods against one another...

To be clear, the torque needs to be checked doing a cut at some traversing speed, say .007 per rev at 300 RPM or something, which might translate to .210 ips leade or 1.6 RPS - just under 100 RPM on an 8TPI lead screw.

 

[ducdon]

YES I am an C0636 owner. I would be willing to participate in a group focused on the C0636. However Electronic Lead Screws, digital readouts and such aren't currently in my budget or on my agenda.

 

[Susquatch]

I have read - and I have no experience here - that typical socket type torque wrenches are inaccurate at rotation rates above a very low minimum. Something very well emphasized by the guys that make wireless torque devices for higher RPM applications.

I can see that. Prolly a result of large variations and data rates too slow to digitize and track them. An analog manual gauge might be better. But you have me on this one too. I just don't know.

 

[gerritv]

Our new lathe is similar design... I'd be interested in our proposed methodology for measuring the torque requirements and participating. I'm going to convince my brother to upgrade this lathe to a smart lathe... not an ELS because I definitely want radius and taper turning in addition to threading.

Rocketronics ELS 4 Pro is your answer. I don't recall if John's does those funstions as well. Well worth the time to read through both manuals.

 

[TorontoBuilder]

Rocketronics ELS 4 Pro is your answer. I don't recall if John's does those funstions as well. Well worth the time to read through both manuals.

Rocktronics does seem to be the ticket, especially since someone (janger I think) told me I don't need a pendent to use the lathe in manual mode.

I can always think of another electronics project...

 

[gerritv]

Rocktronics does seem to be the ticket, especially since someone (janger I think) told me I don't need a pendent to use the lathe in manual mode.

I can always think of another electronics project...

that was me. I bought their expansion board instead of the pendant. It will get an MPG and maybe a joy stick instead of buttons for x/z moves. I have though touched the pendant a friend bought, very well made.

This manual is worth looking over, all buttons are available on the expansion board. https://www.rocketronics.de/shop/en/handwheel-pcb.html I'm usre that with the addition of some smarts it can be made even more useful, e.g. sensing that you are using a X mpg, then enabling the x axis button etc.

 

[TorontoBuilder]

that was me. I bought their expansion board instead of the pendant. It will get an MPG and maybe a joy stick instead of buttons for x/z moves. I have though touched the pendant a friend bought, very well made.

This manual is worth looking over, all buttons are available on the expansion board. https://www.rocketronics.de/shop/en/handwheel-pcb.html I'm usre that with the addition of some smarts it can be made even more useful, e.g. sensing that you are using a X mpg, then enabling the x axis button etc.

sorry my memory is not the greatest. I appreciated that input very much.

 

[whydontu]

I have read - and I have no experience here - that typical socket type torque wrenches are inaccurate at rotation rates above a very low minimum. Something very well emphasized by the guys that make wireless torque devices for higher RPM applications.

I'm not partisan here, I'll check both methods against one another...

To be clear, the torque needs to be checked doing a cut at some traversing speed, say .007 per rev at 300 RPM or something, which might translate to .210 ips leade or 1.6 RPS - just under 100 RPM on an 8TPI lead screw.

Ok, super-kluge test.

My 3/8" click torque wrench goes down to 20 in-lbs. Video attached of it in my vice, one finger click.

1.040" diameter chuck of 303 stainless round bar.

Cheap carbide bit

My handy-dandy RPM chart says 375 RPM for 1" 303 stainless at 100 SFM is a reasonable cut using my lathe.

400 RPM

0.050" depth of cut

Torque wrench attached to lead screw using a genuine Craftsman 1975 1/2" x 1/2" drive check (use with an impact gun to sub for a hammer drill). No gears, driving direct at 7TPI.

No click. Couldn't get any cut that would trip the torque wrench at 20 in-lbs of torque. My guess with uncalibrated finger is leadscrew torque is significantly less then 10 in-lbs.

 

[YYCHM]

This video is private?

 

[whydontu]

This video is private?

fixed it. I had the wrong settings in YouTube

 

[Susquatch]

Ok, super-kluge test.

My 3/8" click torque wrench goes down to 20 in-lbs. Video attached of it in my vice, one finger click.

1.040" diameter chuck of 303 stainless round bar.

Cheap carbide bit

My handy-dandy RPM chart says 375 RPM for 1" 303 stainless at 100 SFM is a reasonable cut using my lathe.

400 RPM

0.050" depth of cut

Torque wrench attached to lead screw using a genuine Craftsman 1975 1/2" x 1/2" drive check (use with an impact gun to sub for a hammer drill). No gears, driving direct at 7TPI.

No click. Couldn't get any cut that would trip the torque wrench at 20 in-lbs of torque. My guess with uncalibrated finger is leadscrew torque is significantly less then 10 in-lbs.

Kudos to you @whydontu for being the first to try "something". Now we all have something to shoot at and build on.

FWIW, I was not expecting a big number at all. So, what did we learn here?

Another number to play with is the shear pin. Mine is a 4mm double acting brass pin at a shear diameter of 0.875. I'll have to calculate that failure torque later cuz I don't have the shear strength of brass handy.

 

[whydontu]

Kudos to you @whydontu for being the first to try "something". Now we all have something to shoot at and build on.

FWIW, I was not expecting a big number at all. So, what did we learn here?

Another number to play with is the shear pin. Mine is a 4mm double acting brass pin at a shear diameter of 0.875. I'll have to calculate that failure torque later cuz I don't have the shear strength of brass handy.

What I learned is the 1600 oz-in / 100 in-lb NEMA34 stepper is probably overkill, and I’ll use it for something else. The NEMA 23 stepper at 425 oz-in should work just fine. NEMA 23 only weighs 3 lbs so shouldn’t put much stress on the change gear banjo.

Math gets better. My lead screw is 7TPI, so a 70-tooth gear on the stepper and a 100-tooth on the lead screw makes a virtual 10 TPI lead screw, so the Arduino math is simpler, and the stepper RPM / pulse rate is increased 30%, but still over at the left side of the torque graph.

I even found a torque graph!

 

[whydontu]

The other thing I learned is I’m hijacking a thread regarding a lathe I don’t own. Somehow I got confused between the ELS thread I started, and this thread on C0636 lathes. Probably when I did a search for ELS, then down the rabbit hole! My apologies. So my torque measurements are likely useless for a C0636. Maybe not, YMMV.

 

[Former Member]

Ok, super-kluge test.

My 3/8" click torque wrench goes down to 20 in-lbs. Video attached of it in my vice, one finger click.

1.040" diameter chuck of 303 stainless round bar.

Cheap carbide bit

My handy-dandy RPM chart says 375 RPM for 1" 303 stainless at 100 SFM is a reasonable cut using my lathe.

400 RPM

0.050" depth of cut

Torque wrench attached to lead screw using a genuine Craftsman 1975 1/2" x 1/2" drive check (use with an impact gun to sub for a hammer drill). No gears, driving direct at 7TPI.

No click. Couldn't get any cut that would trip the torque wrench at 20 in-lbs of torque. My guess with uncalibrated finger is leadscrew torque is significantly less then 10 in-lbs.

I think if you go back in the thread you'll see I said 100 in oz which is about 6 in lbs. Problem with a clicker is you need to set and test. Digital is best with peak reading or old school beam type with a tracer needle on it (simple enough to fix up).

https://www.amazon.ca/Performance-Tool-M195-Newton-meter-Torque/dp/B00SNICDJC/ref=mp_s_a_1_6?crid=EKROPATAT8LQ&keywords=1%2F4+beam+torque&qid=1671628163&sprefix=1%2F4+beam+torque+%2Caps%2C97&sr=8-6

 

[slow-poke]

I realize this thread is a bit old, but I'm going to contribute another data point. On my ELS equipped CX706 lathe, I'm using what I originally thought was likely a too small stepper (I used what I had on hand to try out the concept), and since it worked I have not bothered to upgrade it yet. I have cut some threads and it works well however I have NOT done exhaustive testing.

I'm using a NEMA23, 1.9Nm, the gear ratio between the stepper and the transmission is 1:2, and I'm using position C in the transmission for another 1:2, so the leadscrew turns at 1/4 of stepper motor speed.