Anyone assembling the Clough42 Electronic Leadscrew system? I have questions...

[luxige]

I’m sure I’ll have many, many questions, but first and foremost is figuring out how much servo motor I will need.

Here is the open-source project I’m talking about:

Lathe Electronic Leadscrew

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James is driving the combination feed/leadscrew of his Grizzly G0602 benchtop lathe (10x22”, 1hp, 432 lb. shipping weight) using a Nema23 hybrid servo of 282 oz/in, about 2 N-m.

My lathe is 70s vintage, unknown maker, 12x36”, 3hp, about 1500 lb. Obviously I need a bigger servo, but I really have no idea how to go about calculating the torque I need. For now, my only idea has been to search for a CNC conversion kit for a similar lathe and see what they spec.

Picture below shows the condition of the QCGB and the reason I’m planning this conversion:

 

[luxige]

And the next question is what’s a good source of cogged belts and wheels in small sizes?
North America shipper preferred.

I’ll need a small set to drive the encoder from the spindle, and something larger to drive the feed shaft with the servo.

 

[RJSakowski]

I’m sure I’ll have many, many questions, but first and foremost is figuring out how much servo motor I will need.

Here is the open-source project I’m talking about:

Lathe Electronic Leadscrew

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

www.youtube.com

James is driving the combination feed/leadscrew of his Grizzly G0602 benchtop lathe (10x22”, 1hp, 432 lb. shipping weight) using a Nema23 hybrid servo of 282 oz/in, about 2 N-m.

My lathe is 70s vintage, unknown maker, 12x36”, 3hp, about 1500 lb. Obviously I need a bigger servo, but I really have no idea how to go about calculating the torque I need. For now, my only idea has been to search for a CNC conversion kit for a similar lathe and see what they spec.

Picture below shows the condition of the QCGB and the reason I’m planning this conversion:

You pose a very good question. There is a long thread on the ELS subject which discusses this.

electronic lead screw

I'm wondering what is state of the art for electronic lead screws these days and if anyone has advise based on implementing on on an import lathe?

www.hobby-machinist.com

For my part, I installed the ELS I have a 602oz-in hybrid stepper on my lead screw with 2:1 gear reduction driving with a 42 volt switching supply @ 8 amps.. My G0602 lead screw has 12 tpi. I ran some tests where my carriage is lifting a bucket of lead over a pulley. The stepper started to lose steps at around 3.5 mm/rev. at the lead screw and a dead weight of 105 lbs. which corresponded to 890 rpm at the stepper. (post #287)

You will find out that torque on a stepper motor drops fairly quickly with increasing speed. Also, lead screws are very inefficient at transmitting power. The finer the pitch, the more inefficient it is so although you get more torque multiplication as the pitch becomes finer, the efficiency loss eats up a lot of that gain. On contrast, my Tormach mill with ball screws uses 600 oz-in steppers with no issues.

I would suggest that you pour yourself a couple of your favorite beverages and start reading the above thread. If you have any questions after that, we'll try to help. Rather than continue with this thread, they would probably be best added to the above thread so we can keep all the discussion in one place.

 

[RJSakowski]

And the next question is what’s a good source of cogged belts and wheels in small sizes?
North America shipper preferred.

I’ll need a small set to drive the encoder from the spindle, and something larger to drive the feed shaft with the servo.

You can try here. http://shop.sdp-si.com/catalog/product/?id=A 6R51M150030
I bought mine on e-bay and some came from China. The delivery time was around two ro three weeks (pre COVID 19) Some parts were sourced stateside and came within a week.

On your first question, this may be of use.
https://www.daycounter.com/Calculators/Lead-Screw-Force-Torque-Calculator.phtml The big unknown is how much force do you need at the carriage to make the type of cuts that you want.

 

[luxige]

You can try here. http://shop.sdp-si.com/catalog/product/?id=A 6R51M150030
I bought mine on e-bay and some came from China. The delivery time was around two ro three weeks (pre COVID 19) Some parts were sourced stateside and came within a week.

On your first question, this may be of use.
https://www.daycounter.com/Calculators/Lead-Screw-Force-Torque-Calculator.phtml The big unknown is how much force do you need at the carriage to make the type of cuts that you want.

Thanks and thanks again!
I’ll check into the thread you referenced and continue there.

Re: pulleys etc., I did find Polytech Design, looks like quality but a little pricey. However, they are stateside.

 

[RJSakowski]

Thanks and thanks again!
I’ll check into the thread you referenced and continue there.

Re: pulleys etc., I did find Polytechnic Design, looks like quality but a little pricey. However, they are stateside.

That's the reason that I went across the pond for my belts and pulleys. I couldn't find any flaws in mine FWIW.
encoder pulleys https://www.ebay.com/itm/401625859109
stepper pulleys https://www.ebay.com/i/173908654969?ul_noapp=true
encoder belts https://www.ebay.com/itm/142829943316 (I ordered two different lengths as I didn't have a final position for the encoder)
stepper belt https://www.ebay.com/itm/3M-HTD3M-3...83.l10137.c10&nordt=true&rt=nc&orig_cvip=true

 

[ttabbal]

Electronic Lead Screw

I'm going to attempt to adapt clough42's ELS to my PM1127. I figure I might as well do it publicly in case it ends up being useful for someone else. I have most of the parts now, and have the electronics and servo running on the bench. The first thing I decided to mess with is the rotary...

www.hobby-machinist.com

My build on a smaller lathe. For yours, you will likely need a bigger servo to not be limited by it. I would probably go about 2x the torque.

For belts and pulleys, I went with a vendor in China on ebay. The cost was a small fraction of the local sources, and look identical. I ended up buying one from a US source for speed, I couldn't tell the difference. For the smaller size GT2 stuff, Amazon had a decent selection. Not that they would be faster than direct from China these days.

 

[kb58]

I finished mine about 6 months ago. Yeah the required torque is nearly impossible to calculate due to all the variables. Just guess, really. Pick one maybe twice as strong as what he chose, and you can further increase torque with the gear ratios. As far as where to buy the belts and gears from, I used the place he recommended, which as I recall was on Long Island, NY, can't remember the name though, sorry.

 

[luxige]

That's the reason that I went across the pond for my belts and pulleys. I couldn't find any flaws in mine FWIW.
encoder pulleys https://www.ebay.com/itm/401625859109
stepper pulleys https://www.ebay.com/i/173908654969?ul_noapp=true
encoder belts https://www.ebay.com/itm/142829943316 (I ordered two different lengths as I didn't have a final position for the encoder)
stepper belt https://www.ebay.com/itm/3M-HTD3M-3...83.l10137.c10&nordt=true&rt=nc&orig_cvip=true

Again, extremely useful; and again, greatly appreciated!
Now that I see a few pertinent products, I have the right terminology to search on. Although I may just go with the same vendors you did.

 

[luxige]

Electronic Lead Screw

I'm going to attempt to adapt clough42's ELS to my PM1127. I figure I might as well do it publicly in case it ends up being useful for someone else. I have most of the parts now, and have the electronics and servo running on the bench. The first thing I decided to mess with is the rotary...

www.hobby-machinist.com

My build on a smaller lathe. For yours, you will likely need a bigger servo to not be limited by it. I would probably go about 2x the torque.

For belts and pulleys, I went with a vendor in China on ebay. The cost was a small fraction of the local sources, and look identical. I ended up buying one from a US source for speed, I couldn't tell the difference. For the smaller size GT2 stuff, Amazon had a decent selection. Not that they would be faster than direct from China these days.

Excellent! That’s a really nice looking installation.
I took a quick run through your thread, and I’ll go back and study it carefully tomorrow. I have some questions that I will post there. TIA