Stepper short list on VM32L Weiss mill advice - low inductance

Hello everyone,

Been out the picture for a while due to health reasons however I am now finally designing my CNC conversion for my VM32l.

I have read loads of posts and spoken to various members - and from their excellent advice I have finally narrowed it down.

The mill will be fitted with Ballscrews (2005 on Z / 1605 on X and 1605 / 2005 on the Y undecided still ) and driven directly (no reduction/ gearing )

Power will be the custom Toroidal power supply - as in many of the forums.

The Z already has a internal gas strut.


I have 3x drivers already - (0~7A - 18-80V DM860H) DM860H - however I can sell or save these.


After looking at low inductance I have the following shortlist for all 3x axis:


This stepper with above drivers (0~7A - 18-80V DM860H)

4 Wire- Inductance: 1.85 mH ± 20%(1KHz) - Holding Torque: 4Nm(566.4oz.in)


or a Closed Loop Kit

4 wire - Inductance: 1.8 mH ± 20%(1KHz) - Holding Torque: 3 Nm(424.92 oz.in) with 0~7A（0~5 RMS）+24~50VDC (Typical 36VDC) Driver

or

Closed Loop with separate Driver for the extra vdc

4 wire - Inductance: 1.8 mH ± 20%(1KHz) - Holding Torque: 3 Nm(424.92 oz.in)

0~8.5A（0~6 RMS） - 20~80VAC/30~110VDC (Typical 48/60VDC)

I have tried to keep inductance below 2.0

Any other suggestions are welcome including different motors for different axis and nema 34's etc; however re the torque curves, I see very little benefit and they have a higher MH (3 and upwards)


BONUS QUESTION :encouragement:

How much roughly do people pay re customs and VAT form BST for ballscrews - working on costings

Many Thanks

Mike

I found that trying to get a decent torque rating with a good low inductance was nigh on imposible in the crappy uk. There's a lot of junk around!!!
I'm using these 4nm (566oz) 3mh ind steppers in parallel with 60v psu on my Amat25lv and don't regret it so far.
https://www.cnc4you.co.uk/Stepper-Mo...H401-03-Nema23
Bit pricey this company though.

I'd go with this closed loop myself. Wish I'd gone this route earlier.
https://www.omc-stepperonline.com/cl...2CNema%2024%5D
Now. It's 2.6mh but when compared with the one you linked that's 1.8mh
https://www.omc-stepperonline.com/cl...1%2C1168.53%5D
The torque curve looks the same for both once you get past 500rpm.
So this 566oz in my view is just as good for speed but should give better acceleration as it's higher at the start of the chart.
Get the AC driver and just stick a toroidalol it.


However. I just looked at your very first standard stepper one
https://www.omc-stepperonline.com/ne...m-4-wires.html


If I wanted closed loop I'd go with the 566oz and if I wanted open loop I'd stick with the 495oz.
I'd likely use AC drivers either way.
Wish you'd linked these a couple of month ago :rolleyes:


My machine is slightly lighter than yours though but I can't see the table and carriage on yours being massively far off it.

Many thanks for the info -

Would you have any recommendations for some good AC driver for open and closed loop setups ?

Thanks

If your going to go with Closed loop then your better going with 3 phase closed loop. The step angle is 1.2deg instead of 1.8deg so much smoother and the extra phase gives them a bit more torque higher up the speed curve. Only down side is they only come with 50Vdc Max drives unless you go upto Nema 34.

I've fitted loads of these and this company is good to deal with.

https://www.aliexpress.com/item/3303...61cf761f3tsKRK

RE Vat then it's dependant on the amount declared on the customs paper work (and there in lies a clue to getting it down) usualy there is no import duty other than a rip off fee of around £15- £20 the shipping agent charges for paper work.

Quote:

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Originally Posted by dazp1976

So this 566oz in my view is just as good for speed but should give better acceleration as it's higher at the start of the chart.

---

Don't be fooled by those Speed/torque charts, in my experience they are unrealistic bullshit, they mean nothing in real world use.!!

Quote:

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Originally Posted by JAZZCNC

If your going to go with Closed loop then your better going with 3 phase closed loop. The step angle is 1.2deg instead of 1.8deg so much smoother and the extra phase gives them a bit more torque higher up the speed curve. Only down side is they only come with 50Vdc Max drives unless you go upto Nema 34.

I've fitted loads of these and this company is good to deal with.

https://www.aliexpress.com/item/3303...61cf761f3tsKRK

RE Vat then it's dependant on the amount declared on the customs paper work (and there in lies a clue to getting it down) usualy there is no import duty other than a rip off fee of around £15- £20 the shipping agent charges for paper work.

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Thanks Dean,

They probably the best performance to cost ratio currently ? As still have the ballscrews to purchase so trying to get good performance as like everyone I have a budget :untroubled:

This will be paired with UCCNC and a u300eth (bought already) - If I get these I may need help wiring hehe

also would the 50Vdc make a massive difference compared to a 2 phase with 70-80Vdc driver

thanks again

Quote:

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Originally Posted by Hulksmash

also would the 50Vdc make a massive difference compared to a 2 phase with 70-80Vdc driver

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Yes it will mostly make a difference to the speed but not by a massive amount, roughly 300rpm, these will give 1200rpm and the others will be 1500rpm.
They are not exactly like a standard stepper system and the encoders come into play so can restrict the speeds.

If I wanted to have excess power and plenty of speed along with AC drives then I'd fit these and sacrifice the smoothness 3phase offers as they are 2 phase.
Nothing gets close to these for power in the Nema 24 range. Again I've fitted plenty.

https://www.aliexpress.com/item/3279...16523421DXQOr7

The wiring is easy enough just shout if you need help.

Thanks again will go take a look

Quote:

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Originally Posted by JAZZCNC

Yes it will mostly make a difference to the speed but not by a massive amount, roughly 300rpm, these will give 1200rpm and the others will be 1500rpm.
They are not exactly like a standard stepper system and the encoders come into play so can restrict the speeds.

If I wanted to have excess power and plenty of speed along with AC drives then I'd fit these and sacrifice the smoothness 3phase offers as they are 2 phase.
Nothing gets close to these for power in the Nema 24 range. Again I've fitted plenty.

https://www.aliexpress.com/item/3279...16523421DXQOr7

The wiring is easy enough just shout if you need help.

---

Not fair!!!!! :grumpy::upset::miserable::sorrow:
Just looked at buying 2 and it wants £90 shipping?????

Quote:

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Originally Posted by dazp1976

Not fair!!!!! :grumpy::upset::miserable::sorrow:
Just looked at buying 2 and it wants £90 shipping?????

---

email them.

I spoke to Annie from there. The postage is between 90 and 140 USD. This is because of the virus and very few flights. Also you will get a better price going via Alibaba with them. She said better to wait till things get back to normal

Quote:

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Originally Posted by Hulksmash

I spoke to Annie from there. The postage is between 90 and 140 USD. This is because of the virus and very few flights. Also you will get a better price going via Alibaba with them. She said better to wait till things get back to normal

---

Yes I'm getting the same problem with stuff sent via Air. If your in no rush then wait it out, it will come down sooner or later.

Quote:

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Originally Posted by JAZZCNC

Yes it will mostly make a difference to the speed but not by a massive amount, roughly 300rpm, these will give 1200rpm and the others will be 1500rpm.
They are not exactly like a standard stepper system and the encoders come into play so can restrict the speeds.

If I wanted to have excess power and plenty of speed along with AC drives then I'd fit these and sacrifice the smoothness 3phase offers as they are 2 phase.
Nothing gets close to these for power in the Nema 24 range. Again I've fitted plenty.

https://www.aliexpress.com/item/3279...16523421DXQOr7

The wiring is easy enough just shout if you need help.

---

Jazz. I was wondering if you could clear something up for me. I was looking at these motors and drives you recommended and on the pics it says 20-70v ac. Is that correct or is it 220 ac straight input.

Quote:

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Originally Posted by johngoodrich

Jazz. I was wondering if you could clear something up for me. I was looking at these motors and drives you recommended and on the pics it says 20-70v ac. Is that correct or is it 220 ac straight input.

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Yes John it's 20-70Vac or 30-100Vdc. The AC option Just saves messing around with Bridge and Caps but still need a transformer to get from 230Vac to 20-70Vac.

Some of the Larger Nema 34's drives like these work direct from 230Vac mains. These are great for larger machines because they spin fast and have loads of torque.
https://www.aliexpress.com/item/3279...3cac6f37mUvHpT

Ok fair enough. I might still get some as I would like to go closed loop and I can run them at higher DC voltage than I am at the moment anyway. Currently at 68vdc but could get them up to 90 to get a bit more oomph

I haven't used close loop steppers myself yet, but just had an open loop stepper stall that messed up a piece with a lot of work in it. If I was building a new machine I would only go with closed loop.