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What spindle motor should I use?

TorchHypnosis

Plastic
Joined
Apr 8, 2019
Location
Lacey WA, USA
Hello, and thank you for reading. I built a mill/lathe hybrid to manufacture graphite tools for glassblowers as a proof of concept. I made my own spindles out of parts from McMaster-Carr and McGuire bearing (that's a lot of Mc's) and drive the spindles with a blower motor and for the end mill tool a vacuum cleaner motor (because the RPMs were ball park) but it is now time for me to step up my machine now that I know my proof of concept checks out, and I have already started production.

The lathe turns at about .75 revolutions per second, which turns the graphite blank I am milling. The end mill turns at about 30,000 RPM's. I am milling high density fine grain EDM graphite. I already purchased a variable frequency drive, 2.2 kw. I bought a Telemechanique French made one because I didn't want to purchase a Chinese VFD because I wanted support on the unit. I would (of course) rather buy a high end spindle motor made in Germany, Italy or the States, but I simply cannot afford one at this time. I am looking at some Chinese HSD clones. What I am looking at are the square ones with ceramic bearings. I know I need ceramic bearings, but I do not know what RPM's to get, there is one that spins at 18,000, and there is another spinning at 24,000. I know for the rough cuts, slower RPM's is better. I understand the spindle will heat up if the VFD sets the RPM's too low...I'm thinking I need the 24,000 model, but I am not sure. But, MOST IMPORTANT, when it comes to the Chinese spindles, the way they rate their watt usage is not the same as how German, US and Italian manufacturers rate their watt rating. I think I may need to get a 4 kw spindle motor to be driven by my 2.2 kw VFD just to have the headroom. Is that going to break my inverter? Is a 4 kw motor going to draw more of a load, or does it just have more power? Any information anyone can give me on how many amps a spindle will draw would be helpful. I don't want to trigger safety on my inverter (I need it to RUN!) or burn any of my components out. Does this make sense? Thanks again!
 
See my post in this thread from like 20mins ago: Hyrbrid Steppers : Encoder Resolution vs Microsteps
Substitute spindle motor for servos.

tl;dr when it comes to picking a chinesium spindle, the DIY router guys over at the 'zone know the good from the bad and will nerd out over stuff with you. I bet someone there has the power data you seek as well.
Professionally made industrial CNC discussion: Here.
DIY stuff of pretty much any variety: there.

Not trying to gatekeep too hard, but it's a thing. each site has it's own distinct purpose, knowledge base, and audience.
 
Thank you for your response. I'm not sure what you are trying to say here, it sounds like you are saying that DIY's should be posting on another thread. I am sorry if I am posting inappropriately, I wasn't sure which thread I should be posting on. I am a systems engineer, rooted in automation (mostly Allen-Bradley) so I would not consider myself a DIY'r. I run a manufacturing business and since I am an engineer, I think outside the box. I did, however, build myself a mill, NOT rooted in G code. I'm using Ladder Logic on a Compact Logix L45 PLC. It has been a while since I have had to do any electrical engineering outside of "plug and play". I THINK that using a 4 kw motor will draw more of a load than a 2.2 kw motor...so I am inclined to think that I should just stick to a 2.2 kw spindle motor to use with my 2.2 kw VFD. But some things I read lead me to believe that because of how Chinese manufacturers rate the watt ratings in their motors make it difficult to match a VFD with a spindle motor as a Chinese 2.2 kw motor is roughly equivalent to a 1.5 kw motor from Germany, Italy or the US, I feel like I should be purchasing a higher watt rating spindle motor than my VFD if I am purchasing a Chinese made. Sorry if I did not explain myself well. Again, thank you for your response. -Monte
 
Thank you Jacques, I did look at the video and sent the manufacturer an email. I hear the square spindles are better than the round ones, but I am not dedicated to either at this point. I am at a loss because I cant spend $2,000 US dollars on a spindle motor right now, so I'm going to have to pick a Chinese one, but I think I am going to have to pick one up on eBay because of their buyers protection policy. I cannot have one DOA. But That guy, Fox, on the video did make me very interested in the Jian-Ken spindle motors. That kind of review cannot be faked...but at the same time I dont want to throw my money at a Chinese distributor when I don't know what kind of support they will offer. Fox said that they had excellent customer support, with regards to wiring and pneumatics, but what I cant have happen is I receive a unit DOA and not get a functioning unit in a timely manner. But thanks for this post, I might very well get a Jian-Ken spindle motor anyway, this Fox guy sounded German, and if a German guy is using Chinese equipment then it MUST be good...I dont know what I will buy tomorrow, but I am definitely considering one from Jian-Ken. Looks like a solid product. My buddy bought a famous scooter company and got some of the parts made in China. The first three Chinese manufacturers told him what he wanted to hear, and then he spoke with another Chinese manufacturer that told him what he DIDN'T want to hear, and he ended up going with them...because they told him that if they changed the piston size, they would have to change all these other things...and if they changed the exhaust size, they would have to change a bunch of other things...other Chinese manufacturers told him, "yea, we can do dat, yea, no probrem", but the one company that he ended up going with was straight up and told him how the engineering of his bike would have to be changed with every modification he was trying to make happen. Point being it can be hard finding a quality Chinese product, but they are out there...my friend's bikes beat Honda. Hopefully I hear back from Jian-Ken before I make my purchase. Thanks again!
 
Thank you for your response. I'm not sure what you are trying to say here, it sounds like you are saying that DIY's should be posting on another thread. I am sorry if I am posting inappropriately, I wasn't sure which thread I should be posting on. I am a systems engineer, rooted in automation (mostly Allen-Bradley) so I would not consider myself a DIY'r. I run a manufacturing business and since I am an engineer, I think outside the box. I did, however, build myself a mill, NOT rooted in G code. I'm using Ladder Logic on a Compact Logix L45 PLC. It has been a while since I have had to do any electrical engineering outside of "plug and play". I THINK that using a 4 kw motor will draw more of a load than a 2.2 kw motor...so I am inclined to think that I should just stick to a 2.2 kw spindle motor to use with my 2.2 kw VFD. But some things I read lead me to believe that because of how Chinese manufacturers rate the watt ratings in their motors make it difficult to match a VFD with a spindle motor as a Chinese 2.2 kw motor is roughly equivalent to a 1.5 kw motor from Germany, Italy or the US, I feel like I should be purchasing a higher watt rating spindle motor than my VFD if I am purchasing a Chinese made. Sorry if I did not explain myself well. Again, thank you for your response. -Monte

Here at Practicalmachinist.com we don't do hack saw, DIY, trash, junk, noname bullshit. Is that clear enough? Go to a different site for toys.

R
 
Here at Practicalmachinist.com we don't do hack saw, DIY, trash, junk, noname bullshit. Is that clear enough? Go to a different site for toys.

R

Look, litlerob, I think there may be a misunderstanding. Allen-Bradley is high end, the Tesla of automation equipment. All three of my axis servos are Allen-Bradley, as well as my contact relays. My fiberoptic units for motion control are Allen Bradley Kinetix 6000, all being driven by Allen Bradley CompactLogix L45 PLC. And I don't just have the PLC, I have the SERCOS unit, a profibus moodule, and TONS of I/O. This machine is COMPLETELY built by me, as well as programmed. Just because I engineered the mill I use for production every day myself does not place it in the same category as some of the sub par stuff you see from the "DIY'ers". I started production only last year and my lampworking tools are already truer and more lathe worthy than all three of my competitors. I attribute this to the fact that I had to build a custom machine in order to gain the "edge".

But yes, If I want to talk toys, I will go to a different site. Thanks.
 
Look, litlerob, I think there may be a misunderstanding. Allen-Bradley is high end, the Tesla of automation equipment. All three of my axis servos are Allen-Bradley, as well as my contact relays. My fiberoptic units for motion control are Allen Bradley Kinetix 6000, all being driven by Allen Bradley CompactLogix L45 PLC. And I don't just have the PLC, I have the SERCOS unit, a profibus moodule, and TONS of I/O.

And then you want to put some cheap Chinese POS spindle on your A-B "Tesla of automation" equipped machine? The cheap Chinese spindles are the domain of the low end DIY crowd. Seriously, you will get better advice on a DIY forum.

BTW, A-B's long since gone the way of dinosaurs as far as the CNC machine control world. Anyone else remember the 8400????
 
Look, litlerob, I think there may be a misunderstanding. Allen-Bradley is high end, the Tesla of automation equipment. All three of my axis servos are Allen-Bradley, as well as my contact relays. My fiberoptic units for motion control are Allen Bradley Kinetix 6000, all being driven by Allen Bradley CompactLogix L45 PLC. And I don't just have the PLC, I have the SERCOS unit, a profibus moodule, and TONS of I/O. This machine is COMPLETELY built by me, as well as programmed. Just because I engineered the mill I use for production every day myself does not place it in the same category as some of the sub par stuff you see from the "DIY'ers". I started production only last year and my lampworking tools are already truer and more lathe worthy than all three of my competitors. I attribute this to the fact that I had to build a custom machine in order to gain the "edge".

But yes, If I want to talk toys, I will go to a different site. Thanks.

Ohhh shit, the "Tesla" of a thing must mean it's good? I'm sorry.
 
And then you want to put some cheap Chinese POS spindle on your A-B "Tesla of automation" equipped machine? The cheap Chinese spindles are the domain of the low end DIY crowd. Seriously, you will get better advice on a DIY forum.

BTW, A-B's long since gone the way of dinosaurs as far as the CNC machine control world. Anyone else remember the 8400????

Your right on the cnc world but in the industrial automation they are one of the most expensive systems out there.
I would rather get a used good spindle then a chinese.

Edit:
Instead of discussing if its professional or diy, i'll just say i will be surprised if you will get the answer you are looking for on this forum.
 
Dick wagging aside,

Milling graphite, for your needs one of the half decent Chinese spindles should work fine, i would go water cooled for certain though, to avoid cooling issues when the graphite dust builds up. Some of the better ones even have air purge which may well be a benefit to you too.

Ceramic bearings are great at speed, just remember, they don't like to crash. Weather you like it or not, on any rolling element bearing north of 10K you have a limited life span, north of 20K your going to have to change em once in a while, not once or twice in a typical machine life span but in the low single digit month range at best if running a decent number of hours a day. I don't know - have never worked out if the extra life of ceramic pays off over just changing out cheaper conventional bearings more often.

Sure the cheapest chinese spindles are not the best, but the middle of the road can make you money, equally you can buy a lot of Chinese spindles for the cost of a supposed superior one and trust me even the superior ones won't run forever. In fact i would go as far to say having a Chinese spindle in the machine and a spare on the shelf is probably a lot better way to garrentie uninterrupted production than just relying on the one high quality option.

Im in the own machinery to make money camp, not own machinery to show off. I expect a return on my kit, i aim for sub single digit months of production before it starts making me money. if your already outdoing the competition, ignore the nay sayers, some one richer can always go out and buy more machine than you, yeah, they will have machine tool sales guys sucking em off, yeah they will have finance suppliers doing the same and probably a bank manager that takes em golfing. Because there the people that are actually making the money out of the expensive machinery!
 
.....Im in the own machinery to make money camp, not own machinery to show off. I expect a return on my kit, i aim for sub single digit months of production before it starts making me money. if your already outdoing the competition, ignore the nay sayers, some one richer can always go out and buy more machine than you, yeah, they will have machine tool sales guys sucking em off, yeah they will have finance suppliers doing the same and probably a bank manager that takes em golfing. Because there the people that are actually making the money out of the expensive machinery!

Nobody is telling the OP that he can't or won't make money with the machine he built. I also don't see any posts where anyone is bragging up their expensive machine versus a DIY machine. Almost all the threads have politely tried to point the OP to a different forum where folks have more experience and knowledge of the type spindle he is looking at.

Are all Chinese spindle crummy? I'm sure they are not. So far I only have experience with one from my son's DIY router. It might have had 3 run hours on it before going up in smoke.

The real point in trying to shoo away these folks posting about really cheap low quality machines or components is to keep this forum focused on higher end, more pro quality machines and components. It will be a shame if this forum becomes clogged up with countless posts about hobby level stuff. I'm certain that many of the most knowledgeable posters here would drift away should that happen.
 
"BTW, A-B's long since gone the way of dinosaurs as far as the CNC machine control world. Anyone else remember the 8400???? "

Yea, on a Motion Master Router- not sure which was a bigger POS, the control or the machine. Too bad, as the 7360's and their relatives were rock solid controls and built like a brick s-it house.
 
To me the OP is /seems a professional, with a professional-grade machine, asking a professional question.

To the OP:
Match the VFD to the motor, a bit bigger VFD wont hurt.

The chinesium spindles and motors are a luck-of-draw, mostly.
Not *necessarily* bad.

Most or a lot of industrial stuff today is built in china, after all.

I doubt that you need 4 kW or anything near it.Fwiw.

4 kW of power milling graphite would generally need extreme rpms, feeds, and balanced very expensive toolholding systems, and something approaching lasers, with linear motors and a high end motion control system.

The answer.
A 4 kW motor wont need any more power than a 2 kW motor.
The losses are immaterial.
A bigger motor will last longer and heat less.
(It will accelerate a tiny bit slower but this wont matter at all.)

Aside:
I very much doubt you can mill graphite in a lathe-type spindle at 4 kW, or near it.
2 kW, maybe, but doubtful.
Unless the graphite blank is supported at the TS end, in which case higher power is probably possible.

Your setup is probably not rigid enough to actually mill-turn something with 2 kW of power output.
Do you have 90 mm D spindle bearings ? and a 250-300 mm separation with 10 mm+ spindle wall thickness ?

A 2 kW output lathe, small, 12x24 (mine), with 2.5 kW ac servo spindle (c), masses 450 kg for a short lathe.
Anything less will not have the rigidity required.
 
To me the OP is /seems a professional, with a professional-grade machine, asking a professional question.

To the OP:
Match the VFD to the motor, a bit bigger VFD wont hurt.

The chinesium spindles and motors are a luck-of-draw, mostly.
Not *necessarily* bad.

Most or a lot of industrial stuff today is built in china, after all.

I doubt that you need 4 kW or anything near it.Fwiw.

4 kW of power milling graphite would generally need extreme rpms, feeds, and balanced very expensive toolholding systems, and something approaching lasers, with linear motors and a high end motion control system.

The answer.
A 4 kW motor wont need any more power than a 2 kW motor.
The losses are immaterial.
A bigger motor will last longer and heat less.
(It will accelerate a tiny bit slower but this wont matter at all.)

Aside:
I very much doubt you can mill graphite in a lathe-type spindle at 4 kW, or near it.
2 kW, maybe, but doubtful.
Unless the graphite blank is supported at the TS end, in which case higher power is probably possible.

Your setup is probably not rigid enough to actually mill-turn something with 2 kW of power output.
Do you have 90 mm D spindle bearings ? and a 250-300 mm separation with 10 mm+ spindle wall thickness ?

A 2 kW output lathe, small, 12x24 (mine), with 2.5 kW ac servo spindle (c), masses 450 kg for a short lathe.
Anything less will not have the rigidity required.

Thanks for the well thought out response, hanermo.

I ended up getting a used 2.2 kw Telemechanique (French) VFD and a square 2.2 kw spindle 24,000 RPM spindle which I am in the process of installing. I am currently milling at about 30,000 RPM on a belt driven spindle which I built, driven by a 1500 watt motor. My "proof of concept" spindle housing is only 3/16" wall thickness packed with 4 bearings, probably a little too small because I can only mill about 100 tools before needing a bearing change. But this was a proof of concept spindle, never intended to actually use it for production. I DID look for a decent used American German or Italian spindle, but I couldn't find anything in my price range. Trust me, if I could get ANYTHING other than a spindle made in China, I would. At least the one I purchased is packed with 4 ceramic bearings.

I have spring loaded bearings securing the EDM.
 
Your right on the cnc world but in the industrial automation they are one of the most expensive systems out there.
I would rather get a used good spindle then a chinese.

Edit:
Instead of discussing if its professional or diy, i'll just say i will be surprised if you will get the answer you are looking for on this forum.

Thanks for the reply Vancbiker.

I worked as a systems engineer for a solar panel manufacturing facility, there I designed systems for manufacturing processes. What I am doing here is exactly that...designing systems for my manufacturing processes. That being said it should make more sense to you why I decided to go PLC with ladder logic instead of learning G code. I'm sure G code is better suited for setting positions of axes than RSLogix5000, but it's what I know, and I can control a S%*T ton more than just motors and axes with what I have. Hope that kind of explains my reasoning with what I am trying to accomplish here.

CLARIFICATION: This purpose of this post was to collect data for the purpose of selecting which spindle I should purchase to replace the "proof of concept" spindle I have been using. I was not intending on discussing the quality of different spindles manufactured in their respective regions. Thank you all for providing me with your two bits...it helps!
 
.....I'm sure G code is better suited for setting positions of axes than RSLogix5000, but it's what I know, and I can control a S%*T ton more than just motors and axes with what I have. ...

You are correct in that thought. I get that you already have a solution that is working for you but switching to a CNC would not be a bad idea. In the A-B world I did some of SLC-500 and Micrologix programming about 15-20 years ago and I applaud that you have been able to do interpolated motion with a PLC. That is far beyond anything I worked on.

In addition to motion control, any modern CNC will incorporate an integral, full featured, PLC that the machine builder writes the ladder for. Operation of all the machine peripherals like tool changer, multi gear heads, workpiece loading/unloading are all the responsibility of the machine builder's ladder.
 
You are correct in that thought. I get that you already have a solution that is working for you but switching to a CNC would not be a bad idea. In the A-B world I did some of SLC-500 and Micrologix programming about 15-20 years ago and I applaud that you have been able to do interpolated motion with a PLC. That is far beyond anything I worked on.

In addition to motion control, any modern CNC will incorporate an integral, full featured, PLC that the machine builder writes the ladder for. Operation of all the machine peripherals like tool changer, multi gear heads, workpiece loading/unloading are all the responsibility of the machine builder's ladder.

I worked on CompactLogix and ControlLogix but i only did motion systems on Beckhoff, i have not done any interpolated motion but they have a whole cnc function library, G-M codes including look ahead.
 








 
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