Spindle motor to servo

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Re: Spindle motor to servo

Postby ThreeDJ16 » Thu Aug 30, 2018 3:20 pm

Sorry, I did mean to say thank you for the other information about speed. I'm curious as to why the manufacturer tech support told me on the phone that 120v supplied I can only get 3K max RPM and supplying 220v to the DYN4 my max would be 5k RPM? So there is a way to make it faster than 5K without using a physical timing pulley/belt 1 to 2 ratio? I'm really a lot confused with the DNY4 setup. The only portion that seems clear to me is the power input side. They have so many options on the control input that is gets a lot confusing...LOL.

Anyway, again, thank you. FYI, still love my ScreenSet 2017. When you coming out with a 2018 version? Really hope you implement a few ideas I passed on to you during the past year or so.

-Jasen
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Re: Spindle motor to servo

Postby ger21 » Thu Aug 30, 2018 3:38 pm

RPM is proportional to voltage, so you are limited by the max input of the drive (220V).

I probably won't have time to start the new screen until the end of the year. I'm not starting it until the next release of UCCNC, though, so I know what needs to be included.
Gerry
UCCNC 2017 Screenset - http://www.thecncwoodworker.com/2017.html
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Re: Spindle motor to servo

Postby ThreeDJ16 » Thu Aug 30, 2018 3:45 pm

ger21 wrote:RPM is proportional to voltage, so you are limited by the max input of the drive (220V).

I probably won't have time to start the new screen until the end of the year. I'm not starting it until the next release of UCCNC, though, so I know what needs to be included.

Both makes sense. I'm disappointed that I don't have the Z on the tool touch off position on the screen still, but at least I know where to add it in the code. So do I need to download ScreenSet2017 again for the latest release version of UCCNC now? I see I'm a version behind right now. I know at one point, when they switched (I think away from openGL or something like that), you stated not to use those beta versions. Just wanted to make sure everything was still good for the latest releases?


My apologies for totally side tracking this topic. No more questions from me on this subject. But if the OP is interested, I will post my results for my DYN4 / 750w spindle motor? I'm doing an R8 installation this weekend, but within another week or two, the new spindle motor will be installed. Anyway, just offering since I got so far off topic.

Thanks again,
Jasen
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Re: Spindle motor to servo

Postby Robertspark » Thu Aug 30, 2018 5:36 pm

I'd be interested in any and all info as I'm about to take the plunge with a servo for the spindle, looking at htd pulleys and taperlock bushes (40t >64t)

Just not sure about 5m or 8m as 5m taperlock appears to be only 15mm belt width (I've presently got a j profile 10rib v belt... About 25mm wide).... So I was looking at 8m htd pulleys (need to get the spindle dims tonight)


Anyone used Delta drives and motors? (Asda-a2)
Rob
Einstein ― “If you can't explain it to a six year old, you don't understand it yourself”
...working my way through the 1000+ ways things don't work to find the one that does
UC400eth, UC300eth, UCCNC v1.2106, Neuron Lite
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Re: Spindle motor to servo

Postby ThreeDJ16 » Thu Aug 30, 2018 7:13 pm

I prefer timing belts and used them on my Emco turret lathe and Taig mill. I like the XL version, 40 tooth to 30 tooth on my lathe (as it has a 6500RPM BLDC motor) and 40 to 20 tooth on my Taig with the ER16 spindle (and currently the 6500 RPM Consew BLDC). Now that I have an R8 spindle for my Taig (and a massive new frame), I'm switching for now to a 60 tooth to 30 tooth and doing initial test with the Consew (as the existing pulleys I have are bored 15mm). Haven't decided yet on the ratio I'm using with the DMM 750w, but will probably buy a new 60 tooth so I can still get at least 10k RPM. Unfortunately the 30 tooth was the smallest size to fit the R8 shaft. I use .375" belts. Here is a link to a calculator that really helps out if you want to buy timing pulleys. Pretty sure they sell more pulleys and belts, just prefer timing as they've yet to ever let me down.

https://www.bbman.com/belt-length-calculator/

Here is a copy of the correct CAD for the DMM 750w servo motor I have (they sent me a new version today). And it shows the 14mm diameter shaft. I have the DYN4 CAD too if anyone is interested. Just remove the txt at the end since the board won't allow step file uploads.
86M-DHT-A6MK_FP051502A.step.txt
Remove the .txt extenstion
(854.33 KiB) Downloaded 21 times
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Re: Spindle motor to servo

Postby Robertspark » Thu Aug 30, 2018 7:35 pm

Ok, here is a bit of a dopey question, but I can't get it right in my head.

My CNC lathe (denford orac) has a manufacturer declared spindle speed of 2000rpm in the literature.

The motor is a 4 pole, 3 phase motor rated at 1/2hp

The motor end pulley is 35mm diameter, and the spindle pulley is about 63mm diameter.

The variable frequency drive was a Parametrics FHP Parajust motor speed controller. (Long since sold to ABB and now brand no longer used)

I need a bit of help with my math here....

The motor is rated at 1/2hp on a 50hz supply with 4 poles gives a motor speed of about 1480rpm allowing for slip. The Parametrics drive seemed to be adjustable to 100hz.... So the motor speed could be ramped up to ~2960rpm....
But the motor has a 35mm diameter pulley on it and the spindle has a 63mm diameter spindle on it (10rib j profile v-belt)... So the pulley ratio is ~ 1.8:1 is it not...
So if the motor was running at 100hz from the vfd (2960rpm) the best the spindle could have done was 1644 rpm... Am I missing something? ... Again manufacturer stated spindle speed adfustable from 0-2000rpm

Ok now onto torque, given I'm metric 1/2hp ~ 373watts.
At 1480rpm (rated motor rpm) the motor will develop 2.41 n.m of torque (21.3lb.in)

Now onto servo motors....
The DST-880 listed earlier has a rated output of 2.39n.m of torque and 750w and it's rated at 3000rpm.
Servo motor torque is flat up to the rated output, so doing the math, 750w at 3,000rpm does in fact equal 2.39n.m. of torque....

http://www.wentec.com/unipower/calculat ... torque.asp

Now the catch....
Given the servo is rated to 3000rpm, should I design / select my pulley speed according to this?

Because the spindle speed is supposed to be able to go up to 2000rpm, that would mean I should select a 1.2:1 drive....
Problem is the old drive was ~1.8:1..... So the torque was multiplied by 1.8 so even though the motor was only rated at 1/2hp and developed 2.41n.m. at ~1480rpm, the torque at the spindle (cutting force) was 4.3n.m.

Where as if I use a 750w servo motor rated at 2.39n.m. of torque running at 3000rpm and want the spindle to do 2000rpm with a 1.5:1 pulley arrangement the cutting torque would only be 3.6n.m. of torque at the spindle (83% below that of the vfd 3phase 1/2hp motor)

Should I not be looking at a higher rated servo motor because of its rpm limitation?

Should I select a similar to the existing1.8:1 pulley ratio and overdrive the servo motor to 3600rpm which is within the "intermittent" region of the servo motor rating where the torque drops off a bit (it will be way less than what it ever dropped off with a 3-phase induction motor)

Should I add heat sinks to the servo motor?

I am guessing I will only use anything between 1600 to 2000rpm spindle speed very occasionally (if ever!) given 2mm diameter at 1600rpm is a surface speed of 10,000 mm/min (395"/min), and 6mm dia (~1/4") would be 3x this at 30,000mm/min (1187"/min)

Been looking at the Delta ASDA-A2-0721-M drive & Delta ECMA-C20807RS motor (750w/ 2.39nm / rated 3000rpm, maximum 5000rpm / 80mm frame size, 19mm spindle / 17bit encoder).... Basically very similar to the DMM servo and drive
Rob
Einstein ― “If you can't explain it to a six year old, you don't understand it yourself”
...working my way through the 1000+ ways things don't work to find the one that does
UC400eth, UC300eth, UCCNC v1.2106, Neuron Lite
UCCNC v1.2105 Macro Manual
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Re: Spindle motor to servo

Postby ThreeDJ16 » Thu Aug 30, 2018 7:44 pm

My brain hurts after reading that.

Only thing I'd point out is that the DYN4/750w is rated at 3k RPM at 120v and 5K RPM at 220v, torque is the same either way (according to the tech guys at DMM).

A few pics of my lathe setup. And FYI, that little 550w just finished cutting 1 5/8" steel round stock last weekend for my R8 tophat bushing. Little motor never slowed down.

20180511_155047 (Small).jpg


20180511_155100 (Small).jpg


20180511_155108 (Small).jpg


30741170_985870814910796_4182824883857653760_n.jpg


30714157_984843375013540_6950953734448873472_o.jpg
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Re: Spindle motor to servo

Postby Robertspark » Thu Aug 30, 2018 8:07 pm

Nice & Neat Setup!!
Hey thats a sewing machine servo motor (I know I've got one in "error" when I was thinking about cncing my old lathe)

____________________________________________________________________________________
If that last post made your head hurt.... this will make it hurt even more. :lol:



Belt Profile: I tend to use Gates HTD (High Torque Drive) belt profile as it is recommended for Linear positioning and Power Transmission.
http://www.gatesmectrol.com/mectrol/bro ... chure=3143

Yes it is metric, where as XL is imperial pitch. XL however does not seem to be rated for power transmission or at least it is below that of HTD because of its trapezoidal tooth shape. "XL" seems to stand for "Extra Light" Duty?
http://www.sdp-si.com/D265/PDF/D265T016.pdf

The HTD tooth profile as I understand it is superior as it has a smoother transition as the tooth engages and disengages from the pulley in a "sort of" more involute profile which is more representative of a gear drive.

I use HTD 5M 20 wide (non standard size) on my plasma and they work well. Gates (the "inventor" (patent holder) ) of the HTD profile have since deveopled the "GT" tooth profile which is suppose to be more superior than the HTD belt, the tooth is ever so slightly larger on the edges where it meets the flat belt profile.... this apparently leads to more torque apparently and a quieter drive / motion and a smoother motion.

HTD profile belts do make a fair bit of noise when you push them (I have a supercharger which uses HTD 8M 30Wide belt) and that can make a noise with belt whine ..... it is pushing a fair few HP and its also should we say on (above) its design limits..... but it fits in the space I have.

I keep looking for GT replacement belts but they are not that common (yes I know GT2 with a 2mm pitch has flooded the 3d printer world.... but I suspect that they are copies.....) When I did find some for the plasma a while ago to try to improve my acceleration even more they were quite pricey and I could not justify the additional extra over cost against the steel wire reinforced HTD5M belts I'm running....

You can use HTD pulleys with GT belts of the same pitch (GT2 or GT3 are the designated range {the number is not the pitch, but the profile variance}) hence it "should" be just a straight belt swap for improved performance..... I don't expect the performance to be +10 % against the HTD I'm running though acceleration wise, and they probably will be a bit quieter (does not make any difference with plasma when the compressor is running ;) ) but they also will be a bit smoother as I can see some cut lines which I've put down to the belts on the parts I cut.... but really that makes no difference to me as I'm normally welding the parts up anyway and a quick tap with a flap disc and they look fine.
https://www.rydell.com.au/uploads/sproc ... 0guide.pdf
Rob
Einstein ― “If you can't explain it to a six year old, you don't understand it yourself”
...working my way through the 1000+ ways things don't work to find the one that does
UC400eth, UC300eth, UCCNC v1.2106, Neuron Lite
UCCNC v1.2105 Macro Manual
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Re: Spindle motor to servo

Postby Robertspark » Thu Aug 30, 2018 8:10 pm

And you're on the dark side with a centroid Acorn..... :lol: :mrgreen:
Rob
Einstein ― “If you can't explain it to a six year old, you don't understand it yourself”
...working my way through the 1000+ ways things don't work to find the one that does
UC400eth, UC300eth, UCCNC v1.2106, Neuron Lite
UCCNC v1.2105 Macro Manual
Robertspark
 
Posts: 1117
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Re: Spindle motor to servo

Postby ThreeDJ16 » Thu Aug 30, 2018 8:15 pm

LOL...yeah I'm an electrical guy, not a mechanical guy.

But I tried GT belts first and my large chuck (even for a small machine) didn't like it one bit. Of course the part I left out was I didn't know what size to get...LOL. I'm embarressed to say that I bought either GT 2 or 3 belts and it jumped several teeth at every stop and start. So far, that AT belt has been adequate for 1 5/8" steel round stock, which will be the largest thing it ever sees. So pretty sure I'm good for now...LOL. But I did read up and agree, a GT5 or so would probably be the best choice for the belt size if I was going that route again and have read they are the most quiet and accurate of any timing belts today.

Forgot to toss in a before picture of my lathe controls....and yup, that is a little sewing machine motor, but it packs a nice punch. This pic was after my buddy removed the old 3-phase motor and giant red plc box for me (3 back surgeries don't allow me to do that stuff anymore).

28471670_961066047391273_5702180152233141074_n (Small).jpg
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