MechMate CNC Router Forum

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-   702. Power Supplies (http://www.mechmate.com/forums/forumdisplay.php?f=10)
-   -   Calculate the Voltage and VA size of the DC power supply for stepper motors/geckos (http://www.mechmate.com/forums/showthread.php?t=56)

Bazza Thu 25 June 2015 18:45

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Hi Gerald

I am trying to get an understanding of Toroidal power supplies so put together a spread sheet to help me
I tried using Richards numbers initially then ran another program using your methodology
The results of your methodology gave me the results you see above
Whilst I'm having great difficulty in contacting Antek, would this PS be suitable for those motors being wired in Parallel?
Cheers
bazza

Gerald D Thu 25 June 2015 22:51

Sorry Bazza, my appetite for getting involved with detail numbers in individual cases was killed long ago. :o

Bazza Thu 25 June 2015 23:07

Mate
Sorry to hear that but thanks for getting back to me
I'm pretty sure I have it sorted after reading your stuff on PS. Its the last bit in my combo of stepper drivers, stepper motors, (preferred wiring) break-out boards etc as you among all people know the combinations are endless.
I will work it out and will have another MM numbered down under!
Cheers
Bazza

MetalHead Fri 26 June 2015 06:03

http://www.mechmate.com/forums/showt...&postcount=146

Read this post. I would go with the 34HS9802 and a 48V power supply.

The KL34H280-45-8A is a great motor as well and shorter (78mm vs 98mm) and also uses the 48 volt power supply using 4 or 8 wires(Parallel)

Motors and power have been covered a lot in the forum, so read the build threads and the Motors sections a lot.

http://www.mechmate.com/forums/forumdisplay.php?f=26

Gerald D Fri 26 June 2015 09:23

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I would add 20% to voltages calculated by Mariss, which takes the 48V to 58V.

The shorter motor has much more chance of loosing steps because it has less torque. (Torque is directly related to the length (and diameter) of the rotor inside)

danilom Fri 26 June 2015 10:04

Is 1800 RPM on a 1610 ballscrew on Z axis lifting 10kg of aluminium and 5kg spindle along with spindle bracket too slow? (18.000 mm/min Z axis)

I manage to rapid on X and Y up to 43.000 without stall

I am running 48V on 9802 motor for 5 years on 4 machines without lost steps.

I must disagree Gerald really this time. If you need more torque then there is something wrong in the system or you need a different motor or a ac servo.
It might be the case that you need 20% on your motors but 9801 and 9802 work perfectly with the formula running on full nameplate current and heating is kept within limits.

Gerald D Fri 26 June 2015 13:18

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You might also be able to run even less voltage without lost steps . . . . just as you are able to get around in a small car without bumping into anyone. It proves nothing.

If you seriously want to push production, take deep cuts, allow cutters to get blunt, and not worry about loosing steps, then you maximise the voltage until the motors get too hot. . . . . . . . and then trim back on the set current to keep them just nice. However, if you start off with a too low voltage, you will never get to the point where you can use the current adjustment, and you handicap the whole system by not allowing the motors to deliver the occasional extra load when you forgot to put in a new cutter.

It is the same logic as saying you will buy a small car engine because you will never have to drive over a hill.

danilom Fri 26 June 2015 14:44

1/2 " or 12.7mm compression spiral endmill full depth 19mm particleboard cut can't remember the feedrates I only done 5 sheets with that one.

35mm ogee bit 6mm depth in one pass 2500mm/min after 10 or more doors when the cutter gets blunt VFD load gets to 100-110% load on a 2.2kw spindle.

6mm spiral endmill one pass cut 10mm MDF 3500mm/min

10mm ballnose 125mm endmill taking 4mm off a 3D mould for finishing pass 8000mm/min

9802 motor on a 20mm dia 10mm lead ballscrew easily lifts 150kg head while drilling with blunt 25mm drill (MK3 drilling machine total weight 750kg)

And I never saw motors to be a limiting factor to a mechmate production speed to be honest, its the lightweight car, wheels and Z axis along with low power spindle (2-3kw).
Rated feedrate at 19mm cut for a 1/2" compression is 12.000mm/min or 500ipm that requires a serious spindle along with a serious machine. So we can't talk here about production speeds dictated by catalog feedrates.

This could really go on... I don't want to argue with anyone I just put out my real world numbers not any workbench testing and that's it from me on this matter.

Bazza Fri 26 June 2015 18:18

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Gerald
I plugged in the specs for 34HS9802 and also get about 58VDC (59.5VDC)
To further support Gerald's opinion, I sent this email to ANTEK

"Hi
A week or so back I asked your advice on which Toroidal power Supply would suit a Mechmate CNC Router
The stepper Motors will be (wired Parallel) 4 x 34H2A9840 (used to be known as 34HS9801)
The drivers will most likely be 2LD880H (can handle 80VAC)
I originally thought your PS-8N56 would suit but realised the 56 was VDC
I now think the PS-8N77 would be far more suitable
My questions are:
What size would you recommend?
How much is the shipping cost to ......."

I received correspondence back from ANTEK
where John agreed that using 4 x HS349801 wired parallel the PS-8N77 Toroidal power supply would work just fine

Conclusion:
I will buy the 34HS9802 stepper motors (Thanks Mike)
The power supply to match these motors will be either the PS-8N56 (out of stock) or the $10 more expensive???? PS-8N63

Bazza Fri 26 June 2015 22:11

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Gerald
I'm reffering to Metalhead Mike's advice on stepper motors and have made my own conclusions as to whos advice suits my level of understanding
Cheers
Bazza

Richards Sat 27 June 2015 06:55

Bazza, Mike's (Metalhead) advice is good advice. Using the 34HS9802 motor with a 48V power supply will give you 580 oz*in of holding torque without a belt-drive and 2,320 oz*in with Metalhead's 4:1 belt-drive. With that belt-drive, you will have 3X more torque than with the PK296A2A-SG7.2 motor/gearbox. With a 1.25" diameter pinion gear (25-tooth) on a 4:1 belt-drive, your per-step resolution will be 0.000490875". Your total cost will be the same or lower than it would be if you used the smaller PK296A2A-SGxx motor/gearbox. The 34HS9802 with 48VDC power supply uses the formula given by Marriss.

MetalHead Sat 27 June 2015 21:49

I have made a few edits to this thread to remove argumentative posts and comments I feel are not promoting the point of this thread.

Also please stop using reference quotes. We can all read.

javeria Mon 29 June 2015 02:31

58V DC would be just about fine for the motors -go ahead - some times we use fans to cool down motors on X and Z - especially when they are working on 3d jobs, else there will be sometime a loss of torque due to over heating and a spoilt work before you know it.

JedNaus Thu 12 November 2015 19:57

I want to know something that the power supply has two black and two red leads and for 110v need to tie both blak together and both reds together running parallel.
Also for 220v it would be serial?
Do I need both blacks and reds?
It seems I am getting the right output by just using one black and one red.

bradm Fri 13 November 2015 09:09

Jed, you are getting the right output but at high current draw, you may have heating in the single set of primary wires you are using. You bought the transformer to hit a certain VA specification, for example purposes, let's say that was 330 VA.

If you wire it with the primaries in series, and run it as 220V, then 330 VA / 220V = 1.5A of current flows through the primary wires. If you wire it in parallel and run it at 110V, then 330 VA / 110V = 3A runs through the primaries, but it's two in parallel, so divide and each wire is carrying 1.5A again. If you use a single primary, you're now carrying 3A of current on one set of wires. The transformer manufacturer created the VA specification based on the size of the wire used to wind the transformer. The wire gauge is likely to be too small to draw that 3A on a continuous basis without heating up.


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