Selecting motors for the MechMate

[Richards]

The data sheet for the MT34FN26 motor looks similar to the data sheet for the Oriental Motor PK296-F4.5. With about 450 oz*in of torque, it is a motor that I would normally use with a belt-drive (3:1 or 3.6:1). Assuming that you use a Gecko G201, G202 or G203v, the motor should work well with a 35VDC to 40VDC power supply if you wire it bipolar parallel or unipolar (half-coil). You would need a 70VDC power supply if you decide to wire it bipolar series.

I don't think that I would use that motor without a belt-drive, even on the Z-axis.

[gorantec]

hi are any one have expirience with this driver http://www.routoutcnc.com/10ampdrivecard.pdf my motors are MT34FN47 http://www.tinel.com/products/pdf/MT34FN_GB.pdf will be good this ? Since Gecko are only 7A and my motors need 8A in bipolar parallel conection ?

[Richards]

The data sheet for the MT34FN47 motor shows that the 035x8yy motor has 8.3mH, making unsuitable for the driver you listed. (To get full speed and power, you would need a power supply of over 250VDC). The 060x8yy motor has 3mH inductance, which would require a power supply up to 55VDC to get maximum performance out of the motor.

I prefer to use a motor that has about 1.5mH to 2.5mH inductance, which would allow the use of a 35VDC power supply (1.5mH) or a 48VDC power supply (2.5mH).

[Gerald D]

Let us look at the basics - this is from the document you linked:

Clipboard01.gif

It looks like the MT34FN47 motors are supplied in two versions: 035x8yy and 060x8yy. Which version have you got on your table? (I don't want to waste time discussing the wrong motor).

[gorantec]

hi Gerald thanks for answer

my motors are 060x8yy they are 6A in unipolar if you wire in bipolar series need 4.2A and if you wire in bipolar parallel need 8A driver i like to connect in parallel i have made some 5A driver and connect in series but performance was not good .

Please prefer some driver

[Gerald D]

Which driver did you use for your test? What was the supply voltage?

You say the performance was not good . . . . . not enough torque, or not enough speed?

[gorantec]

i have made this driver http://www.fisertek.it/images/schema...04%20amper.gif there was no torque and also slow speed and power suply was 30V

[Gerald D]

Okay, now I understand the poor performance.

I do not agree that you have to go for a bipolar parallel connection to get a good performance. With a good driver and a good voltage you will get a nice performance from half-coil connections. There will not be as much torque at low speed as with the parallel connection, but the router does not need much torque at low speed. At the high speed side, the torque of parallel and half-coil is nearly the same. If you wire half-coil, a 6 Amp driver at 55 volts is going to give you a very good performance.

[gorantec]

So Gecko drive will be excellent for this motors

[Gerald D]

Yes, I think so. But maybe you can find a driver nearer to you?

[gorantec]

Gerald will this stepper be good for Z axis 86HS2802 http://www.driver-motor.com/ProductContent.aspx?ID=47 this is from Claudia web site or please preffer some step motor from theat in the list since i will order 4 drivers from there and i like to oreder just one for Z

[Gerald D]

Gorantec, you already have 3 motors of 3.0 mH inductance and that will decide the power supply voltage. Now you need a number 4 motor and you will run it off the same power supply, so it must also have about 3 mH inductance.

Then, for the z-axis, you need some detent torque, so that the router/spindle does not drop when you switch the motors off. This means that the z-motor must be about the same size as the x and y motors.

If your z is also direct drive then I agree on the 86HS2802 motor (the motor weight is probably 3.8kg and not 1.8 as the web page shows)

It is very difficult working with the specification sheets you have given because of some strange differences between them. It looks like the 150mm long motor of Deitech has the same torque performance of the 118mm motor of Tinel and I don't believe the difference will really be that big. That is why I agree on the 126mm motor of Deitech.

hi every body,

I have this stepper motors
I brought 5 stepper motors from old printers :

SANYO DENKI
3,25A
1,8° DEG v=1.9v
type 103H7124-1041 FH6-1177 01, six wire.

I search alot in the web there is no data sheet for this motor.this all what i know.
Can I use this motors FOR THE Mechmate. Six wire motors are unipolar(Iam right?) if yes, can i connect it pipolar? sorry for my ignorant.
help me plz.

waleed

[Gerald D]

http://db.sanyodenki.co.jp/stepping_..._e_079-086.pdf

They are too small.

[anton]

Hi Gerald,
Would the pk296a2a-sg10 motors make any difference in performance to the standard mechmate, considdering I am planning on using the mechmate to route aluminuim?

Anton

[domino11]

Anton,
I had the same idea when I first started looking at the MM. The problem is that Mach3 can only output pulses so fast. The additional gearing in the 10:1 gearbox puts you out of the Mach3 limit. This forces you to go too slow with the additional gearing. Check out Mikes post here
http://www.mechmate.com/forums/showt...70&postcount=2 that talks about gearing, step resolution and backlash to see if it really would make a difference to you. The backlash seems like it will be more than the resolution at 7.2, so going further wont really get you that much perhaps.

[obuhus]

Hello, Gerald. My name is Dmitriy, I from Russia.

I am going to build MM and now I select stepper motors. In Russia the motors Vexta, unfortunately, are difficultly accessible and very dearly.
I have found analogue in China. I plan to use Geckodrive and,maybe, belt-drive transmission (3:1).
It is my choice.

LDO-86STH80-4208A

Size - Nema34
Rated Voltage - 2.4V
Current/Phase - 4.24A
Resistance/Phase - 0.75ohms
Inductance/Phase - 3.4mH
Holding Torque - 46Kg.cm
Leads Number - 8
Rotor Inertia - 1400g.cm2
Approx. Weight - 2.3Kg
Detent Torque - 1.2Kg.cm
Body Length - 80mm

( http: // www.ldomotors.com/st86.htm)

Say please, I on a correct way?

[Gerald D]

Those motors are definitely okay for belt drives, and I think just okay for direct drive. For direct drive I like to see a motor about 3 kg in mass. Maybe this sounds strange, but there is a direct relationship between the size of the motor, its mass and its torque. The direct drives we have used have always been 96mm long and 3kg in mass - 80mm and 2.3kg is quite a bit lighter.

The length and the mass are easy to check, and a supplier cannot tell lies about those numbers. But, they can give us false numbers for the torque, and we cannot check it easily.

If you are definitely going to run direct drive, then I would take the LDO-86STH118-4208A.

[lumberjack_jeff]

They appear to be the same motors I am using on mine, except mine are branded "Fulling Motor".

They are available with gearboxes.
http://www.mechmate.com/forums/showt...4&postcount=13

[obuhus]

Thanks, Gerald.

You very much have helped to me.
But your variant not too large?
"... at about 96mm [3.78"] long. Avoid motors much longer than this - see point 3 above. (bigger motors bring other problems) "

[Gerald D]

No, not too large. 118mm is not too much larger than 96mm. I was actually surprised to see the results of the guys in Brasil with very much longer motors. See the pictures and videos near the end of thread:

Cutting small gears and 3D puzzles! - Curitiba, PR, Brazil

and:

Building control desk #17 - Sao Caetano do Sul, SP, Brasil

[obuhus]

Thanks, Gerald.

The job of these guys looks nice.

Once again thanks for the help.

[m_leblanc]

Hi everybody, and congratulation for this great forum, very informational. I have been reading quite a few treads and always want to take a look at the next one or link.
About choosing the right motor, Gerald, you started this tread on oct 2006, if you had to buy new motors would these choices be the same today.
Thank you

[Gerald D]

I update the first post of this thread every time there is significant change in ideas. It was last changed 7 months ago and there have been no new ideas since.

[m_leblanc]

Thank you, I have been through the post and haven't seen it

[sprayhead]

Wondering how the PK299-F4.5a (NEMA 34, ~860 oz/in) runs at very slow speeds? I suspect that it would have at least decent linearity, since it is from O.M. It should have a much "better than typical chinese" manufacturing processes.
If I am right, the OM motors are made in Japan?

Thanks,
Francis

[Richards]

I run the PK299-F4.5A wired half-coil on my test bench and as an auxiliary motor on my Shopbot all the time. It runs very well at all speeds; however, I haven't specifically tested it at "very slow speeds". All stepper motors resonate at certain (usually slow) speeds. It is a characteristic of a stepper motor but the G203v has a trimpot that does a very good job of canceling out that problem.

The Oriental Motor factory is in Japan. Here in the United States, most of the motors are assembled in Torance, California. I visited the plant several years ago and spent a few hours on the assembly line watching them assemble the motors. They impressed me to the point that I have not bought any other brand since that visit. They use quality parts, quality people, and quality methods. Most importantly, each person does a quality check before passing the partially assembled motor to the next person in line. They teach the concept that the "customer" is that next person in line, meaning that each assembler's job is to insure that his "customer" is satisfied. On some stations, that "satisfaction guarantee" was as simple as orienting the motor so that the next assembler could pick it up without wasting time turning it in another direction.

The PK299-F4.5A motor is my favorite motor. I wire it half-coil and use a 48VDC power supply to drive it. It runs about 65-degrees C with that power supply and the load that I require it to drive. If you prefer a six wire motor, the PK299-03AA motor has the same electrical specs.

[sprayhead]

Wow, that's nice facts, it makes me think even more about going Oriental Motors, increased peace of mind.

on a new note:
I was having a read on this thread at the beggining and trying to find out more facts about the PK296a2a-sg7.2 and how to size the power supply for it, when wiring it half-coil and using a Gecko 203v.

Still unsure what inductance value I have to use on the formula to calculate the optimum power supply voltage for the motor, for half coil wiring. (32 * (√mH inductance) = Power Supply Voltage)
Is it the bipolar series inductance rating divided by 2? or is it the unipolar rating?

Would it be a problem if I go over the limit with the voltage given by the formula by a small ammount?

thanks,
francis

[Richards]

Francis,

The PK296A2A-SG7.2 has 1.5mH Inductance unipolar (or half-coil) and 6mH Inductance bipolar series. Inductance is 'caused' by the number of coils and how they are connected. Data sheets always show the half-coil rating as 1/4th of the bipolar series rating and the bipolar series rating as 4X the unipolar rating.

In this case the formula is: 32 * SQRT(1.5 mH) = 39.19 V = MAXIMUM voltage.

Voltage causes heat. The higher the voltage, the great the amount of heat. Mariss determined that a modern 'square' motor is rated at 100-degrees C, so he selected a maximum voltage that will keep the motor slightly under that limit (85 C). If our shops were always 25 C or lower, we could safely use the maximum voltage, but, at least in my shop, summer-time temperatures often rise above 45 C in the afternoon (that's where my thermometer pegs, so I don't know how hot it really gets).

I de-rate the maximum voltage by about 15% to 20% so that I'll never have a motor that gets above its rated temperature.

[sprayhead]

Mike I cannot thank you enough for your help on this forum

BTW, talking about heat generated by a stepper, here's something that looks like will be very nice, and allow us to keep our stepper motors nicer and cooler and yet more powerful...

THE G203X..........
http://www.cnczone.com/forums/showthread.php?t=79500


Mariss is also working on another, even more audacious project, the StepperServo...

just love it
F.