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X/Y motor specs vague

Hi,
First of all, nice project. This could be a welcome addition to my current panel cutting rig.

One snag I’ve found though are the X/Y motors. The other custom parts are easily replicated, but the motors are not.
I’ve browsed the forums and even the GitHub for some days, but the specs seem to be vague.
In older posts i read about 300 ish ratio and later posts about 200 ish ratio. Knowing the rated speed would be very helpful.

Also, how custom is the integrated encoder?

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Welcome to the Forum!

289.776:1

Encoder MY-37

With our gearbox that makes 8113.728 pulses per revolution.
The post with this numbers is here: Whats inside the gearbox/motor?

The max torque is around 30KG and is quite high, can be traded for speed.
In GroundControl the steps/revolution, number of teeth on the sprocket and feedrate in mm chain/min can be set manually to adjust different motors.

Kind regards, Gero

Edit: Old post and some links might not work, could still be of interest:
where-to-obtain-the-main-motor-worm-gear-encoder

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Gero, thanks a million. Exactly what i needed, and a very nice encoder BTW.
Encoder is 7PPR = 289,776x7x4 = 8113,728PPR right?

To be honest, i did not check the math of my fellow chip-monks.
They seemed to agree on this numbers, so i accepted them as the ‘current truth’ :slight_smile:

Edit:The big lesson was not to trust the supplier, who said the motors had 291:1.


Counting the gears for the actual ratio improved a big step.

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Haha, that’s ok. But very interesting, i think i will order two motors from AliExpress then, see how that goes.

Would increasing the ratio improve accuracy? Or make things too slow?

I’m the wrong person to answer that. From what i seem to remember is that the encoder pulses is already more we need for accuracy. Current posts read that we are close to ~1mm and a gantry build is reporting ~0.5mm. Calculating chain-sack and chain stretch over length are not something that could be improved with more encoder-steps is my non engineer opinion.

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Agreed, but i think the ratio of error would reduce, also we might be able to get away with even cheaper motors.
For example the JGY-370:

For the experienced online shopper these can be obtained for less than 10 euro’s :see_no_evil:

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Keep it coming! The one that took over spare parts does not deliver to my end of the world, so i would be the most happy to have an alternative if more of my motors gives up. (1 down, 2 running, 1 spare)

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Exactly, the gearbox is the weakest part so breakdown is inevitable. Therefore i believe the motors should be easy and cheap to replace. I’ll try those JGY-370’s can’t co wrong for 20 euro’s a pair :grin:

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actually, at the top of the workpiece, we start running out of power (the ‘hook’
in a horizontal cut across the top of the workpiece is from the motor not
pulling hard enough and having to catch up at the end)

So my initial idea of replacing the 10 tooth sprockets with 25 tooth sprockets
won’t work (unless you adjust the machine dimensions so that the max force
needed is much lower than stock see the spreadsheet at


)

David Lang

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we currently are at >8000 pulses per 2.5", this is ~0.0003in (0.008mm) per
pulse, since our desired accuracy is ~0.05mm (1/64"), we could probably get away
with ~2000 pulses/rev with the current gearbox (or a sprocket 4x the size if we
had a motor with 4x the torque)

the one problem you may run into buying these motors is that there is one gear
in them that is very weak. When the Maslow suppliers order the motors in
quantity (say 3000 or more at a time), they get them with a stronger gear in
them than used to be supplied. We can’t know what you will get when you buy them
from ebay/amazon/etc

David Lang

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the JGY-370 motor will be half the speed of the stock one (10 rpm instead of 20), and while it lists a max torque of 25kg-cm, the seller says it will not last at that load https://www.amazon.com/ask/questions/Tx2WCNMCDUEUP2T/ref=ask_dp_dpmw_al_hza

it also does not have an encoder on it, so you would need to add that, negating your savings on the motor.

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On my side this was solved with a 10A power supply and the TLE5206. With a 15kg sled at 8°.
With the TLE it was the first time to see a motor actually stall. Before it was just killing the original shield chips and/or the 5A power supply. I can’t calculate it, but i’m testing and observing for some time.
straight-line-curves-down-at-top-of-the-sheet-solved

David, thanks for the additional info. That is quite a lot :slightly_smiling_face:

I was already considering to increase dimensions a little bit since my build will use a brick wall instead of a wooden frame (further reducing cost).

Good to hear the official maslow motor will have a better spec gear soon. I’m trying to make an El Cheapo maslow CNC. My aim is 150 euro for a running machine, not sure if i will succeed at that, but I’m going to try anyway.

To put an official number out there the X/Y motors have 30kg/cm of torque at 18rpm and spin at 20rpm under no load