[Firecnc]

Hi Guys,

advice is needed. I'm about to build a cnc for milling and drilling PCBs, wood, and occasionally aluminium.
I choosed NEMA23 57HS76-2804A (1.9Nm, 2.8A, 57x57x76mm) motor, I think this will be strong enough. (what do you think?)
Please help choosing the correct driver for it. Some youtube videos suggest TB6600, but I read some topics here and in other forums about that it often looses steps. Is that right?
Could you please recommend me any other driver? I prefer cheap solutions shipped from China or Europe to avoid duty. I ordered other cnc parts from ebay, bangood, ali, etc.

Thanks in advance,
Steve

[peteeng]

Hi Steve -Look at stepperonline Peter

[joeavaerage]

Hi,
the stepper you have nominated has a moderately high inductance (3.6mH). Ideally with a 23 size (57mm) stepper
you would select 1-2mh, 1 mH preferred and reject anything over 2mH.

All steppers lose torque as speed increases, the lower the inductance the more torque will be retained at speed.
In some respects low inductance is more important than holding torque. You'd think a 600oz.in stepper of say
6mH would be better than a 400oz.in 1.5mH stepper. The 400oz.in stepper will probably
have about 150oz.in at 1000 rpm whereas the 600oz.in will have 30oz.in if it ever makes 1000rpm, its more
likely to stall long before it gets to 1000rpm.

The 400oz.in unit is better overall....it will go 1000 rpm whereas the 'apparently more powerful' stepper will stall long
before that.

To counteract inductance use the highest voltage drivers and power supply you can find. Gecko drives
are the gold standard for reliability but Leadshine AM822 are cheaper and still 80VDC capable.
You want 80VDC drives and use an 80VDC supply, transformer/rectifier design preferred.

Some youtube videos suggest TB6600, but I read some topics here and in other forums about that it often looses steps. Is that right?

No, its the stepper that loses steps but because the TB6600 has such a low voltage capacity it means that the stepper it drives IS more
likely to miss steps and the faster it goes the worse it becomes. Aside from that the TB6600s tend to blow up fairly easily.

Craig

[machinehop5]

2 posts no flag...why?

[Firecnc]

Thanks Craig.

I haven't ordered the motors yet, so I can change them to an other if you suggest that.
I saw Nema17 motors used for milling PCBs with 0.5Nm torque, and the other I mentioned has 1.9Nm, I tought it will be ok, but I accept your explanation of course. Every advice are welcome
Speed is not the most important in this project, so I can keep the motors on low rpm for having the best performance.
The drivers you mentioned are too expensive for this project

Steve

[joeavaerage]

Hi,

Speed is not the most important in this project, so I can keep the motors on low rpm for having the best performance.

Heard that many times before.....and even more times I've heard 'I should have got...so and so motors' when the hapless buyer realises
that speed was more important than he thought.

The drivers you mentioned are too expensive for this project

Heard that before too....and yet the same buyer seems to scrounge up the money to buy the right ones....eventually.

Craig.