Quote Originally Posted by 01012f View Post
Hi JazzCnc

I think I over-spec'd the rails, I could probably get away with smaller rails but I have them now.

I only have 50oz nema17 stepper motors and the way I had it all assembled, the motors can't cope. On each side of the gantry I have a 20 tooth pulley on the stepper driving 60 tooth pulley on a shaft with a 20 tooth pulley on the other end. A GT2 belt runs around 2 idler pulleys to that last 20 tooth pulley. I think my dual y-axis controller board is splitting 1 stepper output rather than having 2 full power outputs. It would probably work as planned if they were full power outputs.

So, my thoughts were to replace the belt drive with lead screws. That should give me a ~10:1 advantage rather than the belts 3:1.
And yes, lead screws are expensive, so I'm first going to test the princliple using m10 studding.

I have some (lack of) progress videos on my youtube channel
Hi, Yes I went to your Youtube after posting what I did and saw what you are planning and what you are working with!

I understand testing the waters with what you have but what you have is just wrong in every department, but I think you get that by now.
My strong suggestion if you are serious about a router worth the effort is to forget all the electronics you have, right down to the PSU.? They will only frustrate the hell out of you and massively underperform.

NEMA 17 motors are ok for a small super lightweight machine ie: 3d printer using thin light belts etc but they just can't handle the inertia of larger lead screws and linear rails that you will need for a router this size. You'll need at least 2Nm Nema 23/24 and ideally 3Nm or more, however, the real key is the voltage you run them at and this requires the drives to match and have a little spare overhead.
This is why I said "right down to the PSU" because for a typical 3Nm stepper you want to be running them with around 50-55Vdc, smaller motors like 2Nm you can get away with a little less at 40-44Vdc. If you run them with less voltage than this you will be compromising performance and it's just not worth doing.

Regards the drives then don't buy Cheap analog drives, they are old tech and run very rough compared to digital drives, there is a night and day difference in performance and smoothness. You also want to leave a 10% margin of safety on the maximum voltage they can handle compared to the voltage you run the motors at.

Lastly the controller.? This is another KEY component to a good machine and especially a router as you need a nice fast and smooth pulse train.
If you want a stable machine and one that performs well then don't use the parallel port (Unless you use LinuxCNC, but that's for another time!) because again it will frustrate the hell out of you and is relatively slow.
I would avoid a USB-based controller because while better than PP they can still be a little flaky depending on which controller you use and the PC it's used on.
An Ethernet-based controller is the only real sensible choice if you want a rock-solid machine that performs great.

In my experience, any trying to cut corners is always regretted and costs more money. I've seen it time and time again and what's crazy is that it doesn't actually cost much more to do it right the first time. It also makes the build go much smoother, far less frustrating, and enjoyable.

Good luck and if you are unsure of what to buy just ask. The golden rule is never Buy before asking or checking if it's right for your application.