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[RobC]

I would say a proper set of drivers would be a better solution and go with a dedicated controller that you can do much more with. I use a very cheap generic 5 axis bob but then I've had to buy a more expensive UC100 so I can use it and it's worked great now for 4 years but it's dependant on how much money you want to spend on this. I personally would go back to using the Hiwin rails over the round rails after using round rails for years.


Rob

[01012f]

At the end of the day you say you want something that will do aluminium and wood.
It will need to be fairly rigid and have some decent drive.

Mainly wood with a bit of aluminium but yes, I get your point

If you try and do it really low budget, try to fudge controls and are willing to cut corners. Then I suggest you abandon it.
It's a far cry away from a £50 3d printer kit.

hmm, maybe a misunderstanding.
I'm willing to fudge and cut corners to test if something works, if it does then I do it properly :)

I'm surprised the steppers moves at all with 3:1 (big pulley stepper > little pulley screw) yes?.

no mate, the other way around, little pulley on stepper -> big pulley on shaft, little pulley on other end onto the drive belt. so the stepper will turn 3 times to make the belt pulley turn once.
But as mentioned above, I've already decided to drop that in favour of dual lead screws

Most machines I see this size are direct driven (no belts) or 2:1. The long base driven by 2 steppers 1+slave.

that's where I'm headng

I fully accept I'm doing this with no experience but it's getting there, slowly, and i'm learning and having fun. Hopefully I'll end up with something that does what I want but either way, I'll enjoy the journey :)

Thanks for your input

[JAZZCNC]

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.

[01012f]

Hi Dean

That's a great post, thanks.

I've just has a look at your site, wow, you build some gorgeous machines

After feedback from here, the upgrades include lead screws, nema 23 steppers, decent drivers and a new controller so they'll come as funds allow.

Thanks everyone for the help and suggestions

[Doddy]

Ooof, Just watched your videos - you've receive good advice so far.

One point from me which I don't think is covered from what I've skim-read - please don't connect/disconect steppers with the drivers powered/active. Being an inductive load, and that the stepper windings are under constant excitation you will generate high-voltage spikes on supply interruption to the stepper that can damage your drivers. Not much of an issue if you're replacing that kit, but useful to get into a habit of powering down. The problem gets bigger as the steppers (and drive currents) get bigger.

[01012f]

Time for a long overdue update on my progress.

I followed advice from here and upgraded -
1, all the steppers to 425oz Nema23s from 60oz Nema 17s
2, the stepper drivers to external drivers
3, to a 48v 600w power supply from 12v 750w
4, the y-axis to dual leadscrews from dual belt
That lot is all in and working a treat

I've got limit switches on both ends of each axis
And I've made x-axis and z-axis carriages from 6mm aluminium

I think I'll need to spend time tuning it all in, it's a bit noisy and lumpy in places.

It's all there really. It just now needs tidying up, ie cables in drag chains, a controller board making up, e-stop etc.
Then I need to sort out a waste board and a router/spindle of some sort. The original plan was to use my main router but I've since realised that it doesn't dis-assemble to a mountable form.

It's been fun building it

latest update video https://youtu.be/loWaDqnpO-Y