Where is the fountain of knowledge for learning about CNC setups / understanding them

**Palletlad** · 13-02-2018

I do plan on doing the checks in stages but I thought about seeing if I can prepare a check list and go through it step by step.

I have ordered another db25 cable so going to check the cable.
I am going to grab lithium WD40 spray and give the ball screws and rails a coat.
I am going to test the motors on their own.
If still no luck I will check the board settings as Doddy suggests.
If still no luck then I will purchase PSU I found this one https://www.ebay.co.uk/i/15261107092...9916224&crdt=0, are these safe to purchase or do i need to go to some specific website to avoid dodgy components?
then go from there by purchacing a bob and stepper drivers as recommended by M_C.
Thanks guys btw for the help thus far and don't panic I am not going to do all and everything in one go.

**Doddy** · 13-02-2018

Originally Posted by Palletlad

If still no luck then I will purchase PSU I found this one https://www.ebay.co.uk/i/15261107092...9916224&crdt=0, are these safe to purchase or do i need to go to some specific website to avoid dodgy components?

VM (Max) for a TB6560 is 40V. I'd suggest a 36V PSU.

**Doddy** · 13-02-2018

Originally Posted by Palletlad

I do plan on doing the checks in stages but I thought about seeing if I can prepare a check list and go through it step by step.

Don't forget the cordless drill test on the ballscrew that m_c suggested - it's a good idea.

**m_c** · 14-02-2018

Just checked, and I should of said get TB6600 drivers if you do replace them.
TB6560 is the older chip, whereas the TB6600 is newer, far more resilient, and has better performance.

Which has also reminded me that the TB6560 has quite a large pulse width requirement. It needs a 10uS minimum pulse width, which limits it to 15KHz step rate. Some where in the Mach settings (think it's the motor tuning screen), there is a box for setting the pulse width. Make sure you have it set long enough.

The attached chart shows the key differences between the chips.

**Doddy** · 14-02-2018

Originally Posted by m_c

Just checked, and I should of said get TB6600 drivers if you do replace them.
TB6560 is the older chip, whereas the TB6600 is newer, far more resilient, and has better performance.

Which has also reminded me that the TB6560 has quite a large pulse width requirement. It needs a 10uS minimum pulse width, which limits it to 15KHz step rate. Some where in the Mach settings (think it's the motor tuning screen), there is a box for setting the pulse width. Make sure you have it set long enough.

The attached chart shows the key differences between the chips.

I was about to dismiss this - the controllers I've seen (and modded) have had a 74-series monostable oscillator to pulse-extend the clock signal - however the image of the board (and various clones thereof) don't appear to have this luxury, unless it's rear-mounted on the board? If not, this board is seriously junk. The 10us minimum pulse width is actually dependent on a capacitor value, and can be significantly longer than 10us dependent on value. Mach3 advertises a limit of 1-5us for step/dir pulses, but appears to let you enter a larger value (I can't test as my motion controller is hard-limited to 2.5us). I'd agree - experiment with larger pulse widths (and reducing the micro step to 1 will also help to limit the PRF to a sensible value)

EDIT: My bad - just checked, and the controllers I did modify are TB6600s, not 6560s.

**Palletlad** · 14-02-2018

Just a quick update, I have confirmed that there is no issue with the frame alignment or ball screw.
I tested the motors when not connected to anything and even on low settings (320,1000,150,0,0)=motor settings.
And they still jam/jar.
so definitely something to do with the electrics/settings.

**Doddy** · 15-02-2018

What's the

Originally Posted by Palletlad

low settings (320,1000,150,0,0)=motor settings

part?, have you not tried larger pulse widths on step/direction?

**Palletlad** · 15-02-2018

Doddy I did attempt with pulses as well but no difference it was the same result what ever setting I attempted.

**A_Camera** · 15-02-2018

Originally Posted by Palletlad

Just a quick update, I have confirmed that there is no issue with the frame alignment or ball screw.
I tested the motors when not connected to anything and even on low settings (320,1000,150,0,0)=motor settings.
And they still jam/jar.
so definitely something to do with the electrics/settings.

Good. At least we know that the mechanics are OK. Now change the pulse width to 10. If that doesn't help KEEP it there and change speed to something really low, like 500. If that is still an issue then you probably have a faulty driver card, or a faulty PSU, or both.

I started off with a 3 axis 6560 (blue card). Fixed all the electronic design issues but still managed to fry two before I gave up. In the end I bought a $5 BoB and a handful of DQ542MA drivers and never looked back. My CNC immediately became more quiet, more powerful, faster and with much better acceleration, even though at that time I still had a crappy 24V switched PSU. Changing the driver was the key to success in my case because it solved a lot of issues. That's the route I'd advice you to walk through even if you manage to sort out the current issues. I am still using the same drivers but upgraded the PSU and the CNC in many other ways...

**Palletlad** · 14-02-2018

Ooh just remembered to ask I saw the TB6600 stepper motor drivers via amazon and ticked them for a purchase later idea, however when looking for a standard BoB (I know so little on them) I found https://www.ebay.co.uk/i/25208589694...4960578&crdt=0 and I kept having this one pop up https://www.newfrog.com/product/elec...waAsFpEALw_wcB everywhere I looked but not many others? I would have thought there would be all sorts of brands, low, medium, high spec etc