Missing Steps Poss TB6600 Fault

[Clive S]

Hi does anyone know of good supplier of shielded 2 or 4 core cable.

Cheers Neil

Search for 1mm or 0.75mm cy4 cable like https://quickbit.co.uk/Cable/CY-Cabl...-0-75mm-4-core or https://www.cse-distributors.co.uk/a...Y_4C_0_75.html

edit only connect the screen at one end to a star point

[neilricketts]

hi clive s thankyou for the links i will order some first thing monday. Just wondering has anyone any experience with these stepper drivers

http://www.ebay.co.uk/itm/CNC-Single...3D251425126351

Cheers Neil

[Clive S]

hi clive s thankyou for the links i will order some first thing monday. Just wondering has anyone any experience with these stepper drivers

http://www.ebay.co.uk/itm/CNC-Single...3D251425126351

Cheers Neil

As I have said before you need to up the voltage on the power supply. I would do that first. Those drives you linked to are 50V drives so you should be able to run them at at 40V

[neilricketts]

Hi, i know what you are saying but i am happy at 24v with the speed and that. it is just the missing steps that i think is being caused either through electrical noise which i will try changing the wiring first. However reading here and on other forum the tb6600 drivers are a common cause of lost steps and failing that is why i am asking about the other drivers as a possible replacement if i have to go down that route.

[Clive S]

Ok if you are happy so I won't mention it again but just let me say you will need all the power you can get using threaded rod. Turning the power up will help with lost steps.

[Neale]

My mk1 router, built from MDF, used M10 threaded rod as leadscrews. I used M752 drivers running off 68V. Never had a missed step, as far as I could tell. Had a lot of other structural problems, mind you... That was a bit OTT but I intended to re-use the electronics in a later version.

I'm still slightly unsure of the "missed step" assumption. Can you measure how much error there is after, say, 50 vigorous Z moves? 100 moves? Are the results consistent, or random? Change the speed and acceleration and try again? Before junking the drivers and replacing them with different cheap low-power drivers, it might be useful to get a better handle on the underlying problem. I might even swap a couple of drivers between axes and see if the problem follows the driver. Reroute the wires and see if anything changes. A bit of science is called for, carefully measuring and only changing one thing at a time, despite your obvious frustration! I found my Z problem when I was able to see that the error in microsteps after each height-setting operation was almost always equal to the number of direction changes during height setting, for example, and the error was independent of how far the axis travelled.

[neilricketts]

Hi Clive S thankyou and I do appreciate your advice its just I know of cnc machines running on 24v and m10 threaded bars with no missing steps. I will consider changing and increasing the psu voltage if necessary I want to explore all avenues. The machines I know of that run on 24v don't use the tb6600 drivers but they use gecko ones which at the moment are out of my price range as I am just a hobbiest. I will however keep your advice on hand increase that is the route I decide to go.

Cheers Neil

[neilricketts]

Hi, Neale the missing steps on the z axis is after doing a v carving of a Harley Davidson eagle plaque for example the bit will have raised above the work piece by anything from 1mm to 3.6mm. It is not consistent. I have tried switching drivers from other axis. Changing stepper motors from other axis. I have also changed from 1/8 step to 1/4 stepping, I have tried lowering and raising the amperage settings on the driver. I have also tried slowing the ipm to just 5 with acceleration to 5 and it still raises up from the work piece. I have made numerous different anti backlash nuts and my current design is spring loaded. The only thing that I notice is the alarm led is constantly flickering on and off on the driver when it is changing direction. However all the drivers do this on all of the axis and I do lose steps on my axis just not as much as the axis which is the hard working one.

If I do just normal cutting for example 2d cuts I don't have a problem only when there is a lot of up down movements. At first I thought I may have been my nut but not so sure now.

cheers neil