What Current Limit and Microstep Rate for TB6600 driver


(David Field) #1

Machine: K40

Board: LaserBoard

Firmware: Smoothie (whatever it came with)?

I’ve decided to use external TB6600 drivers on my K40/LaserBoard/K40 stepper motors set up. Just wondering what current limit and microstep rate to select on TB6600 modules so that the feed distances will be correct without changing config?

Is there enough 24V power from the LaserBoard to power two TB6600s with stock stepper motors?

Regards
David


(Jamie Richards) #2

There should be enough to supply them, but why are you changing to externals? Are you installing larger stepper motors? The LaserBoard drivers are capable of providing too much current to the stock motors as it is, so I am confused as to why you want externals, unless you are upgrading the motors?


(Jamie Richards) #3

Here’s some information to help guide you.


(David Field) #4

To answer my own question for the benefit of others…

I tried setting the TB600 switches to 1A per phase and 1/16th microstepping and these appear to be good. I may try setting the current a bit lower but it is working very well for now at 1A


(Jamie Richards) #5

I’m still curious as to the need for this. Were you having problems with the integrated drivers, adding larger stepper motors etc? Just doing it because?


(David Field) #6

Stock K40 motors were connected to LaserBoard.

I was losing steps on the Y axis when accelerating between cuts after a few minutes of cutting. I think I overcame this by increasing the current and decreasing the speed for the Y axis in the config.txt file but I didn’t trust it.

I decided to use the TB6600 as I thought there may be a thermal issue with the on-board drivers. My X axis is still connected to LaserBoard through the flexi-ribbon cable until I can get the right cable/connectors to replace them.


#7

The default physics values are set quite high and the currents quite low in the config file.

Increasing the currents (even up to the 1.2 max) and decreasing the acceleration should certainly help.

We have tested the board extensively with no cooling and all the drivers at maximum current while hauling a 1kg weight on the head of a COREXY machine. Nothing exceeded 70C on the board. The physics values were certainly different for that machine though.


(David Field) #8

Thanks for the feedback. I’m not trying to suggest that there may be a issue with the Cohesion3D LaserBoard. I hear nothing but praise for them. I have only had mine a couple of weeks and am really impressed with it.

Perhaps I have a problem Y motor on my machine or there is some twist in the carriages that is causing an excessive load?

Jumping straight to external TB6600’s may have been influenced by very recent issue trying to upgrade my 3D printer from Pololu A4988’s to DRV8825’s. Where my Z axis parallels 2 motors off one driver I was losing a lot of steps. I modified this to drive two external TB6600’s to overcome this problem. The thing is though, the A4988’s used to work fine. I only switched to DRV8825’s for the higher current capability.

You have made a very good quality product with so many useful options. A great deal of thought must have gone in to designing such a versatile board. Thank you


closed #9