Max Speed Settings

Machine: K40 - M2 Nano Board (ribbon style)

Board: Standard Cohesion3D

Firmware: GRBL-LPC

Problem/ Question: I have been using the board that came with my machine for a while and that thing moved!! I was able to get around 550mm/s. I wanted more control and better features so I bought the cohesion board and am using lightburn. For the life of me, I can’t get this moving very fast. I installed it with the standard smoothieware but read GRBL-LPC is faster. I have modified the config file, the device settings, the machine settings and set the speeds in the “fill” and still looks about 20-30% slower than the stock board. Any suggestions?

Anyone got any suggestions?

Hi Brandegee,

Apologies for the delay in responding. We were at a trade show over the last week, just got back, and are recovering and getting caught up on support inquiries.

To start with, what is it you are trying to do (raster engrave an image, cut out a shape…)? You may have set the stock board to go to 550mm/s but there is no way it actually moved that fast. For reference, the machine would literally shake itself apart at or above 350mm/s.

The C3D board has max speeds, accelerations, and a number of other settings. It can also control the power of the laser and engrave in grayscale. All of these things can play a role in the setup.

By telling me how you are testing this and what you are trying to do, I can better advise you.

Hi there,

I was starting to get a little worried. Hope the show went well.

We only ever engrave stainless steel powdercoated cups. All the files are vector images. We almost never cut. I know that the machine wasn’t moving at 550, but I did visually see a significant difference between the max speed of the nano board and the cohesion board. (I kept increasing the speed of the nano until it had a heart attack and then pulled it back about 50. We always ran it a programmed speed of 550mm/s.

If you want, I can send you a video of it operating at max speed on the nano and the cohesion boards so you can see the difference?

Thank you,
Brandegee Pierce

It did. I didn’t realize exactly how non-productive I would be after only sleeping 3-5 hours a night for a week straight. Trying to get caught up now.

That would be great. You can upload to YouTube or some such and post the link here.

Also, have you made any modifications to the GRBL settings on the board by means of the $$ commands in console or Machine Settings in LightBurn?

I will not be able to upload until next week since i am going out of town for Memorial Day. 3-5 hours seems like plenty of sleep! LOL.

I have made some settings in LightBurn to the GRBL settings. Only changed settings related to speed.

If it’s skipping or grinding, you should up the motor currents. I’d do that anyways. You can go up to 1.2 amps.

Since we actually have acceleration that can be defined it’s possible that having the max speeds increased isn’t enough as the acceleration is limiting you from actually hitting the max speed.

I would test by:

First, home and then bring the Y down halfway.

Run G0 X300 F6000 command where F is the feedrate (speed) in mm/min so that’s 100 mm/s

Then G0 X1 to bring it back to the left side while not fully hitting the endstop.

Repeat and increase the F by 3000 which is bumping up by 50 mm/s

This tests the raw physics and is not constrained by how much data the board can take, as a raster engraving sends a lot of data.

Sorry for the delay. So I bumped the speed up but it didn’t change at all. Even when I dropped it to
(G0 X300 F500) or increased it to (G0 X300 F30000) it still moved at the same speed.

This is the code I used but copy/pasted like 10 times. I changed the speed as mentioned above.

G0 X300 F500
G0 X0 F500

Here are the videos.

Cohesion3D Board
M2Nano Board

Oh yeah, this definitely looks like the C3D board respecting the acceleration values set for it on the board’s config. For GRBL-LPC firmware, get LightBurn --> Edit --> Machine Settings opened up. There are some values that will need to be played with, in particular the max speeds and acceleration values. If you can show me a screenshot of what values you’ve got in that Window I can better advise.

Also, that’s a cool rotary design. I’m not 100% sure what I’m looking at, but it looks cool!

So I tested about every option and did everything I could and nothing worked. Does that just mean the stock board is much faster than the Cohesion3D board?

I made a 15mmx200mm rectangle and this is the M2Nano board. Calculated the speed and its around 480mm/s.

Everything I did on the Cohesion resulted in the slower video.

I slowed it down a little in the settings but the speed was the same.

This is 550.

I definitely don’t think that is close to 550 but it is much quicker than my board is running. The hardware is close enough too that I should be able to achieve those speeds.

Oh, that is 550mm/s, with an acceleration of 10,000.


This looks pretty quick. Mind sharing your settings for the K40? Were you using GRBL or Smoothieware? Any other mods? I have very little added weight to my head so I can have max speed. I have a fan blowing off the part but its not attached and there is no positioning laser because it would increase the weight quite a bit. I only ever do the exact same job so once I get it setup (and since the Cohesion3D allows for X,Y, Z, and A axis’s) I never have to move anything end don’t care about the positioning laser.

GRBL-LPC, stock C3D settings and a good belt. My K40 mods were fairly standard, except I created and integrated my own motorized Z into the case for less than $60. Right now, it’s gutted and I’m in the process of expanding the cut area to 305mm x 610mm+. Experimenting with what works and what doesn’t using V-Slot.

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