K40 control board omtech upgrade problems

I purchesed the omtech upgrade motherboard probably a month or so ago, and boy that was a big mistake. it was just ok until i tried to add a lightobject z table. omtech on amazon touts their superior tech support etc. the board they say comes with the install manual and is easy to install, NOT ! no manual was supplied and it took many emails to finally get a responce from them ( At that point I should have trusted my instinct and returned it) but NOOO . I finally got it up and running in order to use lightburn which I had already purched for another diode laser . Everything was ok untill I plugged an extra stepper motor in to test it, I could control the stepper motion in lightburn no problem. The problem came when trying to hook up limit switches to their board, which does have a specific jst connecter plug on the board, its a 3 pin . to make a long story short their tech support gave me info that would be great for an electronics tech and when i followed them the limit switches would not work and the follow up emails from china at 3 am were impossible to understand . They offered me a $50. refund if they could fix the problem or a complete refund if they couldnt, guess what , they couldnt so Im sending it back.
so now I look into cohesion 3d board and from the complaints I see about their support, I dont think ill go with them, I am looking for a recomendation for a board that I can add a z table to and maybe later a rotary . but I need one that you can actually get support for. PLEASE HELP

Did you post with the issue? There are people here competent with electronics that will help you.

Good luck on the upgrade…


The real problem omtechs terrible support, Im done with them and looking for options with companies that have real support that you can rely on

Not having a K40 I haven’t had to deal with it.

Omtech support is great, relatively speaking… compare it to ones that have far worse English or don’t respond until you use external force on them. And it’s the same delayed email game as they are on the other side of the planet…

You might try threads like this and see if they help… Lots of people have upgraded K40’s. Keep in mind it’s a couple years old…

Good luck


if you can send that board back do so and get a VMS board, not Cohesion, you wont regret it, customer service is brilliant and the board is made in the US and is the fastest and probably the best control board for a co2 laser upto 100 watts, I have it on mine and replaced the steppers to 2 amp ones as directed, totally different machine now, this was on my K40 but its now on a much bigger machine.

All you need to do is send in the details of what youre doing with the Z and Eric will sort that for you in the firmware,

I can not fault the board at all. they are on Facebook, boards start from 180 usd now for the one including Z plus 40 usd in you want support, and its worth it 150% support all the time. Takes around a week to 10 days for the board to be made as they are made to order.

I hope you get it resolved. But before you do anything with regards to a Cohesion board talk to Eric on facebook Messenger and tell him your issues and he will be able to help you. I recommend paying the 40 usd for support, I’ve have the manual its written by him and is about 50 pages long and quite technical in places, it is made with the hobbyist in mind but still assumes you have some knowledge. What the board cant do is measured by what it can do speeds of 1000mms are quite achievable with new steppers installed. My Laser is now 1 square metre in size and is really run as a K80 now, I built the laser from some plans off the internet, printed most of the fittings after I altered them in 3d software as I needed a different setup and well its flies on this board. The old K40 I still have running on a MKS Makerbase Card Version 1.3 if you budget doesnt go to the VMS board you can pick up this card for about 40 usd , i can send the firmware and its a fairly easy swap over and runs lightburn ok, no where near like the VMS board though and theres no Z axis or any support at all for it. It does work though and suited me for the first year or so.

I have a up down Z table on the K80 which I am currently building and Eric, the board developer is just waiting on me for the final weight and sizes so he can re write my firmware so it goes up and down correctly etc.

this board also runs a rotary and has Trinamic drivers for torque and quietness… i really cant fault it in any way or Eric himself, one of his problems was the level of service he was giving was phenomenal and it was causing him a lot more time that he had so this week he has changed the level of service and its important to buy it with the board if you want him to help you install it and get it setup correctly.


What does the laser type or power have do with the controller?


it doesnt its just most people seem to go for a RD Works type controller on the larger machines and then you pay a lot more for lightburn and obviously you get more features etc For me GRBL is fine for what I do, I was in the flow writing away when I wrote that…Hope you sort it out…

grbl is pretty lacking compared to a Ruida. Usually when you spend more money you want more options and abilities.

Got it… :slight_smile:


look no further than VMS…

thanks everybody, Im taking a self taught crash course in smoothie editing, learned a lot today, turns out that omtech sent me a supposedly corrected file for the micro sd card and after todays research I found that they never changed the gamma homing for the z table port from false to true. I am also looking at the retract amount for the mechanical limit switch which is set at 1 mm. I have a cnc that runs in grbl so i know it should be at least 5 mm or it wont retract enough so you can reverse it.
I think my problem is I never dealt with smootieware before and had no clue how to deal with it. so I need to get my hjead out of my ( you know what ) and it will all work out

Lots of these are out there. The last little cnc3018 I purchased has limit switches. The Z axes homed down :frowning:

My grbl board was labeled X, Y, Z for limit switches, and they were Z, Y, X… right to left…

That’s the option that comes with ‘low cost’…

Good luck


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