OMtech K40 Laser Utilizing the K40+ Smoothieboard Upgrade Processor Card Adding Rotary Problem to E-Axis Solved

LightBurn Hardware Compatibility Smoothieware
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I have recenetly purchased an OMtech K40 laser printer and wanted to add a rotary device. Not wanting to be required to unplug the Y-Axis cable each time and plug in the rotary, I purchased an optional K40+ Smoothieboard which came with and E-Axis to support rotary devices as an additional Axis and also gave the capability to use Lightburn Software with the K40 Laser.

After installing the K40+ upgrade card and connecting the rotary device to the E-Axis port, I used the Rotary configuration in LightBurn to enable the rotary and run the test for the Rotary. I found I had to configure the CONFIG file on the SD card on mounted on the new processor card. The CONFIG file has three places that need the E-Axis pin numbers saved onto the card. These are silk screened on the back of the card for each of the onboard Axis. In Lightburn, the A-Axis is the software name for the E-Axis on the K40+ board.

With the SD Card configured with the correct pins for the E-Axis per the silk screen, I used the Rotary configuration in LightBurn to enable the rotary and run the test for the Rotary. The Rotary would spin in one direction only, pause and then spin again in the same direction making two revolutions in one direction instead of spinning one direction for a full turn, then reversing back to the starting location.

After much research, and speaking with OMtech tech support, I finally found a solution on Amazon Feedback page for the K40+ board that resolved the issue and allowed the rotary to spin and reverse.

Below is that information, It has taken much research to find and I want to include it here for easy access to others that maybe trying to install the K40+ Upgrade Board in their K40 Laser and save many grey hairs and frustration filled hours.

From Amazon Feedback:

This is a drop in replacement for the existing K40 controller board. If the only thing you want is to add Lightburn support then it works without any tricks or modifications. 5 stars for that.

I have to deduct a point for inconsistent labels. The board has one of the axis labelled “E”. In the documentation that axis is called “U”. In the smoothieware config file (which you will have to edit) AND in Lightburn it is called “A”. Not sure why they couldn’t just call it “A” all the way through.

Adding a rotary is not straightforward. In order to work right you have to do 2 things. First, you will need a pin jumper cable. On page 2 of the manual, you will see a diagram. Pin# 2 on the block labelled “3”, which is known as the “Multiphase U Axis Driver Signal” needs to be connected to a specific pin on the header labelled P12. See the attached picture. If you don’t do this then the rotary device will only spin in one direction. Minus 1 point for this. This one boggles my mind.

Once you’ve done that then you need to modify the config file. The settings you need to change are under the “A axis” section:

====================

A axis

delta_step_pin 2.3
delta_dir_pin 1.31
delta_en_pin 0.1
delta_current 0.8
delta_max_rate 8000
delta_acceleration 200

Two pins must be jumpered together on the board itself. I cannot upload the photo showing the jumber placement photo, but the following link will take you to the Amazon page and the photo:

https://www.amazon.com/gp/customer-reviews/R1SP9A5KWKDY79/ref=cm_cr_arp_d_rvw_ttl?ie=UTF8&ASIN=B09MD249K7

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Hi,

I’m actually the person that wrote that review. :smile: I’m thrilled that it helped you get up and running.

A couple other things I didn’t post was that the connector on one of those blocks is a JST 2.54 pitch. The jumper I initially put on it ( and is in the pic ) would bump out if not careful. Using a 5 pin JST 2.54 made it solid.

The next thing is that even though the Z-Table initially worked, for some reason I’ve found that I have to go into the Move section of Lightburn then click Go and then Home. Once you do that then the Z port starts working right.

I’m not sure if just going past the normal boundaries resets something on the controller or if lightburn is sending a command that it’s not logging, but either way just do Go and then Home and the Z will then work.

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Hi,
Thanks for replying and going through the process of findiing the solution. It was a pain running down the fix you found. I had to take one end of the jumper and crimp it ever so slightly to keep it from randomly slipping off.

Another question, have you had problems with the Laser losing serial connection with Lightburn? The console shows almost 100% usage and the Laser just stops talking. If I right click the Device button to reset the board, Lightburn just goes to Disconnected status and I have to power cycle the machine to get connection back.

I have tried lowering the USB speed in the config file in steps down to 2400 which has improved the situation some, but still it is not dependable to do a project of engraving. I also tried changing the transfer mode to Synchronus from Buffering and that also has not helped and I have swapped the USB cable twice but that has not helped.

Any suggestions?

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I have not had that problem.

When you connect your machine to the laser does it act like a thumb drive where you can drag / drop files to it?

I’ve been playing with the firmware and I ran across some issues where if the mass storage device setting is turned on then the laser freaks out if windows accesses that drive while running.

If you don’t see it as a drive then that is definitely not the issue.

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:slight_smile: updated the firmware and set the USB on the config file to 115200 and it appears to be solid now. Thanks for your feedback and again, thanks for the hard work you did to get the rotary working. I know from experience that it was a hair pulling effort. =:)

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Another question, in your config file, what steps per mm are you using? If you are using 19 per Amazon config, how did you calculate that? I have a NEMA 17 stepping motor.

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I’m using the FTG Rotary. My delta_steps_per_mm is set to 17.

My current config file is at: #Omtech LaserBoard v0.2 #If editing with notepad++ then click Encoding -> ANS - Pastebin.com

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