Homing issue with K40

[Rick Hudson]

Hello, I have a last resort question about a homing issue on a K40. I have talked with Lightburn and OMTech and basically struck out.. 

We have an older K40 that was stored for several years, and I am trying to resurrect it. After aligning the laser, I tried to get it working (probably should have tried that first..) but it is not cooperating. The machine simply sill not home..... The board connects and is communicating properly, but it is gantry operation challenged.. The Smoothieboard seems to be working properly otherwise, but since it does not know where home it, it will not cooperate. I updated to the latest firmware to see if it would fix the issue, but it didn't.. 

The machine simply will not home..  I can use the movement arrows and get a response (barely) but it's very challenged. I can move it once, then nothing..  I can hit home, and it will return to where it was before I issued the move command. 

I have tested the end stops with an ohmmeter, and they are working correctly all the way up to the PCB.  I also checked them with the M119 command and verified they are working. I tried reversing either, both of the endstops and it makes no difference.. I know the machine used to work, but it's being hateful..  Did I waste my money on the new set of mirrors? 

If the opinion is that the board is defective, I may just toss it out an upper floor window, I'm not about to give OMTech $250 for a replacement PCB (even if they did have them in stock..) so any help is greatly appreciated. 

Let me know if there is any other info I can provide, I attached the config.txt file in case it's needed.   Thanks much for any help you can provide.

Rick

[wolfmanjm]

The first issue I see is your max feedrates are WAY too high for a K40. In my experience the maximum it can do is about 100mm/sec (6000mm/min)

So set your maximum actuator feed rates to that. The issue maybe that the step rates being issued are too high for the stepper motors.

I am not sure why it won't home. Did you try the $H command to home instead of G28? G28 in cnc mode is return to saved position which it sounds like what is happening. $H will always do a home regardless of which mode it is in.

Try those two things then get back to us.

[Arthur Wolf]

On Mon, Nov 3, 2025 at 9:25 PM Rick Hudson <rick...@gmail.com> wrote:

Hello, I have a last resort question about a homing issue on a K40. I have talked with Lightburn and OMTech and basically struck out.. 

We have an older K40 that was stored for several years, and I am trying to resurrect it. After aligning the laser, I tried to get it working (probably should have tried that first..) but it is not cooperating. The machine simply sill not home..... The board connects and is communicating properly, but it is gantry operation challenged.. The Smoothieboard seems to be working properly otherwise, but since it does not know where home it, it will not cooperate. I updated to the latest firmware to see if it would fix the issue, but it didn't.. 

The machine simply will not home..  I can use the movement arrows and get a response (barely) but it's very challenged. I can move it once, then nothing..  I can hit home, and it will return to where it was before I issued the move command. 

I have tested the end stops with an ohmmeter, and they are working correctly all the way up to the PCB.  I also checked them with the M119 command and verified they are working. I tried reversing either, both of the endstops and it makes no difference.. I know the machine used to work, but it's being hateful..  Did I waste my money on the new set of mirrors? 

Ok so this is common with people asking for help with these sorts of problems: you're not giving us the information we need to actually understand the problem.

That's fine, let me help you.

Tell us exactly what happens when you send what Gcode.

Like, I send G1 X100, this happens.

I send G28 X0, this happens.

I send G1 X100, then G1 X0, this happens.

I move it manually to the middle of the frame then do G28 X0, this happens.

Which firmware are you using exactly?

What happens if you reduce the feedrates a lot when doing moves like G1 X100 F100 is it better able to move if the speeds are reduced?

If you set much lower homing speeds, this group in the config:

alpha_fast_homing_rate_mm_s                  50               # feedrates in mm/second
beta_fast_homing_rate_mm_s                   50               # "
gamma_fast_homing_rate_mm_s                  4                # "
alpha_slow_homing_rate_mm_s                  25               # "
beta_slow_homing_rate_mm_s                   25               # "
gamma_slow_homing_rate_mm_s                  2                # "

 

Like divide every value by 20, does it help?

Same thing for your max feedrates overall, they seem high for a K40.

And another thing, your config file is extremely old/outdated, if you're using the latest firmware, you want to take the latest config file example from the website, and "move over" your values to the new config file, and then use that.

Do that then show us the resulting config file.

If the opinion is that the board is defective, I may just toss it out an upper floor window, I'm not about to give OMTech $250 for a replacement PCB (even if they did have them in stock..) so any help is greatly appreciated. 

If the board is really defective (I suspect not at this point), there are quite a few ways to around that on a smoothieboard, it's pretty agile / modular, but let's worry about that only if you actually have that problem.

And if it's defective and you don't want to bother with hacks, we can arrange a new v1 board or even a rebate on a v2 board.

Cheers.

Let me know if there is any other info I can provide, I attached the config.txt file in case it's needed.   Thanks much for any help you can provide.

Rick

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勇気とユーモア

[Rick Hudson]

Thanks for the info and response. I updated the config file and made the appropriate changes. I'm not sure what the firmware version is, it's the latest one on Github, in the Wolfman firmware folder. Attached is the config and the console files. No change really, it still hates me.. As you can see by the console, Lightburn thinks everything is cool, as it gets the response from the controller. When you see a halt message, that is me hitting STOP to try and release the gantry, which now does nothing (it used to work) the gantry remains locked. I have to turn the power off to release it, and when powered back on, it immediately locks it again. I tried reversing the endstop for X, and it made no difference.. 

Using the commands gets a response usually, but not a good one. G1 X100 causes it to crash against the endstop with a horrible stepping motor noise. All the other commands do the same thing basically. Moving the gantry to the middle and issuing G28 X0 does nothing.. This machine is absolutely ignoring the endstop switches, and since it has no clue where the gantry is, it does not cooperate.. As I mentioned I checked the endstops with a meter and they work as the M119 command also proves. They are NC switches. $H also does nothing except causes Lightburn to go Busy and I have to hit STOP to clear it. 

This is really confusing, I own 3 printers, and never had an issue like this. At least this machine does not have a Z to worry about so it's not really that complicated. 

Thank you all, I greatly appreciate your assistance..  

Rick

To view this discussion visit https://groups.google.com/d/msgid/smoothieware-support/CAMHZkm42Kf_r%3DC-%3Db6jmu6%3Dqkx4-ksFQW5agSdL9u5qado%2BHGw%40mail.gmail.com.

[wolfmanjm]

Ok first thing is DO NOT USE lightburn to talk to smoothie as lightburn does not know how to talk to smoothie properly. For now use a console only and issue commands through the console. Then try $H as I said G28 DOES NOT WORK on your version as a homing command, in CNC parlance G28 is move to park position.

So do the tests outlined earlier but through the console ONLY.

Also show the results of M503 I suspect that the speeds being defined in config are being overidden by an override file.

Let us know the results this time.

Also where did you get the version from? there is no wolfman version AFAIK that is valid.

https://github.com/Smoothieware/Smoothieware/tree/edge/FirmwareBin 

is the directory to get firmware from.

Type version at the console and give us the results...

[Rick Hudson]

OK, well, if you are trying to confuse me, you have done a great job! Have you used that link you provided?? It CLEARLY says wolfmanjm at the top of the folder..  Maybe I should have said 'wolfmanjm' firmware folder???

Also, the whole reason we have this machine, and the reason it has a Smoothieboard is to make it compatible with Lightburn.. At least, that is what I know, and why we have the K40 with the Smoothieboard upgrade. Was that a lie?

I DID use the console (in Lightburn) which is what I copied and placed into the txt file, is the Lightburn console not valid either? If not, what console does work??   Version is edge-cf1a3ac Dated Dec 30 2022

We are a contractor for the DoD, and are limited to what we can use for software. If I can't get Lightburn to work, we will have to forget this and obtain another engraver that will work, like the Galvo fiber laser we also have. 

See the attached console file for the info you requested..  Thank You...

To view this discussion visit https://groups.google.com/d/msgid/smoothieware-support/d05c0d60-418a-4aa7-9aee-9e1f99e93b33n%40googlegroups.com.

[Arthur Wolf]

Ok so you ignored the most important part of both Jim and my message :) 

That's fine, this is more familiar to us than it is to you, let me tell you again.

What you describe **most** of the time is the result of the board trying to move too fast for the steppers/machine/drivers.

Ie your default speed settings being way too high.

This is why Jim and I asked you to try reducing your default speeds, and why I asked you to try using G commands with low F parameters (F is feedrate), 100 (mm/min) is a good place to try.

Please do that, try starting the machine, sending nothing else, and sending a G1 X100 F100, and see if that actually results in a move. Which should be very slow, that'd be a full minute to move 100mm, very approximately 1mm/s.

If it helps, then this means you have a feedrate/default speed issues and you need to tune your config's speeds way down, then move back up until you reach a reasonable point.

Also Jim is right that you shouldn't be using Lightburn to debug these sorts of issues, one of the issues with it is it's likely just going to "eat up"/hide from you useful debug information, like for example if the board goes in alarm mode, it's likely it won't show you that.

So please try using something like pronterface, or cutecom, or smoopi something more straightforward like that, at least while debugging things, once you get everything working you can try to go back to using more "fancy" software.

Try this, give us the results, try to be very clear and complete in your answer, like, methodical, as much as you can, and it's likely we'll be able to help you figure this out.

Cheers.

To view this discussion visit https://groups.google.com/d/msgid/smoothieware-support/CAAScDg0K25iTNdbozopc9Dm819vENP4PjEWCt%3DMz40qoj-kRhw%40mail.gmail.com.

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勇気とユーモア

[Don Royal]

sorry. I have a million things going on.  I would like to try first replacing the config file with a known good file.  May I trouble you for a link.  Machine was perfect one day, next day micro sd card is blank.

To view this discussion visit https://groups.google.com/d/msgid/smoothieware-support/CAMHZkm4xuSsvr6kZo9q76544CNiaVnc%3Df6faxZD20JM%2B6rfqZQ%40mail.gmail.com.

[Arthur Wolf]

Unless this is another email for Rick Hudson, you are highjacking somebody else's mailing list thread, this is generally not a great idea, you should start a new thread instead.

To answer your question:

If you want a known good config, simply go to https://smoothieware.org/ , navigate to « Configuring Smoothie », and there you should see a big «Click here to get the latest configuration file example» blue button, simply click there and you'll get to a working config file, that you'll need to adapt/adjust to the exact specifications (like steps per millimeters etc) of your particular machine.

Depending on if it's a laser cutter, 3D printer, cnc mill, etc, I also strongly recommend you follow the corresponding guide, that you can find prominently on the homepage at smoothieware.org.

Don't hesitate to ask if you have any other questions, but try to do so in a new/fresh thread that you start just for your question.

Cheers.

To view this discussion visit https://groups.google.com/d/msgid/smoothieware-support/CAJBozgb2mUeaPRvGjzH4NfneYBeySFY9bKr08UBz4-4NpTHGMw%40mail.gmail.com.

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勇気とユーモア

[Don Royal]

very sincere thanks.  I'll get to as soon as possible

To view this discussion visit https://groups.google.com/d/msgid/smoothieware-support/CAMHZkm6fxMBQobdMzWWU-AWtAtrA4Z9XZnWVaWRLK94G5gfRBw%40mail.gmail.com.