Confused about homing?

I have just upgraded my K40 to a mini gerbil controller.

It’s a standard k40 with limit switches top left etc… I have checked the wiring a million times.

My axis move correctly direction wise.

When I set the origin to bottom left (which I understand is normal for the k40) the bootom left is not 0,0. Instead 0,0 is the bottom right.

Does this mean I need to set the origin to bottom right?

When I do that however my axis don’t work correctly direction wise.

My homing is also not working as the limit switches just don’t stop the machine and it just bumps the rails.

So confused.

I love Lightburn as used it with my diode but this is confusing me.

In the standard setup from your Mini-Gerbil, home is top left for a K40. It fits nicely here with me.
Is it a fairly normal standard K40 you have?

I was hoping you might reply as I saw you had the mini gerbil…

I will reset mine to top left for origin and work from there.

I think the process is:

  1. Origin top left
  2. Adjust $3= (to get the axis moving in correct direction)
  3. Adjust $23= (to get the homing in the top left corner

Not sure why my limit switches are not registering!!!

i will check it right again, wait a second or 2

Strange, sometimes you get insecure about the most basic … I just had to be sure.
End stops are of course both on the left side and the origin is with a K40 top left.
My $3 is 1
and my $23 is 3

are you missing any other info?

Mine was the same when I first installed the gerbil…

The laser just won’t home… It moves towards home but the limit switches don’t seem to register and it just bounces/grinds into the corner.

I have checked and checked every wire/connection… I’m a bit lost with it.

try making a $$ and show it here

have you in LightBurn chosen Gerbil-STM? … and the right Origin in the initial setup?

Yep gerbil-stm chosen

$0=10 $1=255 $2=0 $3=1 $4=0 $5=1 $6=0 $7=0 (ATC M6, pulse/ff) $8=100 (ATC Tool Td, milliseconds) $9=100 (ATC M6 Td, milliseconds) $10=1 $11=0.010 $12=0.002 $13=0 $19=0 (Softstart, milliseconds) $20=0 $21=0 $22=1 $23=3 $24=2000.000 $25=2000.000 $26=250 $27=4.000 $28=5 (Spindle freq. 0 to 15) $30=1000 $31=1 $32=1 $100=157.000 (x:stp/mm) $101=157.000 (y:stp/mm) $102=160.000 (z:stp/mm) $103=160.000 (a:stp/mm) $104=160.000 (b:stp/mm) $110=12000.000 (x:mm/min) $111=5000.000 (y:mm/min) $112=5000.000 (z:mm/min) $113=5000.000 (a:mm/min) $114=5000.000 (b:mm/min) $120=8000.000 (x:mm/s^2) $121=3000.000 (y:mm/s^2) $122=3000.000 (z:mm/s^2) $123=3000.000 (a:mm/s^2) $124=3000.000 (b:mm/s^2) $130=320.000 (x:mm max) $131=230.000 (y:mm max) $132=200.000 (z:mm max) $133=200.000 (a:mm max) $134=200.000 (b:mm max) ok

it’s 100% like my settings, there must be an error in your LightBurn settings, try deleting the profile and make a new one with STM and left top origin and autohoming.
I’m here for another half hour or so

I’ve had to come inside as the weather is making too cold to be in the garage, and it’s quite late here…

I’m going to try tomorrow. I will let you know how I get on.

Solved it👍
The back limit switch was not actually being activated by the rails… It was too far away. I have added a shim and now all is well.

Signal noise was a pain also, need to improve that scenario bit this is a 100% improvement so far…

How have you shielded your usb cable??

Nice that you are laser running again.
Electric noise always fills a lot here in the forum, you can read about the problem for “hours”.
I personally have bought many usb cables which all claim to be electrically insulated ect. It turns out that I have finally found a double insulated cable, put some large ferrite cores at both ends and I have cleaned up my cabling as well as possible. It is an advantage to have the shortest possible usb cable and no hub or sharing with e.g. a camera. I think a K40 in itself bothers a lot of noise with its high frequency power supply here you probably can not do much about it. What is important is a working earth connection, here it is an advantage if one’s house installation is in order and not from 1864. If possible, one’s K40 should preferably run on a group without other major electric pre-consumers because powerful power consumers such as angle grinder vacuum cleaners and the like have the bad habit of sucking too much “start” power when turned on.
I hope you get to run with your system as well as I run with mine. I am very happy with my K40, the Mini-Gerbil controller and of course LightBurn.


I have purchased a short usb and it is working now. I have to run the cable outside my k40 to the laptop in order to prevent noise but that’s no biggy and I will solve that issue shortly.

I’m pleased to have Lightburn back … I used to be a diode user with Lightburn… as it’s so intuitive.

I managed to run a raster with the pwm without interruption etc so all seems ok.

I’ve just got to get the raster settings mastered now… My first image was a bit lacking shall we say!

It’s a great start, congratulations.
In the upcoming version of LightBurn we will be able to adjust the images “live”, so it will be much easier to find the right settings before we engrave them.
I also have a 5.5 Watt diode laser which runs very well under LightBurn. I think there are many who start just like you and me. My next wish is a larger laser. They are just the physical dimensions of my workshop access which limits how big it gets.

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