Autofocus Adjustment on Omtech


I recently purchased my 100w Omtech laser, after a few months of using it i discovered i had not been cleaning my lens as often as i should of been which resulted in having to buy a new lens. I bought the same one that was stated in the manual. Replaced the lens only to find that my focus is now totally out. I have autofocus with this machine, i was advised to do a ramp test and found my optimal distance from the bottom of my laser head but i am having trouble adjusting the autofocus to get it to suit what i need!

Does any one know what steps i need to take to adjust the autofocus correctly in order to match up with the focus distance i need for my laser. The optimal distance from the bottom of my laser head to the material is 5mm

Thanks in advance

Check this forum post and see if it applies:

Thanks for the info. One other issue i think i might run into is that the 5mm i need from the bottom of my laser head, could be shorter than the length of the plunger on the autofocus pen? This would result in the plunger hitting any material i have under my laser?

Why is the new focal distance so radically different than before? Did you get a different focal length lens?

If 5mm doesn’t clear the pen then you’d have to relocate but I’m concerned that you’re not able to account for the difference. That could imply a different problem.

That is what is confusing me too. According to the manual that came with my machine i have bought the right lens for the machine i have. I am assuming i can relocate but would i not run into the same issue if the 5mm clearance is not sufficient?

There was a post from a different user where when she bought what she thought was an identical replacement lens from the manufacturer that it didn’t match what she had previously. Turns out that her original lens was not actually what had been advertised to her initially. She actually preferred the “wrong” lens that had been initially shipped to her but didn’t actually match the advertised spec.

Wondering if that’s the same situation here.

Not following. You’d need to physically relocate the pen to clear the 5mm distance so that it would be sufficient.

I did think that could be the case. Would there be a way of comparing the two lenses to make sure they are identical?
I understand that i would need to physically relocate the pen but i am pretty sure the distance of the plunger and the end of the pen is longer than 5mm in length. if this is correct then would it not hit my material?

Sorry, i am not at my laser so i cannot confirm if the plunger at the end of the pen is longer or shorter than 5mm

Physically examine the lenses to see if you can notice a difference in geometry.

Also, is it possible that you placed the lens in reverse from how it was? As in convex side up vs down?

I will examine both lenses when i am back at my laser. I did also think that but i assume after everything i have read online, convex side should be pointing up?

This is a point of argument but yes, the traditional school of thought is that convex should be up.

If you do find that the lens is a different focal length lens then you’d typically use a different length lens tube to accommodate. Or in your case, maybe replace with a like for like lens with what you had.

Got back to my laser this morning. I enabled the optimize z moves button but still having the samew issue that the autofocus does not seem to store the distance i require for optimal focus distance. I now have all three of those buttons checked ( Enable z axis, relative z moves only and optomize z moves) Is this correct?

I am just about to check both lenses against each other to make sure the one i was sent is a match for the old one that came out.

Did you check the Edit → Machine Settings called Focus Distance?

Optimize Z moves is unrelated to focus.

Hi, Checked the focus distance, it is set to 0.00. I am really struggling to get my head around how to do this. I know i need the distance from the bottom of my laser head to the material to be 5mm but i am not sure this is even possible as the autofocus pen will scrap on my material. the pen plunger seems to be around 8mm so how could i have a distance of 5mm if the plunger is longer than that?

Did you see my post earlier about using a different length lens tube? You change the tube length so that the final distance to the material remains the same. This assumes you’ve determined that the lens you got was in fact different than what you had earlier.

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