new tube > cutting works, engraving not (lo x7)

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Joined: Tue Jun 02, 2015 11:55 pm

new tube > cutting works, engraving not (lo x7)

Postby typomaniac » Tue Mar 07, 2017 5:27 am


maybe anyone can help me. i upgraded from a 30 watt to a 40 watt tube in my diy laser. Everything worked fine bevore. The power supply has enough power for a larger tube. I tested some cutting and everything works fine. But when it comes to engraving things are getting strange. The tube stops firing during engraving and suddenly starts again. It is not possible to finish an engraving. Pushing the laser button for testing purposes leads to similar behaviour. Sometimes the tube fires and sometimes it does not. I would expect the tube being defective if it would not work while cutting.
I use the lo x7 controller and i already increased the power in my settings for engraving in order to make things work with the larger tube but with no result.

Any help is greatly appreciated..


Posts: 158
Joined: Mon Jan 06, 2014 4:28 am

Re: new tube > cutting works, engraving not (lo x7)

Postby SWMS » Mon Apr 03, 2017 12:17 am

Have you adjusted the integrated potentiometer on the laser psu so it's giving enough current?

What is the PWM setting at the moment?

That's all I can think of.

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Joined: Mon Jun 15, 2009 3:00 pm

Re: new tube > cutting works, engraving not (lo x7)

Postby Tech_Marco » Mon Apr 03, 2017 11:37 pm

I don't think the tube is defective. The issue should be that you have too low current setup for the engraving. Remember that laser tube has 'start up' current. For a 40W laser tube, the start up current should be around 3~4mA to enter saturated point (stable point). Just increase the current for the engraving and it should be fine

Also, check the picture for the engraving. Make sure that you have cleaned up some 'left over' pixel (tiny dots) or the laser will fire unexpectedly


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