Power Varies During Cut

[glenboy]

Hi,

Got a new lens from HPC and it's definitely improved the quality of my cuts.

However, When I am cutting a design out of card it will randomly not cut all the way through in some parts, almost as if the tube power is up and down during the cut?

Could this be a problem with the potentiometer? or a problem with the power supply unit? or something else?

Thanks for any help/advice,

Glen

[PhillyDee]

Is the card perfectly flat? Variations in height (such as air assist pushing card upwards or the card twisting or moving) will affect focus. I am having the same issue with acrylic at the moment.

[bobg]

I agree, keeping the card flat is critical. I cut lots of mount card and have modified the bed of my 3020 so the front of the card slots under a piece of MDF keeping it flat. I use small flat square magnets on sides and nearest edge of the card to hold it down.
Bob

[glenboy]

Hi PhillyDee & Bob,

Thanks for the advice. Looking at how I hold my card, it is very possible that the air assist could blow it out of focus. I support the card along 3 edges and have it raised 5 mm off the bed to prevent any backflash. Very possible that the card sags or is blown by the air assist.

Sooner I get my pin bed made the better.

Cheers guys,

Glen

[Pedro_Hernandez]

Hi Glenboy

I mostly cut 280 to 320 gsm stock at the moment and cut straight onto a 2mm brushed aluminium plate.

http://www.laserscript.co.uk/phpBB3/vie ... ?f=9&t=594

I keep my card stored nice and flat so I don have issue with partial cuts.

When I'm cutting paper/card for School on the 1290, i'll adopt a similiar method as you and raise the card of the bed. This because with the more powerfull tube and air assist I cant get away with brushed aluminium plate as I do with my 3020.



Regards

Peter

[glenboy]

Hi Peter,

Thanks for the advice.

I have ensured the card is perfectly flat and supported on the bed. I am still having issues


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Up until a week ago, the laser would cut through perfectly each time - no card "cut-outs" would remain on the finished piece. Now, more and more are being left - the laser is not getting all the way through.

When the laser is cutting, I turn the power up with the pot and the gauge indicates the power is increasing but the laser still doesn't get all the way through even up at 80%.... I know less can be more, but it doesn't get through at low powers either. This is only 250gsm card so the laser should eat through this.

I have put a volt meter accross the pot and resistance varies from 0 - 1K so I don't think the issue lies with the pot. So then it must be the tube??

I have a spare tube, but am not sure how to replace it. The tube that came with the laser has some kind of "potting" material around the connectors. How do I remove this to free the connectors? And will I need to "pot" the connectors for the new tube?

Any help would be apreciated - I've got a few orders to get out.

I have just purchased a new machine (being delivered next week) so I always have a back up incase one of the cutter starts playing funny buggers. Just wish I'd got the second machine a few months ago!

Cheers,
Glen

[glenboy]

Just had another look at alignment...

I am gettin a "double beam" out of the laser. Pic below is a single test fire at mirror 1 and mirror 2. I fire the laser once and I get a 2 burn marks.

Does this mean I can narrow it down to a dying/wounded tube?


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If so, please can I have some advice on removing the old tube and replacing the new one?

Thanks,
Glen

[PhillyDee]

Could also be a cracked mirror or lens.

[glenboy]

Sorted! T'was the tube all along!

New tube installed and cutting is back to normal!

Glen

[endcan]

Good news make sure you have a good amount of water and it doesn't go above 25 degrees this will keep the new tube in good order have fun