Power settings not transfering to machine

[geoff55 (Geoff Fleming)]

Not sure if this is the right area for this but I’ll try here.

I recently got a new CO2 laser to replace one that was destroyed last year. It’s a 100W with a Ruida 8445s controler. The max power setting I run it at (both in the machine and in Lightburn) is 55% and that has the tube draw 22-23 mAmps which I believe is just under the reccommended maximum. My last machine had the same settings. When I first started using the machine it seemed a bit down on power but did what was required except it sometimes dropped power during a job for a short period which made for uneven engraving and cutting (I’m in discussion with the maufacturer about that). Today I ran a job and it ran correctly but I had the speed set to fast and it didn’t cut properly. I ran the job again after adjusting the spped but now the laser barely fires, drawing only 2 mAmps. I’ve tried everthing I can think of incluning rebooting the machine and recreating the job. It still only draws 2 mAmps regardless of the power set in Lightburn. Now here’s the kicker, I can set the cotroller to 55% power and when I pulse it it draws 22 mAmps.

Any thoughts?

[bernd.dk (Bernd)]

@geoff55

incluning rebooting the machine

That sounds drastic and usually erases everything from the machine’s setup, so I hope that’s not what you mean.

How do you measure mA on your machine, do you read it on the tube’s power supply or do you have an external mAmeter?

If you do a test with 15% power 15% min. power and 100mm/s speed, what does your ammeter show?

@geoff55

did what was required except it sometimes dropped power during a job for a short period which made for uneven engraving

Have you checked your alignment and are you sure that the bed height is also the same over the entire area? Another possibility is the nozzle head, does the laser beam come out straight in the middle?, is the lens not loose or defective?

If you do a 100ms test shot directly from the machine, bypassing LightBurn, do you have different mA readings when changing power?

A simple test shot on M1 would also be interesting.

[geoff55 (Geoff Fleming)]

@bernd.dk

How do you measure mA on your machine, do you read it on the tube’s power supply or do you have an external mAmeter?

The meter is on the tubes power supply. Thats the same as my last 2 machines and their readings were consistant as was my new one until today

@bernd.dk

If you do a test with 15% power 15% min. power and 100mm/s speed, what does your ammeter show?

2mA

@bernd.dk

That sounds drastic and usually erases everything from the machine’s setup, so I hope that’s not what you mean.

Just turning the machine off then on

@bernd.dk

Have you checked your alignment and are you sure that the bed height is also the same over the entire area? Another possibility is the nozzle head, does the laser beam come out straight in the middle?, is the lens not loose or defective?

The alignment is accurate, bed is level and mirrors and lens are clean and tight.

@bernd.dk

If you do a 100ms test shot directly from the machine, bypassing LightBurn, do you have different mA readings when changing power?

Pulsing from the controller at 55% gives the expected amp reading of 22mA. It’s when the job is sent from LB it only deliveres 2 mAmp from 10-55%

@bernd.dk

A simple test shot on M1 would also be interesting.

Not sure what you mean

[bernd.dk (Bernd)]

Can you send a small test file that has that problem?

Ps. it’s good that you didn’t reset the ruida itself

[geoff55 (Geoff Fleming)]

@bernd.dk

Can you send a small test file that has that problem?

It’s the middle of the night here. I’ll send it tomorrow. The file hasn’t been saved but it’s still on the computer.

@bernd.dk

Ps. it’s good that you didn’t reset the ruida itself

Don’t I know it. I’ve been there, done that.

[geoff55 (Geoff Fleming)]

1Kerf.lbrn2 (9.1 KB)

Here’s the file. It burnt fine the first time but subsequently it would only read 2 mA

[jkwilborn (Jack Wilborn)]

The minimum power is set to 10%, at this value it may not lase, whereas maximum is set to 55%.

If the 8mm/s speed is at or below the start speed, you will only get minimum power (10%).

Usually these quit lasing at around 10%. I would doubt it’s lasing at 2mA. I wouldn’t expect it to draw any current.

What value is your start speed set?

[geoff55 (Geoff Fleming)]

@jkwilborn

The minimum power is set to 10%, at this value it may not lase, whereas maximum is set to 55%

The tubel fire3 down to 8%

@jkwilborn

If the 8mm/s speed is at or below the start speed, you will only get minimum power (10%).

Usually these quit lasing at around 10%. I would doubt it’s lasing at 2mA. I wouldn’t expect it to draw any current.

What value is your start speed set?

Looking at the vendor settings it appears the start speed is set at 10mm/sec but setting a speed of 9mm/sec will deliver 22 m/A. At 8mm/sec it appears that it was delivering only 10% power which would be pretty close to 2 mA

When I set the speed up to 11mm/sec it all worked fine and cut 6mm easily and cleanly. Now Ijust have to focus it to do that over the entire bed

[bernd.dk (Bernd)]

@geoff55

When I set the speed up to 11mm/sec it all worked fine and cut 6mm easily and cleanly.

Good morning,
@jkwilborn has hit the nail on the head, these are the same settings I suspected. Remember to mark his post as solved, it will help others find the solution to this problem much faster, …you are not the first and you will not be the last with this problem

@geoff55

Now Ijust have to focus it to do that over the entire bed

If your machine is aligned correct, the lens and mirrors are clean and in order, and you are in focus, then there should only be minimal energy loss in the corner furthest from the tube exit. If you get uneven results in different parts of the machine bed, there is one of the previously mentioned sources of error that needs to be corrected.

PS. Also remember that alignment errors will gradually lead to greater deviation of the laser beam down to the nozzle opening. So if your nozzle is not perpendicular to the machine bed/gantry, the beam may hit the inner cone of your nozzle.