Did I break the laser tube?

The laser does not come out normally.
The video has the test button pressed.
Is this symptom a laser tube failure?
It is probable that it was used without running cooling water.

If that is antifreeze as a coolant I would guess the HVPS is toast?

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Keep you fingers out of the coolant :crazy_face:

:smiley_cat:

The pink indicates it’s probably RV antifreeze which uses Propylene Glycol without the other things used in auto antifreeze that are conductive. Did we ever determine the conductivity of RV antifreeze?

When you say the laser does not come out normal what do you mean? Do you get a single spot on the first mirror? Low power?

Did you see it with finger? Silicon tube.

I can not understand.

Yes, I am using propylene glycol.
I don’t know the conductivity.

Symptoms that are not exposed to the laser are low power.
The light illuminated by the video is a laser.
Why are you so weak?

I used it without running cooling water, so I thought it was broken.
Is it caused by propylene glycol?

The light you are seeing at the end of the tube isn’t abnormal. The laser itself is invisible to the human eye.

Sorry, the question about the conductivity was directed at @donkjr.

The concern about using antifreeze is that a conductive cooling water can wreck your laser power supply.

Running without cooling water can certainly degrade your tube.

So is your laser performing poorly?

Can you burn a spot at mirror 1 and post the photo for us to examine?

:smiley_cat:

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I have to look it up but pretty sure rv antifreeze is ng.

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Paper does not burn.
Also, there is no laser irradiation sound.

The tip of the laser tube lights orange.

Antifreeze may have damaged the laser power supply. It’s the worst.
No knowledge of electricity :dizzy_face:

I’ve done it :sweat:

Replace the coolant with distilled water and see if you can get it working. DC laser tubes don’t work properly if the conductivity of the coolant is too high. (Do not touch the coolant when the laser is firing.)

A 50:50 mix of RV antifreeze (propylene-glycol-based antifreeze) and distilled water can be okay. However, the conductivity can be too high due to the used dye and additives. Since RV antifreeze isn’t meant for this use case, the manufacturers do not care about the conductivity of their product.

If you really need the frost protection and do not want to use a heater, I recommend to use a mix of distilled water and pure propylene glycol:

E.g. if you mix 7 liters of water with 3 liters of propylene glycol (30% by volume), the mix will start to freeze at about -12.5 °C, stop flowing at around -15 °C, and burst your tube at around -16 °C.

A higher percentage of propylene glycol causes higher conductivity.

You can check the conductivity of your coolant with a $10 EC/TDS (electrical conductivity, total dissolved solids) meter from Ebay. Make sure it can measure µS/cm.

I don’t have super reliable data on this, but up to 200 µS/cm or so should be okay. But lower than that would be of course preferable.

Either way, try pure distilled water first.

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Thank you again, Mr.tomatsu.
I will try using distilled water.

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I have found it. Is water leaking.
Did the glass tube break?

Yea, that’s bad. There is no way to fix that.

Basically, you got 3 nested tubes. The one in the center is the discharge tube (this is where the action happens), the one around it is the water cooling tube, and the outermost tube is some kind of reservoir for the gas. The innermost and outermost tubes are connected. They contain the gas mix. They are sealed.

If there is waster in either of the other two tubes, the laser tube can’t be used anymore. If the water can get into those areas, the gas is no longer contained.

Here is a diagram of a CO2 laser tube. I highlighted the water cooling parts:

laser tube water cooling parts

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I bought a glass tube and a power supply.
If you have any problems, please help me. :pray: