laser loses power with big jobs.

[Jacala]

Hello!

My laser loses power on big engraving jobs like 2 hours on 80% power.

When I put a piece of paper in front of the laser to check if there is a output nothing happens.

I'm reading that overheating could be the cause but I need some more information.

Is it the water that is to hot for engraving or is the laser power supply overheating?

The temperature of the water is 29 degree Celsius.

When I put the machine on hold/pause and wait for 10 minutes it has normal power again, but 4 minutes into the job it dies down again. There is one weird anomaly thing: A few days ago the laser was cutting on 25% for 8 hours and there where NO problems, the water temperature was more or less the same. Could that mean a power supply problem?

Hoping to learn from you guys!

Jacala from the Netherlands


This is engraving, losing power (checked with piece of paper in front of the laser, nothing happened


This is cutting on the same power, nice and even alignment and a even line everywhere.

[waltfl]

Hi jacala
your water temperature should never be more then 24 degree Celsius. very important is also the max current (mA)
this should never be more then 18mA better for longer tube life is just to go to max 16mA.this can only be measured
with a mA meter on the negative tube supply line ( just between the tube ( black or blue wire ) and the power supply
the power supply is very seldom overheating because it has it own fan for cooling it some over temperature protection.

greetings
waltfl

Hello!

My laser loses power on big engraving jobs like 2 hours on 80% power.

When I put a piece of paper in front of the laser to check if there is a output nothing happens.

I'm reading that overheating could be the cause but I need some more information.

Is it the water that is to hot for engraving or is the laser power supply overheating?

The temperature of the water is 29 degree Celsius.

When I put the machine on hold/pause and wait for 10 minutes it has normal power again, but 4 minutes into the job it dies down again. There is one weird anomaly thing: A few days ago the laser was cutting on 25% for 8 hours and there where NO problems, the water temperature was more or less the same. Could that mean a power supply problem?

Hoping to learn from you guys!

Jacala from the Netherlands


This is engraving, losing power (checked with piece of paper in front of the laser, nothing happened


This is cutting on the same power, nice and even alignment and a even line everywhere.

[Jacala]

Hello Walt!

I know about the 18 milliamp (that is somewhere about 67% of the power)

And I've orderd a radiator from internet to cool down the water.

Lets see what happens then.

[waltfl]

no that's wrong all the K40 machines with the PWM from conversion max out the 18mA between 45 and max50 %
you need to measure both the temperature and the mA "eyeballing" does not work if you wana have a long life with your tube
greetings
waltfl

quote="Jacala"]Hello Walt!

I know about the 18 milliamp (that is somewhere about 67% of the power)

And I've orderd a radiator from internet to cool down the water.

Lets see what happens then.[/quote]

[Jacala]

Ive measured the 18 milliamp with a multimeter so that should be fine.

Multimeter between ground and exitwire of the laser.

Or my multimeter is malfunctioning but i dont think so.

Is 67% such a weard value?

[waltfl]

yes as far as I know nobody could go over 48% for 18mA. you need to cut the negative wire from the laser tube and put
you mA meter in between not to ground in order to get the right measurement.
greetings
waltfl

Ive measured the 18 milliamp with a multimeter so that should be fine.

Multimeter between ground and exitwire of the laser.

Or my multimeter is malfunctioning but i dont think so.

Is 67% such a weard value?

[Jacala]

That is exactly what i did. Mmm weard. Ill measure it again monday

[Toasty]

Hi jacala
your water temperature should never be more then 24 degree Celsius.

Is that correct? My understanding was to never go over 28 degrees Celsius or so. That's the info I got from Marco and lots of other sources on the 'net.

I would think it would be very hard to keep it under 24 degrees on long runs. My water is always around 25 degrees and I'm using around 4 gallons of water
to cool my k40. I've been thinking about getting a small radiator just to be safe but I've been told by several people not to worry about it.

Heck, I think the water pump itself heats the water up to 25 more than the tube does.

[Jacala]

I've ordered a small radiator from ebay, next to the cooling it looks cool

the laser is functioning great and I'm using it for production work, making a dollar/euro.

Some jobs are in the 1500 identical engravings so my big bed of 650x850 is quite handy.

The 40 watt is more than enough for engraving jobs.

Thanks for the info!

[Tech_Marco]

Water temp for CO2 laser should be in a range of 22'C ~28'C (ideal). Plus or minus 1'C is not that critical for small tube. But make sure you don't want to see water temp go over 32'C, especailly for a bigger tube.

I think what we mean the highest temperature shouldn't go over is the water temp coming out from the laser tube (outlet), but not temperature before the intake. For example, if intake temp is 25'C and outlet temp is 28'C, it is totally OK. But if intake temp is 25'C and outlet is 35'C, that means that the water flow rate is fast enough so a bigger pump is needed. Remember that there are two mirros/lens installed on each laser tube, one on each end and need to be cooled. So, if the outlet water temp is over 32'C, it is not good for the the output stage mirror/lens (semi mirror/lens).

For Reci laser tube 80W or bigger tube, you have to use a water chiller to work with or the life span of the tube will be greatly affected. The warranty may voided if no water chiller is used wit the Reci tube. I got to mention again, the CW3000 is NOT a water chller. It is just a water radiator. It is not a good one for Reci 80W or higher laser.

Some folks may complained that his Reci tube last for 1500hrs and die. If that is the case, assuming the tube is not a 'fake' Reci thube, one should pay attention to the cooling system.


Marco

[Toasty]

Marco, that's the first time I've ever seen anyone explain that those temps should be measured on the water outlet from the tube. Definitely not the way I've been doing it. I have my temp probe just
hanging in the bucket of water. Hopefully it's never gotten too hot since I'm doing it wrong.

I'm getting ready to hook up a small radiator with a fan on it. I've never seen any examples of people using radiators on the k40. Should I be cooling the water before or after the tube?

My plan was to put it inline with the water coming out of the tube so the pump doesn't have to work to push the water through the radiator. Any suggestions?

[Tech_Marco]

Dan:

As you may know that, there are two pieces of mirrors installed in a laser tube; 100% reflection mirror at the back and a semi reflection mirror/lens at the output stage
When we feed water (possible 25'C) in at the first stage (full reflection mirror), water temperature may go up to certain degree but don't know by how much. Then the pre-heated water go through a long tube and reach the final stage (output port) and cooling off the the semi mirror/lens. After that, the output running out from the tube. I think this is the most important thing to do is to measure what is the temperature after the tube. Remember that the temperature came out from the tube doesn't means that it the temperature of the mirror. It depends on the flow rate so the real temperature of the mirror could be 70'C or 80'C... again we don't know.

Per Reci specification, the water temperature is somewhat 22'C to 40'C (max). So, I come up my own theory: make sure that water temperature that coming out from the tube never go above 40'C!
Assuming that if the "in flow" temp is 25'C and output is 40'C (note it is a huge increase in temp for such short time, so the mirror must be very hot !!), I think it is time to check for the water flow rate and the pressure. Increase the pump pressure so that it increase the flow rate to speed up the cooling

Also, check the color of metal ring that installed at both end of the laser. If it turned into purple, chance that the tube may be over-heated (I need to verify with the manufacturer later). I think it turn purple when it is under high heat. Otherwise, it should stay as shiny gold color.


Marco