Laser Tube Bad?

[nlucomputers]

The more i read the optimal temp is 70F so putting the water in the refrigerator might be too extreme.

marco and walt,
I have a refigerator on the other side of the wall from my laser, would it be worth getting a stronger pump (im assuming because of the distance, its a few more feet) and putting a bucket in the refigerator?
I dont think that will help this problem but for the future?

EJ

[nlucomputers]

HI
like I said the result looks like that the focal distance changes you can see this how the line gets wider and finally gets totally out of focus.
I had this with some guys who I tutor they have aligned the beam but still could not cut a area. the reason was that the material was not plan or the table was sloping a bit.
I mean the cooling water for cutting should always be between 65 and 68 F the hotter it gest the less cutting power there is, but it will not totally cut of until the water temperature gets over the max 86F this will destroy the tube.
I always use 18 to 20 F. I also set the frequency to 16000 for cutting and I cut up to 6mm with 1 run and 50% power 3mm/s, even oak wood.
greetings
waltfl

is it ok to set the frequency to 16000 using the awc608 and the 40w pwm power supply? I was under the impression that 20000 was the minimum?

I appriciate all your advice.
EJ

[wctx1977]

Now that you mentioned the refrigerator option I have a question for waltfl, mark or anyone else who has done a lot of testing. We know how critical is to maintain the water below 76f BUT what happens if the tube runs around 45 to 50f temperature all the time? Is there any negative effects as power loss, internal lens shifting or any other matter? Has anyone run a true test in a long term for experimenting and valuable data? I have a small fountain water refrigerator that I can modify to dedicate to the machine but I would hate to blow another tube. If someone has done the research please let us know and it would be deeply appreciated.

By the way waltfl, I wish you where in Texas and where my mentor.

[Tech_Marco]

I don't suggest you go for that far (cold). For temperature below 10'C (50'F), it is easy to get condensation. Plus, you may encounter "thermal shock" that may crack the tube. For small tube, the chance to get thermal shock is much less than a high power tube like the Reci 150W. If you'er running Reci W8 (150W) with temp below 10'C, you need to pay extra caution as the sudden change temperature may crack the tube. In most case, you sure don't want to cool the tube below 15'C (60'F). If the room temperature is very low (below 15'C), you may want to do 'warm' up on the tube before set it to full power operation.

Marco

[nlucomputers]

Just an update,, got the laser tube marco sent me, installed it and aligned te mirrors again. and it works like a charm. Now im wondering, about what should i have my settings at to cut 1/8 in hobby plywood or 1/4in MDF. also could someone explain the PPI setting? I set the machine max at 56% so max voltage is currently 17.2-17.4. IM nervous setting it higher. Im curious what marco and walt think though. Also did you try the tube i sent back yet marco? did you see the same results?

ALways Learning
EJ

[Tech_Marco]

Hello EJ:

Limited the tube current by the main power control to 18mA (max) or below is good for the laser tube. Once you the max current output locked up by the 'master' control, you can play around the power setting through the LCD control unit or through the Lasercad power setup per layer. Remember that you should keep water temperature around 25'C (Walt said 23'C even better).

The "PPI" is "pulse per inch". Instead of sending laser beam continuously, it sent beam in pulse instead and the pulse frequency is controllable through the LaserCad. Using PPI for wood cutting can reduce the over-burned (charring) side effect . Doing PPI on Acrylic may reduce the 'bump' on next to the route. However, since PPI is in pulse patten, the output power is considerable less than the non-PPI output and be expecting that the output power is about 40~80% of original (my guess) depends on the frequency you used. Higher frequency will send more power. In other words, the power output is proportional to the frequency. Most folks use 500Hz ~ 2000Hz for PPI cutting.

For 1/8" plywood, I'm guessing that with full power (no PPI), you can do it about 4~5mm/s. When I did a test on a 13mm wood, I set my speed to 1mm/s. You may need to do more test, log it and made up a "library" for future project.


Hope this help

Marco

[Tech_Marco]

I received your tube and tested it for over 15min at10.5mA, it worked fine. Couldn't duplicate the problem you had

Same thing to another customer Jim who return a 850mm tube and complained the same issue. We tested it over 20min from 10mA to 18mA, it burned good. Not sure what's wrong with these two tubes. Now, since it is used and we can sell. Possible to replace my old K40 for experiment

Marco