question on laser tube operation

Discussions on optics for laser cutter/engravers

question on laser tube operation

Postby alan025 » Thu Jul 11, 2013 12:38 pm

We are scoping out the parts to build a 2.x laser cutter and had a question about possible sources of laser tubes. We have an older Full Spectrum Laser laser cutter. When the power is cycled on the pump for water cooling, we end up with an air bubble in the laser tube (see attached photo). It can take days on the pump before the bubble finally collapses. My questions are:
1) Is this sort of air bubble in the end of a laser tube harmful to tube operation in a 2.x build?
2) Do the tubes recommended for the 2.x build have the same problem with getting the air bubbles out, or does some other system feature (like a higher pump flow) resolve the issue?

We are moving forward with the 2.x build, but I'd rather not end up with a system that requires 72 hours of water pump operation before the laser cutter can be fired up.
Attachments
photo.JPG
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Re: question on laser tube operation

Postby jv4779 » Thu Jul 11, 2013 2:00 pm

1) I don't know how harmful it would be, but could reduce the cooling.

2) There is probably nothing different between a FS laser tube and one you would buy for a 2.x build. My 2.x doesn't have any issues with bubbles because I was strategic in how the tube is placed. In your picture if the tube was rotated 90 degrees that bubble wouldn't be sitting there. Put the tube in so that it is slightly higher in the back and the water exit spout is directly on top and that goes a long way toward clearing the bubbles quickly.

Jeremy
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Re: question on laser tube operation

Postby JValliere » Thu Jul 11, 2013 8:16 pm

I loosened the clamps on my tube and rotated it, with pump running and laser power supply unplugged, until it pushed the bubble(s) out. My understanding is that a bubble will create a hot spot and shorten tube life.

I'm looking at elevating my cooling system above the height of the tube to eliminate the backflow/draining of coolant from tube when not in use.
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Re: question on laser tube operation

Postby TLHarrell » Thu Jul 11, 2013 10:06 pm

My coolant bucket is under the table and I don't have any issue with it draining out when not running. I have it elevated on another bucket, total elevation between water level in the bucket and top of tube in laser is about 8" difference.
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Re: question on laser tube operation

Postby macona » Sat Jul 13, 2013 3:31 am

Air bubbles will not make a difference in the operation of the tube. There is just not enough heat dissipated to matter.
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