View Full Version : Working on a cold tube?

James Terry
11-06-2010, 4:43 AM
Being out in the garage, my tube is currently about 45 F. It seems that cranking it up right now might be somewhat of an unneeded stress. Would it be wise to find some way to pre-warm the tube in this situation? Maybe running a small ceramic heater into the cooling fans even before turning it on might be a good idea.

And how might freezing affect the tube?

Rodne Gold
11-06-2010, 5:58 AM
I don't think you will have an issue , heat is the problem more than cold , if you switch your laser on , the tube will warm up by itself. If you really worried about cold , just tape up one or 2 of the tube cooling fans grilles.

Mike vonBuelow
11-06-2010, 8:34 AM
I have the same situation, I've placed a oil heater, turned on it's lowest setting near the tube so that it gets some heat.

EDIT: I plan on making a retractable "cabinet" to enclose the unit to keep the heat in the area so that all parts are kept warmer.
Even here in OKC, temps can get to below freezing, so I dont want to chance it.
I'll also lay some carpet down to minimize temperature transfer from the concrete, even though it may be minimal.

Robert Walters
11-06-2010, 12:10 PM
What you speak of is called "Thermal Shock".

What you might also need to be concerned with is condensation, depending on humidity, etc.

Usually the electronics will produce heat and that would help offset any thermal shock factors. Some lasers have a tickle pulse that it produces to keep the tube "warmed up".

Be sure to check your owner's manuals for environmental ratings.
Usually there are two sections: 1) Operational, and 2) Storage.

Richard Rumancik
11-06-2010, 6:57 PM
James, I don't think that letting it get that cold is a good idea. If you can keep it about 60F you are less likely to have problems. If you repeatedly hit cold electronics and optics with heat it seems to me to be a recipe for damage.

Using the ceramic heater would take too long to get the internals of the tube up to operating temperature. I would suggest some other kind of heater that you can leave on overnight. Here in Canada we sometimes use electric "battery blankets" wrapped around our car batteries in winter - perhaps one of these could work if you have space for it near the tube (not wrapped on the tube.) They are generally about 50 watts or so. A theromostat control would be a good idea.

Maybe there is some other type of heater you could use - like a low wattage pipe-wrap heater used to keep pipes from freezing. If it is a resistance-only heating device you can easily add a dimmer circuit to reduce the wattage.

I'd check the hardware store and see what product might be adaptable to your situation.

Darryl Jacobs
11-07-2010, 1:38 PM
I would agree with Richard. For the long term it is not a good idea to have the laser unit in variable temperature. Though the laser tube will heat up and is use to temperature changes, the less the temperature change, the longer it will last. I spent years building laser lab equipment and though technology and industry have come a long ways, seals, metal to glass/ceramic interfaces always seem to be the place for seals to blow.

A ceramic heater under the laser and at least a partial enclosure around the unit would be a good thing as long as you can do it safely and feel ok with leaving the ceramic heater on all the time. Oil heaters are a very good alternative and somewhat safer. Having the unit against an inside wall towards the house and a new heat vent from the house an option?

Freezing the unit is a bad idea and will definately shorten the lifespan of the tube and electronics if you are turning it on and off.


Dan Hintz
11-07-2010, 2:50 PM
Stick a 25W bulb in the enclosure to run all night... that should keep things reasonably warm.

Darryl Jacobs
11-07-2010, 3:04 PM
Stick a 25W bulb in the enclosure to run all night... that should keep things reasonably warm.

In the bottom if you can, heat rises!

Joe Pelonio
11-07-2010, 4:03 PM
Since I paid the utility bills myself, when I had a commercial space I'd leave the heat down at night and it might get to the high 50's, but I'd turn on the heat as soon as I came in and wait until it got to at least 65 before turning on the laser. The manual lists only a 90F maximum operating temperature, but I know I and others have experienced problems when it's too cold.