Under/over driving a tube?

[Greolt]

I have ordered a 60w power supply and will build space for a 1200 long 60w tube.

However it seems good sense to me to start with a cheap 40w tube till I get everything sorted and learn how to drive it all.

Is there any problem driving a 40w tube with a 60w power supply ?

Limiting current to the tube's specs should be no problem. But will the higher voltage be an issue for the 40w tube ?

And on the other side of the coin, when the machine is all up and running and I start to wish for more watts, how about a 80w tube being under driven ?

CNCOLTECH sell a long life tube in 80w, only 1120 long. 60w power supply is rated at 28kv and 23ma. 80w tube is 20kv trigger voltage and 28ma.

My thinking is that under driving the 80w tube will extend its life and I will still get my 60watts of cutting power.

Is my thinking too simplistic ? Are there issues that I am not aware of ?

Thanks for any advise / guidance.

Greg

[lasersafe1]

You might have a real concern. Longer tubes need higher strike voltages. The strike voltage from a 60W supply will be higher than that from a 40W supply. The run current being held lower would not be a problem, but I would contact a tube supplier to ask about the strike voltage concern.

A 40W supply might not even strike the arc in a 60W tube. If I were you, I would make sure I have a reliable water cooling loop and then run with your 60W tube with 60W supply. Just keep it dialed down until you are comfortable to go to higher power. If you don't have your exhaust system done yet, then don't do anything that can generate much smoke. Smoke residue on mirrors or your laser output window is very important to keep at bay for a 60w system.

[Greolt]

I have communicated with Shirley from CNCOLETECH

She advises there will be no problem driving a 40w tube with a 60w power supply. Keeping the miliamps within tube specs of course.

I also asked about the 80w long life tubes. (I think they get called RECI on another forum)

Shirley also advised there would be no problem running one of these at 60w. It is shorter than the longer, cheaper style tubes and so needs less trigger voltage. (1120mm as opposed to 1200mm for a 60w)

My thought is that this 80w long life tube is only $240 dearer than a cheaper style 60w tube. ($700 as opposed to $460 delivered)

If I drive it as 60w then it should last OK. Also as it is shorter than a 60w tube it will be easier to fit in available space.

Does it sound like I am trying to justify my purchase. Anyway I have hit the buy button so I hope it is sound thinking.

Greg

80w tube.JPG (24.15 KiB) Viewed 18548 times

[mikegrundvig]

That long life 80w tube is what I plan on using for my laser too so I'm very interested in your results and findings.

-Mike

[lasersafe1]

I was also talking with Shirley lately. I was interested in their 150W tube after seeing the Kern video cutting mild steel. Then I read this thread and I'm no longer interested in CO2 for steel. I'll wait for fiber laser prices to drop. 1064nm is much better for steel.

http://www.sawmillcreek.org/showthread.php?161318-Cutting-Very-Thin-Stainless-Steel

[Greolt]

A little googling found why they call these RECI tubes

http://www.recilaser.com/2010/en/index.html

The website makes them sound good. I guess that is what good marketing does.

Also implies that they should be used with their matched power supply. I will have to think about that one.

Greg

[educa]

Correct URL seems to be http://www.recilaser.com/2010/en/index.html , but I didn't really find a lot of info there.

I think cnccoletech is the best provider of these business class co2 tubes. They seem shorter then the other lasers, but a lot thicker with 80mm.

However, if I look at the price on the coletech ebay shop, then this looks like a very nice deal, especially since coletech also sells them with matching PSU.


I do wonder however why they mention with this laser that at 4mA you can engrave at high speed. Would this mean that at 4mA this laser could be fired at much higher pulses per second then the regular ones?

80 Watt certainly should enable a lot higher speeds then the default 40

[Greolt]

The RECI tube arrived today.

Problem is that it is longer than the advertised length.

Advertised 1120mm long

Reality 1230mm long.

It won't fit where it was meant to go.

Sent an email to Shirley. See what she has to say.

Greg

[educa]

Oops thats not nice of them. Maybe you could still fit it in by making an expansion to your cabinet?

Boy am I lucky that my machine case will be 1600mmx1200mm. I can accomodate lasers upto about 1400mm then