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Dennis Rech
10-31-2014, 1:34 AM
For the curious, occasionally, the question of tube life for these low cost Lasers comes up.
The tube in mine was down to about half strength so I replaced it today after 350 (give or take a few) hours of cutting time.
It lost about 10% power a month ago and steadily dropped after that.
Almost all my use of the machine has been cutting 1/8 and 1/4 inch acrylic and some 1/4 inch poplar.
I doubt that there is 10 hours of engraving time on it.
I ordered a new 35 watt tube from Light Object for $236 including FedEx shipping.
It arrived in three days.

Replacing the tube took about 30 minutes and half that time was spent looking for my wire stripper and dragging the soldering station out to the shop.
Plugged the water tubes back on and tested the unit for alignment.
Oddly, the alignment was perfect.
This is probably the first time that I have ever moved the machine without having to tweak the mirrors a bit.

So now the laser cuts just like it did when new, about one inch every 7 seconds through 1/4 inch acrylic.

In the specifications that came with the tube is the recommendation that the amperage be kept to 18 milliwatts.
I have been running mine at 22 because that was what FSE had originally speced so I may have cut some time off the tube life.
They have backed down a bit since then.
The cutting speed at 18 mw seems to be about the same as at 22mw.

$235.00 divided by 350 hours comes out to 67 cents and hour.
So far, I have had no other maintenance expenses.

gary l roberts
10-31-2014, 9:04 AM
Always good to here stories of success.

Dave Sheldrake
10-31-2014, 11:07 AM
22mA will kill a 700mm tube very quickly, 350 hour life for any glass tube is terrible, you should be expecting 2,500 hrs at least.

cheers

Dave

Andrew Holloway
10-31-2014, 5:41 PM
Thanks for sharing Dennis.
I think FSE officially recommend no higher than 15mA.

Bert Kemp
10-31-2014, 8:50 PM
350 hours on a tube FSL says should last over 1000 hrs how could you possibly be happy with that. Oh and by the way that so called 40 watt tube is in reality about 25 watts if that.A true 40 watt tube is much bigger then 700mm x 50mm :eek:

Dennis Rech
10-31-2014, 11:07 PM
350 hours on a tube FSL says should last over 1000 hrs how could you possibly be happy with that. Oh and by the way that so called 40 watt tube is in reality about 25 watts if that.A true 40 watt tube is much bigger then 700mm x 50mm :eek:

Hi Bert,
I do not believe that I said that I was happy with that. It is just what is.
When I bought the machine almost 4 years ago, FSE was saying that the tube would last 300 hours at 70% power.
Back then they were claiming 40 watts, they now claim 40 watts peak and that 70 percent is 28 watts.
FSE laser power is a bit like Sears vacuum cleaner horsepower.
FSE now say to keep the power to 15 ma and that it will then last much longer.

The specs of the tube from the manufacturer is:


Power: 32W (35 peak)
Triggering Voltage: 20KV
Operating Voltage: 15KV
Current: 16~18mA
Life Span: 1500~1800 hrs
Warranty: 5 months


I am only guessing that if I keep the power to 16ma that it will actually have 32 watts of power.
The relevant number is that it can cut 8 inches of acrylic per minute.

Years ago, when I first started looking at lasers, EVERYONE emphasized tube life and cost per hour because tubes could cost thousands.
The tube that I bought as a replacement was relatively cheap and I didn't even buy from the lowest cost vendor.
I am pretty sure that I could have gotten a similar tube for about $150.
When the cost is about 50 cents an hour, whether it last half as long or twice as long or even for all of eternity, what difference does it make?

In the last 4 years, I have made hundreds and hundreds and hundreds of gifts and art items for friends and family members.
When one can make elaborate jewelery boxes for girl cousins with $5 worth of poplar and $1 worth of laser tube, its a great deal.
This thing just spews out Christmas presents.
It is hard to believe that everyone does not own a laser.
How can they live like that!

Financially, it has worked out well.
I have made and given away for free all sorts of gaskets for friend's antique airplane engines, motorcycles, pressure washers, my own obsolete air compressor.
A $4 piece of remnant acrylic and 6 minutes turns into a $25 salable item while I watch a Seahawk's game.
For engineering friends with something to sell, I charge out at an arbitrary $35/hour for cutting out their prototypes and jigs and salable items.
They are tickled to find someone to do it while we watch the big screen TV out in the shop.
The machine only cost $2300 so it took 65 hours of cutting to pay for it.
The next 40 hours bought a new Miller Mig welder and the the next 40 bought a plasma cutter and the last 50 bought a pile of milling bits and tooling.

I am old and retired and this thing has been a bunch of fun.

So how can I be happy with a 350 hour tube life.
I think that I just answered that.

Happy Lasering,

Dennis

John Noell
11-01-2014, 2:59 PM
As another retired guy with a Chinese laser, all I can say is that you are RIGHT ON!

Bill George
11-01-2014, 4:54 PM
And so you over drive it a bit, how is that any different from a Mfg taking a 30 Watt tube, over driving it and calling it a 50 Watt? My new 35 Watt from LightObject is 720-750 mm long and 50 mm in diameter. Longer than the OEM one. I have no doubt if I over drive it at 24 ma it will equal the 50 watts. But my 100% max level I use is 22. So I only get 500 hours vs 1000?

Dave Sheldrake
11-02-2014, 5:23 PM
Manufacturers often call the strike current the max current Bill, same with power, a 35 watt tube does indeed strike at 40 - 45 watts but running it at that reduces it's life by an unquantifiable amount. Electrode erosion isn't a linear factor neither is gas contamination so going up by 10% over on the run current could easily take 80%+ off of the tube life (and in some cases PSU life)

cheers

Dave

Bill George
11-02-2014, 6:22 PM
But in running I do not go over 80% of the power. Funny I am using the same 40 watt rated PS that came with the machine which had a 30 watt (peak and dreaming power) tube and never changed anything except the tube.
Dave I am really curious, you have enough knowledge about lasers to qualify as a Engineer. Is that what you do? Thanks for the reply.

Dave Sheldrake
11-02-2014, 6:35 PM
:) Thanks Bill, it doesn't come from working with lasers (although that is what I do these days) it comes from a rather *unusual* previous career.

I've had many offers of doing paid support work for laser companies / vendors and my answer is always the same....No. The minute I work for one my advice will become financially biased and that's not a way I am prepared to accept. My involvement these days is running a pretty big laser cutting company and a free support forum for laser owners (hence my need to be impartial).

cheers

Dave

abby ZHANG
11-05-2014, 3:40 AM
Hi Dennis

most of chinese 40W laser tube warranty is at least 3 month, if your laser tube have problems in the warranty, you can ask for the manufacture to replace a new one.



abby