Engraving with a RECI tube - what's the general consensus power that actually works?

[Ian Stewart-Koster]

Hi Folks,

Now that our ULS is running, I've been engraving acrylic, and Cermark, but am limited by the 24 x 12" bed area - but it does a beaut job.

Our Chinese Goldenlaser is pretty woeful at engraving - 130w - W4 - Reci tube. Even at low power there are issues, and it's nothing like the quality of the ULS RF tube. I understand that. (nor is it as quick)

My question is which size of RECI tube will do a passable comparison at ENGRAVING, because I'm in the market for a bigger laser (2500 x 1300mm bed), and am considering a 2-head machine, with 2 tubes, one for cutting (W6- 180w) and one for engraving (W1 or W2 - RECI - 80-90 watt).

(I'm not sure I can afford to go to 280 watt with Jongli paired tubes, though it'd be nice, but it's a USD $5k surcharge over the 180watt unit, but I'd still like to be able to engrave on big panels)

Thanks for any opinions...I've been liasing with a fellow in China. (Threecnc machinery co. ) Their big unit has a RD-6442-S controller, Leadshine drives & steppers, CW6000 chiller...

[Ian Stewart-Koster]

P.S. The RECI website is not very encouraging: "Engraving function: Very good. When the working current is 4mA and the tube is in the state of preionization, the laser can be used for high-frequency impulse engraving." applies to ALL their tubes... and I don't believe that in the bigger ones...

[John Lifer]

My engraving is fairly decent. I don't think any glass tube engraves as good as a RF tube, just the nature of the beast. But Mine is only an 80watt, and I do have issues at low power, just won't cycle fast enough. I think if you will read past inquires, there is no one who uses 100 watt and higher for good engraving.
High wattages are for cutting. 130 watt? disappointment will most likely be the result. Just too much power.

[Ian Stewart-Koster]

Thanks, John, that's exactly what I thought - hence my asking those here who might have something in that 80 to 100 watt region, just how or what standard their engraving has been...?

[Kev Williams]

The 80w RECI in my Triumph engraves just fine, and I have the settings dialed in to where the engraving quality is very close to my Synrad powered LS900 and GCC Explorer.

Did these samples awhile back with all 3 machines, black Rowmark,
I believe the plate size is 1/2 x 2-1/2", as you can see, not much difference between the 3 machines-
(btw, "sample" font is Cloister Openface, which is why it has hollow spots missing)
sb.jpg
Note the power used is 16%, I can run consistent marking at 8% power, which isn't enough to engrave Rowmark.
FWIW, a 70% setting entered = 26mA (100%) on my meter...


My Triumph did this on aluminum, pretty impressive small detail.
Neither of my Synrads have enough power to fuse Cermark to aluminum at all.
ceralum4.jpg

[Bill George]

Kev, When do you have time to work? Or to wind down? Your always solving problems!! Kind of like my new Border Collie pup.

[Dave Sheldrake]

80 watt is the upper limit in reality Ian, above that the tubes won't fire low enough on occasion to be useful. Added to that, the bigger tubes have a bigger exident beam therefore a smaller spot size hence higher power density compounding the problem.

[Ian Stewart-Koster]

Thanks for the replies, and info.
Dave, by 80w, do you mean eg a 100 watt tube that masquerades as 80 watt because you should not go up to 100% - like the Reci W1 ?
Or a lesser 80 watt tube?

The Reci W1 says 80-100w, but the Reci W2 says 90-100... That's weird sort of semi-deceptive marketing ploy, I'm thinking...

[Dave Sheldrake]

That's weird sort of semi-deceptive marketing ploy, I'm thinking...

It is

seen it many times from vendors including Western vendors

"100 watt laser" and it's partly true, when it triggers with it's spike current it may well put out 100 watts but if you tried to use it at that power for any length of time the tube would quickly fail.More often that 90-100 watt Trigger spike will settle back to 85 - 90 on a new tube and 75 - 80 on an older tube.

So yes, it's technically a 100 watt tube as for a split second it was emitting 100 watts, soon after though it was back to 85

[Kev Williams]

FWIW, awhile back I was reading directly from some RECI webpage (that I can no longer locate) that they test their tubes at something like 34mA - don't remember if this was specific to 80w tubes? Anyway- my tube has a 'tested' output noted on the tube of 110w, which sounds feasible if tested at mA's well into the 30's. It also sounds feasible to me then, that at around 25mA my tube should be putting out an honest 80 watts.

But it sounds like many sellers would market my machine as equipped with a 110w tube, just because it tested that high... not a lie, but not exactly true

[Ian Stewart-Koster]

I've just discovered the same thing, Kev.

Our Chinese laser I'd always called "130 watt", and started assuming it was 130w, therefore rated at 100w, a reci W4 tube.
I'm wrong!
I've just put a tapemeasure over it, and the tube is about 1600mm long, plus end caps, 80mm dia, which put it as a W6, 150/160 watt peak, but rated at 130 working watts.

That explains why people keep telling me I cannot cut 20 & 25mm acrylic with it when I have been doing just that.
It also explains the purple band at the negative end - which suggests it's nearing the end of its 5 year life.
When the software is at 100%, it's now putting 19 mA out to the tube, whereas 6 months ago 100% was 21-22 mA.

(I'm going to assume that's a tube problem and not a power supply problem.)

[Mike Thornbury]

Thanks for the replies, and info.
Dave, by 80w, do you mean eg a 100 watt tube that masquerades as 80 watt because you should not go up to 100% - like the Reci W1 ?
Or a lesser 80 watt tube?

The Reci W1 says 80-100w, but the Reci W2 says 90-100... That's weird sort of semi-deceptive marketing ploy, I'm thinking...

Reci aren't deceptive - they are the most honest and thorough of the tube makers.

They give you four ratings: max, rated, operating and long-term power.

Reci, EFR and SPT are all reliable and honest with their descriptions.

As to 'not go up to 100%', where did you get that nugget of misinformation?

IF you don't calibrate your machine properly, you're bound to have issues.

[Kev Williams]

My Triumph is 'calibrated' by mathematics --

I have NO idea if my power supply can be adjusted to match actual power percentage relative to max mA output to what the software thinks it is, and honestly, I really don't care- From day 2 (day one was a nightmare ) I figured out that (a) I should not run my laser at higher than 26-27mA, and (b) 72% as sent to the laser to vector nailed 27mA dead on (and still does). And the down slope is fairly linear, 36% power hits around 13mA, etc., which should equate to about 40 watts, and it's output is very close to that of the 40w Synrad in my LS900...

It's my understanding that most fareast lasers act much the same way, around 70% power hits the safe mA max, and 100% is going to hit the MAX max, with mA's well into the 30's...

That, in my mind, explains the 'not go up to 100%'...

[Mike Thornbury]

My Triumph is 'calibrated' by mathematics --

Versus mine being calibrated by tools. I guess guessing is OK for you - for me, not so much.

It's my understanding that most fareast lasers act much the same way, around 70% power hits the safe mA max, and 100% is going to hit the MAX max, with mA's well into the 30's...

That, in my mind, explains the 'not go up to 100%'...

Your understanding is flawed. The maximum current you can put into a Reci W6, for example, is 32mA. That is what they call the 'test current', used to calibrate the tube and to QA its maximum power for the rating sticker they put on it. At 32mA that gives you ~160W output. If you put more than 32mA in you will kill your tube in tens of hours.

If you run it at 32mA for any significant length of time, you will run it out in a thousand hours or so.

Their recommended operating current is 30mA, which gives you the power they rate the tube at for marketing purposes - 130W. You can run it at that for ~3000-6000 hours. If you mostly engrave or your cutting needs are less than maximum, you can extend the tube's life significantly by knocking a couple of mA off the maximum operating current and get up to 8,000-10,000 hours operation. For a tube that costs ~$1000, 8000 hours+ operating at ~120W is pretty damned good value for money. At the far end of that period, expect to still be getting 85% of the rated output.

All laser tube makers make tubes and rate them at X power for Y mA input. The '70%' BS has infected the industry from those hundreds of thousands of 'K40' analog-controlled rubber-stamp engravers that have been adopted wholesale by hobbyists and forced to do things well outside their design specification.

Laser power supply manufacturers make PSU's and give them a range of output, adjustable via a potentiometer. Through the use of accurate tools, you set the peak output of the PSU to match your desired tube current. It's not rocket science. It's as complicated as when I set the motor speed on my wife's 30 year old sewing machine.

If you don't match one to the other, then I guess you have to use 'mathematics' to guess at your settings. I prefer the use of a calibrated laser power meter and an accurate RMS Multimeter.

If you use accurate tools to calibrate your tube, you never have to do guess and can safely and reliably use the full range of your tube's output, as well as the full range of power steps from 0-255 to fine-tune your output.

Disparaging those manufacturers that strive to create better products for us to use because you can't or won't be bothered calibrating the equipment you have is, I find, borderline ignorant.

[Clark Pace]

I have a redsail and engraves great. Slower though. I had a uls for years but had to sell it. Engraving on my redsail does not engrave as good but its close