glass tube ramp time

[Brian Leavitt]

I'm wondering if better glass tubes ramp up faster than their cheaper counterparts. My Chinese machine is useless for acrylic because I have to run it either too hot or too slow to make a decent mark on it. Same for plastic. Basically it's either too deep or doesn't ramp up quick enough for thin things like serifs to get etched. I mainly use if for wood, and on that it's not a problem, but I would like to run some acrylic at home rather than having to take it to the shop all the time.

[Klaus Madsen]

Hi Brian. What software are you using? RDWorks?

[Dave Sheldrake]

They do indeed Brian but not even the better tubes ramp anywhere near as quick as as an RF unit, it's also a product of a decent matched power supply as well

[Brian Leavitt]

Thanks, Dave. Yeah there's a Huuuuuge difference in response time between the Chinese machine and the other ones. I'll do whatever I can to reduce that, though. Over time the China Special will improve.

Klaus - yes I am using RDWorks

[Ron Gosnell]

How about dithering, would that help ?

[Dave Sheldrake]

You can pre-ionise the better tubes by running a trickle charge through them, that helps quite a bit

[Brian Leavitt]

I don't think dithering is going to help in this situation. This laser tube just ramps up really slow. If I run it at 75 speed and 21 power on acrylic, the engraving looks OK. It doesn't miss the serifs or thin strokes, but it is too deep and the edges are all still sloped. With letters it almost looks like it was done with a round nose rotary bit. 21% is essentially the minimum I can run this tube, power-wise. If I speed up the machine and up the power the engraving looks bad. One problem is I need a bearing upgrade on this machine, but that has nothing to do with the acrylic issues.

This is not an issue on wood. Wood looks fine at I generally run it at 400 speed and 50 power, but it is much more forgiving. Acrylic and plastic are not so forgiving.

I did not know there was a way to pre-ionize any glass tubes. I'll have to look for information on that when I actually decide to spend the money on upgrading the tube and PS.

[Bill George]

My 40 watt Gweike Chinese machine did acrylic engraving just fine. Are you using cast or extruded acrylic?

[Brian Leavitt]

Cast acrylic. I'm using left over acrylic awards that have been sitting around for testing.

I was hoping it's just the cheap tube and power supply that's causing this. Seems that may be the case.

[Dave Sheldrake]

A cheap PSU can often cause problems Bri, go with a matched tube and PSU from EFR and you won't have anywhere near the problems ;)

[Brian Leavitt]

That's the eventual plan. I have to milk what I have for now. I'll just run acrylic on the good lasers for the time being.

Here's what my acrylic lasering at home looks like. Not good. The bottom line is the best I could get out of it. The edges of everything is basically beveled.

[Kev Williams]

Have you tried dithering what you're engraving? As in, change everything to 80 or 70% black and change it to a dithered bitmap? If your laser's software will 'automatically' dither imported photos, try changing to 70% black and saving the job as a JPG image and see what happens-- might work, might not, but if it DOES, it'll look much better, as the dithering causes the laser to 'artificially' pulse, which helps even out the burn...

[Joseph Shawa]

A cheap PSU can often cause problems Bri, go with a matched tube and PSU from EFR and you won't have anywhere near the problems ;)

Dave, does your tube fire when the PS is turned on? With my EFR PS the laser fires upon power up of the PS. They said that this was "Normal". I say bunk. The tube should NOT be firing unless I send the instructions to do so.
That said, I bought a very stable PS from LaserSPT. http://www.laserwd.com/ Everything works as it is supposed to.

[Ron Gosnell]

Have you tried dithering what you're engraving? As in, change everything to 80 or 70% black and change it to a dithered bitmap? If your laser's software will 'automatically' dither imported photos, try changing to 70% black and saving the job as a JPG image and see what happens-- might work, might not, but if it DOES, it'll look much better, as the dithering causes the laser to 'artificially' pulse, which helps even out the burn...
Yeah that's what I was trying to say (artificial pulses) instead of just plowing through it like a glass tube does

[Brian Leavitt]

Have you tried dithering what you're engraving? As in, change everything to 80 or 70% black and change it to a dithered bitmap? If your laser's software will 'automatically' dither imported photos, try changing to 70% black and saving the job as a JPG image and see what happens-- might work, might not, but if it DOES, it'll look much better, as the dithering causes the laser to 'artificially' pulse, which helps even out the burn...



Yeah that's what I was trying to say (artificial pulses) instead of just plowing through it like a glass tube does



OK I get it now - Sorry. I have not tried this. I'll give it a whirl. I've never tried any kind of bitmap on the China Special.

[Brian Leavitt]

The laser supplier is recommending the "T60" power supply, but I think that's the same one I have. On EFR's site, they suggest part number "PS-N80" for the 1200CL tube. This power supply is for a 60 or 80 watt tube. I can't find it other than through a different supplier on Alibaba.

[John Noell]

I am not sure, but I think that the PS-Nxx series power supplies are actually from Hongyuan. I was told that EFR is no longer using or selling that series, although their website had not been update when I last looked. They are now using PSUs with displays, like the RECI power supplies. (FWLIW, I never could get a RECI 80W supply - supposedly matched to my 80 watt RECI tube - to stop saying there was a short somewhere. I even put the entire length of the high tension wire inside thick-walled silicone tubing, to no avail. I finally gave up and went back to the cheap PSU that came with my Shenhui.)