Is a Galvo right for us?

We are engraving rulers, up to 17.5" long on Anodized 6061 aluminum. Our accuracy tolerance is ±.005"

Our current machines are a pair of Trotec Speedy 300 80 and 60 watt with C02 laser. We have far too many problems with the machines going in and out of tolerance, intermittent behavior, we have a tech out every 6 months to adjust or replace parts etc. and in between that time, we spend countless hours chasing our with adjusting our files to the machine's intermittent behavior.

I've always been told that a Galvo will be too inaccurate due to the wide table and central focal point nature of the machine versus a gantry setup but how is something like the Epilog G2 looking these days? Does anyone have experience using Galvos to perform highly accurate engravings without tons of maintenance and calibration issues?

While galvo's can be inaccurate, they ARE very consistent. Which means that, no, you can't just enter in 12" worth of tic marks and have them end up being accurate, but if you take the time to adjust each tic mark of a ruler until it's right then save the job, all subsequent engravings will be accurate repeats. You'll also need to precisely measure your focus distance (as the vertical space between the lens and your work increases or decreases, so does the overall size of the engraving), and have some sort of jig set up to position the parts in the same place in relation to the lens. And keep a reference ruler handy to run a red-light check for alignment on every startup.

A 300/420 lens (which only comes in an M85 size at the moment) will engrave 12" at a time, meaning your longest rulers can be done in just 2 shots. Just make your jig with a stop at each end for running each half, and the engraving will be cake.

You may need to make minor adjustments occasionally, usually limited to when re-starting the computer or program, but they'll be very minor tweaks.

Not an expert by any measure but I don't think a co2 gantry type machine can be expected to consistently produce work to your tolerance. That you've had some success is a surprise to me.

I am also curious as to why you don't do your own calibration.

Too many inherent issues with belt driven gantry machines; belt stretch, belt tooth spacing, belt tooth wear, drive cog wear, belt tension, backlash settings, debris within the belt teeth and/or drive cogs, gantry bearing free play...

Quote:

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Originally Posted by Kev Williams

Too many inherent issues with belt driven gantry machines; belt stretch, belt tooth spacing, belt tooth wear, drive cog wear, belt tension, backlash settings, debris within the belt teeth and/or drive cogs, gantry bearing free play...

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This reflects our experience. Do you have a specific galvo in mind that would be good for what we are trying to do?

Hello,
this problem was resolved 15 years ago and you can easily just enter tic marks and don’t worry about the deformations and distortions of any kind, and have them end up being completely accurate and exact. You need to have galvo with dynamic focal point. This link – if it will not be removed - picture number one will explain it
https://drive.google.com/drive/folde...TyRA6LVtqZ1v-t
I do a lot of very highly accurate marking with galvo lasers and there are no issues with maintenance, non with calibration nor any distortion nor deformation – NO issues at all. Kind Regards.

If it were me, I'd buy a couple of two or three 30 watt fibers with 300mmx300mm lens and get to work. You can buy close to 10 identical Chinese for what one G2 costs last time I checked. And set each up with a fixed layout for each of your rulers. Simple Jig would work really well and would run anodized faster than your fastest Trotec. (and if you wanted a deeper mark you can most easily do that also which you CANNOT do on a CO2) New product offering.

I'm not crazy about this advertising :mad:
Attachment 460701
the reason? The ad purports to say that THEIR lens aberrations can be corrected.
But it fails to mention that cheap Chinese machines and their their lens aberrations can be corrected too.
Just my opinion, but that's riding the line of false or deceptive advertising...

-correcting lens aberrations is what this menu in EzCad is for-
Attachment 460702

I DO agree cheap lenses have issues with simple 'set and forget' type of accuracy, I know mine do. But as I pointed out above,
once I make adjustments, and save the job, I never have to make them again. Because as I noted above, repeat-ability
and consistency is amazing, even with the cheap machines I'm using--regardless of the lens quality.

IF you're constantly doing new, unique jobs that require new setups and high degrees of accuracy, then a 30-50k $ machine will be worth it-

But if you're running the same 12" and 16" rulers over and over and over and over and over and over and over and over... ;)