JTech Add-on lasers for Shopbot

In this thread Brady mentioned a JTech laser option for the Shopbot. I read about it on the JTech website.

Is there anyone on this forum, who has this add-on, and would be willing to share their experiences with not only the product but also the company? Product quality; complexity of installation (physical and electrical); customer support quality (it's tough to compare with Shopbot or Vectric); longevity of the product; pluses and minuses of going this route versus a dedicated laser, etc. I have a 2009 PRSAlpha 96x60 CNC.

My plan is to not do cutting with it (I have access to the local high school shop where they have a really big laser machine, and I'm a volunteer teacher and a substitute teacher). That's what I have a Shopbot CNC for. I would, however, like to start doing some engraving work and don't have the budget, or the physical shop space, for one of the standalone machines.

Thanks!!

I'm interested to know this too. I looked at their site and did a little reading and it doesn't look too hard to integrate (that's what he said). I'd be interest in engraving wood, not much more. As if I really need something else...

Don,
Here's the thing...You can buy the most powerful version (3.8w currently), but output is most likely going to be less. Furthermore, unlike professional lasers, the power is not modulated while it is cutting. It comes on at set power and goes off at set power. There is no pulse width modulation going on like a 'real' laser here. This is fine for a lot of things, where you just want on-off control, like simple engraving etc. When you get into photo engraving or even 3D (yes this is totally possible with PWM control + more power), this is where the laser power needs to be modulated. As it is, the power is modulated by move speed, so the faster you go, the less material penetration there will be. This is very similar to plasma cutting in that regard, although you can modulate the amperage somewhat on the fly.

So in terms of integration with your existing machine, it is super simple. The ONLY thing that is happening is that the laser is being turned on & off between jog moves. Nothing more. In their ShopBot example, they suggest using output #5 as the switched trigger for the unit, but you can use ANY output that isn't currently in use, but it has to match the output called out in the post processor. They also have a Vectric post processor for SB for download on their site. There's really nothing more to it than that - Uber easy!

Now in terms of cutting anything useful with it...that is a matter of interpretation. If you need to cut paper, cardboard or other thin materials, I think it is possible - even thin plastics in the sub-1/8" range. I might just get one to slap on the machine for cutting gaskets for various pieces of equipment on the farm.

If you start getting thicker than 1/8", and it may still be doable, but you will want to do several passes at the same focal length, then move the Z down and do it again in order to burn all the way through. Keep in mind...this is less than 4W max...it isn't going to blow your mind as to what it can cut...HOWEVER - it seems to be a really good option if your sole intention is to engrave the surface with your logo, signature or part number etc. I think it would be interesting to see a 3D relief with some lasered details in the background. Now that I am thinking about it, I wonder if laser power could be quasi-modulated by moving the Z up and down like PhotoVCarve - where the out of focus laser would burn less in the lighter areas...(thinking out loud again)

Another competitor to look at is the stuff from OPT Lasers. I believe they are out of Poland, but they've got some really slick ways of mounting the laser and taking it off to protect the optics when routing. I know the JTech has their own driver, which outputs more than the generic Chinese counterparts, but I am not sure on the OPT. Have a look. If anybody gets one before me, post up pics of your playtime ;)

-B

Addendum: It IS possible to add some kind of PWM using their custom board that converts S&D to PWM signals. HERE You'd just need to pick up those signals in the control box and run them to the board. Not sure if it is worth it or not...you'd be into it for $600+ with the 3.8w version. Support seems to be very good though...

-B

You can get a NUBM44 6W diode in 12mm module from DTR Lasershop with lens for a modest $115. Suitable Blackbuck control modules are also quite cheap and some allow PWM.
I got one like that but in a more expensive 25mm module. So far I only played with it but at some point I will mount it on my CNC. The output is impressive and it is supposed to cut 1/8" wood at quite reasonable speed. Also very impressive shining a beam just across the back yard at night. They do require quite a heatsink as the power input is about 20W and most of that is converted to heat. Obviously this is no turnkey solution but one that requires a bit of fiddling.

The hitch with these laser diodes (to a lesser degree also with the 3.8W or 2W varieties) is that the emitting semiconductor area is not a circular spot but a narrow line and even when focusing pretty close the resulting focus "spot" is also a line. As a consequence it has really high power density when the machine is moving parallel to this line but no so much when moving in perpendicular direction. That is probably O.K. for engraving where the part is scanned in parallel traces but not so good for cutting complex parts. I will probably rig up a stepper controlled tangential knife like holder so that the beam is always cutting in the most efficient direction. But that is probably #35 of my project priorities...

I am wondering how long such modules will be freely available because they are quite dangerous (especially without filter glasses) and some people apparently build their own light sabers with it. While you can not lop off an arm, you can blind or burn somebody instantly.

this would be easier then loading a pen in my machine. but what would it take to hook it to my prt alpha?

Hello,
Yes, I did this some time ago with a Jtech laser. We needed to mark a machined wood terrain map. The result was OK, it worked for the product but compared to our Epilog laser/engraver the results are crude. As Brady points out there is no power control. As a result in an egrave mode when your motors ramp down to turn a corner, if the laser is on, it will burn more leaving a darker spot. You can turn down ramping but then you have to run slower or put up with ring/vibration. We only did vector engraving not raster engraving.

We have another project we need this on but would be willing to outsource if anyone knows of someone who can engrave large (4") z height objects!
Thanks
Charles

Quote:

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Originally Posted by cwho

Hello,
Yes, I did this some time ago with a Jtech laser. We needed to mark a machined wood terrain map. The result was OK, it worked for the product but compared to our Epilog laser/engraver the results are crude. As Brady points out there is no power control. As a result in an egrave mode when your motors ramp down to turn a corner, if the laser is on, it will burn more leaving a darker spot. You can turn down ramping but then you have to run slower or put up with ring/vibration. We only did vector engraving not raster engraving.

We have another project we need this on but would be willing to outsource if anyone knows of someone who can engrave large (4") z height objects!
Thanks
Charles

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That is GREAT feedback!!! Thank you. I was thinking about pulling the trigger on this, but after your review I think I'm going to look at another solution for laser engraving.