My Jtech Laser / Shopbot Journey....So Far

I know there are a few people out there interested in lasers and their shopbots. This is just some info on my particular project.

I have a older Gantry Shopbot that I recently upgraded to an RBK box and spindle. Love the machine but wanted to update it. It already had dual Z's on the Y Carriage.
I ordered a 3.8w Laser kit from Jtech and mounted the laser on the Second Z (My B Axis). Used our 3D printer to make a small holder box for it along with a cooling fan above it.

Yes, I know all the bad things said about lasers and CNC routers. I've been hearing I'll put an eye out since I was old enough to run with Scissors. As with all things, proceed at your own risk. You are your own best safety.

As far as running my shopbot I know about 3% as much as most of the guys on this forum. I basically use it to do cut outs for my wifes Paint studio. Have done a couple simple Vcarvings but thats even new to me.

With the Laser properly focused I am running it at .9ips and getting good markings. I am still working on upping the speed to see when it drops off. The focus was way off when I got the laser and that gave me some issues. Easy enough process to fix though.
Still working on getting the post figured out so that I can auto move the Laser to correct focus range for whatever material thickness I am using. Getting close on that. For now I just set it before I start but all the ingredients are in place to get it done.
I am using output 2 to turn the laser on/off which is working very well, no issues.

Anyway, few photos attached showing the mounting and the type of cutouts we normally do. I just wanted a neat way to put our Logo info on the cutouts. I know when I was considering the laser I was on the forums looking for anything I could find which wasn't a lot.






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Just a note for you. The focus was not "way off" when you got it. These lasers are designed to be manually focused. Most commercial lasers are manual focus.

You would have to invent a computer vision/autofocus feature to have it work as you plan to. It takes just under five seconds to focus the laser manually. I don't think you are going to get an accurate and repeatable enough focus for your efforts. You can probably get a rough focus, but not a fine one. You will have to double check it anyway and it is no effort to grab the lens and twist, so why bother?

Your speed is probably OK. For rasters, I run 900mm/min which converts to .58ips and run the laser at about half power over plywood. I vary power settings based on how the darkest area and most detailed areas appear in tests. I usually choose a square inch portion of my project to use as a test. I am not using a ShopBot, so you may be able to go faster. Your power may vary as well, depending on distance from the substrate.

You will see huge speed differences using vector vs. raster styles. Use vectors if possible so the laser will cut the lines rather than spend time time in transit over blank areas. You will have to use rasters for photos.

It would be a good idea to model a funnel into your 3dprinted mount to focus the airflow straight down to the laser cut. Check thingiverse for ideas http://www.thingiverse.com/thing:1636811 Also you might want to set up a small desk fan to blow across your work. Getting the smoke out of the way gives a cleaner cut at higher power.

You should call yours the ShopDot. :)

Hi,

Nice clean install. Sounds like fun! I also have a PRT with the second Z Axis which is currently laying in a box on the shelf.

John

Thanks Will for the notes. Didn't think about the smoke being a factor in the laser beam but it makes total sense. The 80mm fan completely moves all the smoke from the area.
Your right on the focus, I'm just lazy and want it to be as close as possible before I have to touch it.

John, My Z sat dormant for a long time as well. I finally get to use it for something.

Burnt the lense out of the laser a couple days ago and awaiting a new one. Didn't notice a small piece of debris that got on it and it did a great job of burning itself up. Luckily the lens isn't expensive and the laser isn't damaged.
All my machines in the shop have names.... I think the shopbot may be Dottie now. Its kinda catchy.
Already got a Scarlett and Richard. Had a Trixie but she had to go. She pissed me off one to many times (Tormach CNC mill), got replaced with Scarlett (Haas CNC mill).

An update to running slow IPM's. I recently dialed down the current on my drivers specifically on the second Z. So much quieter now. The Second Z is now almost silent, like my first one always as been and super smooth. I found it was set way above any of the other drivers.
Turning down the X/Y drivers resulted in a lot less noise and also heat. My motors were running so hot on long Laser jobs that they could not be touched and made a lot of noise. They now run at a nice hot but not unbearable to touch heat and are much quieter.

Hello CStevens. Could you include some pictures of vector images you have engraved with your laser? Mayo Pardo engraved some vector images for me last fall using his Trotek laser, and I was enraptured with the details rendered on my design (even though I don't especially like my design!) I am not going to spring for a dedicated laser like a Trotek. And some of the things I want to engrave are large. Here is what Mayo "burned" for me. http://www.talkshopbot.com/forum/att...id=30153&stc=1http://www.talkshopbot.com/forum/att...id=30154&stc=1 Thanks, Chuck

Nice hack! Don't burn the house down... where did you get the laser? and can you describe how you hooked it up? I have access to a laser but the materials are restricted and I would like to etch corian, doing it on my shopbot would be stellar.