DIY Laser Roller Engraver

This is a DIY Laser Roller Engraver for those who don't want to spend a huge amount on basically an extra stepper motor. You can see my first commissioned job using this roller here https://youtu.be/rmjKO0JR8uE

• 3D printer
• CAD software (Fusion360 for me)
• CNC machine
• Laser engraver
• MDF board
• Rubber Gate Rollers
• Stepper motor
• Stepper motor gear and belt
• Metal rod
• Hardware

Selecting a stepper motor

Since you're essentially going to be adding a new axis, you need to buy a stepper motor that your machine already uses and is compatible with its power supply and motor drivers. In my case my cnc uses nema 23 motors all around so I went with that. To drive the whole thing together I used a 20&60 Teeth 6.35mm Bore Aluminum Timing Pulley with 2PCS Length 200mm Width 6mm.

Mounting the motor:

The first issue is finding a way to mount the motor horizontally and in a way where I wanted it to be modular and capable of being moved around. The mount is made up of 3 parts. The main block in black is where the motor mounts directly, its mounting holes are slots that allow you to pull the motor away from the gear in order to add tension to the driver belt. The 2 other parts are brackets that attach to the main block in order to hold it down to the base.

Rod Holders:

These white pieces are where 6.35mm steel rods that I bought at Lowes will go through. These will make sure the rods are level with the main block where the motor is attached along with holding the cylinders where the bottles will be laying on

Bottle Holder and plate:

This white piece mounts to the top of the main motor mount. From experimenting from earlier builds, bottles will eventually move up or down like a threaded screw so these pieces help keep it in place. The red plate is paired with it by sticking another 6.35mm rod through both of the pieces. Holes are on top of them to put 5mm screw inserts so that the rod placed through them can be tightened and secured.

Cylinders:

I opted out of using these but they worked fine enough if you clean them up. These 2 cylinders are where the rods will go through and the bottle will sit on. They don't have much grip straight out of printing so I sanded them a bit and plastidipped them, be careful and make sure you apply an even coat. I knew they weren't going to be my permanent solution so I did a rough job with them but they worked out good enough, you just had to engrave slowly. A helpful thing to do is once the rods are inserted through the cylinders, hot glue the ends of them so that they don't slip while turning with weight on them.

When putting everything together it's important to pick a base that is pretty sturdy to hold all components but also big enough to move things around in the case of smaller or bigger bottles to engrave. I used 13mm mdf board as my base. I started by first deciding where my main motor brackets were going to be and marking those on the board. After that I went ahead and marked where its corresponding rod holder would be across from it. Make sure to check that the rod is straight when marking things or else it will be bowing and rolling weird. The other Rod holders should be square with the main motor mount and its corresponding rod holder as well or you may run into issues with accuracy. Something I found helpful was countersinking all the holes so that the board will sit flush.

Hardware: in total everything is mounted with to the ground with M5 screws in 25mm length.

The motor mount and its brackets are held together with M5 screws 55mm in length

The motor mounts to the main bracket with M5 screws 45mm in length

in total

14 M5x25mm

4 M5x55mm

4 M5x45mm

11 M5x6mm inserts

Calibration

This is possibly the most important step in the whole process and can be broken down to varying between your motor drivers, machine settings, and gear/belt used.

I'd first begin by making sure that all your motor drivers and motors are calibrated just to be safe. That means that if you tell your machine to move 10mm that it moves 10mm. There are plenty of great videos on how to do this if you need help with this.

Next is your machine settings, assuming that it is calibrated I would turn down the acceleration speed because if it moves to fast it can cause a bottle to jump or move up and down too much.

To calibrate your rotary device now I highly suggest replacing your Y axis with the rotary so that the bottle isn't moved back and forth when engraving or else it'll suffer from too much movement resulting in streched images (blue bottle in the picture)

Calibrating the steps per mm can be done a variety of ways but the way I found best was by getting a bottle with a known diameter and masking tape around it. Next create an svg or dxf of a rectanlge who's length is the same as the bottle and run the engraving over the tape. Compare how far off the end points were and use a steps per mm calculator to determine how to change that axis' steps per mm settings. You can repeat this process until you get an accurate reading that you're happy with.

After calibrating you are now ready to use your rotary engraver, grab a test bottle and run your favorite logo or image. (The bottle furthest to the left was the final result of testing, middle blue bottle was where I was using the x axis for the rotary instead of the y, and right bottle was before I had calibrated the motor for the rotary it resulted in stretched images slightly)

Personally I wanted to keep this project as close to only using open source as possible so for that reason I am using Lasergrbl to control the cnc and laser while my machine is running off an arduino Uno with GRBL.

You can use lightburn as it is a nice program and very popular but I personally feel like I can do everything lightburn can do using free tools. Another Note is I feel like I prefer the way Lasergrbl would handle the images when engraved.

Both engravings pictured were done with the same settings at 300mm/min, 10mm/line at 15% power on a 10w output diode laser.

On Lightburn I had the rotary setting enabled along with the cylinder diameter. I actually used lightburn when I was calibrating the rotary and thought it would create the better results but to my surprise I found to like LaserGrbl better. I found the Lightburn engraving to look squished/ compressed somehow without having done anything to the image. I'm not sure if there were some extra settings I had to tweak as I'm not as familiar with Lightburn and only using it's trial version but it also produced more visible spacing between each pass of the laser.

On LaserGrbl I simply input the same settings as Lightburn aside from the rotary settings as LaserGrbl doesn't have this option and I found to like the engraving it produced better. I found it to not look squished along with the spacing between each pass was much smaller resulting in a high resolution of the image.

Overall personal preference and knowledge of the software will vary in your results but for me I'm more comfortable with LaserGrbl and it produced better results for me without having to change as many settings aside from disconnecting my Y axis.

This change was done as a way to add more grip for the rollers. I took apart 2 roller guides from a fence and used the rubber from them as they seemed like suitable replacements over the printed ones I had. Since the diameter for them was a lot bigger than the rods diameter I had to create an end cap that fit perfectly that also had an insert so that I can screw down my rod. Overall this was a huge improvement and I'm very happy I added this. I believe the technical name for them is a slide gate roller and I had taken apart 2 6 inch rollers.