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Laser Cut Mini Mill

Mini Mill that can be cut using a 3020 laser engraver

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A small milling machine that can be made with a Chinese 3020 laser engraver. The main material is 5mm plywood (sold as 1/4" birch plywood at Home Depot). The primary goal is to mill circuit boards, but it should be able to mill other light materials. The cutting area on the current design is approximately 6"x7". The first iteration will use a rotary tool for the spindle, however the carriage will be designed to allow different tools to be mounted easily.

The goal of this project is to produce a small milling machine that can be cut on increasingly common small laser engraver/cutters like the Chinese 3020 laser engraver.

The current design goals are:

  • All structural parts can be cut on a small laser cutter, largest size cut area is under 300mmx200mm
  • Produce milled PCBs using SOIC, QFP and 0603 packages reliably
  • Interchangeable heads

The current design will be using standard threaded rod attached to Nema 17 steppers, and 8mm linear rods with LM8UU bearings for the linear motion. Basic anti-backlash nuts will be included to help reduce backlash, but software compensation may be required.

The core electronics will likely be an Arduino compatible board with Pololu stepper drivers running GRBL. The intention is to make a web based interface to the milling machine using either a Raspberry PI or an OpenWRT router which will give the commands to the Arduino over serial.

Systems Design Diagram:

  • Aluminum Test

    Wudagem07/31/2014 at 14:07 0 comments

    I haven't had a lot of time to work on this, but yesterday while I was doing something else I put a piece of 1/4" aluminum on it to see what happens. I wasn't expecting it to work, I assumed it wasn't rigid enough to actually mill the aluminum, but it worked surprisingly well. 

    I used a 1/16" end mill in a 0.3mm depth cut. It didn't plunge perfectly at the start, there is a small ramp down at the start of the cut to the full cut depth, it looks like it got to the full depth after about 10 degrees around the circle. This is probably due to a combination of the zip tie mounting on the Dremel and give in the linear rod/bearing setup. It also doesn't help that the Dremel is still not vertical, it leans forward a little bit, I need to get some shims in behind the Dremel at the bottom and then adjust the cad drawings for the Dremel mount.

    I am hoping to get more time over the next week or two to work on this. The next step when I get a couple hours is to try milling new end stop boards. That should let me see if anything goes wrong when I run it through all the steps from milling the traces, to drilling the holes, to milling the outline of the board. I will record that process and post the video when it's done.

  • First Sucessful PCB Milling

    Wudagem07/12/2014 at 01:37 0 comments

    The end mills came in today, they work much better than the other cutters I had, this was cut using a 0.011" 4 flute end mill. Once the engraving bits come in I'll do a comparison between them to see if there is a significant difference. The end mills are quite a bit more expensive than the engraving bits, the end mills I got were $6 a piece on sale from $23 and the engraving bits can often be had for under $1 a piece. 

    I didn't get a great deal of time to work on this project in the last couple days, but I made some progress on the GRBL electronics to replace the RAMPS board. I am aiming to build a "shield" for the RaspberryPi that will have an ATMEGA328 and 3 stepper drivers on it and plug into the gpio header. The atmega and RaspPI will communicate over the serial port on the gpio and I will hook a couple of the gpio pins to the atmega for feedback and so the RaspPI can program the atmega. I believe I have all of the components in the schematic and the layout is probably about 90% done.

  • First PCB Milling Attempts

    Wudagem07/09/2014 at 22:22 0 comments

    I made the first attempts at milling a PCB, I generated the G code with the pcbgcode ULP for Eagle. I also experimented with pcb2gcode program as well but it produced gcode that pronterface didn't seem to agree with. I will look into it more once I switch over to GRBL and see if it understands the compact gcode pcb2gcode appears to produce.

    The first cut, pictured above, nearly worked, it got through 2 passes of the isolation milling, out of 4 then the bit broke. I was using a cheap cutter I had in a kit that was an elongated ball cutter with a pointed tip, it broke just behind the ball at the narrowest point in the shaft.

    I tried twice more with diamond abrasive bits, which were the only other bits I had with small tips, they failed to remove copper and mostly just pushed it around.

    Overall the mill seems to behave, the movements were good, it didn't drift during multiple passes. I just need to work out the appropriate cutting depth and cutters. I have a few 0.010in end mills on order that should arrive in a couple days, and a set of triangular engraving bits that will likely arrive in a week or so. 

    Until the new cutters arrive I will continue working on refining the cad models, and investigating the various tool chains. I am also going to start doing schematics and board design for the final electronics and probably start laser cutting updated parts for the second prototype as I finish the cad updates. I am planning to produce build instructions while I assemble the second prototype, which I should get through over the next couple weeks.

  • Dremel Mounted and First Cuts

    Wudagem07/06/2014 at 21:55 0 comments

    I finished the first iteration of the Dremel mount (added to GitHub), while doing that I found a couple more changes to the Z carriage that I want to make. The Z Carriage needs to be about 6mm taller, it doesn't currently clear the Z stepper motor, so the dremel mount needed spacers. I also want to make the outside bearing mount pieces protrude out from the carriage so they can act as alignment tabs for tool mounts as well.

    Currently the tool is attached by wire tires, but I am going to make a bolt on bracket to hold the tool once I fix the Z carriage and tool mount. The tool doesn't sit perfectly vertical I didn't get the curves on the mount quite right, the bottom standoff needs to be a few mm smaller diameter than the top two.

    Once I got the tool mounted and did some more basic movement tests to ensure the added weight didn't cause problems. I double sided taped a piece of 1/4" hard board to the bed and did some test cuts, the line and the box on the top of the piece were the first and second cuts. They were both cut with manually entered gcode, after they were successful I started trying to find a reasonable tool chain to generate milling gcode. I ended up with CamBam which isn't free but has a reasonable trial option. HeeksCam looks promising and is open source but isn't obvious how to use it.

    I didn't get the origin coordinates quite right in the g code file for the logo, it ended up missing the piece by a little bit, but it came out better than expected for a first real cut. It was cut with a ~1.5mm diameter end mill I had for the dremel. It was a deeper cut than I was trying for ended up cutting a little over 1mm deep in one pass but the machine seemed to handle it fairly well. The logo is about 5cm square.

    I don't have any PCB material currently, I'm going to pick some up tomorrow and try that out. Unfortunately I don't have any engraving bits for my dremel currently. I'll see if I can find any in local stores, but I'll probably end up using a diamond bit and see how that goes.

    The next major hurdle will be getting the software chain sorted out and getting a web interface up and running on it.

  • Completed X,Y and Z

    Wudagem07/05/2014 at 13:23 0 comments

    I finished assembling the Z carriage, I had to reduce the flange on the anti backlash nut for the Z axis to fit the space in the carriage. Mounted a temporary end stop for the Z axis, it limits the travel a little bit but it will work until I can mill smaller PCBs to make the proper end stops.

    I got the wiring hooked up for all three axis to the temporary RAMPS board, currently all three axis are running in full step mode so they take 3600 steps to move the carriages an inch on the 5/16-18 threaded rod I'm using for lead screws. The highest speed I can currently run them at is about 125mm/min, I suspect with some lubricant and a bit more tuning I can get it a bit higher but in the end the best way to get higher speed if needed will be to switch to a higher pitch lead screw. 

    All three axis now work, I haven't yet done accuracy testing on the other two axis. I'm currently using Marlin firmware and Pronterface to do the movement testing. I'm hoping that I can get a couple good circuit boards out of this setup so I can mill the final PCB to run GRBL with this machine.

    My next step is to design and build the Dremel mount and attach it to the Z carriage.

  • X and Y Mechanics Completed, Partial Z

    Wudagem07/03/2014 at 00:35 2 comments

    I finished cutting most of the wooden parts and assembled them, I cut all of the linear rod and the remaining threaded rod. Most of mechanical assembly is complete. I put together an end stop based on the DarwinOptoEndstop for the X axis and hooked up a spare RAMPS board I had and did some basic motion testing. I tested the X Axis against a dial indicator to see how it performed, initial tests put the error at around 1 thou over the inch travel of the dial indicator.

    I found a problem with the bearing mounts, they aren't quite tall enough and the platforms collide with the linear rod supports by about half a millimeter, this reduces the travel of the table by about 10mm. I will have to extend the bearing mounts in the next version. The Z carriage was also very tight and I may make it slightly wider in the next version. With it built this far I am also fairly sure the gantry mounts are too far forward to get the full cutting area once I get the Dremel mounted, so in the next version I'll move it back some to extend the cutting area. The last major design piece to do is create the Dremel mount.

    I've also posted the current CAD drawings to GitHub, I have not fixed the issues above and I suspect as I finish the first prototype I'll find other problems. The drawings were done in Geomagic Design, but there is an exported DXF in the repository that is used to create the files to cut on the laser cutter. I use Inkscape to split the DXF into 300x200mm plates for the laser cutter. Currently I am generating plates as needed for parts that I've made changes to, once I get a finalized design I'll post the final plates I used.

  • Base Partially Assembled

    Wudagem05/03/2014 at 13:32 0 comments

    I cut the parts for the base and the main table and glued them together, as well as reduced the end of the threaded rod to fit into the flexible coupler. The next steps are to cut the linear rods to length, make an anti-backlash nut, mount the first stepper and get some basic electronics going to drive it. Then I can test the quality of the movement on the base table and see if any design revisions need to be made.

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Discussions

George I Fomitchev wrote 06/25/2017 at 20:53 point

you may also add powerful laser on your device:  

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George I Fomitchev wrote 08/15/2016 at 06:50 point

you may also replace a spindel with diode lasers. For all Hackaday community i can give 10% off for all Endurance Lasers

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dandumit wrote 12/10/2014 at 05:35 point
Hi, I had a look on Git DXF file and I'm a bit confused about material thickness. I have found 2 dimensions : 6.35 and 4.75mm . is it true ? it must be cutted from 2 thicknesses/sizes sheets ?

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dltruchon wrote 06/30/2014 at 16:12 point
Nice, but light on info....

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Wudagem wrote 07/02/2014 at 23:05 point
Yes, it is quite light currently. I've been away for a few weeks I should get more content up shortly.

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Adam Fabio wrote 06/17/2014 at 03:50 point
Nice project Wudagem! Thanks for entering your engraver in the running for The Hackaday Prize! Don't forget link in your build instructions and source code as you work on your project. The more open you are, the better you'll do!

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Wudagem wrote 07/02/2014 at 23:04 point
Hi, and thanks. The intention is to make it fully open, I wasn't planning to post the CAD drawings until I had completed the first prototype but I've created a GitHub repository and posted what I currently have. There are a few known issues that I've run into while building the prototype that I haven't fixed yet.

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legenduno wrote 01/31/2015 at 06:41 point

Hello, thing is , you never link your GitHub page !!! Please share, i want exact mashine on my table :)

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Stefan Lochbrunner wrote 01/31/2015 at 12:23 point

I thinks it's that issue where GitHub links don't show up under the project links which has already been reported (seems to depend on the browser). Try using another browser and you should see the link. I don't see the link in Firefox either but Chrome works fine.

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