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Turning a Makibox into a PCB Mill

I bought one of the ill-fated Makibox 3D printer 4 years ago. Time to make it earn it's keep - but as something it was not intended to be.

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I've had a partially broken Makibox A6 sitting in my workshop for three years. I don't think it will ever work again as a 3D printer (even if I could be bothered putting it back together and trying to get the now-abandoned software to work, I'm now the proud owner of a Lulzbot Mini, so there is little point), I hate to see a couple of hundred dollars of hardware sitting with nothing to do.

I've always wanted a way to make my own PCBs at home, but I've never been a fan of using chemical etching (It's messy, and getting rid of the chemicals is not fun), so I've decided to see if I can cobble together a PCB mill.

I want to see how far I can get armed with the parts that I have (Motors, driver board, some of the mechanisms) and a 3D printer.

You might remember the Makibox A6 - it was a sub-$400 3D printer that, like a lot of cheap printers at the time, was crowd-funded. It took forever to deliver, and there were a lot of problems with it.

Personally, I managed to print a single cube on my first print. On my second print something went wrong and I blew up the control board. I suspect because of the stalled extruder motor. The extruder needed replacing, as did one of the plastic lead screws (that was my fault - I over tightened it).

In the process of trying to get the parts replaced, the delivery got lost - they claimed it had been delivered, but I hadn't received yet. While trying to work this out, I had to quickly move interstate for work. To make matters worse, the company that made the Makibox disappeared around the same time, so I resolved myself to writing off the printer.

I decided to move to Melbourne permanently, so I flew back to Perth to collect my belongings - included what was left of the Makibox - and jammed it into my car for long drive over the Nullarbor.

And there is sat almost three years - dejected, in a cardboard box in my workshop.

On a recent trip back to Perth, my mother handed me a package which a person I worked with have given her. Apparently. it was delivered to the office years ago - so I had no idea what it was.

Low and behold, It was the replacement parts from my Makibox! Well, this was a sign. I put the parts next to the printer, as I wasn't sure what I was going to do with it. I had an M3D printer which was pretty terrible - maybe I could frankenstein the two designs and get one printer out of them?

Fast forward a couple of months - I come in to a bit of spare cash after selling off my time tracking application, and I decide to bite the bullet and buy a real 3D printer - a Lulzbot Mini. After setting it up and kicking out a number of awesome prints, I placed the M3D next to the Makibox. I now had a collection of old, cheap and not very good printers. I had to do something about that.

The Makibox has some decent steppers and screws in it (the M3D really doesn't - half the problem really) so I started looking at the parts and wondering if I could convert it to a PCB mill. Ideally I'll eventually want a proper mill that can do aluminium and stuff, but I reckon I can cobbled together something good enough to grind a few hundred micros of copper off some fibre glass. Bonus points if it'll drill through holes.

What's the worst that can happen? I have a broken Makibox?

  • Designing the Y-Axis

    Myles Eftos2 days ago 0 comments

      I’ve been iterating the Y-axis in Fusion 360. A common design I have seen on other moving-bed designs is four linear bearings - one bearing at each corner of the bed. The problem with this design is you lose the distance between the bearings in travel. Since I have only have a maximum of 165mm on this axis, I didn’t want to lose too much to dead play.

      My first thought was use a single bearing on each side, introducing a minimum lost travel of 12mm (the width of the bearing). This looked like it would cause rotation problems, though - especially when dive cutting in the outer edges of the build area.

      I went back and looked the parts I could salvage from the Makibox, and it turns out I have four 170mm linear rods at my disposal. This means I can create a passenger carriage - one that isn’t driven by the lead screw, but instead is pushed along it’s rails by the bed itself. This design gives four points of contact, eliminating the radial moment of the two bearing design (Note: this doesn’t deal with linear rod or bed flex, just the rotation issue). The disadvantage is the base is now double the size, but as the bed would have moved outside of the frame envelope during operations, it’s not that big of a deal.

      Here is a render of the Y-axis. If you imagine a bed on top of it, attached to the two carriages - the left (driver) carriage is driven by the lead screw, while the right (passenger carriage is pushed by the bed. (I tried making a video, but the Fusion 360 animation workspace doesn’t support animating joints!)

      The Y-axis will have a 131mm travel - the loss is 7mm from the ball bearing, 7mm from the coupler and 20mm from the anti-backlash nut.

      A couple of side issues I still need to work out:

      1. The mount holes for the anti backlash nut are too close to the shaft, so I can’t heat fit brass inserts to screw in to - I may have to thread the plastic. I may be able to find some small nuts to secure it. Ideally once the mill is working I’ll be able to machine a bracket from a small plate of aluminium 
      2. I have brass inserts in the carriages because I initially thought I would screw the bed down from the top - making replacement of the spoil board easier. This may not be an actual problem though - I’m not sure how often the spoil board needs changing. I may just make them screw holes, and be done with it. I have to think about it a bit more.

      Next up: the X-axis

  • We are back on!

    Myles Eftos09/15/2016 at 11:12 0 comments

     Time to unshelve this project. 

    I have been doing some research into PCB mill designs over the past couple of weeks, and I've decided to move from a fixed bed, to a fixed gantry design (based heavily off the cheap Chinese machines). This means I only need three motors, and three lead screws rather than 4 of the original design.

    I'm giving myself a $250 budget for the conversion.

    Due to the existing hardware that I want to reuse, the actual build area for this machine will be relatively small, so I'm hoping that will help with the rigidity of the system (smaller builds should be stronger than larger ones). Given that this PCB millgets decent results with a wood base, I'm feeling pretty confident we can get some good results with this.

    So, a stock take of what I have from the Makibox:

    • 4 x NEMA 17 sized motors (Longs: 17HS 42BYGH 1.8°)
    • 1 x 218mm T8.8 (8mm diameter, 8mm travel per revolution) trapezoidal lead-screw
    • 1 x 165mm T8.8 trapezoidal lead-screw
    • 1 x 147mm T8.8 trapezoidal lead-screw
    • 2 x 226mm x 4mm steel rod
    • 1 x 170mm x 4mm steel rod
    • 1 x 164mm x 4mm steel rod
    • A bunch of cap hex screws
    • Plastic couplers
    • Plastic anti-backlash nuts

    The plastic anti-backlash nuts are surprisingly good - I can't detect any backlash (with the naked eye). The injected plastic piece has some thread that acts as a preloader - quite clever really. Regardless, I decided to order some metal anti-backlash nuts - I'm not sure how the plastic will hold up to the additional force of milling.

    I also ordered some aluminium couplers (to replace the plastic ones), LM4UU Linear bearings (to slide on the steel rods), and round bearings to hold the lead screws. Total cost so far: $79.68.

    Everything else looks useable (at this stage) - I'm a bit concerned that the steel rods aren't straight enough, but I'll run with them for the moment.

    I'm going with 4040 aluminium t-slot for the frame. I've found a Melbourne based supplier so I should be able to get high-quality stock quickly (and cut to size!). But before I order them, I'm going to design the mill in Fusion 360 so I can test for fit and size.

    You can see the render of the Y-axis here:

    The X-axis will be basically a copy, rotated 90 degrees. The Z-axis will still need some thinking.

    The motor bracket, bed and bearing holder will be 3D printed on my Lulzbot Mini. This is is the cause of the weird design - it needs to fit in the 150mm x 150mm build envelope of the 3D printer.

    The design should allow a Y-axis travel of around 156mm. I still have to work out the X-axis travel.

  • Inventory

    Myles Eftos09/12/2016 at 13:06 0 comments

    So I had a look at the parts I had tonight. Four steppers, three with screw attached. Three plastic lead screws, a Print5D D8 printer controller, a bunch of screws and metal rods, and a 3D printer.

    I've been amazed that the Lulzbot has so many 3D printed parts - this makes me far more confident that printed parts will hold up strength wise for what I need.

    I think I'll rip off the Z-axis design of using two steppers and screws for the X axis. That will need to be able to drive the Y-axis reliably, so having two motors doing that work sounds like a good idea.

    I have two motors and screws that are almost the same size, and two matching plastic lead screws. If I take out the metal rods that are and use the two larger rods to join them together, I'll get little gantry system going.

    It looks like it might work.

    The one in the foreground is longer than the one in the background, but that is ok - the travel will be limited by the shorter of the two (it's about 10mm shorter, so not a big deal).

    So now I guess I have to print some mounts for the motors and the rods... and formulate a plan for the Y and Z axis.

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Myles Eftos wrote 12/06/2016 at 00:54 point

Thanks for the comments. This project is on hold at the moment, while I finish some other stuff.

Power supply and controllers aren't show, but they are there :)

I have similar concerns around the plastic - it might just end up being a pen plotter. We'll have to see!

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agp.cooper wrote 12/05/2016 at 08:27 point

Hi Myles,

PCB Milling

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I have done it but not that keen anymore. With my eyesight and no solder mask, it makes PCB isolation a pain.

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Software is no big deal, search for grbl and xLoader (you will need that to upload the hex file).
Search for GCodeSender (dead simple) or GrblController361Setup (or GrblController351Setup) for a grbl controller. There are others.
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Creating gCode for the PCB Isolation will be a little harder. There is a plugin for Eagle PCB (http://www.pcbgcode.com/) that may work for you (there is a free version of Eagle Cad that is limited to 100mm x 80mm PCBs).

I wrote some code for DeltaCad that converts a BMP into a DXF to do my PCB isolation if your interested (DeltaCad costs about A$80). See https://hackaday.io/project/12900-pcb-isolation-macro-for-deltacad. But I have a Cut2D to convert the DXF into GCode.

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As far as what I see in inventory, where is the rest of it? No power supply, spindle, stepper controllers, Z axis??!

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Those plastic support look as if they may be too light to give much satisfaction with the mill that you plan to build (i.e. not rigid enough). I have a cheap Chinese 3040 and that is not rigid enough to do a good job with speed. The bed and the Z-axis needs to be spot on for PCB milling. At speed the machine flexes and can take out your tracks.

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Hope this helps, AlanX

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