Introduction: DIY PCB Milling Machine - Part 3 - X and Z Axis
Hi Everyone. Welcome to the third episode of PCB Milling machine build. I am JCRP and this is Media Milan.
If you want to watch the other episodes in this build series then you can click here. Till now we have put these smooth rods. In this episode we will make the X-Axis mount which will also house the Z-Axis. So lets dive in.
Step 1: 3D Printed Parts
All these parts were modelled using Fusion 360 and printed with ABS plastic at 0.2mm layer height. Having a separate box for the different screws helps. This housing was printed along with the plate to house the motor. A separate piece was printed to house the threaded rod and the nut. The smooth rods go into these linear bearings. The flexible shaft coupling attaches the threaded rod to the motor. All these will fit into this housing which took 19hrs to print.
Step 2: Bearing and Nuts
CNC machines are prone to vibrations. And most of the connections between parts are going to be made with M3 bolts. So for the nut I am using nylock nuts so they don’t unscrew due to vibration.
All the holes in this build are almost 3mm with light tolerance. And places wherever necessary I used small 3mm washers. The washers are pretty cheap and adding them will certainly wont hurt. You could tighten the allen bolts using allen key but I just used my drill on a slow speed to tighten it. Its tough to tighten because of the nylock nuts so this helped.
Step 3: Z-Axis Motor Plate
Next! The brass nut fits snugly into this 3D print. Just had to align the holes and screw it in place. I kept this a separate piece just for easy 3D printing. I avoided the supports wherever possible to get clean prints. Just a test to see if the threaded rod screws in properly.
Now I can mount this on the motor plate. I used button head allen key bolts so that when I house the motor the bolts won’t be out too much. This is a 12v DC motor which is used inside cordless drill machines. It has enough RPM to drill through PCB. I am placing this motor at the top because at the bottom there will be a chuck and then the drill bit. So having the motor at the top will give me enough Z-Axis height. But if you want you can move it wherever you want. That’s why I have given these extra holes on the sides. So you can attach the cover plate wherever necessary.
Step 4: Z-Axis and X-Axis Marriage
Now I need to attach the main X-Axis housing to the smooth rods and bearings. And to do that I have to remove the smooth rods. These aluminium extrusions were getting in the way so I had to do this. I wish I had the right length of the allen bolt coz I don’t like this protruding so much. Well I can replace that later when I go to the market and get new ones. Now I can slide that to one corner and tighten the smooth rod holders. And then I do the same on the other side. This way I can be sure that both the rods are parallel. To test the smoothness you should be able to move the entire assembly with just one finger and not much force. You should feel it running smoothly and not snagging at any place.
A Nema 17 4.2kg stepper motor goes on the top to drive the Z-Axis. It receives the flexible shaft coupler. Time to attach the Motor plate of the Z-Axis. The threaded rod can be screwed in from the bottom. Usually at the bottom a bearing is added to keep the rod in place. But here I missed it and there is just a 8MM hole. But this also worked fine. But in the design that I will release I will give provision to add a bearing. Then the 8mm smooth rods can go in place. Using Fusion I was able to align the holes to slide in. And I am happy that all aligns properly because I designed them with the exact measurements. Sure ABS shrinks a bit after printing but I had taken that into account and gave some tolerance while designing. So it's all good.
After tightening the shaft coupler to the threaded rod I can give it a test. Such a happy feeling when it all comes together. Guess this why I love making such things.
Now I can seal off the top end of the smooth rods with a small 3D printed piece. This will help avoiding the smooth rod sliding out. There is no need to use a nylock nut here.
And with that the X and Z Axis are done.
Step 5: Conclusion
I can already see few things that I will be updating about this build. Just to make it better. But ill wait until the end because I want to see how this works and based on that I can do more modifications. And of course I will keep you all in the loop. And thats why you should subscribe to my channel so you dont miss these updated. Search me on it as @mrjcrp to see the latest updates as and when it happens. Sharing is caring. Thank you for reading. Until next time. Happy Learning.
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