Desktop CNC Machine – What I’m Working On

 

Some of the items used for my machine:
SFU1204 400mm Ball Screw – https://www.banggood.com/custlink/mGmGYQ6POB
SFU1204 L700mm Ball Screw – https://www.banggood.com/custlink/G33GhnBHL2
22mm Hole Ball Screw Nut Housing – https://www.banggood.com/custlink/mGKKys6tBi
6.35x10mm Motor Shaft Coupler – https://www.banggood.com/custlink/3v33yNgHgO
Machifit MGN12 600mm Linear Rail – https://www.banggood.com/custlink/GGKvEsetgm
Machifit MGN12 400mm Linear Rail – https://www.banggood.com/custlink/vKKGdN6PeM
MGN12H Linear Rail Block – https://www.banggood.com/custlink/Kv33Rn6tU1
Black 2040 Aluminum Profile – https://www.banggood.com/custlink/DKmmRs6tw4
Black 2020 Aluminum Profile – https://www.banggood.com/custlink/Kv3mYb4iDc

But the full pats-list with measurements will only be available on my patreon (when ready): https://www.patreon.com/EducatingSavvas

 

I’ve barely finished the last machine and I’ve started building another one. This one’s a little bit difference. I’m using ballscrews 1204 SFU. There’s one here and two on either side, and a shorter piece for the z axis. I’m still using the MGN12 linear rails but this time along the y axis I have a single one on either side. You can just about see that one there. The plates are about 5mm thick – actually 4-5mm thick. What I wanted to do when I started designing this machine was to really pare it down from the previous one – which is over there. And to reduce the number of parts and the overall thickness of the aluminium profile. You can see here the z axis uses a single 20 by 20 aluminium profile on either side. All the aluminium profile for this machine is the leftover parts from the x-carve – which has been sitting around my studio for a number of years now. I cut the plates myself on that machine there. I didn’t bother filming anything but there’s plenty of pictures.

I’m using an 80mm water-cooled spindle at the moment but I’m not really a fan of water-cooled spindles. And I’ve designed some mounting holes on the back plate so that I can use one of these openbuild router spindle holders which is about 70mm if I remember correctly. Simply braising the pieces and spacing the rails a little further apart has meant that this machine is already a lot more rigid than the one I designed using the c-beam. And cost-wise it would work out a lot cheaper.

I simply push fit the bearings into the end-plates. And the SFU ballscrew just sits in place. If there a little bit loose I can put some shim washers, which come in sizes from 0.1 of a mm to tighten that up. I designed the machine in such a way that the ballscrew is on the inside of the plate along with the linear rail, and the reason I’ve done that is so that I can minimise the amount of or eliminate the amount of surfacing I need to do – or what you would otherwise do to machine plates which dramatically increase the cost of parts. So in theory I only need to surface one side of this plate and in this case I didn’t surface anything.

I’m also working on a new touch probe using a nice metal momentary snap to action button. And I’ve also got a pilot light here. This is a for terminal – two are normally open and two are normally closed, and the light would connect to the normally open so that when it’s pressed it turns on, and the normally closed goes back to the probe terminal on the controller that I’ll be using when the signal is broken  that is read as a probe cycle being complete. And in particular g38.4 or 5 probe cycle.

This is a bit of valchromat. I think it looks very nice. I’m still not sure whether to fit it into the table or to try offset it, but my spindle doesn’t overhang that far so I’m not sure if this is even able to reach. It may have to be this way.

I’m using some melamine here for the sub wasteboard which is a little different from most CNC machines but essentially it’s waterproof and it’s nice and flat. I’ve got another version of the plates here in high pressure laminate. It’s pretty good. I’m really impressed by this material I think it’s a good alternative to acetal and aluminium. The only thing is I don’t think this would take a thread that well so anywhere where I’m mounting stuff I need to make sure that there’s plenty of room to also put a bolt on for example the stepper motors, or the proximity sensors that I’ve decided to use which are different from the barrel types – which are more rectangular.

Down here are some barrier blocks which I’m wiring up in anticipation of a method I’ll be using to connect everything up to the controller, which I’ll be doing though relay modules. These are opto-isolated relay modules and what that allows me to do is to use 24 volt DC power to the limit switches and buttons and so on, the e-stops and to create a logical connection to terminals on the controller. This is a gradus m1 pro which I decided to go with. There’s not much information about this board – the one thing I will say is while I was flashing the controller, I noticed that I had a compile error. The chip on this uses the same as the arduino uno but the bootloader is different. It uses the bootloader for the pro mini which takes up more space. So  I had to flash that or burn the bootloader to an uno and I had to use there ICSP cables here and a USB bootloader to  do that. So if you do buy this controller you will need to get yourself one of these as well and that’s not in the instructions.

I’m planning to have this machine inside an enclosure and for the parking and door enclosure features to be activated on the firmware so there’s a bit more security to operating this machine. My thinking is that this is something once completed will meet some of the criteria to then be able to find itself in an educational setting and used as an educational tool. I think what I will do, is talk more about that when I’ve got the rest of my components for the controller and I can actually demonstrate how that works.

The last thing I’ve done is wired all the stepper motors and the limit switches. And this is what this coil is here or collection of wires coiled. The wires for the stepper motor are 4 core and the wires from the proximity limit switches are 3 core.

So there’s not much more for me to say other at this point of the build. I’m sure lots of people will have opinions about how I’ve set this up but I wanted the machine to very utilitarian and for it to be very visible how it works.

In the next video I’ll look at how I assemble the new controller box, and talk about some of the decision I made along the way – so stay tuned for more chin scratching.

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