CB CNC Part 21 – Upgrading CNC Machine with Acetal Plates

In the last video I took the bull by the horns, so to speak, and cut the redesigned plates out in Acetal as I had designed them in Fusion 360. And in this video I’m going to make a complete the upgrade by assembling the new parts.

In some respects it would have been easier to build a new CNC machine and make it into two sections. The base, with the gantry and spindle and join them together. Now I’m going to have to…

It was very difficult to imagine dismantling and reassembling the machine without making the process convoluted. In retrospect, I should have dismantled the entire thing, and re-build it in a manner which might help someone coming to it for the first time. Alas – it’s not my first time, I’ve been here before. This project has been going on for so long, I often think I can smell the pongy odour of that unusual cheese déjà vu.

So the new plates are going to have an extra foot here so I may need to cut a little strip on this so I can have that making contact with the table.

I decided to begin by dismantling the front motor plates. For the one with the proximity sensor and with subsequent ones, I had to cut a little notch to free the cable from the wooden plate. I didn’t want to unsolder and remove all this wiring.

I could have been a surgeon.

After replacing the plates, I kept the stepper motors off as I would have to move the TR8 thread at some point, and the motors would just get in the way.

I then turned the machine around and removed the opposite plates. This time so I could access the Y Plates.

Ok I think I need to put something over here to stop that from dropping. I’m going to take these three machine screws off, cut that pull this out and then take the gantry out.

Ok so before I put this on this entire section needs to come out. Just have to replace these two machine screws here which are holding the z axis, with these low profile ones. Just because it was hitting onto the aluminium extrusion.

Ok it looks alright.

These have saved me on many occasions.

Ok this didn’t occur to me. This is where I noticed some new mistakes. When I cut my anti backlash nut blocks, I had inadvertently flipped the DXF illustration. Luckily when I designed the plates, I based the openings on the nut-blocks available on the OpenBuilds part store. So someone building this CNC machine doesn’t have to make their own nut blocks as well. But I have four openings, of which three are in the right place for the ones available on the parts store but not the ones I cut myself. What I decided to do, was move one of the nut block tensioning windows on the y plate, so it had the correct orientation for the ones that could be purchased.

I’ve updated the files for this CNC machine but it looks like I’ll have to carrying on for now.

I’m just going to replace these angle brackets just because there’s these little notches here which will press into the acetal. This is so hard it will just bend. Luckily I’ve got a few of these.

I’ve got to try put this under there now.

I’ve just put some brackets in the corners here, there and the other side. It’s something I’ve been meaning to do for some time. What this does mean is the aluminium under here will bump into the screws so loose a couple mm on either side.

Ok I’ve done it here as well. That really annoying.

Ok the low profile machine screws turned up.

I checked the x, y and z movement and it seems to be ok. The next thing I need to do is embed a piece of metal into the edge of the plates, so the proximity sensors can detect incoming parts. I decided to use small M3 grub screw to do this.

So what I’m doing is only going a small amount of the way so the grub screw has to sink into a little bit of untapped Acetal and that should hopefully hold it and stop it from vibrating loose, otherwise I would have to leave that out and lock it down with a nut.

What happen there? Ahhh, I see what it is. So since I’ve mirrored these on this side here, the proximity mounts. This one’s hitting onto it right there. Now I’ve cut it. You can see there’s about 5-6mm clearance there.

This one’s a little more tricky because the surface I’m drilling into is curved, but that’s also why I curved the material so there was a bit more there to drill into. And I’ve also got the brackets under here, so I need to make sure that the wheel doesn’t hit onto that. It’s really hard to see. I need like a dentist mirror.

I can already see the spindle is about a fair bit over on this side. I then insert another the grub screw onto the opposite side of the gantry.

The new design of the plates, along with the narrower spindle mount has increased the cutting capacity of the machine.

Now the bit is overhanging by about 15mm so I should be able to pull this forward and do some finger joins on a piece of 9 or 12mm, and I guess if the bit is a little bit bigger I could get through a piece of 18mm. I still have a few mm that I could move forward  as well. Form the home position moving forward until the red light turned on I counted 33.4 cm. That’s already a lot bigger than my current wasteboard which is 32cm – but I think I have brought this forward a little bit so I loose a bit of space at the back.

Ok the final thing I’ve done is cut out an adaptor ring so the dustshoe can still be used on this machine. I really didn’t fancy going through that process all over again. it’s very simple, I used the DXF file I had originally designed to create an elliptical shape with a hole cut out int he centre and it fits perfectly. I glued it down with dychloromethane plastic cement. I’ve blocked some of the holes so I can’t get the magnets out but this dust show is working really well, and actually for the size it’s really convenient to pop the brushes on underneath like that, and take them out and have access all the way around.

So that’s the CNC machine assembled. It’s shame that I’d accidentally mirrored the anti-backlash nut block, but the threads are under tension. And if I have too I could always make some new ones with the correct orientation, or just buy some from the parts-store. This machine feels very sturdier and I am happy with how it has come out.

So it’s time for me to say thanks again for watching, for sacrificing those thumbs along the way, and in particular to all the patrons who have been supporting this channel and build. In the next video, I will level the waste-board, squaring the axes, and tram the spindle.

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