3D Printed CNC Machine / Prototype Assembly

Ok I’m going to start assembling the new CNC machine. I’ve managed to print all the plates, although I might reprint this one as I changed the joining mechanism. You can see an additional semicircle here and there isn’t one on this side. I added another fixing point a little bit further down here, and changed the way these two pieces join. This was just because of the footprint of my 3D printer that I was actually making the plates on. I’m not going to start with those yet. I’m actually going to start with the gantry. So you can see the way I’ve designed these so that space for the heads of the machine screws that are holding the pivot plate onto the Z axis, to move around. In fact you still get the same movement that you would if the machine screws were placed in position. I’ve already put the grub screws in here. This is what’s going to trigger the proximity sensors, and the back plate should look like this and the opening should be on the bottom right. And then the front of the gantry plate have the grub screw holes at the top.

This is the voice of oversight. You’ll be hearing me periodically interrupting myself to mention things I forgot to mention while doing the thing I was doing. So, while I put the gantry assembly together I’m going to verbally explain the parts and positioning. The top line of wheels uses eccentric spacers while the bottoms ones are fixed. I happen to have ¼ inch ones, but you can get and use 6mm. I went for the cheaper parts. The spacing is very simple. It is a fixed spacer or eccentric spacer, a precision shim, a v-wheel, a precision shim, a spacer, two precision shims, a wheel, a shim, and either a fixed spacer or eccentric spacer.

So the thing to just mention at this point is that, between the spacer here there’s one shim on one side but two on the other. Opposite wheels. If the wheel doesn’t pop down it might be because the shim between the two bearings has slid out. Just use a stick or something and push it to one side. I think I’ll actually put the nut block on as well to make sure I’m not putting it on the wrong way around. Ok these are 25mm M5 machine screws, and they hold the nutblock. I’m missing the spacer, and I’ll just workout what that’s supposed to be. This is great, I’m reading my own instructions because I’ve forgotten.

I’m placing the anti-backlash nut block onto the rear gantry plate before assembling the section. I intended to space that with 4 precision shims but later on in the video I realised I needed 5 to line everything up properly. When I first made my original CNC machine with ply plates, I also made the nut blocks myself so the spacing between them and the plate wasn’t so crucial as it was bespoke. But I wanted there to be an option with this machine to use shop bought nut blocks.

Ok that’s good. And then you have the access for that if you need to tighten it up.

I then placed the final fixed and eccentric spacers in position on the opposite plate, and assembled the gantry section.

Ooooh they’re cutting really well now. Ok that’s pretty good. So I got this from Ooznest and asked them to cut it to size and it’s bang on. So now this just slides on like that.

I’m now fitting the gantry to the c-beam aluminium profile. This involves adjusting the eccentric spacers at the top of the assembly, so all the wheels are running along the aluminium but ensuring they are not too tight.

So I’ve already put this together, making sure the Z axis aluminium extrusion is in place. When I was screwing it on I pushed it to one side just to keep it square.

I haven’t tightened it all the way so it’s pivoting.

Ok this is the z plate, woh, and those are the nuts. These fit on like this and bolted on here. But what I’m going to do first is start to assemble the the wheels.

Here I’m using 30mm M5 machine screws with either an eccentric or fixed spacer, a shim, a mini v wheel, and a locking nut. I’m using this to push the eccentric spacers in and then I can fit it onto the C-beam z axis.

The notch is facing outwards for these four and inwards for these four. And what I’ll do because I’ve locked these down, I’ll adjust the first and second one. If it’s a bit too tight slack it off. You don’t want to force it in. When you drop it in, you want to be able to feel the wheel moving. I’m just doing the other wheels now. Turning it till I see it moving. Ok that’s feel good.

When you’re happy that all the wheels are in the correct position, you can do a final tightening of the nuts.

The next thing I’m going to do now is screw these sections in.  That’s not going in. Aaah, so these are rubbing on the bit here so I’m going to have to change them to low profile ones. I’ve just put on two on for now. Yep so, that was the problem so I’ll have to take these two off as well. So that’s all four of them. I’ve left the two as they are, because that shouldn’t get in the way (wrong).

I also changed the centre spindle mount machine screw which would be hidden by the anti-backlash nut block, with a 35mm low profile one as this was obstructing the not block.

Yeah ok so that’s not going to work.

So I had to take this part off so I could get the allen key in. These are long ones. I specifically bought because I knew I’d be using them for things like this. If you find it difficult to tighten up, holding the short end you can use a pair of pliers to hold these. Ok that is very close there.

If feels super rigid (it’s super super rigid), and like the gantry plate I’ve up a grub screw in here which will detect the pivot plate (I meant proximity sensor). These are the 688z bearings, and these are going to help keep the tr8 threaded rod in the right place. I’m hoping I’ve done this correctly. If it was off, if it wasn’t centred properly I shouldn’t be able to pull down that far. Although when I do line that up, the top plate is a little bit far forward, I could push it back. I think it’s going to work. This is the washer or the shim that goes on top of the, 688z bearing, which is this one here and the locking collar goes on top. This isn’t from any CNC place, this is actually a seal washer which is for plumbing. I’m just going to put the washer at the end of a pair of mole grips, and then by hand take an 8mm bit, and that’d made all the difference.

The next thing to do is assemble the Y Plates. I printed these out in two sections because my 3D printer wasn’t large enough and after bolting them together I began to fit the wheels, bearings and nut blocks.

I think that’s going to go that way… Nooo, you’re wrong it’s the other way. Is that right? No that’s wrong.

I’ve just realised I’ve made a mistake which means I’m going to have to go print another one out. It’s really silly because I wasn’t paying attention. Essentially the opening for this nut block, means that when it sits in this position I can access the grub screw which tensions the thread against the nut block. But when I went to print these out I must have flipped this design in Cura, instead of exporting the opposite side. And you see this positioned here, the opening for this plate should be lower down so it’s in line with the grub screw. Just an oversight. I knew this and added in into the design but there’s only so much you can keep inside your head. So I’m going to have to go back an print these out.

A coupe of 25mm machine screws. And five precision washers. So I’ve put all the wheels on, they’re a little bit loose. It just means I can adjust the spacers to make sure there’s a snug fit. Ok I’ve just done the opposite side. You can see there’s a slight difference here if I turn these around. That is the opening here are set apart and it’s because the nut blocks when you turn those around the grub screw changes position. Ok these are seating pretty well. There’s no noticeable wobble and no gap between the pieces.

I’m now finishing the assembly of the Y-Plates to the C-beam and the lower 20×40 support profile but I have to tap some holes first.

Then just to make sure that this remains nice and flat I’m using a large drill bit to take off the raised edge at the top there as the aluminium gets pulled out a little bit.

You need to remember to put the nuts in on the side that have the stepper motor. I think originally I had it on the right hand side, which is that side but this time I may put it on the left. And I have to remember to put the 20×40 in the bottom side. So these two pieces here have been cut exactly the same size.

I later managed to break a bit in the aluminium which I couldn’t get out. I will show that later in the video but if you’re following along I would recommend to do this by hand or get the correct bits for use with a drill.

So there’s a bit of flex in the y plate but then again I haven’t actually tightened this section up so you can see how the pivoting mechanism works. this is where I begin to run into problems because my work area is not big enough. Lets see what happens. I was rushing tapping the holes in the other pieces of aluminium extrusion and my tap just broke. You can just see it poking out right there.

I decided to cut the two pieces of c-beam down to 670mm using my table saw sledge and extension arm. I would also cut a few lengths of 20×40 profile down to use later as supports for the waste-board.

I probably could have done it 68 but I might have nipped the end of that bit. Anyway that’ll have to do.

These are the re-cut x axis c beams and I want to re-tap the ends and I’m going to do it by hand. No machine, nice careful, one rotation forward, half back. Ok I’m going to reassemble everything again. I might be easier to work on my table saw but lets start anyway. If you’re going to use a hand drill make sure you drop the torque settings or trip down quite a bit.

I’m now fitting the front and back motor plates, and then sliding the horizontal support 20×40 profile piece, not before undoing the motor plates machine screws to pop a couple nut into the countersunk nut areas between the plate and the c-beam, and sliding 4 t nuts along either side of the y plate c-beam. Because I forgot.

You can make these quite easily. Buy 3mm aluminium L section, a meter for about £7 but I just 3D printed these. I didn’t have time to wait.

Ok the next thing I’m going to do is put the wasteboard on and these pieces of 20×40 aluminium extrusion. I haven’t quite worked out the best way of doing this. Really I should have cut these shorter, and had a another pieces going across with corner brackets and then the MDF on top of that. I’ve done it a little bit differently. My wasteboard is two pieces of 18mm MDF, with countersunk holes and some channels in the back for the aluminium extrusion. I got that cut externally, it’s a little bit more complicated like that but in reality it could be a piece of aluminium and a waste-board bolted onto that. I think that would have been the best thing to do. Anyway here I am.

I’m going to do the rest like this and I think I’ll try and lift he board into the position around the back. It’s a bit of an awkward way of doing it.

Eeer… Got a tool for everything.

There’s a couple machine screws I need to put down here.

It’s getting heavy now.

I think this videos come to an end now. The machine is more or less assembled. I’m missing a couple things like the bracket underneath this piece of c beam, which will create a positive shelf essentially, for that to sit on. Everything seems to be move really well. Obviously this is a prototype. I don’t think PLA really is the material to use over a long period of time. But I think I’ll get some cuts from this. It really depends on how warm the spindle gets. In this particular section here. Maybe the first thing I’ll try and do is re-cut these out of aluminium. Maybe it’s wishful thinking but if the previous machine managed to do it, I feel like this one should as well. And the advantage I’ll have with this, is I’ll be able to properly tram and square the machine. I’ll have the hard limits at the front. which I’ll be able to keep it square and make sure if I do go off for whatever reason, I can always bring if back and square it. And because I can pivot teh spindle along the x and y axis it should really minimise any errors that can manifest from cutting on the CNC machine, so I’m feeling really optimistic.

In the next video I’ll start to dismantle the old CNC machine and prepare the electronics to be coupled onto this machine. So until then, thanks again for watching.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s