Parametric CNC Machine Design / CBeam Mountain / CNC-Roy

Ok hello, I’m going to make a “quick” video just showing the parametric CNC model I’ve been working on here in Fusion 360. Which is based on the the wooden plate, or the birch ply plate CNC that I’ve been making, which I’ve nicknamed CNC Mountain. I’ve just more or less finished the individual plates and I’ve done this while learning how to use Fusion 360. My machine is based on an opensource series by Openbuilds, and takes inspiration from other similar machines including Open Builds Korea Lead Screw CNC Machine, C-Beam Sphinx, Ultibot CB3030, and the R7 CB CNC, and also the videos of Martin Barfoed. I’ll link to all those things in the description.But I wanted to make my own variation to satisfy some of the requirements that I might have with a CNC machine. And to also add my own design implementations and engineer things into the machine that I think might be useful. The firs thing were openings on the plates which would a proximity sensor. Now while working on this particular machine I’ve been very conscious to try and set up some parameters, so I can make some alterations to the machine which can then allow me to adapt some of the features. So for example if I want to change the opening diameter of the proximity sensor, because for whatever reason I’ve found a new sensor that works better, maybe it’s cheaper and I want to incorporate it into the design – I can track down onto this list of parameters, and I can change an expression and then the opening will change its diameter. So I think I called this proximity sensor. If I change that, this should change as well. And the hole just changed. And the surrounding area which I’ve described as the mount. If I want to change that to 15mm for whatever reason, for aesthetic reasons that changes as well but the spacing of the holes and everything else stays more or less in the same. And if I got to another part of the machine you can see a big chunky mounting plate with the hole. If I undo change parameter, and go back down – in fact I think I’ve changed both there. I’ve also added some openings that I can access the grub screw at the back of some of the plates which tensions or pulls the nutblock onto the ACME threaded rod, so it reduces the play. The other alterations did from my prototype CNC machine was to change from large vwheels to mini ones, for example on the y-plates. When I initially modelled the plates with two types of wheels I noticed they didn’t line up. The larger wheel has a slightly different thickness, and it wasn’t sitting entirely aligned in the centre of the aluminium extrusion. Even if I added or subtracted a shim on the various wheels this didn’t seem to solve the problem. If I show you this side of the machine here, and I get rid of that plate. You can see a similar thing. So there wheels line up well there, but the next wheel is pushing into the extrusion. I modelled this machine with metric spacers but the one I actually built used imperial. So they were 6.35mm and I think that wheel touched onto the opposite side, but of course I was using birch ply plates so they have been other factors involved in the spacing problems. What I’ve actually done in preparation of cutting of some test plates is buy a sheet of 0.2mm PTFE and a hollow punch set with a centring point to make my own PTFE washers to use to space out the wheels a little bit  more accurately. And place them in-between these two washers here until the wheels line up a little bit better and all making contact they way they should be.Designing the machine by parameters has meant that I can adapt thing very quickly. I can go down and change the spindle plate thickness which are these things here, although I’m going to leave them at 15mm. It’s a practical size. I’ve got the stepper hole spacing which are the holes which the longer spaces go between the plate and the stepper motor – and then bolt the motor in place and then the hole for the leadscrew is centred between those four. So depending on the size of the stepper motor I could in theory increase the size of the stepper motors and quickly adapt the plate dimensions. I’ve got the spindle diameter so if I happen to get a smaller spindle – like a 60mm one. Just put 60 and it becomes smaller, but I think I that might be a mistake there. So that’s something I’ve got to work on. So I’ve adapted that but these ones here haven’t updated because I haven’t set the dimension. If I go to this, right click and edit profile sketch it should be able to do this. So D, click, and this will be spindle diameter. Lets see what happens when I do this? Bugger. I need to lock these – fix. Centre to that. That to there.  Raa what’s going on there. It’s 80 – ahh and then we want to divide that by 2. The radius. Ok that looks correct and I can stop sketch. You can see I’ve ever so slightly extended that curvature into the opening so it actually clamps down. Obviously I haven’t tested it out yet so it might need to be a bit more, or less. If I got to modify, change parameters, and spindle diameter, and I change it back to 60mm because I want to use a smaller spindle. Boom it changes. Obviously it’s not in the best position for that size of spindle. I probably have to relate that to overall shape. Don’t know if it’s something I can actually do. Right click, edit profile sketch, I can delete that. D that to that. That’s a bit of an odd one. 22.3mm. Essentially this is how I’ve been doing it, I write some parameters, I include them into the body or the component (sketch) that I am designing, and I make a change and see what happens. Yeah so that’s doing what it should be doing. So now I can adjust the opening of this particular part and it can accommodate different types of spindles. I’ve also made sure that I line up the openings with the plates so this is the z axis here. The only thing I haven’t quite worked out how to do is to line up the centre of a hole on one plate to a edge of a profile, of another plate. So if i change, going back to parameters again. And I look for plate thickness and say we’re making this really thin – like 3mm coz we’re using stainless steel plates. 123, go computer. Don’t break. Spinning wheel of doom. You can see the plates but the hole hasn’t adjusted for that. I can’t quite figure out how to do that. I also got the bearings holes, so I can again adjust the type of bearing – the depth that it goes into the plate and also the opening here for the leadscrew. So if I decided I want to try and make a slightly more robust machine I can get a thicker leadscrew, and then adapt the bearing holes on all the plates. Yeah essentially that’s it. I haven’t done any detail on this machine. I’ve not added screws or brackets or anything that I didn’t have too. You can see I’ve got wheels on this side (at the top) because I needed to identify the spacing but ones I got those right I didn’t bother adding wheels on the other side. This is purely just to illustrate the design principles and make sure things actually line up and actually do what I want them to do. And it’s all joined more or less correctly as far as I can tell. So I can grab on different plates, and move things around as if it was actually a real CNC machine. Ok I just realised something else. This corner here, if I was cutting out with a 6mm cutting bit, I would have a curve edge which would effect how the part of the machine joined together. What I could do is start a new sketch on this plate, and cut a circle into the inside edge, or create a fillet on the outside edge of the adjoining piece, adding a 3mm radius curve. I had to change some of the constraints on the sketches to get this to work, and select new points to join the pieces within the model, but in the end the spindle bracket looks like this now. So you can see the shapes follow the same kinda curvature, on either side. And I’ve tried too add a radius (fillet) onto the design wherever you have an inside corner because that what’s going to be left behind when it’s cut out using a router cutter. So the plates should look like how they would come out. The other thing I forgot to mention is I can actually change the dimensions of the CNC machine itself. So if I want to make it wider, I can put the width down that I want and the machine redesigns and then obviously I can take the measurements off the machine to get a rough idea of how big certain parts would be. When I was building the original machine, I did have some problems with the machine screws because they do come in specific sizes and with some of the parts, for example the y plates and the mini v wheels which go into the c-beam. If the machine screws are too long they will scratch onto the aluminium. So it’s not as simple as it looks but you know, there’s a lot of information in this model that I can extract before going into a new build. And I think the nice thing about this sort of design and this approach to modelling an idea out, is that this is essentially a blueprint which isn’t stuck down on paper. So I think what I’m going to do now is export these plates and make them available first to my patreons who have been supporting me since I’ve started this CNC channel, and I’ll leave it with them for a few weeks so they get a head start with building the CNC mountain – as I’m calling it. And after that time I will make these files available on the openbuilds platform which is where I’ve been sharing some of the videos of the build process. This is an opensource machine so please don’t write down in the comment – you should patent that. This isn’t how it works. This is about working collectively and I wouldn’t have been able to do half the amount that I have done if it wasn’t for the information available on OpenBuilds, and on YouTube, and the generous people who share their creativity and time. So thanks again to them, thanks again to my patreons for supporting me, and for any of you random stragglers who’ve turned up and managed to watch this. I actually fell asleep while editing this video because I found my own voice so boring.

Ok I’m back and I’ve added a few extra features, and changed the design a little bit further since the last video. And I just wanted to recap on those changes. The main thing was I noticed when I started to export the files that, there was a slight variation in what should have been twinned parts. In particular these two the Y Left and Right plates. So what I decided to do was delete one of the plates I designed and use the mirror tool here, to actually create an identical plate on the opposite side. If I click this if it lets me, you can see I drew a line along here with the mirror tool you select your object, in this case it’s the sketches and then you define the mirror line and create an opposite piece. I done that with the base plates, the sections with the motors and their opposite ends, and I’ve also done it with the Y Plates. I’ve actually changed the Y Plates a little bit as well. I’ve made them more squat. So I’ve pushed this section here forward by about 15-20 mm, and the reason I’ve done that is because I noticed that initially when the gantry was bought forward… the centre of the spindle was set quite far in and this way I can cut close to the edge here. I’m actually changing the geometry of the cutting area. I also inset the openings for the mini v wheels along the c beam by about 5mm. They were quite close to the edge and I had a bit of problem with the locking collars on the acme threaded rod actually hitting onto those delrin wheels. So by moving that in a bit I should be able to increase the movement between the sides of this c beam. This should mean I have a larger waste-board and cutting area. The height is the same. Like I said this area here has been moved forward. Just so the centre of the spindle ends at the edge of the wasteboard. I can align this right to the edge – I think that will just look a bit neater. The main thing I’ve done as well, is added a notch here. So I changed what was an opening here for the proximity cable to a notch, and what this is going to allow me to do is when I’m rebuilding my CNC machine, I’ll be able to take the proximity sensor cable off – all be it cutting off a bit of material off the wooden plate and fitting them without having to do any re-soldering. This is mainly just to make my life easier when I rebuild this machine. So that’s the main development, so the plates that are going to be available will not be the ones from the previous video in their entirety. You’re going to have these which are mirrored and are therefore more consistent. Because even with all the constraints for some reason somewhere along the way I added an error – on these two plates – those were fine. And I just couldn’t identity where I’d done that. And it makes sense to have these identical coz it means depending on how you plan to set up the machine, you can have the motor on either side therefore the drag chain and exit cables going towards a controller where it’s better suited for the area you are working. So there’s a bit more flexibility with how the machine can be assembled. There was something else… what was it? Ah yes, I’ve added some feet onto these plates, so cutting across here about 8mm. You can see that shoots down and acts like a foot to raise the machine up, so the base y support doesn’t drag along the table. At the moment I have a couple bits of wood under there on the prototype machine. Oh yes there’s one more thing. Just to support the drag chain along here, because these two plates on the Y are identical you could attach a piece of aluminium angle bar along here. Simply just drill a couple holes on these plates over here, even a single holes might be enough. Tap and bolt that on. And then the drag chain can rest against that. And you don’t have the risk of it possibly falling into the material. It’s not a problem with a machine this size but if you’re going to make one larger it will probably be a problem. For the top piece here I’m going to stick with aluminium method I used on the prototype. I think that is affordable and works, so I don’t think I need to re-design that. Although I could add a bar onto this plate here to line up with potentially where that will go. It’s adds an extra element there that might not be needed. I’m not sure. You’re talking about something potentially coming out quite some distance. I’ll have a think about that. Maybe I’ll incorporate that in a swing off version, and just have that as an alternative plate. If you want an advanced copy of these plates they are available on my Patreon page, the link will be in the description. Anyway thanks again for watching.

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