It is time. We’re building the MPCNC! I actually had one more video planned to go
up before I started on this build, but Adobe just didn’t want that to happen.
So… we’re going to live-build the MPCNC together, like with Dolly, the Prusa MK2,
uh, clone, but unlike that, this one is going to be the real deal. A full MPCNC in the burly
version, which is the current, sturdier design variant. In this video I just want to go over
the parts I’m using, why I’m using them and what alternatives there are. But first,
what even is the MPCNC? As a full explainer, check out my interview
with the MPCNC’s designer from MRRF 2018 up here, but basically, this is a closed-source,
3D-printable, where it makes sense, CNC router, engraver, let’s just call it a light-duty
CNC. The base is any sheet of flat material you want to use, the frame and linear rails
is steel tubing, if you have it available, you can use electrical conduit, the motion
is done with just 6mm GT2 belts and NEMA17 motors and a 3D printer control board, any
board you have will basically work. And of course, there’s a toolhead, I’m using
a spindle, but you can of course also use a 3D printing head with an extruder and hotend
or a pen plotter, drag knife, paste extruder, whatever you want. The nice thing is that
you can easily scale the machine by using a larger base and longer tubing and belts.
I’m building mine with roughly a 50x50cm build area and 15 or 20 centimeters of vertical
travel. I’m not exactly sure how large the actual usable build area is going to be once
you add fixtures, the tool and so on, but it should be comfortably large in either case.
So looking at these parts, it should be obvious that this is not a machine that will be massively
rigid and end up cutting stainless steel or titanium, at best, I’m hoping for some drilling
and light cutting in aluminum, but I think this machine is much more comfortable cutting
or engraving wood, plastic, foams, those sort of softer materials.
So, parts, let’s start with the printed parts. These were printed from simple PLA,
which is rigid and strong, exactly what you want out of a CNC frame. Unlike the topology
optimized shelves, there are screw heads pressing against the parts and potentially hot components
touching the prints, so I’ll have to see how well it holds up. These parts were printed
on a bunch of different printers with a bunch of different PLAs and, I don’t know, the
color scheme is definitely... disagreeable. Overall, this is one and a half kg of filament,
two small spools, so it’s quite a bit of material, but these parts are designed quite
chunky, so you don’t need to use your fanciest filament for this. In fact, I used up random
bits of old PLA that I had hanging around, so excuse the color scheme.
The set of parts is the Burly set from V1 engineering, and I’ve also printed a mount
for my spindle, I believe off thingiverse. There’s a healthy ecosystem of modified
parts available already. And speaking of the spindle, calling this
thing a spindle maybe is a bit much, but that’s what the seller is calling it. I’ve used
a similar one in the Mendel Max CNC conversion, but this is a brushless version of that “motor
with a chuck” assembly. I’m hoping that the controller might be a bit smarter and
give consistent torque over the RPM range. For the brushed version, the only sort of
RPM control is by adjusting the power supply voltage, but this one has a special power
supply included in the kit that not only lets you adjust RPM, but also has a digital readout
that displays RPM in real-time, and I think that’s a huge deal when it comes to tuning
in cutting parameters, it just takes the guesswork out. The alternative is using a trim router
as I’ve got in Bob, the Sienci CNC, but I find that to be one of the worst options,
as they tend to be super noisy and in my case, getting collets for the thing turned out to
be an absolute nightmare, so I could only really use 6mm shaft endmills, which is actually
really large for how rigid these small machines are. These smaller motors just have an ER11
collet chuck, and the collets for those are incredibly cheap and available everywhere.
It’s just a standard size. Next up, the frame. For the base, I used this
piece of particle board that I glues some MDF to, I like the smooth and flat surface
of MDF, you could probably use just a thicker piece of MDF, or plywood, really, as long
as it’s flat and you can screw things to it, you should be fine. You could probably
even use a T-slot table, that way you’d directly have a way of clamping down parts.
These tubes doubles up as both the frame and the linear rails, so it’s a really good
idea to use something that’s fairly rigid. The MPCNC files are available for 23.5, 25
and 25.4mm aka 1” tubing, which I believe may be fairly common in the greatest country
of the world, but for me, I could really only get hold of 25mm tubing, this really is just
standard tubing stock, I ended up using this ground stainless version, which is more expensive
than conduit would be, but not unreasonably pricey by any means. The sizes that would
be really easily available here would be for things like galvanized water pipe, which comes
in nominal ½” and ¾”, which actually is 21.3 and 26.9mm on the outside. Don’t
ask me how those sizes make sense, but maybe we’ll see an MPCNC version that supports
one of those sizes at some point. Now, for the motion system, I grabbed some
random NEMA17s, as well as a fresh roll of GT2-2M 6mm glass fiber belt, the same stuff
that’s being used on 3D printers; interestingly, V1 say that you should not use this steel-reinforced
belt, so I’m not doing that. For electronics, I’m using the Duet Wifi
- for now. It has strong drivers and great software, but I may swap it out for something
simpler at some point as I might need the Duet back in my Mendel9000 test platform which,
yes, is finally printing. It should be an easy configuration swap moving the board between
machines. So one last thing you need is a bunch of fasteners.
You can use both metric or imperial sized hardware, but the parts are designed with
imperial parts in mind as far as I’m aware. Oh, and you do need a leadscrew and a coupler
and pulleys and cables, but that’s really unexciting stuff that you kinda need for every
build. The same goes for tools, you need a few basic things like hex keys and maybe a
few spanner for some nuts, and I believe you also need a way to drill a few holes into
these tubes for the Z-axis. But, for example, the base, you can get cut at pretty much any
home center in any size. Now, you can buy all these parts, minus the
tubing, and I think the base, directly from V1 engineering, but of course, there’s also
the option to self-source, which I tried, and I ended up a bit cheaper than what the
kit would have cost. Of course, which option is better for you depends on where you live
and what your preferences are in self-sourcing vs. buying a kit, but just like with Dolly,
I’ve created a full list of parts over on toms3d.org with options of where to get each
part. So over the next days, I’ll be building
this MPCNC together with all of you in a series of livestreams, the first one will start tomorrow
on Sunday, August 25th 2019, so if you’re free, come join in and maybe even build along,
the link is in the description so that you can enable that notification,but these streams
will also be available as recordings for your enjoyment. The great thing is, you can skip
forward in recordings! So I hope to see you there! As always, thank
you for watching, leave the video a like, get subscribed or even support the channel
through YouTube memberships or Patreon, and I’ll see you then! Bye!