Hello Apple Valley High School FabLab students, today what I'm going to show you is how to prepare
a piece of material for cutting with our desktop mill. So the piece that
I'm going to use is what we are going to be creating for this, uh, first assignment
and the dimensions are, it's 135 millimeters along the long edge; so i'm going to call that the x
axis and then on the y axis it's 76 millimeters, and then on the z, the height,
it's 18 millimeters. So when you're designing, you got to make sure that the material that you use is
actually going to be bigger than your design. So in your design file you have to have it much smaller
than that and I will go through that when we look at, um, setting up for printing.
The first thing that we're going to do is we're going to mark the center of this, uh, because the
machine starts cutting from the center out. So the center point is going to be the middle, so
what I'm going to do is take my straight edge and just draw a line on the material and you
usually want to use pencil. Most of the time the stuff gets cut away but you want it so that it's, um,
something that you can leave a mark but get rid of it later, and then I'm going to do this second,
two corners and then where they meet, their intersection should be the very center of the
block. So that's our intersection point; I'll mark that with a sharpie so you can kind of see it a
little better, and that's what I'm going to use when I'm centering this when it's in the machine.
The next thing that we're going to do is we're going to
take some Turner's tape, and this is used for, um, holding materials on lathes, so it's a really
sticky tape. It's two-sided, so I've peeled off a little bit of the back and I'm gonna make some
slices on that so that I can cut it off, and I'm going to really, you want this to not move. One of
the biggest issues we have with this machine is that the material doesn't stay stuck. Um, I've made
a jig to hold things pretty tight but we're not going to be using that jig for this, we're going
to just use the tape and hopefully the tape will hold it in place. And I'm going to actually make a
couple different setups with the same basic design so you can see how the machine runs differently, uh,
and that's what we're going to look at next. So I'm going to pause this we'll bring it over
to the machine and then we're going to put this into the machine.
Okay so now what I'm going to do is I'm going to place our block
on the the build plate but I want to make sure that it's parallel to this front edge, so I'm
going to look at this front edge and really try to line it up so it's nice and parallel,
and that looks pretty good and then I'm just going to push it down hard onto the material like that
and that looks pretty good; I think it's going to be pretty centered.
Now what I'm going to do is I'm going to turn on the machine and then
turn on the software that runs the machine; so I'm going to probably record that
and then also have this recording so you can kind of see what both things are doing at the same time.
I'm going to take out my my flashlight, uh, we'll probably need that to center things, so I'll
probably be using that as well in a minute and I'm going to pause it again to get things set up.
Okay so what we're going to do now is turn on the machine and it takes a little minute to boot up
and then what I'm going to do is open up the software that, uh, runs the machine and that's
called VPanel for SRM-20. The first thing that we want to do is we want to get, um,
our drill bit so the, the bit right in the center. So I'm actually going to move it by
hand, so I'm going to, I can change the, how many steps; so I'm going to start with continuous,
and at the same time I'm going to be watching where that is on the machine.
And a lot of times what I do is I'll use
a flashlight so that I can kind of see what's going on
because it's really hard to get this lined up,
and then I'm going to change to, uh,
10 for the step process because then it moves much more slowly. And you want this to be just above
the plate or the part that we're going to cut into; so
I'm going to use that piece of paper and if this barely moves, then it's at the right height.
And you can see it's starting to hit the paper now, so I might go one more step down;
it's actually a step of ten, maybe one more. You have to have the lid closed
when you do this or it won't move, it's to protect, um, us. So that looks pretty good, yeah,
it's barely coming out and you notice it's not quite centered, so I'm gonna move it a little bit.
I gotta lift it up just a little bit so I can move it
and that looks pretty good,
and then I'm gonna drop it down. I moved it up a couple so I can barely get this through, that looks
pretty good; so now what I can do is I have to tell the machine in the software that that's my zero.
So right now it's not quite zeroed, so I'm going to go over here, I'm going to set my origin point
and I want to do that so those change to zero, and then I also want to change the Z
height to zero; so now that's all set. So now I'm good to go, so what I can do now
is open up the software to prepare the file for printing and that's called SRP player,
and once that opens, what I can do is I can bring in my STL file.
So I'm going to open the file up that I created and the first one that I want to do
is the cutaway one, so we're going to actually cut away the material.
So I'm going to open that up, I want to show you different ways of doing this because
you get different effects. Uh, now what I told you earlier, my block was 130 by 70 by 19,
but the original dimensions I showed you were 135 by 76 by 18. So we had to make it a little
smaller to make sure that everything would fit, so what I'm going to do now is I'm going to kind of
cheat on the machine; I'm going to uncheck this, I'm going to change that to 17 because I don't
want it quite that tall, and then we're going to cut from the top, so I'm going to leave that.
The type of milling we're going to do is faster, uh, we have lots of flat planes and we're going to only
cut from the top; you can also cut from another side so you can rotate it after it does its cut.
For creating the tool path, first thing it wants is the actual block size, so you see that it wants
to have a block bigger than what I've told you. So I'm going to just put those default numbers
in and then what it'll do is it'll actually mill off of the block, which that doesn't really matter,
but the height is really crucial; if we go down too far it's going to cut into the build plate,
we don't want to do that, so that's why I made my Z height a little bit less than the actual.
So that looks good, this, I'm going to move the start point to the top of the block so it doesn't
mill on the bottom, and then under the tool path before you create it, you want to look at what, um,
type of bit you have. So I opened up the roughing and that's, um, the eighth-inch carbide flat bit that I
have in there, so that's good. The same thing with the finishing, it does a roughing cut and then a
finishing cut and we're not going to change the bit, so I'm going to keep those the same.
So I'm ready to create my tool path, so it's creating now;
it does the roughing tool path and then the cutting one.
Once it's finished, then what I can do is preview it and I want to show you the preview
because when I bring in the other ways for cutting these, um,
you get different results. You always have to be aware of the size of the tool bit
because if you're, what you're cutting is too big, the tool bit, or too small, the tool bit won't
cut it. So I'm going to preview this, it's going to take 0.8 hours; about 50 minutes.
So it's going through and creating that profile; you notice we put in dimensions that are a
little bit bigger so it thinks that it's gonna leave some stuff here, but that'll all be gone.
So that looks good, I'm happy with that, so we're ready to cut it, so I can perform cutting. Um, you can
also output it to a file; this tells you how tall your, uh, bit needs to be. It needs to be at least 18
millimeters tall and ours is about 25 or 30, so we're good for that. So I can hit start cutting, um,
we centered it so it's all centered where it needs to go, it kind of reminds us to put in the correct, uh,
tool and we have that. Uh, we're starting at the center,
so I can hit next and now I'm going to start cutting.
And then you notice that it spins up to the correct rotational speed and then
it's going to come down and start cutting. And the first cuts are a little bit above
where it needs to be because we had, had it the width of that paper and now it's starting to cut into it,
that looks good. So I switched over to the other software so you can see what the machine is doing,
and it shows the depth that it's cutting, it shows the rotational speed and its travel speed.
And it's going to continue to run for about 50 minutes, so I'm going to actually pause this now
and then we'll come back and look at it when it's almost finished.