I want to try to make a belt sander similar to this one,
and I came up with a design for one in 2012,
but I never got around to building it.
and I went through some of my junk, and decided to use
this 14 millimeter shaft for the main shaft, because I've
bearings that fit on there, and for the idler shaft,
I figure I'd use this 3/8 shaft, or about 10 millimeters.
Now, the drive wheel on one of these things, ideally would
have rubber on it, and for that I bought this inner tube,
which will hopefully be usable.
Well, it turns out the rubber on the inside is a little bit
thicker than the rest of the inner tube, so that kinda sucks.
Here's a bicycle inner tube, a really thick one,
and I just cut a piece off the end of that, and it looks like
I can stretch that quite a bit, so maybe I can use
this inner tube. The drive pulley's gonna be
8 centimeters in diameter so I'm just making a whole bunch
circles out of plywood that size.
I'm gonna glue all these together on the shaft,
and to keep them from spinning, I want some kind
of a keyway in there, so first I'm gonna mark
where this comes to.
Now, I have to cut that cylinder perfectly round, which I could
do by sanding or lathing, but instead, I'll spin it
over my table saw, just with a cordless drill.
It's taking quite a bit of tweaking, but the shape
I actually want is for this to have a bulge in the middle
and that will help the belt in the middle.
It had been my plan to just stretch rubber over this,
in longer sections like this, but I found this is already
too much to try to stretch over this,
so instead, I'm gonna try to coat this with silicone.
The weird thing is I didn't get any silicone on my hands.
I made the idler drum the same way, except the disks
are smaller, and the shaft is also smaller.
I also have to slightly modify my jig for rounding it,
because the diameter is smaller, and the shaft was shorter.
Let's see if I can get those pieces of inner tube on there.
They still need quite a bit of stretching.
Yeah, it's doable.
I'm not sure if those ridges have much of an impact,
but they're easy enough to cut off with a knife.
Now that I have the rollers made I printed some one to one
drawings from the SketchUP model using my BigPrint program.
Now, I don't have all the dimensions on here,
but all the ones that I didn't label, I can just measure
straight off the drawing.
These bearings are 32 millimeter outside diameter,
which luckily makes for a tight fit, in a 1 1/4 inch hole
from this drill.
So, the important thing is, to still have a way to get
the bearing back out.
So, here's how this fits together,
these two things form the sides, and then in here,
we have a cross-brace that's here,
and another one here, and then we have
this piece here, and that's elevated a little bit
Fits underneath this part here.
And, this part fits on top of here,
and this is actually a little bit further up,
and then there's this funny part
which gets pulled on here, and pushes this part out
that way, and then we have the pieces here
for mounting the bearings. And, on top of all that,
we have this part here, and the backer for the belt
goes on here, and of course, the rollers
are here and here.
Before putting in the ball bearings, I drilled a couple
of holes, which allow me to push it back out,
and I also drilled another smaller hole in there
to make sure the inside part of the ball bearing
won't be rubbing against the wood.
The roller is about 3 millimeters higher than
this piece of wood, which is about where I wanted it to be.
This part goes on here, and that needs to be square,
and looking at it, I can tell that it's not quite square.
I start by drilling pilot holes for the screws,
and then I drill a larger hole for the shank,
and after that, I countersync then,
and then I drive them in with a drill.
This cross-brace goes in right about here,
and I'm just gonna use the tips of the screws to mark where
I need the pilot holes. I want to make sure
I don't accidentally drill the pilot holes
through the plywood, but this spacer is just perfect for that.
Now, there's a slight screw-up here, I have a gap
of about a quarter millimeter here,
and it sticks out here, so I'll have to trim that down
a little bit on here, and shim it on this side.
When I need to trim off just a tiny bit,
I'll often just push it against the stationary blade,
and then when the blade spins, it cuts off a tiny bit.
Now, this part is gonna go on here,
but I'll touch that later. and then this part goes on here,
and this goes on top of here, like so,
and there should be enough room in here for this to slide.
And, I've got that in here a bit tight, so I have to add
a shim here. So, I decided that I do need
this part on here to figure out how the rest of it goes together
but to not wear out the screw threads too much,
I'm using some screws that are shorter and smaller
than the final ones, just to hold it together
while I work things out.
So, here's the shim I made for here to compensate for the fact
that this didn't have enough room to slide in here.
And, again I'm using smaller, shorter screws, because
this is not the final assembly.
The idler roller is gonna mount here,
and I'll make some wooden bearing blocks,
and those will be attached to these pieces of plywood.
I just cut out some wooden bearing blocks made out of
Lignum Vitae, and I'm gonna screw these in place
before I drill the hole through them.
The bearing blocks need to be mounted to this part here,
so that this roller is gonna be about 3 millimeters above
this surface. When I first put this together,
I found the bearings very hard to turn,
and so I put a 3/8 inch drill in there and just, sort of,
spun it around while tilting it to the side
but it got caught, so now I have a huge hole right here
but as it is, I'm just gonna leave it like that.
If those blocks wear out, with this gash,
I can always make new ones. Not now.
This thing is supposed to be able to pivot a little bit
to control the tracking, but to keep it from moving
side to side, like this,
it's supposed to have this part fit in between here,
but this is a little bit too wide right now
and plus I also need to cut that same profile
into the thing that's the top of the sander,
so I'll just do that while it's assembled on the bandsaw.
The way the belt tensioning is supposed to work
is I need something to push this out here,
and for that I've got this, sort of, lever thing.
And, for now, I'm just gonna attach it with a screw.
So, that pushes out her, like this, as long as something
pulls on here, and for that there's
a threaded rod with a knob on it here and the nut that goes here
and to keep that nut from spinning, I made this block
that the nut fits into.
To control the tracking, I need to control
side to side here, which is with a threaded rod
through here, and I think I'm just gonna put a couple
of T-Nuts on here to push that one way or the other.
And, that turns out to be a bad idea,
because the problem is the T-Nuts get stuck
on these edges here So, I made this funny shape
block of wood, which holds the T-Nut,
and then that fits into the slot together with the T-Nut,
and it keeps it from spinning.
Well, I think I'm ready to try this with a sanding belt.
The shaft is 12 millimeters, but this hole is 1/2 inch,
and that makes for way too much play,
but making a shim out of a pop bottle
I can get that to be a fairly snug fit.
And, I also drilled a hole for the set screw,
so I should be able to lock that on.
There's still quite a bit of work left to be done
on this, including some sheet metal to go underneath
the belt here.
I am pretty confidant now that this belt sander
will actually work, but that's enough for this week now.