So I want to build this counting mechanism
which I've drawn up a CAD model for.
And it's based very much on one of these
little counter wheel mechanism.
This one's out of an old tape deck.
And they all work, pretty much, the same way
with a special little gear.
that does the carry for 1 digit to the next.
So I've printed out my 1 to 1 templates
from my CAD model.
And I've already prototyped some of the mechanisms.
So, for instance, here is my counting mechanism.
It's got this special partial gear, which on 1 side
has only got the 4 teeth.
And that, working together with a special shape notch on here,
allows for a carry. So when 1 digit wraps around,
that increments that by 2 teeth
which in turn increments the digits on the other wheel.
The more tricky thing to test has been my
increment/decrement lever.
So, here's my first prototype.
And if I move that lever to the right, and back,
that increments this wheel that you can see there.
And if I move it to the left, it decrements it.
So I've refined that a little bit
and here's my second prototype.
And again it works the same way.
Except you don't need a scroll saw to cut this one out.
So I cut out my templates and arranged them
as tightly as I could on odd shaped scraps that I've got.
So, after 40 minutes on the bandsaw,
I got all my gear shapes cut out.
So I just drilled these gears out so that they
just barely slide freely on the shaft.
And spin freely. And next thing I need to do
is I need to cut away every other tooth to a certain depth.
And I'm gonna do that on the drill press.
So this side panel has got this big opening on here
just so you can see the inside a bit more.
It's not really necessary. I'm gonna cut that on a scroll saw.
But if you don't have a scroll saw, you can just cut in a
slot from the bottom and then cut all around it.
It won't matter if there's a gap in the bottom because
the bottom base is gonna hold that together.
So, here's checking some of the gears. I'm just gonna
use some bits of shafting and put them into this frame
to see how they run.
Now these two work perfectly together.
But, I've actually had to do a little bit of sanding
on the edges here because I didn't cut to the line everywhere.
Here's checking one of those funny partial gears.
This disc has to fit into the notch in here
so let's put this on here.
And that seems to work.
So, I should have not so much play in here and then
enough for that to go through here.
And, that's a bit tight.
I think I'm gonna sand this a little bit.
And here's checking that this gear works.
It's a bit tight here so I'll have to sand that.
Right about here.
So here's checking this gear again.
It's essentially these two teeth here that do all the advancing.
And then we put the other layer on top of here.
This layer here.
And that makes sure the lever gear doesn't turn
when we're in between. Because
otherwise this guy could just be free-running.
while nothing is happening.
See, without this guy, if we're turning too fast,
we could just spin that gear up.
So now that I've got this shape fully tweaked
I can glue it together with the next layer on top of it.
I really have to make sure this is really tweaked
because this edge here becomes impossible to sand
once it's glued.
I'm running a bit low on the 3/4 inch plywood.
So I've been gluing together various scraps to make the
double thickness layers for the big routers that have the
numbers on the outside of them.
Next I need to make these little things here.
These are actually...They don't advance anything
but this one down here just provides a detente for the
click stops. And the one on top makes sure this hook here
is always in the right orientation to grab it.
And they both have a little bump on there.
And I could cut these out of plywood but
I'm just gonna use some solid wood.
And I've already cut this on the table saw to be about
the right thickness.
And by using solid wood, I get a smoother surface.
And I've already got 1 straight edge.
So, I'm just gluing my pattern to the edge of that.
So, I've got this lever out like this but
next I'd need to put this template on here and
cut the profile from the other side.
But because I've got this belt on here
that makes it difficult.
So, I know this part here is 6 millimeters wide.
just gonna use my calipers to score a line on here.
And then I know where to cut.
And for that last little line here
I'm just gonna freehand that.
Before I cut this part off, it's important to drill
a pilot hole through here, all the way through here
because otherwise, once I cut that off
that mark is gone.
So, I haven't actually changed this lever in my design, so
I'm just gonna use that one for the actual one.
Except I need to glue some bits of reinforcement to that
So, there's a disc that needs to be glued on the back.
Just to give the screw a bit more hold.
And let's put a nail through there, just to make sure
I've got the pilot hole centered.
Good. And another disc goes on here
for another screw to reinforce.
So this lever mounts on here and this pivots on here.
Now for hinging that, the nails worked out pretty good
but they don't attach anything.
And ideally, I would use a screw
that has a smooth part of the shank
like this one. But, in the right size, I cannot find
any screws like that, so I'm just using some
3/4 inch, number 4 screws.
And then relying on the counter-sync
to hold it in position.
And these need to be counter-synced so
that the head is just below the surface.
And so this part can still turn freely.
That's good. Now let's attach that on here.
So far so good.
So, I've just attached this lever which provides detente
with the ratchet wheel. And then this one here
keeps the lever centered with this little notch here.
And also makes sure this thing tilts in the right way
so that these hooks actually end up engaging that wheel.
Now I'm attaching this with 3/4
inch screws, like the rest of it,
and I've actually counter-sunk these below the surface
with another drill, just so that you don't have to buy yet
another length of screws.
Using longer screws would be better but I'm doing it this way
just to make sure you can.
So, I've just hooked up the rubber band and let's
put the sprocket in here.
And let's see that's in there, and let's try it out.
Seems that this is a bit tight.
There you go.
And in the other direction.
So that all works.
And that gets attached to the first router
and I'm putting a little cardboard spacer behind it
just to give the mechanism a little bit more slack.
So let's make sure that goes on exactly in the right position.
Let's screw it down.
Now next part here is a bit tricky because
I need to make sure
that this wheel and this wheel
will actually ratchet the next wheel
onto the next digit, right with one click of this here.
So that needs to be lined up with the wheel here.
So the easiest to do is to make sure this detente
is exactly between 2 digits.
And that should put us right in the middle
of flipping this sprocket here. That means this part
here, needs to be exactly here
where it's just in the process of flipping the next digit
with this wheel. So that tells me the position I need
to screw these things down at.
So, I can just mark those holes with an awl.
So, here's my increment lever turning the first rotor.
And I've got the special wheel on here and that engages
with this here. I've got the flat part here and
that goes against here. And then let's put
the next gear to engage with that.
And now as I increment, and on the next one we have
the carry, so now they both rotate.
And now we're rotating just one for the next while.
Until we do a whole 10 turns, 10 increments.
And here it goes again.
Now with the first and second rotors here
I have to now make sure that when
this next thing goes on here
when this takes over, that will also be in the middle
of this one here, so that when it uses the next sprocket
to drive the gear on the last rotor
it will do it all in sync. But that's actually relatively easy
because all I have to do is make sure that this gap here
lines up with this gap here, and they'll all be in sync.
So, I put a light coat of paint on these rotors.
And the next challenge is gonna be where to put the
numbers on here. Where does which number go?
So, I'll start by putting the top of the counter on here.
And the numbers obviously have to show up within
this window here. But where do we put the zero?
Where do we put the one? So the easiest way to
do it is to just increment
until they both rotate.
And now they both just rotated so,
if I'm counting, I must have just rotated up to zero.
So, let's just make sure we're in the middle of the detente.
And that tells me now, zero goes here.
And just to make sure I'm not gonna get the direction wrong
I'm gonna mark where the 1 goes as well.
So, going up by 1, there's the 1. Just in case I
end up putting it on in the wrong direction.
I could add the numbers by gluing
numbers on a piece of paper
onto my rotors but, I don't want to do that.
I actually want to paint them on here.
But I'm gonna use these as a guide
for where they go, which is why I printed these as a
mirror image so that, I'm gonna attach these, like so
and then rub them through.
So, let's take this rotor out again.
So, what I want to do is to just wrap this around
and rub all the digits through but it turns out
my scale is not entirely bang on. I didn't make
these rotors as precise as I should
and so I end up with a little bit of drift, so what I'm
gonna do is just take 1 digit at a time
center it on a tick-mark, and I've added tick-marks for
every digits around the rotor, so here's one for zero.
And I'll just rub that one through.
I don't really need to get the whole thing,
just trying to get the shape.
See, there's the 1 so let's center that.
I need to move it a little wee bit.
Let's rub that one in.
And center it too.
So you can see the digits quite well all ready.
So, I've put the rotors back in here
And let's put the cover on here.
And we've got the 8 here, 9.
And then as we wrap to the zero, this one should
move. Yup.
So these are good. I can go ahead and paint those on.
Now to mark the positions on the next row
I'm just gonna spin this one by hand.
There's the next position, and I know that's zero
because this one moved.
Which makes this one 1.
OK, back to zero. Now I need to do this one.
And rather than turning this one by a thousand digits
I'm just gonna take one of these gears out
so that now I can rotate this one independently.
And let's mark the last rotor.
So, there's a digit.
And because this last one isn't driving another digit
we can put the zero anywhere we want to.
So, now I'm just gonna use some acrylic paint
to paint these digits on much better.
Now, a thing about painting with acrylics
or oils, for that matter is
It's not the size of the brush that determines the level
of detail that you can paint. It's the quality of the brush.
So, I've put my rotors in there with the washers in between
And I'm checking here that this is the right size.
I just cut my base to the right size.
And now let's see how that lid fits on there.
I haven't cut that to final size yet.
So, just to make sure everything fits together.
So, I should cut that here.
And this is just about flush.
So I figure these 1 and a half inch, number 6 screws
will be a good length to use.
And in terms of drill size, if I hold the shank of this drill
in front of my screw, I can still see the thread
sticking out on either side. So that should be
a good drill for a pilot hole for this screw.
So, I'm gonna drill that pilot hole through both pieces
just to make sure I've got the alignment perfect.
I'm now gonna drill a larger shank hole, just through the
top layer. So that this screw is actually gonna pull the
pieces together.
I'm trying to keep all the mechanism, viable as possible.
But just to give it a little bit of lateral stability
I'm gonna add this block in here and that makes sure
nothing can tip sideways.
So, I've just varnished all the pieces.
And 1 more thing I'm gonna add is I want to have a knob
on the outside for spinning the first rotor so I
put a little screw in here on an angle
to lock the shaft against this rotor.
And then that goes against the first side and I've got a
knob that's gonna go on here and just like
the other one, I have this screw here at an angle
for locking this knob onto here.
So I've got the increment/decrement mechanism
put together here. So, let's put
the shaft and the first rotor in here.
And there's a little washer that goes right behind it.
And now the middle rotor.
My washer.
And the last rotor, and another washer.
And now the final side.
These all spin nicely so I can screw that together.
Now to get the small gears in, I have to make sure
these digits all line up with the proper digit.
And then put these in here. The flat part goes against here.
It's best not to use 9 or zero for the digits you're selecting
on the top, just to keep it easier down here.
And so let's put this one in.
And let's see, that one commits where it's supposed to.
And let's bring it down to zero here.
And that carries to all the digits. Good.
Now, let's attach this knob here.
With the screw at an angle, that locks it in.
So I've just installed the rubber band for the detente.
And this little hook thing.
And now it's all together so, 999
zero. 1 - 2 - 7 - 8 - 9.
10. And it counts backwards, too.
And to quickly reset it, I can just turn the knob.