Hello welcome to Enots engineering I'm Alan.
Today I'll start making some knobs for my stepper motors,
we'll be having a look at cutting a hole in plastic using a hole saw
and also for beginners I'll be looking at changing the jaws on a three jaw chuck
so let's go into the workshop see how we do it
Today I'm making some blanks to turn into handles for my machine I've just cut those out
I think its Nylon a big block of Nylon.
and like all plastics as soon as you get the tool warm it starts to melt and stick.
You may remember these sort of hole saws where you select the blade
fix it to the disc then use that in your drilling machine to cut a hole,
and the problem with these type of thing the teeth are very small and this generates a lot of heat when it's cutting.
so it just melts the plastic. Now I was trying to think of a way of cutting these discs
when I found this old hole saw it's called a dial saw and you can cut a hole
from 1-1/8" up to 2.5"
it's got a fixed drill in the middle and these teeth around the edge will move in and out to give you the diameter you need.
So I've set it at maximum locked it up and we'll see how that cuts,
each tooth on the end is the same as a saw blade you've got two teeth
and they are offset so it gives you a wider groove than the tooth
and that's easier to sharpen any downside on this as far as I can see is
the length of this drill that they fitted instead of fitting a short drill that comes maybe 1/2 inch over the end
of the teeth they fitted a standard drill and you have to have clearance on your drilling
machine to get this in and the part it didn't need to stick out this far
I would have had a shorter drill made to fit that but I can't see any way you can change that drill.
it looks as if it's made as part of the the unit.
you have a nut on the back, the nut on the back is a left hand thread
that slackens the two plates off and then if you turn the plates the teeth can come in to a setting
then lock the nut up so when you unlock the nut these are loose.
When you lock the nut up the two plates come together and these become tight.
The only disadvantage is you can't tell exactly what size hole you're cutting,
and you can't put a vernier across because they're odd.
I just thought I would show you that maybe people haven't seen it but this one's about ten years old at least,
I don't know whether they still make them but it's just another take on the old circle
cutting saw blades that you can get
For anybody that's just started or purchased a lathe and are just learning
about the lathe I'll just show you how you change the jaws
I've taken the jaws out just by unscrewing and eventually they will come out and I'm replacing the jaws.
which is that one which grips there and inside a bore to this one which will grip on the outside.
The reason for that is when I open this up to fit one of these plastic disks in
the jaws are right on the edge of the scroll the scroll is the part in the middle
which acts as a part of the thread that holds the jaw in,
I've changed from holding it there to holding it on the inside of this jaw
so this jaw won't be so far out and it be fully engaged on the scroll
and on the three jaw chuck you should have each slot for the jaw numbered up
with a number and on each jaw you have a number marked.
That tells you which jaw it is
you can only fit number one on to slot one because the thread or the teeth on the back here
that form part the thread are all different they're in sequence.
so if you put them together you'll see number one
which is the top one starts lower down than number three.
If I put one on three side-by-side you can see the difference in the teeth
So if you put the wrong jaw in the slot when you close it down
one will close down before the other so they're not going to be equally spaced
they'll be one tooth in front or behind so it'll probably close down something like this
This will hit the center first and this is nowhere near it
so these jaws are numbered for that reason.
That's number one slot here if I turn this round you can see in the slot.
the first thread or the first part of the scroll just coming into the slot.
So I'll back that off put number one jaw in
Then holding it down turn the chuck so that the jaw goes in.
That's in
Rotate the Chuck to the next one keep turning and you can see the scroll
has just come through there for the tooth so now I'm on number two
take number two jaw feed that in push it in at the same time.
close the chuck with the chuck key and that will start to feed in
Rotate round to number three, there's the scroll coming around put number three jaw in
hold it in turn the scroll with the chuck key and then they should all start to go in
Wind the chuck key in and what I do is I will go in until the outside of the jaw is level with the chuck
and they should all be the same if you've got the positioning correct on the scroll
if you put one jaw in on the wrong thread one will either be deeper or not as deep
So you will have to back it all out and start again
That's how you set your chuck jaws, I can put the plastic in.
Now because there's already a hole through the middle
I'm putting a 7mm drill through
Now I've reamed an 8mm hole in the center of these plastic parts
I want to make a mandrel to hold this it' will be interesting to see how these
tungsten carbide tips perform on aluminium
I'll find a cap head and washer to hold that
I've just tighten the cap head it up with a little washer in front so that I'll stop it spinning
now I can true the outside up
this is diameter is 55.7
55.74mm
I'm just getting it so that the tool tip will touch there and they're centralizing the tip in the centre of the the wheel
It doesn't matter what the diameter is I'm just trying to get them all the same
Change it for the next one
Line it back up again
The next thing I want to do is turn the
outside diameter down to half an inch
and part this off so I can use the
mandrel part on my indexing fixture
This part that have made the small mandrel
fits into a 1/2 inch collet
and that goes into my indexing fixture
Then I can take out the aluminium
This is a half inch cutter end mill
Fit the blank on to the mandrel
Fit the cap head and washer
Now set the cutter just less than half way through if you go into there the cutter will jam-up
because it can't clear the center part so I'm going in
about half of the cutter and what I'm doing is making some grips on this
where I can actually turn this by hand because at the moment being smooth
you can't get a grip on it so I'm just putting some semicircles in around the outside
there'll be six of them equally spaced
once you've gone round feed the cutter into the depth you require and complete the second cycle.
and then if you have any sharp edges
you can remove them with the scraper
Thats the handle so what I need to do next is drill a hole through
to the centre and tap that for the grub screw
now I'm using an 8mm tap the pitch of the tread is a bit coarser than a 6mm
or a 5mm so it will grip the nylon better
change the tap for the bottoming tap
you don't need any oil
and the 8mm grub screw can come through the center
on the end of a stepper motor
if you use the motor where the spindle come
through both sides you'll have the shaft
of the motor coming out with a flat on
and the idea of these handles is that I can put the nylon handle on there
once it's tightened down I can turn the end
of this handle which turns the stepper motor and the shaft
I can move the CNC machine when there's no power to it
I've just fitted the one to the z-axis
if you look inside there you can see I can turn the motor by hand
see it moving now
that's a very fine feed and sometimes when you look at the screw thread it doesn't look as if it's moving
you can see from the hand wheel it's moving and that looks a lot better
it feels a lot better than the wooden hand wheels
Well thats the end of another project.
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