h ello welcome to Enots engineering I'm Alan
in today's video I'm looking at edge finding different ways of finding the
edge of component and I'm making a couple of objects just to test them
out in the milling machine
The first one is one of these edge finders which is just a bar with a bearing on
the end this is the one off my lathe
I put this in the tool holder and if I've got something in a four jaw chuck
I can bring this in and it just runs the part true before I finally tighten it up
that's for a big face or something where it's wobbling in and out
it will true it up up so I was looking at this the problem with this is it's a big
diameter for the milling machine this is 16mm and the chuck on the milling
machine only goes up to 13mm so I thought I'd make another one of these
This I use on the lathe it's got a flat on it so it can go in the tool post
clamp it down and you can use this so I'm making one for the milling machine
which is exactly the same without the flat it this one's about two 12mm diameter bar
The same size bearing 8mm bore 22mm OD the thickness doesn't matter
I'll test that and see how repeatable you can get to the edge of a component
and also I'll try this this is a little probe I made
This probe here I used on my CNC machine it's a probe for measuring holes
and for getting the center of a hole and all that did was make these plastic adapter
and that fits in the milling machine chuck
So let's go into the workshop and see how we do it
I've placed my the ER20 collet holder in the headstock
I've just found a piece of steel and what I want to do is make one of these
Which is a just a ball bearing on the end of a shaft this one's for the lathe which goes in the tool post
So I can use it to knock parts true when there in the chuck
I want one for an edge finder on the milling machine very similar to this
But the problem with this one is that the diameter of the bar is over the size of the chuck
I think this is about 16mm diameter and the chuck only goes up to 13mm
so I found a smaller diameter piece of steel and I just want to turn the end down to fit the bearing
the bearing i'm going to use is this one it has an 8mm bore and a 22mm OD
So I only want to turn the last little bit down so I can press this on there
and then what I want to do is test it to see how accurate it is on the machine
first thing I'll face the bar off and turn the diameter down 8mm by about 10mm
this is 0.3545"
It should be around 0.320" at the moment
0.3205"
it just starts to go on there I can press that on now
so I'll take that to the vice use the vice as a press to press that bearing onto the shaft
I've put the dial indicator in a block and I've put the part we've just made in a Jacobs type chuck
with the bearing on the bottom I've selected a slow speed
it's running at about 75 RPM and we'll see how much that runs out
you can see that bearing is not rotating freely
Its stopping the bar is running out 0.001" each division on there is 0.0001"
so that bar is running out by one 0.001"
let's make it a bit easier to see the bearing I've just marked it with some red felt-tip pen
You can see the bearing has stopped as the clocks touching it
When I wind it out the bearing goes around and if I wind it in
It stops so if the dial indicator probe was the edge of your workpiece you would
know that when the bearing stops rotating the center of the spindle is
within half the diameter of the bearing which is 11mm
so then you have to account for the run out of 0.0005"
so if I take the dial indicator out of this jaw and come in against the back jaw
What we should see
When that stops moving I know I'm touching the jaw
that's just touching that
the bearings just touching the jaw so I know I've got thou run-out
there will be some play in the bearing so the edge of that bearing is within a thou
of the edge of the jaw and to calculate were the spindle is you know that
it's a 22mm diameter so half of that is 11mm so you know centre of the spindle
Is 11mm from the edge of the jaw
What I've done now is I've just put a small block of aluminium in the vice jaws
this is still the same I just marked the edge a bit more with the red felt-tip
on the table of the machine I've clamped parallel strip
so that's not going to move it's always going to be clamped to the table
a magnetic base is on the cross slide so that's not going to move and
I've put the dial indicator touching the parallel strip
start the spindle up
and I will zero the dial indicator
and wind it back off I'll come back onto the spindle so it just touches
and stopped so that's repeating with in about a 10th of a thou
I've put a piece of plastic in the collet this is about 13mm
so I want to get it down to about 10mm so it will fit my chuck
this is 0.470" 12mm is 0.472" so that will do or just try and get a better finish
I've just turn it around now
I'm screwing in a probe I have from my CNC machine and the plastic is to
insulate it from the milling machine
I've put the little probe I made into the chuck
Just a screw thread into the plastic we've just made a small ball bearing on the end
now what I'm going to do with this is
I have this Electrical tester all it does is when you join the two wires together a light comes on
so because this is now insulated if I clip one wire on to the milling machine
and the other wire I'll just push this into the crocodile clip and just click that on to the vice
Now what should happen when
the probe touches the edge of the aluminium the light should come on
so we'll look at the light and the dial indicator
so when I move it out come back in
I'm looking at the light just glowing touch it they're you can see it's lit up
the dial indicator is 0.00025" from zero
take it off come back again
there about 0.00025" from zero
so you've got repeatability but the advantage of this is
you don't have to have your machine running you just used an electrical contact
you can go around and as soon
as the light lights up be touching and that's repeating within 0.00005"
see the lights on there and the other thing about this is that that probe will
be able to fit into a hole and if you can ensure that the ball is running true
to the spindle you should be able to calculate the diameter of the hole
and the center position of the hole
and of course if you have digital readouts fitted to your machine you'll be able to
find the center and calculate the diameter a lot quicker with the readouts
well that's it for today I hope that was useful
hope you enjoyed it and hope to see you next time on Enots engineering