This is our second milling project in CAM 1109. So our part here you seen a
picture of it, it's got layout work on it. You've
already had your layout on lab number one - milling, so we won't have to do that
again, but this is a different project, so we'll
start out on this project by getting our overall length on the part.
There's a line scribed on there showing that plus we'll check it with dial
calipers. First thing we're going to do is put in our #4 flute end mill and a
half inch collet. And we're going to machine that edge bringing the overall
length down to three inches 0.250.
Okay, make sure your collet is tight, but do not over tighten it because if you do
you can strip the drawbar that's in there that holds it in there. So it's
kind of a feel thing - we'll work with you when you tighten it for the first time.
Going in the operation of the milling machine should be familiar since you
already did Lab project #1, but just a reminder on this - use your quill as much
as you can instead of cranking the knee up and down, for example you can see how
far our movement we can make here, so we really only have to go up so far. To go
up too far then you're doing a whole lot of cranking up and down.
All we need is enough travel on our quill that we can get our cutter
slightly below. Now lock your quill in place, make sure it's backed up like we did on
the lab one or first one the milling project you did. Now a reminder, we talked
about climb milling and standard milling (conventional milling) and we want to make
sure that we do not climb mill - this means we have to have rotation clockwise of the
cutter and we're coming into the work. For example now that cutter is moving
clockwise, okay. So we come over here and we want to be feeding in this direction
here. So first thing we're going to do we're going to snug our ways up a little
bit and we're just going to come over here and touch off very lightly, and then
come off of the part, okay. And then feed in a little bit and take our cut across it.
Remember rotation clockwise, feeding from that end, not this end.
It looks like we've got about almost 1/4 inch to take off of there so it'll take
a little while. Go back over without feeding in, zero our readout here, so we
know how much we're taking off. So we're gonna do about 30 on that first cut. That
cleaned the part up, so it was sawing off fairly close. Okay, we got one more cut
and we'll be there. We're ready to move on now to our next operation which is
milling that slot. Now we've got that laid out remember and we're going to use
our edge finder again which you should already be familiar with, but we'll go
through it again. If you remember the one thing that we had to really keep in mind
is that when you're using an edge finder, you pick up the edge and then you
have to take one half the diameter and add it to your dimension. But we don't
have to do that here and we're working to an edge instead of a hole, so we're
not worried about the center of the hole, we're worried more about the edge, okay. So
let's change our cutter and put our edge finder in there. Remember once you break
that cutter loose or your edge finder or whatever do about three turns with the
drawbar up there and then you want to tap it out. Because if you do too many
turns, the drawbars floating in there and you'll smash the the threads on the
screw. So about three turns, one, two, three, tighten the back up.
Okay, so now instead of this laying down flat we're up on end, so we got to be
careful that we get the diameter, the largest diameter, on the side there so we
get an accurate reading. And remember now our blue side is a side that we're
working from. And get a little below your part, the top of the part, turn it on,
okay.
All right, try to eyeball with that edge finder in the center, on the side
there, get a little closer so you can get a better look. Okay, now let's look at our
print what says that the edge of that slot is one inch after we pick up. Okay,
so let's get it till it run smooth and then just barely kicks out (over a little bit
more) I think we're pretty good there, okay.
Now we're looking for smooth, it's getting smoother,
there it went out. I'm going to reset my readout and I'm going to move away from
it, tap it out, and do it again see if we got a good reading, just to make sure.
There we go it just kicked out and we are within on thousandths of what we were before.
so we're close enough, okay. So now we're going to come, up pardon me on that it's
actually 1.000. What we're going to do now, if you hold this and loosen this and
bring this back to zero all you're done is zero in it the line on there, tighten
it up. Now every every clockwise rotation from
zero all the way around a zero is one hundred thousands, but we don't want to
do that all in one cut. We're going to go about twenty thousands at a time, okay. So
once we go around and hit zero again we are at one hundredth. We eventually got to
do 0.285, so it will take a little while to do that, okay.
Take a cut
Now we talked about climb milling and conventional milling when you are
supported on both sides of your cutter you don't have to worry about it you can
feed down both ways, okay. Which is a time-saver also, but once you get support
away from one side of the cutter then you got to worry about climb milling.
Okay, all right so we're going to go another 20 40, come back across in
another 20, that's 60 total.
this is a lot more accurate than measuring it with a rule that's why are
we doing it that way
okay we're round of zero again which means that we've done 100,000 total what
I'd like for you to see is the lines that we scribed on there you can see how
what we actually did by using the readout and there where they don't
really match up and that's the reason why we use edge finders okay so now we
got to worry about climb milling so we're going to have to feed only from
this side so we're a half-inch wide and we got to go to 580 so we got to go
another 80 thousands now we can zero our indicator okay or excuse me our a
readout digital readout and move 80 thousands and we're to the other side
that's all there is to it. So we're going to move 20 thousands at a time
forty
Okay, so now we are 80 plus the 500 we already had and we're at 0.580 which
is what the print says we need to be. And that's all there is to do it. so again
you can see how handy the edge finders are compared to trying to use calipers.
And different type rule. So now our next setup is going to be we're
going to do the angle on there, the 15 degree angle, on your print. And the
way we're going to do that is we take a 15 degree triangle. And we've etched
our angle on there also. So we're going to lay this in the bottom of our vise.
And then we're going to stand this up on here and you can see that our
angle that we've drawn on there, so with that laying on there we want to close
our vise and you want to make sure when you get ready to tighten the vise that
you are resting on that triangle so your angle is correct. Now what we're going to
do again to eliminate where we have to worry about climb milling, we're going to
let our cutter overlap both sides because our cutter is wider than that is,
okay. You are feeding down again here until we get to that line.
We're locked in there. Turn it on,
all right now we're just going to come down a little bit at a time, so it just touches.
We're going to zero this out like we did before, so we know how much
we got to take off. Okay, come off,
feed down 20,
another 20,
We have a good ways to go.
Okay we're getting pretty close we've got one more cut after this and should
be it. Now we're running at a speed of about 600 rpm if we were running carbide
we would probably cut almost double that.
Yep that's it. Okay so we're done with that. Now we're going to take that part
out and we're going to deburr it all over and then we'll do a new another set
up. In which is like that, okay, not like this.
One way. All right, we've got our
part out of there now. We are setting up a new to do the half inch threaded hole.
So we're going back to our edge finder again, which we used initially, so now we're going to do it
and we're going to take our dimensions from the blue painted edge, all right.
And then from the backside and if you look at your print you'll see that those
dimensions are coming from the right hand side, the way we're in the vise and
from the the top edge where the slot is. So you're kind of actually you got your
print upside down from the way they've got it drawn,
but that's why we give you a print also. So now using an edge finder,
now we're back to the center of a hole, so we have got to add half the diameter.
So your print says two inches but when we move two inches over it won't be at
that line we laid off, so you've got to add half the diameter. And we'll be
taking it from this edge in the back edge where the slot is. Move and then all
of a sudden to kick out. We've smooth up a little bit,
there we go we kicked out.
Okay, we're going to come up, lift this up. We're going to move our 250 which is
going to put the drill and the edge finder right on the center of the edge.
And then we can use our print dimension. Okay, so now we are at 0.250 and you
can see that we're we're in the center line so now we can make our move.
We can zero that and move two inches. You can look at it visually it looks
like it's right in the center that way. Now we have to take it from the other
direction and we want to come down. We want to make sure that we don't hit the
bottom where the vise jaw is here. We want to clear that there we are. We'll
lock the quill down, alright. We'll tap this out to give us a little more room
to work.
There we are, we're kicked out. You'll raise up, move 250 which takes
us on the center of the back edge. There we are 250, which puts us on the
centerline of the edge and that's where it looks visually. So now we can zero
that up and make our move. Our move is one inch from the edge. Visually we
look okay. We'll go through like what we did on the other mill project, where we
spot drill. I'm gonna have to have some clearance here, off your knee.
Looks like our layout wasn't too bad, but it's not as good as what we got on the
edge finder.
I'm going to give that a little bit more speed. Reminder again when you change
speed make sure it's running like it is right now. Smaller the drill the faster
you run, the larger the slower. That's a little better
The small drills are harder to get in here. I think it might be okay like that.
Okay we're going to drill through. This is what we call our pilot drill and
then we go to our larger drill. Before we drill that hole, where did we determine
the size of drill to run through there? A lot of people get confused, a
lot of students get confused. We're doing a half 1/2 20. 20 is the threads per inch,
half is is the size of the thread, 1/2. But in order to tap a hole
you cannot drill a half inch hole, because then when you go to threaded
there's there's no there's no threads in there.
So there's what we call a tap drill. And a tap drill is smaller than the 1/2
inch if you're doing half inch, if it's 3/8 it's smaller than 3/8, so we give
the students a chart. And here's your chart, for example, let's look down
this column here. The tap size there's 1/2 20, right there. All right so 1/2 20
and they're saying that the decimal is 0.453 which we know is under 1/2 cause
a 1/2 is 0.500 and then they give you the actual size right here 20 9/64.
You always want to do the pecking we call it, a little bit, release it, chips go.
So you keep your chips small instead of coming out here like spaghetti, alright.
We're going to countersink that hole also because it's very important when
you're tapping to have a good countersink on both top and bottom.
I'm going to run that a little slower. Countersinks run at a pretty slow speed.
Looks like enough. We're on the drill press now and just so you get a
little bit of experience on the drill, press we're going to countersink the
backside since the holes already in. Our speed range is all up here,
everything is pretty simple. On tapping and countersinking you want a very slow
speed. So we are on large holes now. That's borderline with it not running. I
like to come down see how that vise moved, okay. Turn it a little bit because
if you turn it on and you hit it see how it moves. That will eliminate some
of that. Okay that looks pretty good. Alright, so we're ready to tap now now.
These drill presses have what they call a tap mode on them, so you can go down so
far and then hit the foot pedal and reverse it. So like right now I'm
ready to go forward and I come down and I get it started in there and let it
feed. Okay and then when I want to reverse it to come out like that it
reverses easily. That's all there is to it. So we're going to put a little bit
of cutting lubricant on here. I'm going to put some on here.
That's all there is to it. We're basically done.
Good job all!