hello welcome to enots engineering I'm Alan in today's video i visit my brother's workshop
as you have a problem with parting off on his lathe we look at the tooling the chuck
and the speeds and feeds so let's go as his workshop see how he does it
The problem i've noticed is when i'm parting off the tool tends toget caught in the the work piece and its
taken underneath the centre line um and then in some cases it locks the lathe solid evenly
if i'm in back gear you know there's a lot of power there it still stalls the lathe and
you can see some some of the movement is in the tool post dropping down but i think some
some of the problems caused by the chuck not registering properly
so here i'm just showing that i'm on centre line with this parting tool
it's not the best parting tool but it's fairly strong because of the depth of it so i'm not going to break
the parting tool but the rake angle could be slightly off but yeah i've just freshly
sharpened this and as you can see it's on the centre line so we've that's set up ready
to go now square up to the lathe
so i've set the centre line on the parting tool so i know this is all set up and correct
so now i'm going to just square it up to the chuck
and the way i do it i'll just use a square and just set it up
and you can feel it quite easily which when it's when it's uh dead on lock that up so
that's square now to the chuck ready to go
seen that that's been very little cut on and we're getting vibrations and it's showing
it's showing us um like notches on there so that's highlighting the problem straight
away isn't it so i'll drop the speed down there to stop that
Ive put it in to back gear so it's completely rattling
some people say don't don't tickle it to put a decent amount of pressure on don't know
when you see the way it locks up you're afraid to it's going to lock up in a minute try to
lock up i can feel it here on the motor
as i say some people say to put a decent amount of pressure on there it's not cutting now
so what was changed from cutting nicely it's nice that's cutting again so it must have
picked up a bit on the tip I suppose Im putting much pressure on that though but it's not
cutting you can
increase the pressure
it's rolling around and it's getting trapped between it does look like that as we've got
into a groove we're trapped in there we can't can't get away
so every time i clear that it cuts nicely then it rolls over on itself
ok so its a tool profile problem that is then Ive just put this blade on the grind stone
just taking this put an angle in here to take to take it down so the metal stops curling
around in this area so obviously right up here and escape out the groove that we've
cut in so we'll try that and see how it cuts let's try again now with this different profile
same speed on the lathe so curling off and it's just
perhaps it'll stop the cut
it can break away
still rolling around on its self just changing the tool to this other parting off tool so
i'm just going to set the height of this
I'm making the groove wider to get down to where it was before its a wider parting tool
that's normally a good indication isn't it
Take it out of back gear and try it
try it at a faster speed
so i don't think it's a chuck or anything its the tool profile definitely definitely is a problem
isn't it so i'm at 5 40 rpm now
too fast so is that the chuck moving on the register so as you can see as i rotate this the
light bounces off you can see it's put like lots of flats on there which is consequences
of the vibration
showing up all right yeah
so what where is that originating from so is it the register which i know is not a good
register on this between the back plate and the lathe spindle
i've just put a bit of tubing in there i'm just going to see how this parts off
slow the speed down which is what I normally do
we're going to the lowest speed of there to go into that gear it should be 210
the idea of changing that metal was so it goes into the jaws a bit further
because there is a bit of bell mouth of the jaws
require a bit of pressure on there
it's coping with that i'll just put it to back gear
so this is now the slow speed this
machine runs at which is 40
it's got rid of the noise but it a bit slow
Its cutting its best on that
a lot of pressure on there
a lot more rubbing than cutting going on there
just change the tip we'll try again with some lubrication
cutting through on the inside
Changed the metal in the chuck
and uh we're going to 5 40 rpm see how this cuts
its cutting as quick as i put the feed in it likes that
like some lubrication
see It snatching the cross slide underneath
i saw it pull it across yeah
so even though that play there is just caused that to be pulled into the work
that's when you got right down to the middle but that cut really nice and i know this is good metal
all right we just just found out the tool height was out
its quite a bit lower i suppose that far lower the diameter of that pip there
so that's why it drew the tool in underneath
so we're just resetting the height
don't really know why it was as we did change the tip
try that at a slower speed
slow it down
see it's on the end of the bar the pip yeah
that's putting quite a bit of pressure on
so i think it just shared it off when it got to that size
in conclusion then having a tool with the correct profile and combination lubrication
does a much better job especially when it's on the right height which i thought it was
so i don't know why it dropped as much as it did
we're just checking the the jaws for wear and tear so put some micrometer blue on this
some silver steel and put it inside the chuck and just nipped it up and slid the bar
out it transfers a micrometer blue onto the jaw
and it's not too bad i thought it would have been put a fairly equal line all the way down the length on all three jaws
that was some of the problems we have when we're parting off
a mixture of tool sharpness speeds and feeds and the material you cuting
i hope that was useful hope it was interesting and we'll see you next time on enots engineering you