Hello welcombe to Enots engineering I'm Alan in today's video we'll start to
make this body for a revolving centre it consists of a number 2 Morse taper but
you can make it as a number 3 and a bore that holds the bearings
So before we start to make this we need a plan so let's go to the workshop and see how we do it
When ever I do anything in the lathe I always make a rough sketch of what
I'm making, these are the dimensions of the part we're making today.
I have problem getting in with my lathe tool on some of the center's.
so if this was a bar I'm turning on this particular one I could get in with the tool.
But a soon as I get to that diameter the tool hits the centre and I can't swivel the tour round
at a different angle because it alters the cutting edge
so you might think I'll use a smaller centre there's a smaller centre there's the bar with this tool
It's a 10mm shank that won't go in the gap between the bar I want to turn and the revolving centre.
What I need is a centre that sticks out further so can get that tool in
but not as big as this one and that's what I'm going to do today make a new revolving centre.
First thing I've purchased is three bearings now these bearings have an 8mm bore 22mm diameter and 7mm wide.
They'll be stacked up to hold the center. I've purchase bearings that have seals on each side.
So I won't have any problem with swarf or suds getting into the bearings
I'll also use this washer I'll use that as a cover and it just wants to diameter reducing
That's the bearings and the cover sorted and for the steel I'll use this piece of steel.
which use about 30mm diameter and it needs to be around 115mm long.
Now when making this part there are two ways you could do it.
if you start it by doing this end and do all this work on this when you take it out the chuck turn it around to do the other end.
You have a problem in how do you know that this is running true to your finished taper.
So if you think of the finished job normally a taper you should be able to run between centers.
and should be true so that's the way I'm going to do this.
I'm going to put this between centres so we'll drill a centre hole in this part and centre hole in this before we machine it out.
Put it between centers and then machine this taper to get a good fit.
I'm doing the number 2 it can be a number 3 if your tailstock is number 3.
That way if you have problem getting the right taper you can have 2 or 3 goes at it.
You just move in further along the bar and you can still finish this off on the end of the bar.
If you start with the taper first, put the part between centers machine the taper.
Get that right then you can hold the taper in your head stock
by using a Morse taper adapter and you know whatever you do on this end will be
running true to the taper, that's the most important thing is that the taper is true to the bearing bore.
Place it in the four jaw chuck and I just clocked it up true.
That's running with in 0.0003" or 0.004"
and the next thing we want to do is face it off and centre drill it.
I've done that now I need to turn it around and do the other side.
What I'm going to do is just undo the jaw were the label is and the jaw in front.
take the bar out turn it around put that back in and tighten the jaw in front then the one with the label.
Just check the run out on that now I'll just put the coil indicator on there
I haven't clocked this up that's running out less than 0.001".
I'll just show you the setup and what I'm doing is using this as a guide.
it's roughly the same length as this bar so there won't be much difference in the
taper but what I'm doing is just running the dial indicator with the flat bottom
along the taper this is in 0.0001" I've got a couple of thou difference.
I'm leaving it at that because being slightly shorter than the bar.
I know I will have to alter it anyway but it is a good starting point.
This end I fitted a 2MT with a female center and in the centre put a ball bearing.
The idea of this is you can use a standard centre
but you put more load on one side of the center hole when you're offsetting it
you're actually pulling it out of center in the hole.
By putting a ball bearing in the centre in the part will run true to the ball bearing.
and the center here will run true to the ball bearing
so your sort of pivoting on the ball rather than using a fixed taper.
If you put a normal centre in what you're doing is bending that like that
so exaggerated you're running on half of your center and it will put marks on the centre.
I think that's where I've got mine from this edge here is digging into the centere
so it's running on the point on the inside and the edge on the outside
by using a ball having a spherical surface it doesn't matter where you are
it will locate itself true on the ball that's the theory behind it.
All you have to remember is when you undo your centre that ball will fall out.
On this lathe the zero marks are on the back here of the tailstock.
This is one of the screws and there's one on the opposite side and it pulls the tailstock top
toward you or away from you depending on which one's you tighten.
I've set that up roughly now I'll put the part in.
On this end I've fitted a carrier that goes on to the center
and on this end the ball goes in there that goes on there.
This doesn't need any oil on this end because as the headstock moves around
You can see that centre goes round with it so there's no wear or movement in the centre on this end.
This is the only end that's going to take any movement or friction.
so you just need to keep your eye on the bearing that it's not getting hot
I've just marked the red line where the taper I want to end I will machine it until
this taper gets to there then I'll measure the diameter see how much I have to come off.
now I've machined all these so far with that ball bearing I'll have to revert
back to my centre because my tool now is not far away from the outside of this.
I can't go any smaller than this diameter and I need to still go down about
another 5mm so I'll put my centre back in
okay I've just spread a small amount of micrometer blue along the taper and I'm
using this is a gauge this is a number two internal Morse taper to a three
external I need to do is put this inside turn it remove it and see where it's rubbing
and immediately you can see it's touching more on this end than it is on
this end so that means I need more material of this so what I have to do is
pull the tailstock away like that so I'm cutting more off this side when
you get down to this sort of level be careful because if you say take 0.005" or
0.006"off the diameter as it's such a shallow angle the Morse taper will probably move up 0.02" or 0.0.03" thirty thou
it's not in proportion to what you take off so be careful as you might think I'll take 0.02" off
there all of a sudden it'll jump up to there so do it in small amounts.
I adjusted the tailstock pulled it back that way so I'm taking less off here more off this end.
I've just tried it again with the micrometer blue on.
as you can see it's not touching this end that much it's touching at the bottom more.
I need to move a few tenths so that I take more off the bottom to do that I've
set up the dive indicator what I'll do is tighten up the grub screw on one side
and slacken it off on the other
that's moved it 0.001" I will move it back so I'm taking 0.0005" more off.
lock it up if you use a dial indicator you can control the amount you'r moving it
without a dial indicator you're just guessing I'll leave that at that setting
and take another cut I've also changed my tool to try and get a better finish
I'm back to the old problem the tools touching the centre
I still need to go in further
here I've reduced the diameter because as you get closer to the finish size you
need the end to start appearing in here as you can see it's a it's got a
diameter there and it's got a flat there so you could end up with the diameter
hitting the flat so I've reduced the diameter because I'm going to have a 9mm
hole this will go anyway when I finish it
I finished cutting the taper
so when the taper goes in I've still got a small amount of your
spare so if I need to I can redo it but you can see on this end that the centre
is now halfway in the middle of the slot so that means when this is in the
tailstock or in a machine the tailstock will eject it.
If this face here doesn't show in the centre of that it won't eject
that fits on there okay
if I just rub it I haven't put any marking blue on here you can see it's touching at
this end it's touching down you'll see down there there and it's touch in there
it's probably be a bit harder on the bottom than it is on the top
so I just polished this a bit more off at the bottom
it's that fine amount now that adjusting it I'll probably go too far
I got my polishing stick
Just put that in it's locked in.
In fact I'll need a drift to get that out That's OK for the taper
I will put the part and the 4 jaw chuck and I've clocked it up to within 0.0001"
What I'm going to do now with the center drill.
I'll just drill this out and then put an 8 mm drill through the length of this
I've drilled my 8mm hole which goes down to nearly were the chuck is is
and it's. taken the pit off the end as you can see when that goes in there you can
still see the end of the Morse taper in the slot so if you put the drift through
you can still get the Morse taper off
This recess is just to fit a washer in there stops swarf and dirt getting in you can make it whatever diameter you like.
But you need to control the depth because by the time you stack your
bearings up in here the bearing should just come over the end of that lip and
leave you enough space for the washer thickness.
And this recess here is for another washer we'll make an 11mm x 2mm washer to go in this.
This is an 8 mm bore so what will happen in here you'll have a washer in this end
with a cap head through 5mm cap head you need to turn the head of the cap head
down to fit this 8mm that tightens up on all the bearings and pulls the centre in
That's the setup for this
now I want to drill the 8mm hole straight through bore this out to 22mm by about 23mm deep
so we've drilled a 8mm hole straight through
now just face that after 30mm because the bearings will take up 23mm
then we've got a washer inside so it leaves me a few mil to spare on the end.
last thing I want to do is a 20mm hole straight through and come out the back.
Iv'e just put a half inch in mill in the Jacobs Chuck .
Use that as a thickness guide just to set my zero on the end of the tail stock
I want to go in 23mm with that
Now I've got a half inch hole 23mm deep and the half inch will allow me
to put my boring bar in
Iv'e set my boring bar up and dial indicator so when I go into the bore
I can go to zero on the dial indicator and i know i'm at the depth I need.
As I come down I hit the dial indicator I go around to one as a warning
and then I stop at the second zero I find if I just got one rotation
it's gone like that before you know it you'v ploughed into your face
so at least I've got one rotation to react and then by the time it comes up to the zero
on the second one that's the depth
I've just finished off the bore I've had to revert to an old boring tool to try and
get a decent finish it's still a rough finish but this bearing now just starts
to go in and this material still hot so I'm hoping it'll shrink down a bit when
it cools down
I've just machined a little recess on the end it's about 25.5mm diameter
and 2mm deep that's for the washer to go in
I'll just have to take some off the outside of this washer
Well I think that's enough for today we'll finish making this project off in part 2
I hope you enjoyed it and we'll see you next time on
Enots engineering