Hello welcome to Enots engineering i'm Alan
in today's video i'm going to modify my indexing ring
to fit the three jaw chuck this is the indexing ring
which we made from a car brake disc and this fitted the four jaw chuck
now last week when i was making the final video of the rotary brooch
i found that i couldn't hold a small bar of silver steel
in the center of my four jaw chuck and i had to use an ER32 collet block
so what i wanted to do this week
is modify the ring so it will fit on the back of my three jaw chuck
so i could use it on either chuck
so let's go to the workshop and see how we do it
and the problem i had the other day was the chuck will only close that much
because of the jaw interference and i wanted to use it
on a piece of silver steel as you can see
that size won't grip on the chuck to overcome that i put an ER32 collet block
in here held the block and then put the silver steel in the collet
but what i want to do is convert this ring on the back
so that it will fit on my three jaw chuck
the first job is to remove the ring and it's held on by these two countersink screws
now these four holes are the original holes of the brake disc
I can take that off
and that's the mounting plate of the chuck
the problem i have fitting it to the three jaw chuck
is it will fit over the clearance hole will fit over
the hole in the body but i have three cap heads
which hold the back plate to the chuck
i don't want to be undoing these every time i want to fit the indexing ring
what i will do is drill out three holes in the back
so that i will go over the three holes in the back plate of the chuck
and then all i need to do then is drill two holes
in the back of the chuck and tap them to fit the countersunk screws
if i take the back plate off this three jaw chuck
you can see there's nothing behind in the middle it's recessed
first of all i have to set this up in the milling machine
the first job is to get the center of the outside
because it's the outside that i want running true and not the centre hole
okay i found the centre of the outside diameter
i've changed to a centre drill
and now what i want to do is use the program in the digital readout
to give me three holes on a 88.2 pitch circle
the first hole being here on the centre line
okay we start off in the centre of the bore
enter the pitch circle which is this one here
44.1 radius enter
start at zero end at 240
that's three holes
direction zero
and it's telling me now
number one hole move 44.095
that's number one hold done
now we want number two hole
so we just press the arrow down for number two
and then it gives you the coordinates to move
to get number two hole
and drill number two hole
press the arrow down for number three move to number three hole
and drill number three hole
when you're finished you just press the pitch circle again
and it'll display the center of the part and you can move back to the center
in the three holes we drilled earlier i've put three cap heads
bolted it to the back plate
i then put this back in the lathe and
check the outside was running within reason to that was about 0.003"
which i thought was okay over eight to nine inches
so now what i've done is put it back on the table
centred on this register in the chuck back plate
and i'm going to drill a hold this side a hole that side
and countersink them for the two screws that will hold the
ring to the back of the plate
okay i'm drilling this to 5mm to tap M6
and that will go down about 10 mil just check the screw
i've changed the drill for a countersink
that should do it
now we move over to the other side
and do the side thing again
okay there's the two holes we've just drilled
and countersunk that's the back plate of the chuck
i can remove the cap heads now
all I need to do now
is drill the two holes out here from 5 to 6 for clearance
and in the back plate tap them M6
that should be finished on the indexing ring
all i need to do now is swap that for the back plate
I'm just tapping the hole M6
on the back of the chuck all i've done is drilled and tapped these two holes
so it doesn't affect the chuck in any way
in the indexing ring i drilled three holes on the pitch circle
and two holes across the middle here with the countersink in and this will
only fit on one way
so now i all need to do is when i want the
indexing ring on the three jaw chuck to put this on
put two countersunk screws in
now i've got
clearance around the three cap heads and these two hold it to the chuck
so go on to the lathe and put it on the lathe see what the runout is
just for those that keep telling me that my dial indicator must be a thou
this dial indicator you can see here it says
point 0001"
that's a thou dial indicator
it says there 0.001" and you can see they look identical
it's just the same outer dial goes up in tens
that goes up in
that goes up in 100 thous
this one goes up in
10 thou one revolution on this is 10 thou
just set it to zero
it's about five thou run out
so that's another job done
i can now use my indexing ring
on the three jaw chuck and the four jaw chuck
oh well that's it for today
hope that was interesting hope you enjoyed it
and we'll see you next time
on Enots engineering