hello welcome to engineering I'm Alan in today's video we start making
the indexing ring and the feed screw for the drill grinding jig the feed screw
has about a five mm feed and uses a six millimeter cap head the
indexing ring has 12 holes why 12 holes that's because 12 holes are divisible by
two three four and six so if you have a three flute drill it's no problem but
first we need to find a way of making the 12 holes for the index ring so
let's go into the workshop making an indexing strip take a sheet of A4 paper
and draw a line across cut the paper so that the line is in the middle of the
strip take the lid that you wish to use and then tape this paper strip to the
edge of the rim mark where the two pieces meet and cut the paper strip so
it's the exact length to the rim
remove the paper and tape it to another piece of paper with a square draw a line
any length and divide that line into the number of indexing positions you need in
this case 12
once you've drawn the 12 lines mark the last line to the beginning of the strip
then keeping that line parallel the first line slide along and marked
the other twelve positions for your indexing strip
once you've marked the 12 lines number the 12 lines and removed a strip from
the paper fixed a strip to the rim of the lid and there you have your indexing
reference. Put the lid in the lathe chuck and drill a hole a size to suit
a nut and bolt that you have bolt through it's m6 which is now going the
collet so all I need is to get something to eye this up level then I
can turn this around and mark off the divisions. I fitted a magnetic stand here
with a screwdriver blade in that is just touching the paper to give me a
datum point
and here's the finished indexing ring I've turned this piece is steel down to
12mm and I'll drill the 5mm hole in the end and then putting an knurl on
this end
make sure this face is parallel and part this off to width to fit inside the
dividing ring
take the corner off that now
here's the feed screw fitted with a 6mm cap head
I've got two blocks of steel there 35mm long 25 mm wide and 15mm what I'm doing is
facing it off putting a 45 degree chamfer on and on this one I faced it off putting the chamfer on
I want this chamfer this way to
blending with a 1 inch diameter the way I'm doing that it's just looking down the one inch bar this radius on the chamfer roughly about 1 inch
I'll set the compound slide at 45 degrees hold a one-inch bar on top of the chuck jaw
gives me a one inch diameter it's not critical
I want to score a line down the middle
of this as a datum line now I've put a thread cutting tool on its side set the
center of the tool the tip of the tool to the center line by adjusting the tool
holder up or down set this square by using the jaw just to look and I want to
put a scratch mark
that you can see there the mark if its out of line or doesn't look right you
can always machine a bit more of taper try again I've just marked out the
position on a centre line which is the distance from the base to the middle
where your index pin will be which is 17.7mm I'm drilling a 7.5mm hole
each side of the center line for the indexing pin this is just to remove
material so I haven't got so much to take out when I start a milling
this is the block I'm machining I've put two parallel strips on the top of the
compound slide washer there to bring the center of those holes on to the center
line of the Chuck the other packing piece I've got here has got a washer on
the opposite side of that a piece of aluminium on the top and I'm clamping it
down using the tool post bolt. I'm just clocking up the front face to get
that parallel for the start of milling each division on there's a tenth
so now that's done 8mm milling cuter in the chuck start to cut
the next thing I want to do is swap the cutter from the 8mm to 10mm and then
go in 7.5mm half way down the block
enlarge this end
15.6 need that down to 12
okay that slides in and out easy the next thing I need to do is put the flat
on the top and the bottom about a millimeter side that's got no teeth up against that
whats a bit more on the depth
I'm just going to drill four millimeter hole straight through that
I've parted it off and turned it around in the chuck I'm just facing up this end
That should fit in the block and move side-to-side
we're making the indexing screw
0.196"
fitted my knurling tool slow the speed
I'm just going to put a chamfer on the top edge there
the next thing I want to do is machine is 60-degree Point on the the front and
then cut the thread so to do that I need to put my compound slide over to 30
just check that fits in one of the holes it's okay I'm not gonna put a
parallel piece on the end because if anything you'll get snapped off I've got
an m5 die this is just a Morse taper with a parallel shank on it the back of
this fits on the parallel shank it's free to move up and down in and out
round put the die on the end I've got my mandrel fitted in the headstock so I can turn the headstock with a spanner
piece of brass with a thread in this is so I don't have to grip this on the
jaws to face this off
there's a screw for the indexing pin
this is the feed screw it has a feed of about 5 mm this is the indexing ring with
the twelve positions and this is the indexing lock so the way this works is
you select your position you want you can under the screw here and it'll
rotate select which position you want to tighten this in no need to tighten it
tight on this side you can wind the feed in as you can notice on this side
the indexing screw travels along the slot that you made in the block but it
won't turn so all I need to do now on this is to mark the positions
of the hole so you can see from the end which one is engaged and mark some
positions on here so once you've ground the drill on the
one side you can see where it is back it off rotate it and then feed it back into
the same position oh well that's it for today and we'll
finish off this project next time on Enots engineering