By
John Morgan
It has been around for a few hundred years mostly with a straight up and
down adjustment and a rotary table and has been added to in various ways over
the years.
I notice in the latest S.O.T., magazine one similar to one
I have made and I hope it might inspire others to make their own, I will give
a rough idea of the sizes as I don’t have drawings.
The main holding slide
is made of an aluminium alloy - supposedly as strong as steel and half
the weight - machined from a solid block.
It is 27cm x 9cm x4cm with
a 17cm x 3cm slot. The thread to screw onto the headstock is 45mm x 2mm as used
in Vicmark large chucks.
So as to be able to use all the adapters, the length
of the travel is 12cm with a valve handle at the top The screw is 3/8"
BSF and 20 tpi and is 29cm long . The sliding block is 8 cm x5 cm x8 cm long
with 16 holes for adjustment up and down a ½" UNF bolt to lock it
in place and 4x4 mm cap screws for locating the angle required.
The next
unit is the 72t x74mm od x 3.5 long worm wheel plus 72 x 3mm tapped holes
used for indexing-locking and as stops for fine adjustments by the micro screws
. This unit is held in place by two opposing deep groove thrust bearings
which only allow rotary movement of 360°. The worm can be moved
out of mesh to allow quick setting up.
The final part of the unit is an aluminium
casting and has been machined all over. The round section is 8cm od x
l.3cm. The platform is 11 cm x 9 cm x 1 .6cm There is a double row ball
bearing holding the rotary table and worm wheel. The thread is 45mm x
2mm to allow for all the adaptors . The rotary table has 72 x 3
mm tapped holes for indexing -.locking and stops for fine adjustment. The
worm can be taken out of mesh for quick setting up .
The two thrust bearings
are NSK 51101-907
The distance from the slide face to the centre of the outside
rotary table is 16.7cm.
I have a 120 t indexing plate on my lathe and two
adjustable stops to control the movement of the whole unit when required.
Please
disconnect your power supply before attaching this unit to your lathe.
Good luck
