Indexing Head with Tailstock.
I built an indexing head made from large pistons
(Toyota Land cruiser), old 2" Dia. high tensile bolts (mandrels) & so
on. This is a simple unit designed for making special milling cutters,
reamers, duplicating lathe gears etc. This is one of those jobs where I am
making the tool (indexing head) to make the tools (milling cutters) to make
another tool (a precision dividing head or rotary table).
I haven't given lots of dimensions - it's a 'make it fit what
materials you have', type of job. If you want to copy it & need more
details, just email me & I will try to help where I can. I didn't make
it from plans, except those I carry around in my head.
Design criteria & materials on hand:
|4 Land cruiser pistons are used, 2 for the headstock & 2 for the tailstock.|
|Mandrel & quill are made from high tensile steel bolts.|
|Locking thumbscrews originate from old broken/retired sewing machines.|
|Aluminium adjuster collar for the tailstock quill, originally from VCR (heads); as were the small springs used on the pawl.|
|Direct indexing by using a screwcutting gear from the lathe.|
|The fittings on the head's mandrel are to match those of the lathe,
allowing use of lathe centres, faceplates, chucks etc.|
|Although for many parts I have used high carbon steel, it's not necessary,
just that's what I had on hand.|
||Headstock - Front view
The body is made from 2 pistons, the top one recessed into the lower one,
then 6 machine screws were used & Loctite all mating surfaces. A
bolt passes through the lower piston, from base plate, to the crown of the
2 springs provide the tension on the pawl; one can be seen just below the
indexer (gear), the other attaches to a slip-ring (a key ring) on the
outer sleeve - just visible at the centre of the gear.
||Headstock - Rear view
2 small machine screws pass through the top of the gudgeon pin sleeves,
locking the mandrel & stopping rotation during milling.
The nose of the mandrel was made to be identical with my lathe -
consequently I'm able to use the lathe's chuck, centres & faceplate.
Note: a compression spring applies adjustable tension to the gear &
hence the mandrel (seen far right).
||Headstock - End view
Shows the outer of the 2 springs between the pawl & the slip-ring.
The surface of the pistons are still a bit grotty as I haven't finished
making my sand-blasting hood yet - it can wait until that's completed.
The gear is a 60T screwcutting change-gear from the lathe. One of my
next jobs will be to make a replacement for the gear, to free this one for the lathe - though it can be removed & used elsewhere in
A 60 T gear allows me to do simple indexing by: 2, 3, 4, 5, 6, 10, 12, 15,
20, 30 & 60 divisions.
The pawl is filed to approximate the shape of the tooth space where it
comes into contact with the gear. This is for positive latching when
||Headstock - Mandrel removed
The order of assembly is: insert mandrel in gudgeon pin hole, put pinned
drive collar on, put gear on, put compression collar on, insert bolt with
spring. Shown laid out in order of assembly, with compression collar
hanging from the pawl by its spring.
||Showing drive pins on the collar, the nose matching the lathe, the
recesses for the lock screws to bear on, the hole for a 'Tommy-bar' is
used for turning the mandrel or removing fittings from the nose.
||Headstock mandrel detail.
Double pins shown about to engage into the mandrel. The single pin
to the left engages with the gear (which also has a single pin fixed into
||The base is 12mm thick aluminium plate. The central hex. bolt
passes all the way through to the crown of the top piston. The six
countersunk machine screws pass into the crown of the lower piston.
The quill of the tailstock is high carbon steel (a large high tensile
bolt), the tip of the centre is hardened to reduce wear in use.
Threaded rod & a special (knurled) nut are used to adjust the
tailstock. The threaded rod is installed in a tapped hole &
fixed with a lock washer & lock nut.
The lock nuts for the quill are visible on the top of the piston (where a
gudgeon pin would pass through).
||Tailstock quill adjustment.
The adjuster nut is high carbon steel (& I didn't want to try knurling
that on my lathe), so I made an aluminium collar which I pressed onto it (the
aluminium being easily knurled) - A small amount of 'doubling' of the
knurl is visible due to the circumference of the piece not being an exact
multiple of the pitch of the knurls - not being a perfect knurl isn't of significance to me though.
The nut is an easy between centres job on the lathe. The threaded
rod & nut, are 3/8" Whitworth (just what I found in my scrap box).
The groove in the quill is milled at 0.25" deep & is 0.25"
wide, the nut was machined to fit this with a clearance of about
||Tailstock quill adjustment - Separated
The aluminium collar is clearly visible here. The collar is a press
fit on the steel adjuster nut.
If you don't recognise the origin of the aluminium collar, it is part
of the video heads from a VCR, hence all the holes.
The underside of the quill is shown. The next photo shows the
upper surface of the quill.
||Tailstock quill, adjuster, alternate tips.
The alternate tips are made to slip over the tailstock centre & accept
a pointed end from any item being milled. They have a taper
internally that matches the taper of the centre.
Note the keyway milled into the quill. This stops the quill from
rotating & permits sliding & locking with the thumbscrews, without
damage to the shaft where it comes into contact with them in the gudgeon