Indexing Head
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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 upper piston.
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 seconds.
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 positioning.
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 it.
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.
Tailstock
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 0.010".
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 pin bearings.