Questions regarding keyed and threaded spindle for Hardinge dividing head?

I'd like to buy a Hardinge dividing head. I've noticed the spindles on some are threaded to accept a threaded chuck. Others accept a keyed chuck. I assume the internal taper for both is 5C?

For the keyed spindle, is the spindle and key unique to Hardinge? In other words, do you have to find a Hardinge keyed chuck to fit a Hardinge keyed spindle? I would assume the spindle is not anything particularly unique, but thought I would ask.

Also, for the threaded spindles, can someone tell me the pitch and diameter of the spindle?

The keyed spindle is unique to hardinge, dont think anyone else used it. Though pretty sure I have seen a few sources for backplates to fit it other then hardinge. The threaded are 2 3/16-10 as memory serves. Has a shoulder on it after the thread.

My Hardinge Dividing Head has the Hardinge Taper w/key.
The ID is for 5C collets with no adapter needed.
spaeth

The Hardinge tapered spindle can be found on the Taiwan copies of Hardinge lathes and on Dunham speed lathes. At one time, most of the major chuck makers would provide either taper or threaded adapters for the Hardinge spindles. Right now, I think Hardinge (Buck) and Pratt Burnerd may be the only sources. The prices are quite high.

For decades, Hardinge made lathes in several spindle sizes, so there were tapered and threaded spindles in several sizes, along with the mating chucks and adapters. The 5C size is the only one in current production, but there are a very few antiques around in the various sizes, including 5C. Franklin Hardinge applied for a patent on the tapered spindle nose in 1904. He did not mention a threaded option in his pre-1930 catalogs, but did make some. Later, the two choices were mentioned in print.

When shopping for a Hardinge dividing head, be aware that they were made with and without an input drive shaft for spiral milling. You already noted the two spindle types, so that makes four distinct models. All of them came with a two-piece collet draw bar that allows the head to tilt to full vertical. Those draw bars are usually missing and are very hard to find.

The heads also came with a tailstock with serial number that matched the head, again often missing, though easier to find on eBay if you overlook the serial number feature. There is also a solid 5C collet with hard 60 degree center and unbalanced dog driver with two set screws (and a mating dog) that can be used with the tailstock. These are also usually missing and sometimes turn up on eBay.

Of course the full set of dividing plates is also usually not included. The Hardinge dividing head internal gearing is 4:1 instead of the B&S standard of 40:1.

Larry

Thank you all for the comments. Very helpful. Larry, I sent you a PM if you don't mind.

I had another question about Hardinge dividing heads please.

So today I looked at one for sale. I measured the runout, which was essentially zero. I could maybe barely see the needle move. The indicator measures 4 tenths for each mark and it never left the mark. So I'm guessing runout was maybe a tenth at the most. I checked the radial play and couldn't get the indicator to move. I checked the thrust play. Again no movement.

I placed the indicator probe in the keyway of the outside of the spindle and checked the backlash. I couldn't really detect any backlash. In fact, the gears were so tight, you could feel each gear mesh as you slowly turned the crank.

My question is a subjective one. Do any of you know if it is very common for tolerances to be this tight on old Hardinge dividing heads? Or is it more common to have some slop in them?

I didn't end up buying the one I looked at because it was really expensive, but I was curious how well they hold these tight tolerances over time. Any of you folks checked a well used Hardinge dividing head for tolerances?