I'm trying to identify this spindle fitting, which is on a Denford Orac lathe. The Denford forums and other Orac-related groups don't have any information on it at all.
Its a short taper, with the chuck backplate fastened into place with three studs.
Quick and dirty dimensions:
- OD: 78.4mm
- BCD: 59.2mm
- Large diameter of taper: 41.1mm
- Small diameter of taper: 39.7mm
- Depth of taper: 7mm
- Mounting studs: M8
- Spindle taper: MT3
- Spindle bore: 20mm
I've included a couple of pics with my calipers for scale. The measurements, especially of the taper itself, are clearly not accurate enough to get any idea of the taper angle which I'd expect to be more like the 7 degrees, 7', 30" angle of US/BS/ISO short tapers if I'd measured it correctly.
My best guess is that its an old US or possibly even BS/ISO A2 short taper, but it is too small to match any of the dimensions I've been able to find anywhere online. Possibly it is a 2"-size, and all the spec sheets start at 3"... I've heard a few people talk about D1-2 spindles for which I've found no published information, so perhaps other tapers existed in the same size.
There are a couple of official standards documents floating around (BS4442 Part 1 and I.S.O. R702 Part 1) but they're not cheap (£50-80) and may not even include this taper so I'd rather not throw away that money and hope for the best.
Any bright ideas? I guess I might have to try measuring it up more accurately and trying to machine my own backplate, but I'm not yet confident in my abilities to make an accurate backplate, even with CNC!