I would like to make a headstock center for my SB 10L but lacking a taper attachment, I don't think I can get the taper right without off-setting the centers and working between centers. Would it make sense to grind a taper on a piece of bar stock held in a collet and use that as a center?
A better bet would be to simply purchase a hardinge center that is designed to fit into the 5C socket of the machine. Basically a solid plug chuck (collet) that has a 60 degree center machined on the outboard end. These are very common and inexpensive, as almost nobody does work between centers anymore. Check on ebay. If you cannot find one, give me a shout off list.
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The normal procedure is to use a face plate that has a slot in it. The dog's tongue goes into the slot.
I don't understand, though. Is there something special about the SB-10L -- that it does not have a morse taper in the spindle? I would think it has an MT3 or 4.5 or something like that. In which case, you just need an adapter sleeve.
I'll keep checking, I couldn't find anything current or in completed items. It does look like a lot more work to set up between centers, but without a taper attachment, which costs about half as much as my whole lathe did, it looks like the only way I have a prayer of doing accurate tapers with shallow angles.
Nothing special about the 10L. You can get a drive plate for one (2 1/4 x 8 spindle, usually). I was just curious how one would drive the work with a
5C center like Jim talked about. Normally the drive dog's tongue fits into the slot on the drive plate, which provides rotational force. With a straight shank center gripped in a jaw chuck the drive dog rests against the side of one of the chuck jaws (though I don't know if I'd recommend that, not knowing how much side force a chuck's jaws can take) I just wanted to know how that would be achieved with a 5C center. My guess would be a set up like you often see on dividing heads where you have a "fork" for lack of a better term, which mounts to (or is integral to, I'm not sure) the head stock center, and the drive dog's tongue fits into the fork.
Since we're on the subject, does anyone know what taper a 10L's spindle takes? I think it's a MT-4, but I'm not sure. I suppose I could just measure the collet adapter.
So, that 0.6023" per 12" seemed like a "funny" number, to me anyway. Not being a math wiz, I AutoCAD'ed it. Turns out that's a 3 degree included angle. So I guess it's not such a "funny" number after all.
But what is the "gage line" Scott. I'm assuming it's the fat end of the taper, and in the case of an internal, it is the "free end" so to speak. Is that correct?
The gauge line is the point at the big end of the socket. The taper normally extends beyond this point, so if you measured at the big end, it would be larger than the gauge line diameter. Some hardened centers have a groove at the gauge line, so you can see whether the Morse taper socket in the spindle has been reamed out too large. The same with a male Morse taper gauge.
As for the fitting of a dog driver plate with the 5C adaptor, I think that it can be done with my 12x24" Clausing (with an L-00 spindle). The main question is whether it could be used to back the spindle adaptor back out once it is installed. This is normally a secondary function of the nose protector which goes on the spindle before the adaptor goes in.
As was pointed out elsewhere, your calculations were off a bit, but the number actually makes a lot of sense if you think about the history a bit.
South Bend was building the smaller, 10-K before the larger 10-L and other lathes. Those smaller lathes used a #3 Morse Taper in the spindle.
When they developed the larger lathes, they used the same rate of taper, just made it larger to accommodate the larger spindle bore which allowed for the use of 5-C collets.
Tooling and fixturing was much simpler, since all they needed to do was to "move the fixture out" as it were. The grinders could remain set for the same angle, just adjusted to a larger diameter.
When referring to tapered bores and adapters, a "Gage Line" is generally the large end of the internal taper, i.e. the diameter at the very front of the tapered bore.
On an adapter or tool to fit into the taper, it is the point at which the adapter's diameter matches the gage line of the bore. Keep in mind that this is usually NOT the largest diameter of the adapter or tool. The taper generally continues larger, beyond the gage line diameter.
These are somewhat theoretical dimensions, however, since it is almost impossible to measure this point directly, especially in the bore. Also, the tolerance does not usually have to be held too close, as far as diameter. In this case, a variation of 0.005" in diameter of the gage line, would mean a change of 0.0007" in axial position.
The rate of taper is VERY closely held, and the tolerances are a little more complicated than I care to get into here and now.
While on the subject of tapers, I have a listing of many of the more common ones at