Old Brown and Sharpe Rotary Table Help Please

What I did for my troyke 8” was turn a arbor between centers 3/4 on one side and turn a mt4 taper for the rotary.
Put arbor in machine then leaving rotary table loose align in taper and lock spindle. Then lock down rotary table. I use a 5” 3 jaw ontop the rotary usually but I put a pin in 3jaw. Indicate to your liking and tighten it down.
For a fixture plate just make the center hole a little oversized. Their is no real need for it to be precisely put on rotary table. Everything you mount to the plate will still need to be dialed in if you want it to be accurate.
Align the RT to the spindle lock the x and y. Mount your slab of metal to the table use the rotary to cut your OD. Then plan out your hold down hole pattern and go at it. If you put a sacrificial piece between the two you can cut the center hole too. Should be some good little projects. Good luck.
 
Janderso said:
Bob,
Could you please elaborate on your statement?
I can see some play due to lack of rigidity from the spindle and collet and length of the alignment pin to the table cavity.
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Pushing a skinny, flexible cone into a fixed cone for an accurate fit has multiple problems. The shank flexes as the cones mesh, and it is difficult to see it happening. You have to inspect it critically to see what is going on. There are front to back and side to side issues, and you can only look from one viewpoint at a time. Bottom line, it looks like they are fitting together better than they really are. Same with a dowel pin, but perhaps to a lesser degree. A beefy accurate cylinder, with sharp square corners, dropping into a barely oversize hole, also with sharp square corners, would be the best way to do this kind of test, but then it would take some fooling around for a while to get it to actually drop into the hole...
 
Not saying you don’t know what your looking at. But I would double check or confirm that the bore is not a Morse taper. Being a good quality RT I suspect it is a Morse taper hole. Take some ID measuring top of table,middle,and bottom. I thought mine was a straight bore till I dropped a #4 in the hole and it fit. Then I found the spec sheet on it and confirm it. Just a thought.
 
Cadillac said:
Not saying you don’t know what your looking at. But I would double check or confirm that the bore is not a Morse taper. Being a good quality RT I suspect it is a Morse taper hole. Take some ID measuring top of table,middle,and bottom. I thought mine was a straight bore till I dropped a #4 in the hole and it fit. Then I found the spec sheet on it and confirm it. Just a thought.
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OK, I'll say it, I have no idea what I am doing :).
I assumed it was a hole. I'll check for a taper.
It is still on the shelf. Dang these things are heavy.
Yep, it's a 1.250" hole all the way through.
I think for me, the 3/8 rod will get it close then I will indicate from there.
The spindle mounted Noga holder Bob showed us,IMG_1183[1].JPG is on it's way to my door step.
 
I cut this center pin to a close fit. There are rough threads I could have used, but it is a locating pin, not a hold-down, so I didn't thread the plug. The bottom .750" of the table does have a MT for what it's good for. The pin constrains X and Y, the t-slots constrain Z.
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(from mobile)
 
Cadillac said:
Yeah I would think any quality one would have it to use a center or drive bar. Do you know what size mt it is?
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On my little 6" table the center hole is a MT2. The table is a Kamakura Japan that I'd guess is 40-50 years old. Using it for a center or a drive hole is the the list of uses I could come up with for it in its entirety. With a lathe on hand, it's short work to turn any type of arbor one could need to accomplish an operation with the RT, which is pretty neat. It's an important capability for manual work on the mill. Edit: The hold down studs and hardware were under $20 from McMaster.
 
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