Attach Rotary Table Vertically to Mini-Lathe?

That won't do because there is no way to feed the work into the chucked drill without loosening the clamp and losing rigidity. You either have to mount a fixed workholder to the (movable) carriage, or have a motion component on the workholder itself.

Then the description is very misleading. Can't very well cut splines.

Attaching to the carriage bed would seem to be simplest method;

I don't believe he has enough height between carriage and spindle, even stripped down.

I already addressed that, saying that there is about a 0.15 inch height difference, which would be the minimum bolt circle radius.

Suppose he could, depending on what his definition of "perfectly spaced apart" is. It might not be the same as yours, or mine. Depending on how large the holes are (i.e. how close together they are), you might easily see the half-degree difference.

John Martin

I haven't run these mini lathes, only the Sherline, Prazi and Craftsman, so I don't really know what the ways look like and gave only a general approach to fitting a plate to them. The milling attachment I made for my 6" Craftsman lathe fitted onto the saddle dovetail but it was done on a Bridgeport.

The usual way to bore offset holes on a lathe is to clamp the part to the faceplate using some sort of alignment fixture, or center punch marks placed by geometric layout techniques. Are the wheels are too large for this?

You could attach a slotted angle plate to the base I suggested and use the lathe like a drill press, although a real drill press is better. The base could be held down at the edges the same way the saddle is.

The obvious answer is to buy a mini mill. See how much trouble milling on a lathe can be?

jw

I appreciate everyone's comments and help. Unfortunately, this discussion has gotten too in-depth/complicated for my level of skill. Using the word "hobbiest" was misleading because when I meant "hobbiest", I meant scale models, not machining.

While I understand some of the suggestions here about creating some kind of attachment for the lathe bed, then mounting the indexer to it,

- it results in a catch-22. In order to create this attachment, I would need a mill. Since I don't have a mill, I can't create the attachment. If I had a mill, I would just go out and purchase a rotary table and be done with it.

Thanks for all your suggestions. What I have learned from this discussion is that there is no easy way to attach a rotary table to a lathe. Guess I better find a plan B.

Thanks,

Kyle

I was suggesting you simply mount the spin indexer to the carriage. This only requires hand drilling.

Rex B wrote: ...

An earlier post ref'ed a webpage with Robert Bastow's comments on ball-bearing-based divisions. He said the 20 millionths tolerance of standard bearings was way too much, and the proper thing to do is make precision toolmaker's buttons. Anyhow, the idea is to capture a ring of n buttons between an inner cylinder and an outer ring, all parts made to high accuracy.[1] It immediately occurred to me that cylinder diameter is non-critical if we use two rows of balls, rather than one. For example, rather than making an inner cylinder of diameter .652382" and putting 7 .500000" balls around it and a 2.404286" ID ring around that, put 7 .5000" bearings around a 1" cylinder, then a ring of 7 more .5000" bearings around that, and then a ring clamp outside to hold it all together. This could be used to make a first- generation index plate, which then could be used with a rotary table to make a more-accurate plate, as he suggested elsewhere in that page.

-jiw

[1] For n balls of radius b and inner cylinder radius r, let angle g = pi/n radians = 180/n degrees. Then b=(r+b)*sin(g) and r=b*k with k=(1-sin(g))/sin(g). For one row of balls, ring radius p = b+r. For two rows and exact fit, p = b + h + s where h = b sqrt(3) and s = sqrt(r^2+2*r*b). Eg, for n=7 and b=.25, sin g =.4339, k=1.3048, r=.3262, h=.4330, s=.5191, p=1.2021.