Spindle indexing

[Lone Watie]

Can anyone explain in layman's terms what exactly is spindle indexing on the lathe? Thanks.

 

[Tony Wells]

Used to determine and fix the spindle to a known rotational position, and move in increments in that rotational axis. It would be used with accessories to mark or create features on lathework that was described in terms of angular and radial position. Think sprocket and gear teeth for example. Wrench flats milled on a shaft for another. These would be marked for layout, or machined in place with an accessory milling attachment.

 

[irishwoodsman]

kinda like timeing on a car, you time your lathe to cut a gear at a certain position, say your teeth on a gear is a 1/8 th inch a part by indexing you get a cut every 1/8 inch, i think i said this right

 

[Tony Wells]

No, actually the position is determined by degrees of rotation and the distance from center. The distance of circumferential movement can be calculated, of course, but would be awkward to work with. Typical callout would be say.....4 holes 1/4" diameter equally spaced on a 6.000 bolt circle. This would place the holes 90 degrees apart, and 3.000" from center, or in the case of sprocket teeth, it would be number of teeth on a given diameter. 30 teeth would be 360 deg divided by the 30 would be 12 degrees apart. The circle the holes would be on is a Pitch Diameter for a given sprocket.

 

[irishwoodsman]

ah ok gotcha:thinking:

 

[8ntsane]

Hi Guys

Tony has given a great description. Jims drilling rig is the same basic tool I have. Very handy for cross drilling, or turn it 90 degree,s and drill bolt patterns as well.
Jim also has a good tip there on using the lathe back gears to get certain divisions.
Many lathes are capable of doing this, some are not. My lathe happens be one that can,t. On my lathe, I use a 360 tape with a pointer.These degree tapes can be wrapped around a backing plate, or chuck, or mounted to a disk. Mounting can also be done on the end gear end of the spindle, with a expanding spindle plug with your disc mounted to it. The degreed tape is from a comany called Oregon Rule. These guys have many for different diameters, and also custom sizes can be ordered. Dividing on the lathe can be done quite accuratly once you get used to it.

Paul

 

[Tony Wells]

You could draw up a "degree wheel" and print it out and mount it to a disc or gear that you could see, and use a pointer to arrive at the location. You'd need to rig up a good brake to hold the position. Not as good as positive indexing, but workable for a few things.

 

[Lone Watie]

Thanks for the great explanations - I guess the thing I'm having a hard time processing is the lathe spinning a piece of work, which I'm assuming it is not on certain operations. I know that seems like a silly thought, but just having trouble putting my finger on it.

 

[Tony Wells]

The lathe would not be under power for most of these operations. Think of it as a substitute for an indexer on a mill table. The cutter of choice would be powered by other means and the spindle holding the work stationary. It has probably been done with both the spindle in motion also, but the term "index" usually implies locked in place.

 

[Lone Watie]

Is it akin to a rotary table with a dividing head on a mill? I just learned of this yesterday.

The lathe would not be under power for most of these operations. Think of it as a substitute for an indexer on a mill table. The cutter of choice would be powered by other means and the spindle holding the work stationary. It has probably been done with both the spindle in motion also, but the term "index" usually implies locked in place.