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Locking toolroom lathe spindles?

jbifs

Aluminum
Joined
Sep 16, 2015
I am tossing the idea of taking our 2015 and make it capable of broaching internal keyways. I can orient the spindle, but obviously theres way too much play. I have heard of people locking their spindles, but how?

I want to be able to orient the spindle, as I want to be capable of orienting off a feature or doing multiple keyways accurately.

Since I made a spider for the rear of the spindle, I was thinking of making a sort of adjusting cradle to be mounted below the chuck, near the bed. Once you orient, you can screw the cradle up tight against the chuck. It would be out of the way and it wouldn't interfere with regular running. Only thing I would question is the upward pressure. Granted it would probably take a lot of pressure to move the chuck/adapter plate out of alignment, but i'd feel better clamping from both sides.

Material to be broached will mainly be 1018 and 1045. Stainless would be done elsewhere. Keyways from 1/4"-1/2". From 1" to 4" deep


thanks,
Josh
 
I definitely wouldn't apply force laterally against my bearings. They are not designed to take that load while stopped. All of the force will be transferred to a couple of rollers/balls which is not good for the races to say the least. I have a C axis and live tooling and it has a disk brake just like a car so the bearings aren't absorbing any additional radial load. You could make one yourself or perhaps If you made a split collar to fit behind/around the chuck and mounted a plate with a couple tapped holes to the the panel behind it you could slap the collar around the chuck or neck behind (not sure how far out the chuck sits). Tighten the collar around the neck or check with two SHCS then put one SHCS through the collar into the tapped plate behind it to lock the collar. Just picture a standard split collar with an arm sticking out from the side. Through hole on the arm and something to put a screw through the arm and tighten to a tapped hole on a fixed location on the wall behind the chuck.

Definitively more work but a lot less work than changing the spindle because the bearings are destroyed from static load at rest.
 
Use a m code to open/close an air cylinder,
1. A simple one sided drum break against the chuck OD (bearings should have no issue. Think large surface area, big pad/ low pressure vs small pad /large pressure) you just need to resist a small amount of rotational force ( if any)
2. Add a disk break to the set up or the front or back spindle mount.

A disk break setup off the rear would be sweet.

How many parts do you need to make?
I've done some interesting things for 1off parts
 
All I can imagine is for one of these home made devices to accidentally be left on/locked or whatever...
:eek:

edit: Have you tried just using the M19? You can't orient the part to a specific C angle unless the lathe is so equipped, but the M19 will "lock" the spindle. I would think it would be sufficient for broaching as you are only taking light cuts anyways..?
Keyway Broach Set Tools for CNC Lathe and Mill Broaching
 
Which lathe do you have? I am confident our TL1 would not have the Z axis thrust required to broach a key way. I have successfully broached small hexes but have to peck to make it work. I would find d out the thrust needed, from the broach manufacture and see if you have enough.
 








 
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