Needing Ideas For Index Pin Block

[npalen]

I drilled holes as shown in the chuck backplate a while back planning to add a block to the side of the headstock for the locating pin. Having trouble deciding what the pin block should look like and probably just trying to make it too complicated. Would be nice, though, to either make it removable or flip out of the way to be less intrusive.

The holes are spaced 15 degrees and probably will add a couple "vernier" holes to the block to get it down to 5 degree increments. The ring of holes is about 1-3/4" from the headstock sidewall. The vertical line is an interior rib of the casting that I can straddle with mounting bolts for which I will drill and tap

Any ideas are appreciated.

[Stu]

You could mount a low profile dovetail bracket to the headstock and make the pin block to slide down onto it

[old mart]

I would see if something like a saddle stop which fixes to the bed with a hinged arm with a locating pin at the end might work. Maybe it could have a double life as a saddle stop with a removable arm for indexing.

[npalen]

I'm liking these ideas. I'm planning to use a threaded and tapered pin to engage the hole positions in the backing plate and lock the chuck in place for grinding or light drilling apps. Been thinking about methods to get precise alignment location for the tapered pin.

[Toolguy]

I would make whatever you do, arranged so the pin is vertical, or nearly so. That way, any vibrations during the working operations will make the pin remain seated, rather than working it's way out as it would in a horizontal position.

[npalen]

Could use some more ideas, guys. I'm sure that after I build this project, there will be all kinds of "ideas" forthcoming.

[ChazzC]

Whatever form factor, use shallow taper pins and holes to more accurately locate? I know, now you’ve got to get more tools and rework the holes you’ve already made.

[npalen]

More tools!!!! Awesome!

[dalee100]

I would drill and tap something into the headstock to rigidly mount the the pin. Or if you want something more easily removable, you could design something to clamp to the bed when you want to use it. Most setups I've seen are done from the back of the headstock with plates clamped to the spindle tube. But that can depend on how easy it is to access the rear of the machine. Not all lathes have an easy open door.

My one recommendation is that the pin should be spring loaded to keep it solidly engaged. Then you can mount it in any orientation you want.

If you want to see some good implementations for indexing on a lathe, checkout what mini-lathe owners do for ideas. Or google up indexing on a 9x20 lathe. If something can be done to mod a metal lathe, somewhere someone with a 9x20 lathe has done it....I swear those 9x20 lathes are must be the most popular HSM metal lathe across the planet.

[Reed]

This is the pin arrangement that I made for the handle to do indexing. The handle is for a home built 5c collet closure. While it is on the back cover, certainly would be adaptable to the chuck side.



The mounting holes also is used for the degree plate's Vernier and clamp.

Geesh, the editing is weird 😐, so I'm figuring you get the idea.
- Reed

[npalen]

Current design progress. Thanks again to Stu for suggesting the dovetail idea for easily removing the device when not needed. I use the AXA QCTP so the holder shown is "stock". May need to add two more hole positions in the pin block to allow for indexing the spindle on five degree increments. The mounting arrangement will have a couple degrees of freedom for initial alignment of the pin with the holes in the index wheel.

[I make chips]

Reed, that wheel is pretty slick!

[Paul Alciatore]

I am reading this thread closely because I have a similar row of holes on my three jaw chuck back plate. So far I have a rather simple arrangement which attaches to my 2" DI which is mounted on the bed for longitudinal measure. But my ultimate intention was to have, not one, but several Vernier blocks. I chose 60 holes because that number provides a large number of possible divisions: 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60. It also provides a nice selection of prime numbers for greater utility of the Vernier blocks. You do know that dividing into equal parts is all about prime numbers. A ten part Vernier will give me one degree increments.

I avoided the the working loose problem by adding a small, retaining thread at the bottom of each hole and threading the tip of the pin. My holes were reamed with a straight reamer when I drilled them to provide accuracy. I did not feel that I could drill and then ream a taper into all those holes with any degree of consistency.

I would make whatever you do, arranged so the pin is vertical, or nearly so. That way, any vibrations during the working operations will make the pin remain seated, rather than working it's way out as it would in a horizontal position.

[npalen]

The locating pin I'm planning on using will be threaded at the rear and then a close fitting portion to engage a reamed hole in the block as shown. The end of the pin will be shaped very much like a center drill to provide reasonably accurate indexing but not super accurate indexing.

[sarge41]

Keep in mind that the larger the index plate, the greater the accuracy.

Sarge41