Quick Change Tool Post Indexing

[kf2qd]

Chamfering? I just have a block that I can load with a chamfer tool.

[BCRider]

Would you let me put a spring and ball in the bottom end of the stud and then lock the stud in the t-nut? This along with about three detent positions in the bottom of the t-slot?

That would be a safer and probably less annoying option. But how would you get at the pin?

If you used a pair of shorter set screws to lock the T nut in one of the positions you could have the set screws fit down into shallow drill point divots. That would give you the three positions.

[Paul Alciatore]

Starting?

I thought he was leading the pack. And looking back at us with a grin!

Doozer, you're starting to sound like an old curmudgeon.... just like the rest of us

[Paul Alciatore]

YES!

This is still a terrible idea. Even worse and more risky that you're thinking to rely on such a setup for positioning. You're setting yourself up to pop off one or both of your compound's T slot lips.

Take a lesson from why T nuts on milling table clamp sets are not done that way. It's due to how when torquing the nut on the top of the stud can result in more friction in the upper nut than on the T nut. Without the staking the stud can screw through and hit the bottom of the slot and force the T nut upwards and burst the ears of the T slot. This is a very real and fairly commonly found issue in old shool lathes and milling machines. Don't set yourself up to be one of those.

You always want the ears of the T slot to be pinched between the T nut and the bottom of the tool post by means of a captured stud that is solid in the T nut. There must never be a situation where you are pushing the stud down through the T nut and against the bottom of the slot.

It's a grand idea to ensure that the T nut on your tool post cannot move. But you do NOT want to use the center tool post hold down stud to do double duty.

[Paul Alciatore]

When I was designing my QC tool post I took the trouble of reading as much as I could about them and making a list of features that I wanted or, at least thought I might want. The first few at the top of the list included repeatability, solidity, and of course, quick tool changes. In looking at the various designs that people sell and have made in their shops, I came to the conclusion that there was no way that I could afford a quality one and any tool post that I was going to make in my shop was not going to have all of those features. I had to make my own and I had to pick and choose the features that I was going to have in the design and those which I was going to omit.

So I did just that. I choose the features that I thought were the most important to my work and that I had the best chance of making to a degree of accuracy that was going to be acceptable. I knew about the 40 position, Multifix system. Frankly, I never could understand why 40 positions, every 9 degrees. Yes, it included 45 degrees, but, as others have pointed out, omitted the 30 and 60 degree positions. 24 or 48 positions seem to be much better choices because they do include 30, 45, and 60 degree positions. But then, that's me. And there are other, less well known indexing posts.

Another thing that I saw while looking into this was that many people had extensive collections of holders, each with a different tool. I saw photos of collections of 12, 24, 36, and even some of over 50 holders. To me, and this was just me, it seemed to make more sense to forget an indexing feature that was either very expensive or difficult to make and just make more holders so that tools of various types and angles could be immediately available. And, getting back to that QUICK CHANGE thing, which this type of tool post gets it's name from, it seems a lot faster to grab and slap on a holder with a 30 degree tool than to try to figure out which of those 40 or 24 or 48 positions I need to mount a holder with a tool with a (quick calculation: Want 30 degrees / 9, 18, 27 OK that's three notches but 3 degrees short / need a holder with a 3 degree tool / but which way, +3 or -3? / etc.) OK a tool holder with a +3 degree tool.

So I decided that a large number of indexable positions was off my list and designed my QC tool post with just ONE position for the holder to index in. Grab it, Slap it on the post. Tighten the adjustable nut I choose to use. That's about a 3 second, no tools needed holder change. I did make the holders themselves with two positions for installing tools at a 90 degree angle to each other. That does provide some flexibility when mounting the tools in the holders.

And I have holders with turning, facing, chamfering, boring, threading, etc. tools at the ready. In use I have found that I almost never need to change the angle of the tool post.

But that's me. And others may decide on a different mixture of features that they consider to be the best.

What's with all these plans to reposition a "QUICK CHANGE TOOL POST" ? Why not "Quickly Change" tools to one with the desired shape?

[npalen]

That would be a safer and probably less annoying option. But how would you get at the pin?

If you used a pair of shorter set screws to lock the T nut in one of the positions you could have the set screws fit down into shallow drill point divots. That would give you the three positions.

What "pin" are you referring to? The pin in the external quadrant shown by the paper in the original picture? Current plan is to possibly replace that pin with a ball and spring.

How would we get at the setscrews? Have to remove the tool post each time to change position?

With the proposed spring and ball installed in the lower end of the stud, the only thing requiring loosening and tightening would be the nut at the top.
Loosen the nut, slide the toolpost over to another detent and retighten the stud.

I promise that a setscrew will be installed in the t-nut to keep the stud from bottoming in the t-slot. I will even loctite it permanent if that helps and even peen the bottom thread.

Edit: I removed the toolpost again to examine the stud and find that the threads on the bottom end are too short to protrude thru the t-nut, so we are safe.

This type of press-in ball plunger would be easy to install but the threaded type would give some adjustment:

https://www.amazon.com/Plunger-10pcs-Stainless-Spring-5mm6mm/dp/B085RWGQVF/ref=sr_1_6?keywords=ball+spring+plunger&qid=1679232245&sr=8-6

[J Tiers]

....................................

So I decided that a large number of indexable positions was off my list and designed my QC tool post with just ONE position for the holder to index in. Grab it, Slap it on the post. Tighten the adjustable nut I choose to use. That's about a 3 second, no tools needed holder change. I did make the holders themselves with two positions for installing tools at a 90 degree angle to each other. That does provide some flexibility when mounting the tools in the holders.

And I have holders with turning, facing, chamfering, boring, threading, etc. tools at the ready. In use I have found that I almost never need to change the angle of the tool post.

But that's me. And others may decide on a different mixture of features that they consider to be the best.

So............ that seems to be trading an easy post movement for needing a lot of holders. Each tool at all the angles ? That's a lot of holders, even though not all tools need moved..

Sure, if you needed to go get a wrench every time, yeah, but moving a lever, turning the post, and moving the lever back? Not an issue, and any angle you need is available.... you don;t HAVE TO use the detent positions if a different angle is better.

[Doozer]

Starting?

I thought he was leading the pack. And looking back at us with a grin!

Originally posted by BCRider View Post

Doozer, you're starting to sound like an old curmudgeon.... just like the rest of us



I appreciate you noticing me as a leader.
I set my own fashion trends as well.

--Doozer

[Mcgyver]

I set my own fashion trends as well.

--Doozer

No, please, not more of the hair shirt!

[ezduzit]

I'm looking at a way to allow indexing (clocking?) of my QCTP at various angles so that a turning tool, for example, can be easily rotated to a chamfering angle such as 30 or 45 degrees...

A dedicated tool holder with the correct chamfering tool works for me.

A pin sliding in a hole must have clearance. So you lose repeatability. I haven't done this, but it seems that a simple shop-made angle-setting jig (for each angle) would be much simpler and absolutely repeatable.

[J Tiers]

A dedicated tool holder with the correct chamfering tool works for me.

A pin sliding in a hole must have clearance. So you lose repeatability.................

You assume chamfering is tha only usage that is an issue

Pins do not lose ANY centering..................if they are tapered. Think outside the box.

[ezduzit]

...Pins do not lose ANY centering..................if they are tapered...

If they slide in a hole they must have clearance, which equals a loss of repeatability. The taper can only take out the play on one of the mating parts.

[J Tiers]

If they slide in a hole they must have clearance, which equals a loss of repeatability. The taper can only take out the play on one of the mating parts.

You taper ream the hole in both. It cannot "snap-in" then, but that is the trade-off for near-perfect. Outside the box!

[ezduzit]

You taper ream the hole in both. It cannot "snap-in" then, but that is the trade-off for near-perfect. Outside the box!

Good luck getting them apart.

[Lew Hartswick]

I dn't get it. Any time you change the compound, the absolute the angle of this "Thingy" is GONE, so what does a "relative" change mean anyway?? :-(
...lew...