Possible to make a qctp "indexing?

[754]

In my post below, can you see why mine would index fairly accurately ?

[Paul Alciatore]

I have a perhaps better way for setting a (any?) tool post to an angle. After mounting it to a desired angle, just scribe a line on the top of the compound along the edge of the tool post. And use a number stamp set to record the angle of that line. Clean up the top surface with a flat stone after doing that. That line will be more accurate than the detent shown in the YouTube video and since you have to loosen the tool post on the compound anyway, you will lose nothing else by doing that.

I put a question mark after the word "any" above because that scribed line would not work with my QC tool post which has a circular base, not a rectangular one.

[754]

If you are going to go through all the pain of accurately positioning tools on a 4 way for some given set of dimensions
and you get jacked up on center height, shims, tool grind, and you want production,,,,,,,,
Get a DRO, loose the compound, and pre-set all your toolholders with X and Z coordinates in the DRO.
Want to jiggle jack around or make some money with your lathe ? If you don't want to make money
then none of this matters.

--Doozer

Let me know how you make these brass pieces and the body and fins of the rocket... without shims, setting tool height, tool grinding or jiggle jack... cuz I need to know
I mean on a manual lathe ..

[Paul Alciatore]

J, what you say about changing tools or parts may be true for most QC tool posts, but it is most definitely not true for my QC tool post. With it the tool holder (and tool) is changed with ONE HAND and in a SINGLE MOTION. Grab the clamp screw handle and twist CCW while moving UP. The tool holder is off: about one second. Grab the new tool holder again by the clamp screw and move DOWN onto the post while twisting the nut handle CW to tighten it. The new tool holder is ON: again about one second. No tools or searching for one. And your left hand is available for a sip of coffee while doing the change; well, that will probably take longer then the tool change.

That is what I call a quick change tool holder. The emphasis is on QUICK. And there is absolutely no loss in positional accuracy. The new tool goes on in exactly the same position as it was when last removed. And yes, I am talking tenths.



On top of that, it is about as sturdy as a tool post can get.

But it does not index to multiple angles and I see no simple way to add that. In reality, I don't want to add it. As I already said, I just grind the needed angles into the tool itself. That's easy enough with the bench grinder.

Really fast tool change, accurate, rock solid, and relatively inexpensive. Of course you must make it. On the plus side, it is easily scalable for larger or smaller lathes.

Original Article:
Quick-change Tool Post, Feb-Mar 2010 Machinist's Workshop
https://secure.villagepress.com/stor...oup/319/page/4

Free Download of later version:
https://www.dropbox.com/s/dxj9jv20ji7043z/QCToolPostRc.doc?dl=0

Latest version:
https://www.homemadetools.net/forum/...st-lathe-52118

It seems that the multifix is no big advantage. To actually move the tool, you have to unclamp, pull out the holder, find the position (among many) that you actually want, replace the tollholder, and re-clamp.

For indexing, unclamp, turn the toolholder, reclamp.

As for the advantage, ot starts with simple things like doing a chamfer. Those are often at standard angles like 45 deg, which are commonly part of the indexing system. And, they are typically not large, so are practical to do with the side of the cutter. Unclamp, turn to position, reclamp, touch off for the chamfer, unclamp, turn holder back, reclamp.

Even for the Multifix, let alone changing tools for the Aloris, there are many more actions ("Therbligs" for you time and motion folks) taking more time. For the Aloris tool change, you unclamp, remove the holder, find a place, transport and set it down, find the holder you want, pick it up, transport it, put it on the post, and reclamp. It is FAR faster than replacing the actual tool tool in the post, but involves a lot more actions that unclamping, turning, and reclamping, which requires no extra selecting, along with zero in the way of "transport" actions.

If you know your sequence of tools, it seems likely that indexing the toolpost to the next tool, or position, is faster than all that is involved with replacing the holder even with a QCTP.

[Bented]

I said it before and I will say it again; I do not think an indexing tool post made with a detent ball is a usable device.

Many lathe tool turrets use Hirth Couplings for indexing between tools, these are very accurate.

https://www.techna-tool.com/techna-hirth-gears/

[Paul Alciatore]

Another thing that is going without comment here is chips. Chips can get on the tool post, the tool holders, the part, or a collet or chuck that the part is held in. So if you change the part or the tool, you usually must be looking out for chips and possibly take the time to wipe something to remove them. My tool post design is self cleaning: any chips on the post or holder that may interfere with accuracy will be wiped off when the holder is installed on the post.

Self cleaning!

[Paul Alciatore]

They do look like a much better idea than a detent ball.

Many lathe tool turrets use Hirth Couplings for indexing between tools, these are very accurate.

https://www.techna-tool.com/techna-hirth-gears/

[J Tiers]

J, what you say about changing tools or parts may be true for most QC tool posts, but it is most definitely not true for my QC tool post. With it the tool holder (and tool) is changed with ONE HAND and in a SINGLE MOTION. ......

You still do not escape the fact that you have to take the first one off, transport it, put it one somewhere, find and and grab the new one, transport it back, and finally fit is on. That's still a lot of "Therbligs" (elementary actions in classical time and motion study).

When indexing, it is all one place, unlock, turn, relock.

Also, one big case for indexing is when you need the shank of the tool to point a different direction to reach something, as opposed to merely changing tools.. Changing toolholders is a lot less useful then.

For standard tool changing, there is a reason why turret lathes usually are a decent bit faster than CNC for suitable parts that require several tool changes. The turret rotates in the time the CNC toolchanger is just beginning to think about starting to get the next tool. Watch a youtube of an automatic screw machine working.

[Bented]

A Hirth coupling of sufficient size and accuracy would likely cost far more then the tool post and holders combined, 1 arc second indexing.

This would be a drawback for a home hobbyist (-:

[Bented]

Watch a youtube of an automatic screw machine working.

Modern screw machines do not have turrets as such, nor tool changers in the traditional sense. Keep all of the tools set and rapid them to the part or rapid the part to the tool. Moving between tools is often less then 1 second.

https://www.youtube.com/watch?v=QDTySdxt5oQ

[Paul Alciatore]

J,

I have not studied turret designs in detail but I suspect that they do not use a ball detent for positioning the tool. And the reason why they are faster than most QC tool posts is that most QC tool posts are not well designed for fast tool changes.

You still do not escape the fact that you have to take the first one off, transport it, put it one somewhere, find and and grab the new one, transport it back, and finally fit is on. That's still a lot of "Therbligs" (elementary actions in classical time and motion study).

When indexing, it is all one place, unlock, turn, relock.

Also, one big case for indexing is when you need the shank of the tool to point a different direction to reach something, as opposed to merely changing tools.. Changing toolholders is a lot less useful then.

For standard tool changing, there is a reason why turret lathes usually are a decent bit faster than CNC for suitable parts that require several tool changes. The turret rotates in the time the CNC toolchanger is just beginning to think about starting to get the next tool. Watch a youtube of an automatic screw machine working.

[754]

A few things about turret lathes you may not known
a lot of ops are single handed, like moving the turret, faster than a QC..and one hand.
really long quick travel on the turret.... and chiprupter on some , quickest way to break a long chip I know of.
turret end has powerfeed.
front and back stops on cross slide, some have 2 speed cross slide.
even the 4way can index with one hand on some or at least advance.

I really wonder where my Herbert advancing 4 way went, never ran it on the machine, kept it around but did not see it in the last few moves.. hmmm

[J Tiers]

All "QC" toolposts must have the user seize, remove, transport, place, and release the old toolholder, and do the same set of actions plus an added "locate" and "orient" to put the new one in place. The "unlock" and "lock" are common to both the 4 way and the QCTP, and, for that matter, to some turret machines of the type that are moved by hand, by actual turning.

That is the most on-topic type, as turning the 4 way is similar to hand turning the turret.

Modern screw machines do not have turrets as such, nor tool changers in the traditional sense. Keep all of the tools set and rapid them to the part or rapid the part to the tool. Moving between tools is often less then 1 second.

https://www.youtube.com/watch?v=QDTySdxt5oQ

The tool change in the case of the old mechanical automatic turret machines can be, at a guess, perhaps 100 msec, from "storage" to being in "use position". When you watch the video, the tool change appears to be "instant", the new tool just suddenly appears in position and the tool stroke is in progress.

Both can be quite fast.

Hand screw machines are slower, but the feed lever type need no extra operation to change tools it happens at the full reverse stroke of the lever..

[Doozer]

Let me know how you make these brass pieces and the body and fins of the rocket... without shims, setting tool height, tool grinding or jiggle jack... cuz I need to know
I mean on a manual lathe ..

Wow ! ! ! Super cool Indeed !!!
Hat is off to you.
(I just made up the word Jiggle Jacking Around. I kinda like it

-Doozer

[754]

Not all screw machines can do all that. That video showed a double spindle Swiss type machine, far higher capability than a simple screw machine...... maybe most are like that now ? I Dont know..