[deadlykitten]

hello control for collet chucks ( please check attached ):
... craft the green piece, basically a solid collet + arbor
... mark the chuck, then insert it in the chuck , then manual rotate it : is needed to see contact loss towards the botoom, towards the small diameters, thus to make sure that main contact occurs near chuck face
... check that orange distance, to be minimal, not only for this green part, but also when mounting collets; if it is too small, then recut the chuck face
... clamp the green piece, and check tir near and far, if it is not ok, then chuck cone has to be refreshed

long term use of -1 range collets and solid nut, leads to wear, because of
... twist :
...... more pronounced wear : between collet small taper and nut
...... less pronounced wear : between collet long taper and chuck, especially towards the chuck face, because original product is designed to make contact towards the face; if this area gets wear, then tir will appear
... drag : like besides twist, the collet had a tendency to scracth the ( slide in ) chuck inside cone, longitudanlly

when h7 range collets, and bearing nuts are used :
... twist does not occur
... drag occurs, but is minimized
* wear manifests later, for both chuck & collet

for same force aplied, a collet with more grooves will deformate more than a collet with less groves, so they will stick diferently to the chuck, thus when reversing the nut, to unmount them, the collet with more groves will be easier to pull out; as a side note, the collet with bigger range, has to be softer than a collet for h7 range, otherwise it will break into pieces; as a consequence, the collets with less groves and less range ( thus precision collets ) make stronger contact with the chuck, so if they are tighetened with a normal nut, then, they won't rotate inside the chuck as much as a many grooves collet does, and this means that during the last few turns of the nut ( or the last 1/2 turn ), the collet being static, wear will appear in the contact area with the nut

thus is better to use a static nut on a high range collet, instead of a precision collet, or you'll scracth those precision collets too fast, but those may still work, as long as the nut won't be able to tilt them inside the chuck cone; a precision collet is harder to tilt, while a big range collet is easier, being less resistive

---

as for threads, precision assemblies, are designed to rotate and fix after a predefined number of turns, preferably minimal; if the number of turns is bigger, then the nut will have the tendency to still rotate for a bit too long, after the collet has allready being fixed in the position; this means that, if someone is stronger, he will torque that nut for too much, while, with a precision assembly, he won't be able to torque it any futher, because it allready blocked mechanically

this type of precision is not comonly found in er systems, but more in gang systems, for collet chuck spindles, that fix/blocks after a small amount of turns; but is one reason why some quality collet vendors recomand their chucks and nuts, so to achieve minimal tirr,

as a conclusion, in the end, you may trust the vendor/dealer as he sais that he has quality, or better have in house control/methods; i mean reliable methods, proven, because, for example, simply a dial inside the chuck does not mean that the chuck runs true; you have to tram it somehow; best quality methods do not evolve from final inspection of random products, but from knowing how to craft them tight, in repetitive manner / kindly

[gimpo]

simply a dial inside the chuck does not mean that the chuck runs true; you have to tram it somehow;

Oh yes indeed, it is true.
if you have perfect circle the cone is squared. Otherwise you would get an ellipse (an angled planar section of a cone) and your dial indicator would reveal it.

[deadlykitten]

hy gimpo that's right in theory, but in reality, the indicator in only one place, may not reveal that a part is tilted

may sound weird, but in the end, is a L/D ratio thing related, and that's the reason why, when grinding for example, is needed to dial the od(or id) + a face ( if is not possible to dial a face, then there may still be variants )

if you dial only the diameter, and the dial looks ok, this does not mean that the face is also ok

going back to collet chucks, during their manufacture, is possible to deliver them without making the face square/true with the inside, and a consequence, is that later on, for example when it reaches the client, it can be tricky to check the chuck condition

---

take a cad you like, take a cilinder, and intersect it with a plane : result will be a circle; if you tilt the plane only a bit, the result is an ellipse, but in reality, you can not detect that ellipse, unless it is far away from a circle enough, so that the dial will detect it; thus the real moment when your dial shows an ellipse, is when you part is tilted too much, like out of spec

same happens also with a cone : when plane is perpendicular, intersection is a circle, while in reality, at the moment you will detect an ellipse, the cone will be tilted too much

[gimpo]

take a cad you like, take a cilinder, and intersect it with a plane : result will be a circle; if you tilt the plane only a bit, the result is an ellipse, but in reality, you can not detect that ellipse, unless it is far away from a circle enough, so that the dial will detect it; thus the real moment when your dial shows an ellipse, is when you part is tilted too much, like out of spec

same happens also with a cone : when plane is perpendicular, intersection is a circle, while in reality, at the moment you will detect an ellipse, the cone will be tilted too much

Got it.

Actually, I measured for circularity inside the cone at three different height from the lower border of the spindle chuck (+2, + 6, +10 mm) but I understand it makes no big differences...

So, in the end, the only way to have a chuck and collet correctly coupled is to have the internal surface of the chuck and the tapered surface of the collet "highly" parallel. In such way, when you insert the collet into the chuck is very rare to get them misaligned.
I'm right?

If the chuck of the spindle is tilted, then I think I cannot do anything about it. I'm right?
How I can verify that? (Just for my personal curiosity).
I was thinking to mount a long "axis" on my "precision collet" (will it be delivered to me). Unfortunately the toolbits I use are too short for that check (max 60 mm). I would need something 100 mm long as minimum.

I can find a lot of cyclindrical axis on ebay, unfortunately their circularity is guaranteed, their straightness is quite crappy instead (I have some of them, and they are slightly curved like a banana along their longitudinal axis).

[deadlykitten]

circularity inside the cone at three different heigh ... I understand it makes no big differences

even if you measure at 3 different locations, and :
... have equal values, all amost 0, it does not mean that the chuck is ok, or not
... have different values, it may show wear, etc
* once you get into alignments, simply have to check few different things, and once one is out of chart, you will have your answer

So, in the end, the only way to have a chuck and collet correctly coupled is to have the internal surface of the chuck and the tapered surface of the collet "highly" parallel. In such way, when you insert the collet into the chuck is very rare to get them misaligned.
I'm right?

if the tapered contact, between chuck and collet, occurs ok, it means that the cone of the chuck, and the cone of the collet, both, are coaxial; let's call this the "main axis"

how a collet is designed to have true id to it's cone, it means futher more, that if you clamp inside a tool, that tool axis will be almost coaxial to the "main axis" as long as clamping process remains true, thus the collet does perform well, etc

if all is fine, then the tool/shank axis will be coaxial with the "main axis"

If the chuck of the spindle is tilted ... How I can verify that? (Just for my personal curiosity).

having your router in good condition, means that the "main axis" must be coaxial also with the spindle axis, and perpendicular to the table

... your story, with the cyclindrical axis; jog z axis, and dial the cilinder, among 2 lines, located at 90* phase difference; like once the dial has to be among x, then among y + tir check
... google "tramming a mill" or a router

slightly curved like a banana along their longitudinal axis

bananas have only longitudinal axis

[gimpo]

... your story, with the cyclindrical axis; jog z axis, and dial the cilinder, among 2 lines, located at 90* phase difference; like once the dial has to be among x, then among y + tir check
... google "tramming a mill" or a router

I know how to tram a spindle. Thanks. I'm not interested in that.
Your indications does not show if the cone of the chuck is tilted. They are a check for perpendicularity. That's a different stuff.

bananas have only longitudinal axis

This does not respond to my question.
Do you have any suggestion of what I could buy to have straight reference on the spindle axis?
A broken tool fitted in the collet? (But their are usually too short.)

[deadlykitten]

If the chuck of the spindle is tilted, then I think I cannot do anything about it. I'm right?

I know how to tram a spindle. Thanks. I'm not interested in that.
Your indications does not show if the cone of the chuck is tilted.

okey ... you wish to check tiltness in respect to what ? titness does not exist without a reference

you reffer to the chuck cone, as not being true to shaft axis ? thus the cone to wobble in respect to ... ? please develop a bit ... i can't see