[Goemon]

You can get .0002" collets for $16 to $20 and quality EMT nuts for $40 so not sure why or where you get $50 to $100 from.

This is CNC stuff - there is always someone waiting to charge you 3x what something is worth... E.g.

ebay.com/itm/283425897391?hash=item41fd7ffbaf:g:06QAAOSwMhVhV0J 2

Or

https://www.ebay.com/itm/19413473241...cAAOSwTj9god1N

And ER25 collets also come in a broad range with sellers describing their expensive ones as "premium" or "high torque" etc:

https://www.ebay.com/itm/31365074099...4AAOSwOM5hJpbZ

I'm certainly not looking to spend more than I need to. I've just been noticing some inconsistency in how certain collets fit.

For example, I have three 1/4" ER25 collets and two nuts (one bearing, one regular). One of the collets is too big for half my 1/4" end mills. One is too tight to fit half of them in one of my collet nuts. The 3rd one mostly works in both nuts but it's not always a tight as I'd like.

I've noticed that if the fit is wrong then it results in excess noise and an inferior finish. When I use one that fits well it's silent (as in no noise is added above regular spindle noise) and I get a nice mirror finish.

I'm just not sure If the inconsistency is solved with the "premium" collets and nuts or if it's normal to need a selection in each size to account for inconsistent end mills.

[deadlykitten]

hello again

One of the collets is too big for half my 1/4" end mills.

check upper play; for example, a 6mm collet, should have it's bore >6mm, but less than 6 +0.015eq; if your colett is too big, then simply don't use it

One is too tight to fit half of them in one of my collet nuts. The 3rd one mostly works in both nuts

hold the nut in your palm, then insert the collet into it; flip it 180* degrees, by holding only the nut : the collet must fall, just because of gravity; if this doesn't happen, then extra useless force is required each time you mount a tool; you can machine the nuts, in order to increase this play

but it's not always as tight as I'd like

this is mostly because of the play between collet thread and nut thread; a smaller play gives more confidence, while a bigger play makes it feel loose, even if you tighten it

---

you can go on a spree, and buy whatever stuff you wish to buy

here are a few recomandations :
... check all collets bore, to be within spec
... check contact between collets and chuck, again, to be towards the bigger diameter, and for at least circa 80% of collet's taper length
... make sure that you use collets designed for h7 clamping range, otherwise, the bigger the range, the greater the overhang, as collets face won't be as close to the chuck
... for small collets, or for big collets that clamp small tools, is better to have more grooves, since less grooves means that the collet is more rigid, thus, when you tighten it, less force will be transmited to the clamp area; the more grooves, the more elastic the collet is, thus it will transmit more force towards the inside
... check the collet chucks:
...... check their threads, and find out their tolerances; you may craft incremenal threads, that you use as a gauge for your chucks, then you may decide to machine one nut size to fit them all, or, for example, only for whatever chuck, to machine a nut that is more special; thus machine your own nuts, adjusting their specs to your chucks; off course, bearing types are a bit more difficult to machine ( it may be possible to replace with a normal nut and a thrust washer, as being said by mactec a while ago, but so far i didn't acualy have experience with this; still, it sounds promising ); if you buy a bearing type, you may have the surprise to see that it doesn't fit well with your actual collets and/or chucks
...... chuck face to be smooth, burfree, perpendicular to chuck axis; some low cost chucks don't have this, but this is not always critical; for example, you can have the face with marks from the saw cut, and still no problems, as long as nice chamfers are there

check for burs at the begining/end of the threads ( chuck , nut ), since they are not always deburred, and sometimes they can generate problems

if you decide to go crafting your own, i can help with specific details if you wish : i have done chucks and nuts (for er and other collet systems), and lately, with the edm wire, i think i could handle also collets, but i didn't so far / kindly

[mactec54]

This is CNC stuff - there is always someone waiting to charge you 3x what something is worth... E.g.

ebay.com/itm/283425897391?hash=item41fd7ffbaf:g:06QAAOSwMhVhV0J 2

Or

https://www.ebay.com/itm/19413473241...cAAOSwTj9god1N

And ER25 collets also come in a broad range with sellers describing their expensive ones as "premium" or "high torque" etc:

https://www.ebay.com/itm/31365074099...4AAOSwOM5hJpbZ

I'm certainly not looking to spend more than I need to. I've just been noticing some inconsistency in how certain collets fit.

For example, I have three 1/4" ER25 collets and two nuts (one bearing, one regular). One of the collets is too big for half my 1/4" end mills. One is too tight to fit half of them in one of my collet nuts. The 3rd one mostly works in both nuts but it's not always a tight as I'd like.

I've noticed that if the fit is wrong then it results in excess noise and an inferior finish. When I use one that fits well it's silent (as in no noise is added above regular spindle noise) and I get a nice mirror finish.

I'm just not sure If the inconsistency is solved with the "premium" collets and nuts or if it's normal to need a selection in each size to account for inconsistent end mills.

You would not be buying those collets unless you had through spindle coolant, those are special for high pressure coolant, note the holes around the front face.

The Nut I would never use, as it is likely to put anything it is supposed to remove from the cut area, right up into the spindle Bearings.

[mactec54]

This is CNC stuff - there is always someone waiting to charge you 3x what something is worth... E.g.

ebay.com/itm/283425897391?hash=item41fd7ffbaf:g:06QAAOSwMhVhV0J 2

Or

https://www.ebay.com/itm/19413473241...cAAOSwTj9god1N

And ER25 collets also come in a broad range with sellers describing their expensive ones as "premium" or "high torque" etc:

https://www.ebay.com/itm/31365074099...4AAOSwOM5hJpbZ

I'm certainly not looking to spend more than I need to. I've just been noticing some inconsistency in how certain collets fit.

For example, I have three 1/4" ER25 collets and two nuts (one bearing, one regular). One of the collets is too big for half my 1/4" end mills. One is too tight to fit half of them in one of my collet nuts. The 3rd one mostly works in both nuts but it's not always a tight as I'd like.

I've noticed that if the fit is wrong then it results in excess noise and an inferior finish. When I use one that fits well it's silent (as in no noise is added above regular spindle noise) and I get a nice mirror finish.

I'm just not sure If the inconsistency is solved with the "premium" collets and nuts or if it's normal to need a selection in each size to account for inconsistent end mills.

These Technik's Collets are only $15 are .0002" collets, you can get .0001" I doubt that your machine would benefit anything from a .0001" collet

[Goemon]

I don't have any expectations of perfection (especially not on a sub-2000lb diy machine).

It's really more about not adding additional problems.

People running small belt drive spindles may not have noticed this but, when working at 18,000-24,000rpm even small issues with a nut not being tight enough, or it being unbalanced can make a noticeable difference.

The aim for me is not to eliminate all tool marks. It's to make it so tool marks can be removed with with a couple of minutes of light sanding vs hours with the 40 grit.

I'm generally getting good results at the moment, as long as I use a properly fitting nut that's sufficiently tight...

[handlewanker]

What is more to the truth is that nobody has the means to check if a cutter is making a truly circular contact on all cutting edges at the same time during a cycle......only a grinder's wheel with it's multi grain structure having millions of cutting edges that have been dressed in situ will produce a finish that is mirror like...... for instance a surface grinder or cylindrical grinder........so many other factors are present in the equation too.
In the quest for a better finish some have resorted to second op vibratory and tumbler finishing.....but not many tumblers or vibro finishers will only take out tool marks in specific areas.
Fine grit blasting can do it followed by a vibro finishing cycle, but it's a very intensive cost program if the need must be.
Ian.

[deadlykitten]

hello to true up some live tools, or at least to reduce tir, i use excentric bushings, that you simple rotate until tir reduces

you invest a bit of time to make those, but it helps for the future; also arround here same trick is used to align some components in their final assambled state

i don't use 20k rpm spindles, those are smaller, so a more gentle aproach has to be used

as for okuma, they have a function that can syncronize rpm with feeding, thus rotary with linear axis, in such a way, that tir effect is minimized; thus if there are 4 flutes, then machine will make 4 adjustements within 1 spindle revolution; it has it's limitations, thus it won't work the same for a big tool as for a small tool / kindly