on collets, chucks and precision

din /isoB sais to measure runout of er (other?) collets at 2.5-3.5 diameter. up to 6mm runout is supposed to be 0.015mm and then 0.02mm. for 3 mm diameter its 10mm from collet, for 10mm diameter its 25mm from collet. for larger it probably doesnt matter that much.

drill chucks are measured at 50mm for 3mm diam. and 100mm for 10mm diam. (according to roehm.)

no idea how lathe chucks are measured. mine has 0.02mm at chuck and 0.03 at 60mm (forkhardt 250).

i can get no spec. er collets (so supposedly 0.015/0.02), 0.01, 0.007 or 0.005. hardinge seems to spec. 0.01 on er. quality is a big problem. i bought a er25 set of "0.007" to be sure its good. it was from an idustial supplier and it was total crap, the bores even had ridges in front. were $8 a piece. sent it back. bought a 0.005 set at $15 per piece. terible, no ridges, but smaller sizes rusted inside, i have a pic. of all the shit that came out of the set after vibatory cleaning. the 16mm collet averaged 25 micron at collet and 62mu 40mm out. 6mm was 5mu and 4mu at 40mm. 3mm was 5mu and 1.5mu at 7mm. this support the theory, that spindle axis and tool axis are two lines in space that do not have to touch and the angle between them is unknown. interestingly the 6mm collet, although rusted inside has 5mu and 4 mu at 30mm (i will keep it, send rest back).

so i got myself a regofix nut and the runout dropped by 50%.

i then bought a regofix up (ultra precision) 10mm er25 collet at $40 and with the regofix nut its within spec. of 0.005mm at 2.8/5.2/6.8 mu at 3/20/40mm compared to the former collets 10/22.5/31mu with the regofix nut.

roehm spiro drill chucks are spec. at 0.05mm run out and albrecht is 0.04m. (had to sent spiro back twice.) so for 10mm its at 100mm. so roughly 3x colet runout. 4/3 x = 0.013mm. similar to "standart" er collet.

above was measured with a holder that shows no movement on a 0.002mm test indicator on top and botom of taper, and validated by a a 0.mm graduated hicator.

so, stating collets are much more accurate than chucks is pretty brave.

is there any u.s. standart for collets and chucks? i have seen 5c collets up to $100 per piece. is the precision up to the manufacturer? so, a set of precision 5c collets will be severat thousands bucks?

If you want to learn more, please visit our website Customized Collet Chuck Accuracy.

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1. select accuracy
2. compare prices for a given accuracy, and feature set
3. pick lowest price

In practice a few problems get in the way:

i) Accuracy is not always described with the same metrics
ii) Dishonest advertised accuracy (or poor inspection, resulting in out of specs components getting sold)

I started looking for an ISO30-ER32 collet chuck, and set of collets, and one of the "almost reputable and almost cheap" vendors advertises compliance to the DIN B standard :

https://accusizetools.com/products/er-metric-collets-sets-din-b?variant=

That sounds very serious, but I have googled and can't even find what this standard says.

I searched on Aliexpress, to find collets with "good specs", with a vendor that is a manufaturer that specialises on this kind of tooling (I avoid those that sell everything from picnic chairs to tractors)

And I see other kinds of metrics:


The advertised accuracy specs is a single number : 0.003 mm

(most vendors also use a single number to describe accuracy, but they are more often higher, 0.005, 0.008,...)

Is that number a TIR (total indicator runout) ?

The collet chuck from the same vendor more generous in the advertised specs:

Material : 20CrMnTi Steel
Product Precision: 0.001mm
Overall Clamping Precision: &#;0.003mm
Product hardness: HRC56°-60°
True roundness: &#;0.4μ
Carburizing depth: &#;0.8MM
Surface roughness: &#;0.8
speed:G2.5/RPM

Here, "clamping precision" could mean TIR, it would make sense, because there is no way a TIR of a collet cannot be measured, without (at least) a chuck and a cylinder that will both contribute to the TIR.

I've been comparing collets and chucks on Aliexpress, and they seem to express the metrics in the same way.

Unfortunately Aliexpress does not seem to provide a way to contact a vendor.

I'm tempted to just buy it and measure myself, but Aliexpress has no "free return & refund" like Scam-ar-zone.

Does anyone have info on DINB ?

It would be a nice "hobbyist community" effort, to find the good manufacturers on Aliexpress, it would result in better tools for less money, or more likely more and better tools for the money that we are itching to spend on tools ! ;-)

One thing I'm tempted to do, is get the chuck and a few collets, measure them, and if they are good, order a whole set.

Perhaps someone has already found the good manufacturer on Aliexpress, and I can benefit from their experience.

Metrology and standards should make purchasing many machining components a simple decision tree.1. select accuracy2. compare prices for a given accuracy, and feature set3. pick lowest priceIn practice a few problems get in the way:i) Accuracy is not always described with the same metricsii) Dishonest advertised accuracy (or poor inspection, resulting in out of specs components getting sold)I started looking for an ISO30-ER32 collet chuck, and set of collets, and one of the "almost reputable and almost cheap" vendors advertises compliance to the DIN B standard :That sounds very serious, but I have googled and can't even find what this standard says.I searched on Aliexpress, to find collets with "good specs", with a vendor that is a manufaturer that specialises on this kind of tooling (I avoid those that sell everything from picnic chairs to tractors)And I see other kinds of metrics:The advertised accuracy specs is a single number : 0.003 mm(most vendors also use a single number to describe accuracy, but they are more often higher, 0.005, 0.008,...)Is that number a TIR (total indicator runout) ?The collet chuck from the same vendor more generous in the advertised specs: https://www.aliexpress.com/item/.html?spm=a2g0o.cart.0.0.73ee38daPC1QoU&mp=1 Material : 20CrMnTi SteelProduct Precision: 0.001mmOverall Clamping Precision: &#;0.003mmProduct hardness: HRC56°-60°True roundness: &#;0.4μCarburizing depth: &#;0.8MMSurface roughness: &#;0.8speed:G2.5/RPMHere, "clamping precision" could mean TIR, it would make sense, because there is no way a TIR of a collet cannot be measured, without (at least) a chuck and a cylinder that will both contribute to the TIR.I've been comparing collets and chucks on Aliexpress, and they seem to express the metrics in the same way.Unfortunately Aliexpress does not seem to provide a way to contact a vendor.I'm tempted to just buy it and measure myself, but Aliexpress has no "free return & refund" like Scam-ar-zone.Does anyone have info on DINB ?It would be a nice "hobbyist community" effort, to find the good manufacturers on Aliexpress, it would result in better tools for less money, or more likely more and better tools for the money that we are itching to spend on tools ! ;-)One thing I'm tempted to do, is get the chuck and a few collets, measure them, and if they are good, order a whole set.Perhaps someone has already found the good manufacturer on Aliexpress, and I can benefit from their experience.

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