- Joined
- Sep 1, 2023
- Messages
- 68
Metrology and standards should make purchasing many machining components a simple decision tree.
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 6499B standard :
https://accusizetools.com/products/er-metric-collets-sets-din-6499b?variant=35246708883610
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/1005006061931370.html?spm=a2g0o.cart.0.0.73ee38daPC1QoU&mp=1
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:G2.5/30000RPM
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 DIN6499B ?
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.
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 6499B standard :
https://accusizetools.com/products/er-metric-collets-sets-din-6499b?variant=35246708883610
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/1005006061931370.html?spm=a2g0o.cart.0.0.73ee38daPC1QoU&mp=1
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:G2.5/30000RPM
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 DIN6499B ?
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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