ER 16 collet size range query.

[Sachakins]

Just got new spindle for my cnc with ER16 chuck.
All sets i have seen, including my own and charts are size range up to 10mm or their equivalent imperial sizes.

Just come across a couple of sellers recently offering 11mm and 12mm.
Anyone else seen these and used this 11 or 12mm collet successfully?

Wonder if there's going to be an 1/2" version? Would be great as quite a few 1/2" ones with my plunge router set.

Cheers

 

[ChaiLatte]

ER collets can be thought of as being invented by RegoFix (the Swiss relation to that fine Irishman Reg O' Fix). Whatever they state in their literature as the range for any particular collet series is how they were originally intended to be used.

Anything exceeding that range is known as an 'extended' or 'oversize' collet, and needs a little care in use as it was not part of the original design. Hence, if one is made, searching for "ER16 oversize collet" would find it.

In particular, you notice that as the collet gets bigger, the part between the tool and the inside of the nut gets very thin, to a point that it can become a razor edge. That greatly reduces the support the collet gives to the tool at that point (maximum bending of the cantilever). It also makes the collet itself delicate.

Hence, you should first measure the diameter of the hole in your ER16 collet nut and determine its difference from 1/2". Ponder on that number and assess the engineering implications. You could also arrive at the same place of enlightenment by looking at the D2 dimension here for an ER16 collet (https://www.arceurotrade.co.uk/Catalogue/Collets/ER-Collets). A third place to measure, if you are not already convinced, is the groove in the collet, that retains it in the nut. Measure its diameter, deduct 1/2" and divide the result by two to give a wall thickness. Assess whether that is reasonable on an item spinning at more than 10 000 rpm.

 

[ChaiLatte]

Should you wish to expand your inner hole, you could purchase one for £0.80 here:

https://www.aliexpress.com/item/1005003775471924.html

 

[Sachakins]

Thanks for this, does make one pause for thought, sounds like having my inner hole expanded is unwise
That Ali link also have a 12.75, so half inch?

 

[ChaiLatte]

That Ali link also have a 12.75, so half inch?

Yes. As you know, 1/2" is 12.7mm so maybe they have made it a smidge larger so the tool goes in easily. If the nose is thin and the collet is exactly on size, you might damage it inserting the tool.

For the price, it is worth a gamble, but use with caution. My general view on oversize collets is that they should be thought of and used in the same way as a space saver spare wheel. Round where I live, that means one on each diagonal corner for six months at a time.

 

[Sachakins]

As you say, cheap enough to try, so ordered one today.

 

[Fergie 307]

Is the chuck machined into the spindle, or could you just change it for a 20. Never a great idea to go outside the sizes intended to be used. That's why there is a range.
I have sets from 8 to 32 for that very reason, on either MT or 3/4 straight shanks so they fit a capstan.

 

[Sachakins]

Is the chuck machined into the spindle, or could you just change it for a 20. Never a great idea to go outside the sizes intended to be used. That's why there is a range.
I have sets from 8 to 32 for that very reason, on either MT or 3/4 straight shanks so they fit a capstan.

Spindle not fitted yet, so will check it, still in boxes.
Sounds a good option, thanks.

 

[Fergie 307]

Have to say I order mine from China on e bay. Very cheap and have never had one that was not very good quality. Massive variety of combinations of different MT and other tapers, as well as different sizes and lengths of straight shanks for any given collet holder.
If you end up with a range of them then I would go for the hex type collar as opposed to one that uses a special wrench. I can always find the correct size spanner, but would probably put the special wrench somewhere safe, and consequently never be able to find it again
If you haven't used them before very important to engage the collet in the retaining clip in the holder collar before putting the tool in. You just put it in at an angle then rock it straight so the clip goes into the groove around the top of the collet.
Makes sure everything is aligned properly, and when you undo the cap it will pop the collet out for you to release the tool.

 

[Sachakins]

Hi, thanks for that, had an motor with er11 spindle and a "castleated" nut. Got rid of it after also misplacing the "special" wrench, violent use of mole grips for a few days till a proper hex nut collet arrived

 

[ChaiLatte]

Hi, thanks for that, had an motor with er11 spindle and a "castleated" nut. Got rid of it after also misplacing the "special" wrench, violent use of mole grips for a few days till a proper hex nut collet arrived

Please be aware that the shape/form of the nut correlates with the thread inside that nut.

So it is sometimes not the case that an ER16 'special spanner' nut would swap with an ER16 'standard hexagon' nut. Please see this picture which gives a fairly comprehensive picture of what is on the market:

https://ae-pic-a1.aliexpress-media....40-milling-maching-clamping-nut-CNC.jpg_.webp

 

[Sachakins]

I've noticed that the thread diameter does vary between the nuts.