Collets

ER collets, stocked in Canada. ER16, ER25 and ER32 in metric and inch sizes, sold individually or as sets — prices and stock on every product page, order without asking for a quote.

One collet covers one millimetre. An ER collet is named for its largest size and closes about 1 mm (0.039") below it — a 10 mm collet holds 10 to 9 mm, a 1/4" collet holds 0.250" to 0.211". Clamping a shank well under that range bends the collet permanently, and from then on it holds every tool off centre.

Individual collets and inch sets run 0.01 mm TIR; the metric sets are the high-precision 0.005 mm version.

Total found: 6

Only new

Only in stock

Sold As: Set

ER32 Inch Collet Kit, clamping range ø1/8" - 3/4", 18 pcs, Runout 0.01 mm

ER32KIT18iIn stock

CA$226.06

excl. taxes

ER16 Inch Collet Kit, clamping range ø1/8" - 3/8", 8 pcs, Runout 0.01 mm

ER16KIT8iRunning out of stock

CA$78.95

excl. taxes

ER25 Inch Collet Kit, clamping range ø1/8" - 5/8", 9 pcs, Runout 0.01 mm

ER25KIT9iRunning out of stock

CA$103.73

excl. taxes

ER25 Collet Kit, clamping range ø2 - 16 mm, 15 pcs, Runout 0.005 mm

ER25KIT15PRunning out of stock

CA$254.97

excl. taxes

ER16 Collet Kit, clamping range ø1 - 10 mm, 10 pcs, Runout 0.005 mm

ER16KIT10PArchive

ER32 Collet Kit, clamping range ø3 - 20 mm, 18 pcs, Runout 0.005 mm

ER32KIT18PArchive

ER Collets

A collet is the cheapest part of the chain that holds your cutter, and the easiest one to ruin. It is also where most of the runout in a collet chuck comes from, so it is worth understanding before you buy a handful of them.

The range below covers ER16, ER25 and ER32 in metric and inch sizes, individually and as sets. Clamping range and runout are on each product page.

The 1 mm rule

An ER collet is named for its largest size and closes about 1 mm (0.039") below it. A 10 mm collet holds 10 mm down to 9 mm. A 1/4" collet holds 0.250" down to 0.211". That is the whole logic of the system, and it explains why a set has eight to eighteen pieces in it rather than three.

Within that range the collet grips properly. Outside it, it does not - and the two ends are not symmetrical. A shank slightly too large simply will not enter. A shank well below the minimum will go in, will appear to clamp, and is the single most common way a collet is destroyed.

How a collet gets ruined

Clamping below the range. Squeezing a collet further than it is designed to close bends the segments past their elastic limit. The collet does not spring back, and from then on it holds every tool off centre - including the correct-size one. It looks fine. Runout tells you otherwise.

Assembling it in the wrong order. The ER nut has an eccentric ring that engages the groove in the collet. The collet must be clicked into the nut first - at an angle, until it snaps in - and only then does the tool go in and the nut go onto the chuck. Pushing the collet into the chuck taper first and then threading the nut down damages the collet and the nut, and it is the most common mistake on the shop floor.

Chips in the slits and the taper. A collet is a precision taper with slots cut in it. Anything trapped in a slot or on the taper seat becomes runout directly. Clean both, every change.

Clamping a Weldon shank. A collet grips by wrapping a cylinder. The flat ground on a side-lock shank removes part of that cylinder, so grip drops and the tool can pull or spin. Weldon shanks belong in an end mill holder, not a collet.

Runout: 0.01 mm or 0.005 mm

Two accuracy classes are sold here. The individual collets and the inch sets run 0.01 mm TIR. The metric sets are the high-precision version at 0.005 mm.

The difference matters where the tool is small or the finish is tight. Runout loads one flute more than the others, and the tool fails at the rate of its most-loaded edge - so on a 1/8" cutter, five microns is a meaningful share of the chip. On a 1/2" roughing tool in a heavy cut, it is not what limits you.

Remember that the collet is one term in a stack: spindle taper, holder taper, collet, shank. A 0.005 mm collet in a tired holder measures like a 0.01 mm one. Buy the accuracy where the rest of the chain can show it.

Set or individual collets?

A set is the right first purchase. It covers the whole range of the chuck, costs less per piece than buying the same collets one at a time, and means the size you need on a Friday afternoon is in the drawer.

After that, most shops use three or four sizes constantly and leave the rest of the set untouched for years. That is what individual collets are for: replacing the ones that actually wear out, and adding a second of the size you use every day so a damaged one does not stop the job.

It is also the honest answer to "should I buy another set" - usually not. Buy the two sizes you keep reaching for.

Nut, wrench and torque

Clamping force comes from the nut, and ER nuts need real torque - considerably more than hand tight, and more than most people apply. Use the figure the chuck manufacturer gives, and use a proper ER wrench rather than whatever is nearest.

Under-torqued is the reason a tool creeps out of a collet during a cut. It is almost never the collet's fault.

Insert the shank so it fills the collet bore. A tool held by the last few millimetres of the collet has neither grip nor accuracy, and the overhang it creates costs rigidity as well.

Which ER size do I need?

The collet series is set by the chuck, not by the tool: an ER32 chuck takes ER32 collets and nothing else. Check what is on the holder before ordering.

ER16 covers small work up to 3/8", ER25 up to 5/8", ER32 up to 3/4". Larger series exist for heavier holders.

Buying ER Collets from CNCmarket

Prices and stock are on every product page and you can order online without waiting for a quote. Delivery is free across Alberta and we ship anywhere in Canada.

We run our own machine shop in Calgary and use these collets ourselves. Tell us which chuck you have and which shanks you actually run, and we will tell you whether a set or a handful of singles is the better spend.

Collets

ER Collets

The 1 mm rule

How a collet gets ruined

Runout: 0.01 mm or 0.005 mm

Set or individual collets?

Nut, wrench and torque

Which ER size do I need?

Buying ER Collets from CNCmarket

Frequently Asked Questions

ER Collets

The 1 mm rule

How a collet gets ruined

Runout: 0.01 mm or 0.005 mm

Set or individual collets?

Nut, wrench and torque

Which ER size do I need?

Buying ER Collets from CNCmarket

Frequently Asked Questions