[wormwood]

Sorta off topic but this relates to the ER20 Collet set I received from Tormach....

Is there a specific size when shank dia. becomes true to cutting dia.? Is it an unwritten rule among mfg.?

Also when buying smaller diameter end mills (</= 0.0625") usually the shank is 0.125" unless it's metric, so what's the purpose of any ER20 collets that are smaller than 1/8"? :stickpoke

Wormwood

[GLCarlson]

I use ER collets to hold drills, so sizes smaller than 1/8" are handy.

Shank size generally matches nominal cutter diameter between 1/8 and around 1/2-3/4 in my experience, but I've never seen an official standard.

[AUSTINMACHINING]

Sorta off topic but this relates to the ER20 Collet set I received from Tormach....

Is there a specific size when shank dia. becomes true to cutting dia.? Is it an unwritten rule among mfg.?

Also when buying smaller diameter end mills (</= 0.0625") usually the shank is 0.125" unless it's metric, so what's the purpose of any ER20 collets that are smaller than 1/8"? :stickpoke

Wormwood

Not sure what you are asking, but... I have cuttino tools with cutting diameters larger,smaller and equal to the shank diameter.

ER collets under 1/8 " are great for small drills,cutting tools where runout becomes more critical.

[IMT]

No standard I know of, but when you order an end mill the specs should specify the shank diameter and the flute length.

[wormwood]

No standard I know of, but when you order an end mill the specs should specify the shank diameter and the flute length.

I must have overlooked them & just wasn't thinking...

Wormwood