[TommyS]

Hello, and thanks in advance for any and all assistance. I am just entering the world of CNC (woodworking), and recently purchased a used machine. The previous owner recently installed a Chinese made router. My question is concerning the collet- most of the router bits I'm familiar with have 1/4" shanks- this machine uses 6 MM shanks. I'm having trouble locating a 1/4" collet for this machine. Do most folks use metric bits? Are there metric collets that will work with 1/4" bits? What's the 'norm'? Thanks again. TS

[ger21]

In the US, most of us use 1/4" and 1/2" bits. What type of spindle do you have?

[TommyS]

The spindle that came with the machine is a 220V Chinese made spindle- the manufacturer name is Zhong Hua Jiang. I actually found collets online to fit this machine, but they are metric, and they come sized to fit bits ranging from 1 MM to 13 MM. I'm surprised to see how difficult it is to find 1/4" and 1/2" collets, knowing how common those bit sizes are. I was hoping that the collets had enough range in them, or there were a metric equivalent available somewhere- some sort of work-around available.

[ger21]

Sounds like you have an ER20 spindle. ER20 collets are easy to find in inch sizes.

This Ebay seller sells just about any imperial size you could want.

allindustrialtoolsupply | eBay Stores

[extent]

clamping range on the collets is about 1mm, 0.5mm for sizes under 2.5mm. But it's best to stay as close to native collet size as possible, so just get 1/4" collets, you can find them everywhere. I get all mine from Maritool.

[TommyS]

Thank you Gerry and Extent for the information. That clears things up. I found that my spindle is an ER11, so I will order the correct collet soon. It seems that the shaft is too small for a 1/2" bit, but I think the 1/4" size will do all I need it to do.
Are there bits made with the variety of metric sizes shown? I had no idea.
Thanks again for your assistance.
TS

[ger21]

With an ER11, you're usually limited to 1/4" and smaller collets.

These collets are used in more than just routers. They can be used to hold drill bits as well, which is why they come in a wide range of sizes.

[GeoffW1]

Hi,

Agree with the above. For the ER11 size locknut you can buy a range of collet sizes, up to and including 1/4" and 6mm, so marked. I found that those last 2 sizes are not interchangeable, the difference in size is too great, so you need both collets. I get my bits off eBay, mostly cheapo Chinese 2 flute carbide cutters, but I'm only doing hobbyist work with my CNC machine.

Cheers