Official Luthiers Forum!

Hey everyone.

I have a really quick question.

I am looking into getting an ATC spindle. I am new to this and do not know much about tool holders.
The taper bore says ISO 20. Can you put an ER20 or ER25 collet in an ISO 20 tool holder? The "ISO 20" part is just the taper bore correct? The pull stud portion of the tool holder is some times not included with the tool holder, is this correct?

I don't want to buy an ISO 20 taper bore ATC spindle and be stuck with only being able to use ER16 collets.
Please advise.

Thanks!

I've not used the ISO 20 tool holder myself but have used a variety of others, if like other tool holders the ISO 20 is the tool holder geometry. When you buy the tool holders you'll need to specify the collet series you want to use in it.
Command makes nice tool holders BTW.

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Jim Watts
http://jameswattsguitars.com

The ER series is the collet and the ISO is the tool holder. The ER collet fits into the ISO 20 tool holder. The ISO 20 may or may not accept larger series ER collets. But what you would look for is ISO 20 ER25 holders. There is nothing wrong with having different sizes in the tool rack for various size tools. No point in putting a 3mm cutter in an ER 25 holder.

You have to be careful about the tool holder and pull stud being appropriate for your ATC. While the taper angle for many of them may be the same, there can be small differences in length and what the diameters at each end are. Therefore if your ATC calls for ISO 20 then use them. If it calls for a BT or NT or other holder, then use that.

As well pull studs come in various styles. 45, 60 and 90 degree, along with propriety styles for various spindles. Most times you have to purchase pull studs separate from the tool holder and install them yourself. Be sure to get the right thread for the tool holder in question.

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Allen R. McFarlen
Barron River Guitars & Ukuleles
Facebook
Cairns, Australia

So I know the taper bore of my ATC is ISO 20. So now I will need to make sure the pull stud specifically fits my ATC and threads to my ISO 20 tool holders.

Allen, that cleared up exactly what I was wondering. Thank you very much.

The biggest chuck I've seen that's ISO20 is also ER20, so you can get away with 1/2" cutters. The dimensions of the pull-studs should be in the datasheet for the spindle, so you can buy ones that match.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Good to know. Thanks Bob!