Holding ER collets for setup/torquing?

There is actually a jig you can buy for those type of collet chucks. Go to the last few seconds of the video for the tightening action needed and why the chuck needs to come out of the machine.

I just couldn't find anything for the ER25 I had and there are many other sizes with this type of holding needed.

It would be possible to put a wrench on the chuck and the nut tool on the nut still in the machine. However for the torque recommended I don't think it would be the best way. ER 25 needs 77 ft lbs ER 32 needs 100 ft lbs.
 
Holding the chuck is only half the job. Torquing the nut accurately is the real problem unless you have a torque adapter to fit the contour of the nut and know the conversion factor to arrive at the correct torque. Many ER nuts are a metric hex, which makes things easier.
 
I also bought a bearing nut for the ER 25 collet holder. Very nice the way the top of the nut holding the collet stops spinning and the outside clamps down as it turns pulling straight down. Compared to the one piece nut that pulls down with circular force on the collet.

 
Last edited:
I work in a machine shop where there are many ER collets, have never seen a single person use a torque wrench on one, we must have been doing it wrong the last 50 years or so.

Thanks
 
Thanks that helps. From what I gather by searching people just make them good and tight with no measuring. Makes it easier especially for just hobby use.

The holding jig makes things easier too with putting it in the vise and tightening on the bench.
 
I think for most milling cutters, good-n-tite is fine. However, there are some cutters that need to run accurately, like woodruff keyseat cutters, and those benefit from all the accuracy the chuck can deliver; that includes torquing to spec.

I have a Keo woodruff cutter that was confirmed by Keo to be accurate; I know this because I couldn't get the first one I bought to run accurately and I thought it was the cutter so I contacted the President of Keo and asked that he arrange for an accurate cutter to be exchanged for the one I bought. He did exactly that. That cutter ran out 0.0005", which is a lot for a keyseat cutter. It produced a slip-fit on the key. Knowing it wasn't the cutter, I suspected my tool holder.

I changed to a Chinese ball bearing ER-32 nut and cranked it down. Still 0.0005" run out. Then I changed to a Techniks collet with the same nut and got 0.0002" run out. Then installed a Rego-fix nut and torqued it to spec with a stupid motorcycle spanner adapter I had and the run out dropped to 0.0001". Then I got an interference fit like I expected.

I learned that accurate collets matter. Accurate nuts matter. Torquing matters for cutters that must run accurately. I had several days of work invested in the lead screw I was working on so it mattered that I got the key seat right.

I think for standard cutters taking hobby guy sized cuts, tightening by hand is fine but as I said, there are times ...
 
You must log in or register to reply here.
Back
Top