ER11 Adapter for the CT

The CT chuck is nearly 1/2 inch higher than the other chucks. This extra space was what I used to slip the dust shoe between the chuck and the board. Well, I just found another use for the space: an ER11 adapter. I just made one out of an old ER11 spindle that I had laying around. It is very simple to make from a cheap Chinese ER11 collet extension (pictured in the background). The neat thing about it is that you clamp it onto a bit and then put it in the CT chuck. It is a variable size adapter. It will hold any size bit from 1/32 to 1/4. I have not had a chance to test it yet but I will this weekend on my friends C machine. I do not think it will run as true as a full ER spindle. But think of the possibilities!


EDIT: From later on in this thread (post 86). ER11M adapters made in China on ebay at: http://www.ebay.com/itm/New-1pcs-1-2...item41756bc469

Definitely pulling up a chair for this one!

You have my undivided attention Dan

You got my attention also , will be watching

I've been doing this for a few yeas now, glad to see others trying it. I modified a US made 1/2" shank collet chuck to work with the Quick Change chuck about four years ago. The run-out was so bad with the QC that it was not satisfactory. With the CT chuck it does work much better and it makes for a nice choice. I bought a few of cheap import collet chucks to give it a whirl and was not impressed with their quality. There are many levels to cheap import quality, sometimes you get a good part, sometimes not.

For folks wanting to make something like this my suggestion would be to start with a 1/2" collet chuck and cut it down to size, i.e. cut down the length. This way you will be certain that the tapered bore is exactly in-line with the shank, and both have been ground to specification. You are still stuck with the run-out inherent with the CT, about 0.0005" on mine, but it does let you use a wide range of bits.

Jeff, what's your source for US-made collet?

The one I used was made by Craftsman Industries. You can find them at Enco and MSC Direct on sale in the $60 range at times. They like to charge about $100 when not on sale.

The thing about this type of retro fit is that the accuracy with which original collet extension is made is irrelevant. I have bought many Chinese extensions and they are soft and usually not very true. It does not matter since the process can make it true. What I do is use a high quality US collet to attach the holder to a true nipple on the lathe. The result is determined by the nipple and collet and has little to do with how true the original holder was. So, why pay for accuracy when you are not going to use it? (The more expensive holders are, however, harder and that might be worth paying for. Maritool is a source of high quality holders and also check out Shars for collets.)

If I used the CT, I would make a whole pile of these things. One for each shank size I use.

The problem is that when turning down the shank you can't ensure that your staying inline with the tapered bore of the adapter. It does not take much difference to create a problem. I think you have an excellent idea, but I think it will be easier for most folks to replicate by starting with a 1/2" shank collet chuck.

Many times the tapered bore of cheap adapters is also not great so the ER11 collet will never seat properly. We see this problem with the precision collets for hand held routers as well. A few times a year every manufacturer slips up and a handful of routers get out with a poorly ground bore. This takes you from a run-out of 0.0002" with a precision collet to 0.005" (or worse.)

If you watch the sales you can get the good quality adapters at the same price as the cheap imports. The downside to the Craftsman industries collet chucks is they do not have the wrench flats on the shank. You need a method of holding the shank in place while loosening/tightening the nut.

There was just another post referring to Shars: http://www.shars.com/products/view/2...Straight_Shank Looks like it has a flat for a wrench.

For those of us without a lot of metal-working tools, any advice on how to cut the shank down to size?