With only 190mm(?) available, saving about 50mm is like an increase of useable headspace of something like 30-40% in practice?

How firmly does an Int30 collet grip? Is it better than making a plain shank holder with a (recessed) set screw?

The taper is the same as for R8, so that should be a guideline.

PS:- have you got a link for the supplier? (Get thee behind me Satan).

Glad you like them John.

As the collet face sits flush with the spindle nose, you've probably gained more than 50mm, but watch out for the drive dogs!

As my machine does not have a spindle brake, I use an adjustable spanner on one dog when tightening the drawbar and then remove them before actually cutting metal.

Mark, they are off Aliexpress:- NT/ISO30 Collets

Bazyle, they appear to have the same grip as an R8. I've had no problem with cutters pulling out, in the 3+ years that I've been using my set and that includes a 20mm cutter.

Edited By Nick Hughes on 25/10/2019 10:11:32

Hi John,

I have the same milling machine, and on mine the BT30 holder was an adaptor, into an R8 spindle taper.

So on my mill the actual spindle is R8, removing the adaptor gave a lot more headroom.

HTH

Do you have a manual drawbar? I looked for the split collets on ebay UK and there were none, but I noticed some er32 ones like this which were shorter than your er16, there may have been other er sizes available.

**LINK**

Hi John, after you said the Novamill was never available with an R8 Spindle, I had to go and check to make sure I was not having a senior moment, the mill is not being used at the moment, but yes it is an R8 spindle.

Photo included of the Coventry Easy Change/ R8 adaptor.

We have a full set of metric, and several imperial R8 collets and I have had an unforeseen problem with one of the first ones I tried using on the Tom Senior. The TS is converted to R8 and I elected to leave out the pin in the spindle which is there only to stop the tooling from turning when the drawbar is being tightened. The drawbar is newly made and can be slightly tight in some of the tooling. This happened with the 5mm collet which I wanted to use, and persisted even when I ran a 7/16 UNF tap down the threads. The downside of the collets is that there is nothing to get a grip on if they turn with the drawbar. I may have to drill three axial holes in the collet nose to use a pin spanner. The spanner would have to work with the 20mm collet downwards, so I will have to be careful with the positioning and size of the holes. A job for the rotary table with a chuck on it, and maybe a small carbide drill. I will do them all to prevent an occurrence of the problem.

Dead right Michael, the problem is that the threads in the tooling are not always exactly in line with the axis of the spindle. The drawbar of the drill mill is more forgiving due to slight wear. There are a lot of tools to test out on the TS, just running the tap down has cured most that I have tried. Having a self extracting drawbar will make the tight ones more difficult as they cannot be slammed home in the taper before engaging the drawbar. However niggling these problems are, I will not put pins in the spindle, or change to a loose drawbar. now I have experienced the advantages of the present setup.

 I wonder if the ISO30 spindle could have similar problems with the drawbar thread being tight?

Edited By old mart on 27/10/2019 19:15:43

Edited By old mart on 27/10/2019 19:16:28