Toolmaster 1b to ER 40 collet question

I have had a 1b for about 10 years after I went to buy a lathe and had to buy the mill to get a southbend 13. I am not a machinist by any means. I saw this forum and rigured I would ask this question here.

I have about 3 Cinnci collets and have been using a 1-1/4 shank ER40 holder for most of my work. I was recently in Ohio visiting relatives and talking to a gentleman (80’s?) who was a retired machinist. He thought with the old 1b that folks would take a 40taper with a bored hole and press it into the quill and then turned.

Looking at my spindle, the ER40 collets are the same taper, they just go in to far. I thought this could work by moving the taper down so that the collet was at a more appropriate depth for the nut. Whether a new nut would need to be made, or just a hardened washer added to the bottom with the ER40 nose taper, I don’t know. I doubt there is enough meat in an ER40 nut to turn out the M50 threads to the 2-1/8x16.

So do ypu think this is feasible, would a boring bar setup on the table give enough accuracy to lightly turn out the adapter (with the head tilted at the taper) ?

Thanks for your thoughts

So I found this https://www.cnccookbook.com/can-you-really-regrind-your-spindle-while-its-on-the-machine/

Which seems to speak to the point. I am going to try two different methods

1- take an old er32 cat40 collet chuck and get someone to turn down the body/drive tabs so that I have about 3/16” left at a 2.0 OD right before the taper starts. The toolmaster nut will go over the collet chuck body and hopefull use the lip tp pull it up into quil using the nut. This should be truer than a collet to adapter. Maybe. The taper might need to be taken down a bit to allow the chuck to sit deaper in the spindle, but that is beyond my means.

2- depending on how that goes, I will take a piece of 7/24 taper stock and bore the id to 1”. Freeze it in dry ice and then press it up into the quill. Tilt the head to 8 deg (with a sine bar) bolt an ER40 flanged chuck with a boring bar in it to the table and very slowly start cutting a taper and fitting a ER 40 collet for depth. The nose piece of the toolmaster nut is 30 deg and matches the ER.

I did check using an ER40 collet in the spindle with an adapter/spacer to push it deeper. Problem is you then only end up with about .375-.5 collet to taper engagement and it would be a bear to get the collet out as the nose is almost flush with the bottom of the spindle

I welcome any thoughts before I start cutting stuff up!

So I went the Er32 route and it works pretty good. Very rigid setup. In hindsight, I should have bought an ER32 stub/close collet in BT40 (as opposed to using one I had) to modify as the nose length is a bit long after the driving lugs/bands are ground down. I left about .16 of the top band with a slight taper where it met the body. I would also take it someone to have it ground as I broke a lot of bits and ended up removing the bulk of the stock on a belt sander. I also picked up a 3/8 monoset collet cheap as it was sitting n a shelf covered in dust. Baby steps

How did this work out? I have a drawer full of Monoset collets, and still end up using a drill chuck a lot. Most of the work I do is metric. Try as I might, the Monosets just don't have the range to grip most of the metric endmills and reamers. (Superflex my a**) I was looking at the ER40, but as you found they sit a bit too deep, and I'm unwilling to modify my quill bore.


thanx

I'm about to go down this road too, but with a stub/flush nut er32 cat40 holder.

I ordered a china.com BT40 holder as a prototype, figuring it would be made of Play-Doh. You should see what it did to a HSS bit in about two seconds. Man, that thing is hard.