Turning threads off rod fine but now rod advances out of chuck.

[helmbelly]

Something like this, but with 3 cuts each side? (This 3/8" OD collet has two on each side.)
View attachment 469621
Seems like a bit of work for not much payback.

can I borrow that?

 

[WobblyHand]

can I borrow that?

Of course you can!

That was a small adapter I made to hold an Interapid DTI stem. Put it in a 3/8" R8 collet, it held the small metric stem of the DTI.

 

[helmbelly]

I made to hold an Interapid DTI stem.

what is that?

 

[helmbelly]

Thanks for the ideas guys- really helped. Skipped the hard wood and went with a piece of delrin I had bored out to 5/16 already. slit one side relieved the other (a bit too deep but it held together) chucked it and worked great. No threading - just a smooth bore. Close up of the tip. Shaves off like nothin. I thought 316 was said to be a terrible tiger but it's not bad at all.

 

[helmbelly]

If this did slip I would remake it with 1 slit and 2 relieves to allign with jaws.

ps. those jaws are my Seneca Falls 9" Star lathe, my grandad bought it used in 1917 when he was at MIT. He used for a couple projects and it went into storage winding uo, stored in my dads shop for 60 years. Funny thing is that's over 100 years old it's really never been used and it's like perfect! No run out (.002 I think) tight and quiet. And she cuts 316 now!

 

[WobblyHand]

what is that?

Dial Test Indicator (DTI). Used for relative measurement.

I made the little collet because I didn't have a 4mm R8 collet. So I made this collet to fit in a 3/8" R8 collet. I use it on my mill to tram my toolmaker's vise (among other things).

The box that came with the DTI had a spot for the collet, but it didn't come with it. I received the DTI and had no easy way to hold it in my mill, so I made the collet. It was better than waiting a couple of weeks for the silly thing to come in the mail... As I recall, they wanted $20 for it. I had the equipment to make it, and didn't want to wait, so I made it.

 

[helmbelly]

ok gotcha. (I know what they are used for) I made a sleeve for one of mine, sorta same deal. I just made a tight fit and chuck it. But what you made is in a diff league. nice!

 

[woodchucker]

Can you use a jam nut?

 

[helmbelly]

Can you use a jam nut?

Hey WC, hell I think I could and it would work, I tried one but didn't tighten it much thinking it was just a safety. Today after messing with this stuff I think the problem is using a threaded coupling at all. it creates engagement- or the potential to engage incline force against the opposing force of the tool bit. Did I say that right? It's simple and complicated - but when holding a threaded rod in a chuck I'd say don't hold it with anythhing threaded. Just hold it with a softer material in a way that applies the jaw force evenly. yeah?

 

[woodchucker]

Hey WC, hell I think I could and it would work, I tried one but didn't tighten it much thinking it was just a safety. Today after messing with this stuff I think the problem is using a threaded coupling at all. it creates engagement- or the potential to engage incline force against the opposing force of the tool bit. Did I say that right? It's simple and complicated - but when holding a threaded rod in a chuck I'd say don't hold it with anythhing threaded. Just hold it with a softer material in a way that applies the jaw force evenly. yeah?

That's why I thought the jam nut. Whatever works for you. when I answered I didn't realize that this had already gone to five pages.. so you have lots of advice at this point.