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

[WobblyHand]

Something like this, but with 3 cuts each side? (This 3/8" OD collet has two on each side.)

Seems like a bit of work for not much payback.

 

[benmychree]

And have 3 pieces?

1.5 is standard for most things with the .5 being referred to as a relief cut.

You’re only looking for about .005-.010 of movement.

Read my earlier posts regarding the two partial cuts. I in no way suggested cutting it in 3 pieces,

 

[helmbelly]

Whenever I'm overthinking stuff the grinder is a good place to refresh. A couple hours ago I spun the bolt on the gray wheel a few turns, no thread left at all. Right now I'm gonna go turn a piece of hardwood round, drill it 5/16, slice one side and chuck it up. With no threads pushing the work piece back in the chuck - can just turn it to .213. So the problem is still anybody's guess (why turning the back of the coupling got me crosswise) but now there is no problem ;-) Like someone said -couldn't get a jack under the bridge so hung around for low tide. haha

Def trying Wolves suggested back relief next time. I do that another way in a circular bar clamp but didn't think of it here.

Re microcarbide/HSS I don't work with SS much i just went with McMaster's catalog suggestion - it's $10. I regrind my HSS bits but resharpening a brazed carbide would be a new trick in my bag!

 

[helmbelly]

besides that what do you call "overtightening" the chuck?

Not reefing on it, just one extra tad of applied man power.

 

[RaisedByWolves]

Read my earlier posts regarding the two partial cuts. I in no way suggested cutting it in 3 pieces,

You didn’t give much detail so I was left to my own devises.

If you’re thinking of the below slit collar….

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.

Something like this would likely squirm in a 3 jaw and is more suited for being used in a collet.

It would hold, but if accuracy is important wouldn’t be ideal.

 

[helmbelly]

Since there are 3 chuck jaws, there should be 3 cuts.

like a 5c collet

 

[RaisedByWolves]

Not reefing on it, just one extra tad of applied man power.

Aww, just get brutal!







No, don’t do that….

 

[helmbelly]

I’m betting you only cut through one side of your fixture and when you turned it down you lost clamping pressure.

I cut it in half- made a bolt sandwich.

I would make a threaded jig mated to the thread pitch, cut through one side fully and half way through the other side.

I gonna try an unthreaded clamp just bc I don't want to pave the road for the threads to travel down. Hard wood ought to bite em pretty good. if not oak then lignum vitae which I keep around (best stuff since delrin)

The half cut on the back side is key, and with the bolt threaded onto the jig you will have tonnes of surface area to grip.

right on, thanks

Also, just use HHS for this, no need to ruin carbide toolbits and micro grain is likely to not get you much in this application.

A 5% cobalt toolbit will probably stay sharp for the whole job.

over my paygrade -beyond HSS - be dragons!

 

[benmychree]

Whenever I'm overthinking stuff the grinder is a good place to refresh. A couple hours ago I spun the bolt on the gray wheel a few turns, no thread left at all. Right now I'm gonna go turn a piece of hardwood round, drill it 5/16, slice one side and chuck it up. With no threads pushing the work piece back in the chuck - can just turn it to .213. So the problem is still anybody's guess (why turning the back of the coupling got me crosswise) but now there is no problem ;-) Like someone said -couldn't get a jack under the bridge so hung around for low tide. haha

Def trying Wolves suggested back relief next time. I do that another way in a circular bar clamp but didn't think of it here.

Re microcarbide/HSS I don't work with SS much i just went with McMaster's catalog suggestion - it's $10. I regrind my HSS bits but resharpening a brazed carbide would be a new trick in my bag!

Resharpening brazed on carbide is no trick at all, it just takes the proper grinding wheel, if you have a sizeable divot to remove, it is best to grind away the shank before grinding the carbide. I use a diamond wheel for the carbide on brazed on tools as well as touching up inserts; where I apprenticed, most work was done with brazed on tools, so I got lots of practice sharpening them, mostly using green or black wheels, no diamond wheels there. I do agree that most hobby work should be done with HSS tools, especially with lighter machines, this job included.

 

[helmbelly]

Resharpening brazed on carbide is no trick at all, it just takes the proper grinding wheel, if you have a sizeable divot to remove, it is best to grind away the shank before grinding the carbide. I use a diamond wheel for the carbide on brazed on tools as well as touching up inserts; where I apprenticed, most work was done with brazed on tools, so I got lots of practice sharpening them, mostly using green or black wheels, no diamond wheels there. I do agree that most hobby work should be done with HSS tools, especially with lighter machines, this job included.

Thanks on that. I didn't know. I have 4 grinders right now, 2 gray, 1 green, 1 3M debur, wire, buffing, sisal. I sometimes think about adding a white wheel and then I think footprint, losing a belt sander and everything goes blurry