Annealing just a section of a arbor ?

[Alcap]

I asked this question in another thread about draw-bar thread size but maybe better it's own thread . I have a 2MT arbor with metric threads I would like to anneal just the threaded end , drill and tap for a 3/8-16 Heilcoil insert . or a threaded plug fitted and brazed on . Can just the end be annealed for doing this ?

 

[Nutfarmer]

An old back Smith operation would be to heat the area of a part to be annealed red hot and then slowed to cool slowly in a bucket of wood ash or other non flammable material. Should work in this operation,but check with a file before machining . Will not work with air hardening or high speed steel.

 

[pontiac428]

I don't see why you couldn't immerse the sensitive end of the part in a bucket of water and heat just the threaded end. I'd be somewhat surprised if the threaded end is hardened at all.

 

[francist]

I think I would also consider how important the arbour and the trueness of it is. Any time you heat something to annealing temperature and cool it there’s a risk of warping the part a little. On an arbour where you want it to be really true, it might not be something you want to mess around with.

-frank

 

[Dave Smith]

definitely do not use a heli-coil insert because they do not work good for more than single time use, and you would have a real problem if your drawbar seized in the MT2
Dave

 

[ericc]

Warping is definitely a risk if you bring the piece up to critical temperature. If you need to use heat, try a sub-critical anneal. No need to take it all the way to non-magnetic. Just a very dull red is great for medium carbon steel. Even better, heat slowly and evenly. A propane torch is better than an oxy-fuel torch in this regard. Barely any color is good, else you run the risk of heat straightening, and this would not be straightening.

 

[rgray]

You probably don't need to soften it. A god drill bit will probably cut it fine.
You need a Time-sert : https://www.specialty-fasteners.com/Time-Sert-Inch-Coarse-Thread-Inserts-p/sku-1922.htm

 

[Cheeseking]

Forget the heat. Arbors at most case but not fully thru hardened. Carbide drill bit will cut it like butta.

 

[kd4gij]

Why not just use a metric drawbar?

 

[Alcap]

My mill uses a self-release drawbar ,there's cap on top which is held in place with 2 set screws . I kind of like that feature so it's a little more involved to swap back and forth