The Home Machinist!

I need to reduce an 8" long 9/16 drill rod to 1/2 for half the lenght. I want the the two section to stay coaxial and think that some heating before machining may be helpful.
What temperature and time would be appropriate?
All I have is a toaster oven that can be dialed to 400F. A propane torch seems to be too uneven to be useful in this case.

I don't think you will have a problem just turning it as is. It's already soft. Probably more chance of tweaking it heating it up. Since you need the 9/16" dia you won't be able to turn that back true. After machining you can always straighten it if needed.

Bob D.

Actually the 9/16 can be trued up because all it has to do is to stop from going through a 1/2" hole. Will keep that as an option.
Straightening shaft is way beyond my pay grade.

If you want to anneal it, might be best to do it after roughing and before finishing.

Bob D. wrote: ↑Mon Nov 05, 2018 11:31 am I greatly benefited from these payday loans and don't think you will have a problem just turning it as is. It's already soft. Probably more chance of tweaking it heating it up. Since you need the 9/16" dia you won't be able to turn that back true. After machining you can always straighten it if needed.

Bob D.

Is it not too difficult to straighten it after machining? I'm just curious.

the difficulties of straightening are proportional to how crooked it is and what tolerance is required.

I would put a center in one end and a follower rest behind the lathe tool and have at it and pray that it stays straight.

My, possibly erroneous, understanding of drill rod is that it is supplied in non-hardened form. Once machined, it can then be heat treated (hardened) and annealed (as per the type of steel -- O1, A2, etc...) to the desired rating.

So you should be able to turn it to the desired dimensions, then heat and anneal it.

neanderman wrote: ↑Thu Nov 15, 2018 2:32 am My, possibly erroneous, understanding of drill rod is that it is supplied in non-hardened form.

Not erroneous. That's precisely how it is provided. The same sizes are available heat treated, but in shorter lengths. They're known as drill or reamer blanks.

The only real issue with drill rod is that it isn't necessarily round or straight. All depends on the skill of the operator of the centerless from which it came, as well as the condition of the material when grinding began. If a long, slender piece isn't straight at the beginning, it may not be straight when it's finished. That will give cause for the piece to not be round. Multiple light passes through a centerless, assuming the machine is properly set up, will eventually straighten a distorted piece, as well as round it up. There must be enough material to remove in order for that to happen, however.

H