I need a metalurgist

[Hugh]

Hi there Everyone,
I need a metalurgist to help me with a problem. I am trying to drill a hole in drill rod that I have heated up and let cool. The drill rod is too hard to drill. What I am doing is making some hollowing tools. I am making a gooseneck tool and I heat up the drill rod to bend it. After bending the tool - I cut off what I do not need (but did need to get the nice bend - this part was held in the vise while I was heating the tool). Then I try to drill the hole in the end for the tool bit. The steel is too hard to drill. I have tried to make a gooseneck tool by drilling the hole first, but I find I do not get as nice a bend due to having to hold the tip in a vise to bend it.

What I want to do is heat and bend the tool, cut off the tip and then drill it. What do I need to do to soften the drill rod after I have heated it up and it has air cooled? I am using water hardening drill rod.

One thought I had was to put the whole tool into the hot coals in the fireplace and let them cool slowly as the coals die out. Will that work?

Then once I get the hole drilled, I can heat up and harden it and then temper it. I can do this. It is the drilling of the hole that is the hard part. Can anyone help me here? Thanks.
Hugh

 

[Vernon Oberle]

boring bar hole

I use cold rolled steel purchased from our local tractor supply store. I use a center drill to start the hole dead center and then finish the hole. Then I use a map torch to heat and bend the tool. You should not be putting enough pressure on the tip to deform the hole (at least I never have) in order to bend the rod. the only reason I can see for hardening or tempering the bar is if it is a small one and you are going to grind the tip of rod into a tool bit.

Vernon

 

[Dario]

Read about tempering here http://www.efunda.com/processes/heat_treat/softening/tempering.cfm

 

[n7bsn]

Dump the drill rod, at least for this project. You are not going to get the drill rod up to plastic in your fireplace. It's simply not hot enough. Trying to bend a rod as hard as drill rod, at "dull red" (which is about all you can do with a wood fire) is simply not going to work. You would be much better off trying a torch (I have used a weed burner to good effect, but not with drill rod)

Go with a basic HC rod from your local metal/whatever shop, form it and then get it hard. Much easier route.

 

[john lucas]

I have made a lot of tools from drill rod. If all you need to do is drill the end heat this end to red hot so it's non magnetic and then let it cool slowly. If it's really cold in your shop this may require putting it in sand or just hit it with the torch occasionally to let it cool down more slowly.
Thick drill rod may require a MAPP gas torch. I have successfully annealed drill rod and other metals by putting them in a charcoal grill and letting everything get red hot and then letting it just burn out overnight. it can easily be drilled and worked after this treatment. Then go throught the hardening and tempering procedure. If your going to use the drill rod just to hold the cutting tool you don't need to reharden it.
I use cold roll steel for my boring bars and save the drill rod for tool posts and making tools where the edge is on the drill rod.

 

[Tom Lewis]

As has been mentioned in the above comments you need to anneal the drill rod. First heat the steel to cherry red which will be 1400+ degrees F. A easy way to tell when the temperature is right is to use a magnet. When the steel turns non-magnetic it is the right temperature. Stick the steel in ashes, lime, vermiculite, etc. Let it cool to room temperature and it should be annealed. If the drill rod is small you might need to heat up a larger piece of steel with it. That way it cools off slower.
When I forge knives out of 52100 steel I stack several blades together to anneal. One blade by itself cools off too fast and does not get annealed.
A easy way to tell if the steel is annealed is to check it with a file. If the file won't cut it, it's not annealed.

 

[GeorgeH]

Russ Fairfield's page http://www.woodcentral.com/russ/russ10.shtml has a lot of the answers you're looking for.

 

[Hugh]

While I have not solved my problem yet - I will try a couple of the methods that you have mentioned. I had the feeling that if I heated the drill rod up to cherry red and then let it cool - it would be annealed. But from your comments - it has been cooling too fast. I am going to throw one onto the coals of the fire tonight and see if that works. Then tomorrow I will heat another one up and put it into some old cool ashes. I might even put it into some really warm ashes and let it cool - it would take longer but might work.

While I was waiting for you guys to tell me ways to fix the problem - I drilled a couple of pieces of drill rod out on the ends before I heated it up and then used a washer (with a hole a little larger than my drill rod) held in a vise and used that to bend the rod after I heated it up. I was able to get a better bend - closer to the end - than I was using the vise.

I like the drill rod as it is a bit harder than cold rolled steel. I have a tendency to get too far off the tool rest for the size tool I am using and I need the stronger rod. I turn wet wood a lot and it does not rust as easily either.

Thanks for all the help everyone.
Hugh

 

[Sky]

My buddy is a lock smith specializing in safe opening. He gave me a special carbide drill bit for drilling hardened safes. It will drill holes in High Speed Steel. Drill press must be going fast, holding presssure onto the metal - it will turn glowing red then drill through the HHS quickly. Piece MUST be held in a vise. Should work with drill rod. Check with a local Safe & Lock Smith if they will sell you one. My bud gets the for about $10 each - his cost.

 

[Joe Greiner]

You don't need hardened rod of any kind for the shank of such a tool. On the basis of geometry alone, even hot-rolled steel will be heaps stiffer and stronger than a HSS cutter insert. If you still prefer some sort of hardened rod (maybe not drill rod, though), cobalt drills are amazing.

Joe

 

[john lucas]

I didn't mention it the other day but drill rod usually comes from the supplier, annealed. It is much harder than cold roll steel but I haven't had any problems drilling it straight from the supplier. You do have to harden it.

 

[Hugh]

John,
My tools are just a piece of drill rod with a hole drilled in the end and then I super glue a piece of tool bit into the hole. Like what David Ellsworth does. I remember seeing him at the Davis, CA symposium and he told me how to make them - which I thought was really cool of him.

I have made a bunch of hollowing tools and have had no problem drilling the drill rod before I heat it up. Drill rod is harder than cold rolled steel but is drillable. In my straight tool and the one at 45 degrees I do not heat them at all. Only once in awhile when I over reach the tool rest do I have a problem with the tool wanting to bend.
Thanks for all the advise everyone.
Hugh