I am trying to machine a Dana 10.5 ring gear on my lathe and find it is some very tough stuff. Does anybody know how I can soften this steel so it will be machinable?

I am using a 13" South Bend lathe with carbide inserted tools and have only removed about .050" from the face and burned up two carbide bits.

If I can increase the inside diameter by about 1/4" and remove about 5/8" from the mounting face I have a clock that would fit right inside it and then I would have a cool clock.

 

Now that I know why you're machining it, it all makes sense.

I'd think you'd have to take the temper out of it. Heat 'er up red hot, then let it air cool. Do that a few times and see if it works.

 

Thanks Joe. I'll try that

 

Don't. Gears are hard for a reason, softening them by annealing them will ruin them. Instead, try this: I often have machine bearing inner races to the desired width, and it's not that bad if you do it right. First, use a carbide tool (which you are doing) with a medium radius. We use Kennametal Tin-coated inserts at work. Next use VERY low RPM's and a decent feed. I use about .010"/revolution feed and light cuts, like .020" or so and about 150 rpm's or so. Also, use cutting oil to cool the tool. By using this setup and feeds you'd be amazed at how hard a stuff you can cut.

EDIT: Sorry, I didn't see you were just using it for a decoration the first time I read it, in that case go ahead and anneal it if you want. I thought you were using them in your truck the first time I read it.

 

Probably too late by now, but for a better anneal, heat it red hot and cool it as slowly as possible. Ideally, bury it it foundry sand. But I guess a big box of "sand-box" sand would work better than just air cooling.
The longer it takes to cool, the "softer" it will be.

Let us know how it "turned" out!!

 

Not too late yet. Since it is only a hobby project I have put it off 'till I can refill my oxy-aceteline bottles.
Thanks for all the responses.

 

would it be possible to use a grinding tool on the lathe, like what is used for grinding flywheels

 

Sure it would be possible. But I don't have a tool post grinder.

 

I used to build handrails, and the quick way to smooth a weld was to chuck the pipe in a lathe, and hit it with an angle grinder while running on low speed. Maybe something along those lines would work for you.

 

Carbide insert tooling just won't cut it (pun intended). If you dont mind spending the bucks go for a CBN (cubic boron nitride) insert. It'll go thru it like butter - and the fireworks display at the cutting tool is pretty impressive as well!

 

Thanks PupnDuck. I'm always up for a new tool. Think I will try it..

 

Even annealed it won't be very soft. It's very high carbon steel. Since precision is not req., I would go with Jarod's idea and use the 4" grinder while turning the gear.

 

Since its a novelty no problem with wanting to anneal the part and machine it.

A 13" south bend lathe isn't rigid enough to properly hard turn the amount of material you want to remove. Don't bother buying an expensive CBN or PCD insert either, the lack of rigidity of your lathe will chip it and render it useless in short order. A cermet or ceramic insert would be the best bang for the buck but again you run into issues with the lack of rigidity of your lathe. If you had a sturdy CNC chucker or engine lathe it would be a little different story.

Grinding the material off will take forever especially on the id even with a tool post grinder. Best bet IMO is to anneal it and machine the material off. I've flame annealed tool steels and high carbon steels already and it can be done. Heat the steel above the austenite-cemntite temp (basically orange hot) and immediatly bury the part in sand completely and let it cool. When the steel is room temperature take it out of the sand. For even slower cooling you could heat the sand in the oven to get it somewhat hot before putting the ring gear in it. Should be annealed enough after that, if not repeat. If a high carbon steel file takes a good bit of material off per swipe you can machine it fairly well with carbide tools even if it is in the 50-54Rc range. Try to make your setup on the lathe as solid as possible, put as much cutting force as possible against the chuck (turning not facing) and go slow. Cutting .010"-.020 DOC at a slightly faster feed rate is better than taking a .050" or larger DOC at a slower feed rate. I would turn the ID first. Stay safe.

 

Thanks dkf. Your info was complete and informative. Although I do not know what "DOC" means I think if I get it soft enough to file then I can cut it pretty easy.

 

I think DOC refers to "Depth Of Cut".