Trueing up a cast iron flywheel

[Kaleb]

For my piston valve engine I took the idea of using a castor wheel as a flywheel, but I'm having some problems machining it. I've got the centre spindle and axle hole running true, but I'm having problems with the rim. My HSS tools hardly touch it, they just rub the surface. Even carbide has trouble. I heard these have a hard outer skin, so I ground the surface hoping to remove it.

Anyone got any ideas? I'm using a Sieg C1 lathe.

 

[Deanofid]

You may have one that's been chilled, Kaleb. Chilled CI is terribly hard, and I don't know what you will
be able to do to cut it on a small lathe. If that's what you have, it will be hard all the way through.
Really hard.
You might have to try something else. When you go to buy something like this, take a file with you.
Regular gray cast iron will file easily. Chilled, or white cast iron will not.

Sorry that I don't have something more useful to you.

Dean

 

[Paul_C]

As Deanofid said, it's probably hard through. Seems you verified that by trying to grind off the initial hard layer. I try not to let things beat me but in this case might be better to start over. But if you do decide to try again my two suggestions would be grinding. You could try single point grinding where you turn the spindle at it's highest speed and with the proper insert set at the optimum angle and using real light cuts and a slow feed the sparks will fly. The lathe needs a decent amount of power for that. The other is actual grinding. I use a Dremel flex shaft mounted in a boring bar holder. It will take a really long time since a Dremel isn't very powerful and also needs light cuts but it does work as a last alternative.

 

[cfellows]

Try reducing the spindle speed to a really low RPM, maybe 150 - 200. Sometimes you can get through pretty hard stuff that way.

Chuck

 

[Kaleb]

I tried again, with a low speed, light cuts, and plenty of oil, and I'm having some success.

 

[rake60]

The "skin" on some cast iron castings can be some pretty tough stuff.

Dean mentioned Chilled Cast Iron.
That is a miserable material to machine, but the finished parts are very
durable. I have machined very large parts that were made from chilled cast
iron. It's kind of like cutting concrete with a piece of chalk.

I doubt your flywheel casting was made to intentionally be chilled cast iron.
However, if the casting was allowed to cool too quickly that tough outer skin
gets thicker.

Slow surface seeds are a 'have to'.
The feed is where you need to experiment a little.
Sometimes it is better to try and plow through it with a heavy feed.
A slow feed will just abrade the edge even more.

There is no perfect answer.
You just have to try all the options until you find what works.

Rick

 

[Deanofid]

Rick, the reason I thought it may be chilled is it's not a regular flywheel casting. He's using an iron roll-around caster wheel. Hopefully it's like you say, with just a hard skin.

The tough materials can just be a hard job for a small lathe. Hope you get it to cooperate, Kaleb!

Dean

 

[tel]

Being a castor wheel it may even have been deliberately chilled.

What diameter are we looking at Kaleb?

 

[rake60]

Somehow I overlooked the castor wheel indication.

It may very well be chilled cast as Dean had originally suggested.

I need to slow down and read more thoroughly before posting.

Rick

 

[jonesie]

you could try and cut it with coated carbide or cbn inserts but you might have trouble with a small lathe. you would be better off if you can take a heavier cut and heavy feed , and the tool will have a less chance of just glazing over the material.do you know someone with a larger lathe that you could use to do the one job.good luck and work safe. jonesie

 

[deverett]

Just a thought. Would heating to red hot and holding it at that condition for a while (say 10 minutes) and then letting it cool very slowly anneal it sufficiently to allow machining?

Dave
The Emerald Isle