Boring Cast Iron

[paulinlapine]

Hi all, I'm new here and a novice with a lathe.
I have a Grizzly 9x20 and am adding a tumbler reverse to it. I've read several write ups on doing this and it doesn't seem too hard. One step is to bore out the center of two of the change gears to accept small ball bearings. The gears are cast iron (I think).

Is there anything I need to know about boring (or turning in general) of cast iron? Does it require any special considerations?

Thanks in advance,
Paul
I

 

[coffmajt]

Turns easily but a little slower spindle speed than steel, with no coolant required [has a lot of carbon which acts as a lubricant when turning]. Rags to protect your ways are a good idea because cast iron produces a lot of small particles which can act like grinding wheel dust. -- Jack

 

[mikey]

How much experience have you had with boring, cast iron or any other kind? I ask because boring for a bearing press fit is somewhat of an exacting thing, especially if you are going for a line-to-line fit.

What kind of boring bars are you using? Do you have a way to accurately measure the bore as you cut it? Do you have the right sized micrometer?

Gears for a newer lathe may be readily available if you screw up. If they aren't then you need to be careful. In the latter case I would obtain some practice cast iron and be sure your bar and your technique are up to the task. Not trying to scare you - just something to think about.

 

[paulinlapine]

I had a go at it today..............with great success

I ground a 5/16 hss bit to my liking and ever so slowly started boring. This was my first time turning cast iron and I was somewhat surprised that the turnings came off almost as a powder. Maybe my cuts were too light, but I didn't want to screw it up. I needed to bore two gears to fit the ball bearings into and due to a dumb math error, the first one came out .001" too large. I locked the bearing in with some green thread locker and I think it'll be fine. On the second one I double checked my math and the hole finished at .001" undersized. Exactly what I was shooting for. I pressed the bearing in and was able to finish the tumbler reverse on my 9x20 today. It works great!

Thanks guys, for your advice

 

[Randall Marx]

Glad it worked out for you. Also, welcome to the forum!

 

[Wreck™Wreck]

Cast iron can be very hard and abrasive if intended, it is unlikely that gears in a Chinese produced tool are terribly hard by design but you never know.

You do know what steel is and what cast iron is correct?

 

[4GSR]

The Chinese cast iron I deal with is tough, very abrasive, and brittle. Works great for the drillable cast iron plugs we provide for the oilfield.

 

[7milesup]

I had a go at it today..............with great success

Thanks guys, for your advice

Didn't happen to take pictures of this did you? Would like to see what/how you did. How did you add the tumbler reverse?

 

[paulinlapine]

Aw nuts, I didn't take any pictures, sorry. As for the tumbler reverse, I basically followed Steve Bedair's mod at http://bedair.org/Tumble/Tumble1.html .
I made a few changes to my liking and use what materials I had at hand, but the basic idea and layout is the same.