View Full Version : General Metalworking cutting (?) cast iron

Michael Ginsberg
03-31-2011, 11:48 AM
Strange situation.... I have to cut a chunk out of an old lathe bed that is cast iron. I need to give it to a friend to extend his lathe bed by one foot. He makes walking sticks for disabled vets. I am not a metal worker... so I have no idea on how to do this. Can I score it with my hand held grinder or a carbide tipped sawzall blade and give it a hit w/ a hammer? The cast iron is about 1/4 inch to 1/2 inch thick. It does not have to be a pretty or clean break. I can smoothe it on the grinder afterwards. The chunk of lathe bed is not going to be actually attached to the other bed, just attached to the bench in line with the other.
Thank you all...

Dan Hintz
03-31-2011, 12:00 PM
Break lines won't work (no crystalline fracture line)... sorry to say, you gotta cut this bad boy the entire way.

Mike Hollingsworth
03-31-2011, 12:06 PM
Cast Iron is very soft.

ray hampton
03-31-2011, 12:13 PM
why not cut it with a sawzall ? why can't your friend use the bed without cutting it ?

Michael Ginsberg
03-31-2011, 12:30 PM
Space limitations. No room for the full 40" bed I have. As far as the Sawzall goes... What kind of blade should I use? Bimetal blade? Carbide?
I am sorry...I am clueless with this....

Dan Hintz
03-31-2011, 1:52 PM
They make Sawzall blades specifically for cast iron, but any metal blade will do it. I prefer rotary diamond blades and let my cut off tool handle it for big items...

Steve Ryan
03-31-2011, 3:12 PM
I have done some heavy CI cutting with just a reg bi metal blade. Be patient, the saw will do its job.

Michael Ginsberg
03-31-2011, 3:15 PM
Thank you. will try the blade. did you lube? Oil -water?

Scott T Smith
03-31-2011, 3:52 PM
No lube is necessary; CI is self lubricating.

A porta-band would be my first choice, easiest to use and cleanest cut. A sawzall would be the second choice.

ray hampton
03-31-2011, 4:26 PM
a metal -cutting blade should work fine, if you use a lube, will it help to keep the saw dust from the cast iron from flying all over the place

Chris Fournier
04-02-2011, 11:14 AM
I'd prefer to use an abrasive cuttoff blade over the sawzall as I think that it would do a tidier job as long as the operator was a skilled pilot!

ray hampton
04-02-2011, 1:28 PM
will the abrasive saw cut all of the way thru. this piece ?

Michael Ginsberg
04-02-2011, 4:04 PM
Do you mean a blade for my circular saw or angle grinder? Please keep in mind I am cutting a lathe bed that is about 6 inches wide, 3 inches high, and apprx 3/8 thick...

ray hampton
04-02-2011, 4:37 PM
Do you mean a blade for my circular saw or angle grinder? Please keep in mind I am cutting a lathe bed that is about 6 inches wide, 3 inches high, and apprx 3/8 thick...

abrasive blades are good at breaking into pieces [at least in my experience ]and will break when use in a cut-off saw, I doubt that we could hold the circular saw steady enough to cut this lathe bed, a angle grinder wheel is thick enough that it may not break

kelly logan
04-03-2011, 9:28 AM
Use a circularly saw with abrasive blade, a 2x6 as a guild and set saw to lightly grind a grove and every pass set the depth a little deeper. The deeper the cut per pass puts extra pressure on blade thatís why you take light passes.

Chris Fournier
04-03-2011, 10:01 PM
I use a 5" disc in my angle grinder. Of course you could use a really big unit.

I would lay out the cut in ink or tape and then use the cut off disc to get the job done ASAP! For me and my shakey hands I find that this method is almost surgical in precision.

Gerald Wubs
04-05-2011, 1:27 AM
I agree with Chris. Use a gas powered construction saw to get the job done if it is a large bed. Otherwise electric will be fine. Wear a dust mask and be prepared to get blackened. Lots of graphite in CI. Don't let things get too hot. BTW, notice the spark color - very reddish compared to steel.

Michael Ginsberg
04-05-2011, 3:41 PM
Thank you all for your thoughts. I will try Sawzall AND cutoff wheel in my Milwalkee grinder... We shall see......


raul segura
06-16-2011, 1:59 AM
I cut my grizzly band saw in half to add an extra 6.5 in. for slicing logs. I scored the deepest line I could with my 4.5 in. grinder (thin cut of wheel). Then finished with the sawzall.Its much more work with the sawzall. If you take your time it'll feel like cutting hard butter. I usually get my cut offs from Harbor Freight in packs. It wont hurt to cool the casting down with a hose .... sawzall blade.

Thomas Bank
06-16-2011, 2:26 PM
Based on my own tools available: porta-band, horizontal bandsaw, or plasma cutter - not necessarily in that order of selection.