[Source] Cast Iron for Parts

EmilioG

EmilioG

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I'm thinking of switching the base of my 3 x 3" finger plate project from O1 tool steel to Cast Iron or some other, harder steel. I may heat treat some other steel, but I'm finding that O1 is very hard on cutters, blades, files, etc... You really need a good, tight mill to get close to accurate dimensions with O1. I'm considering the use of cast iron if I can find a good source. Has anyone used the CI from McMaster Carr? and, what are some good tips when it comes to machining CI? Carbide, cobalt or HSS? Un coated? I would need to square the blocks on all sides, plus a V groove, drill/tap and possibly bore a counter-bored hole. Do you machine CI dry? SFM recommendations? Can a flycutter be used to square flat the two large sides?
 
The only reason to apply 'coolant' to cast iron is to keep the dust down. Don't be afraid of it, it works easily, It's 3% graphite, almost slippery. You might want to use about 2/3 surface feed for high speed steel cutters, just to assure you don't burn them up. It is dirty, leaves black (carbon) dust everywhere. It's the most stable ferric metal to work, too.
 
The cast or rather extruded (continuous cast) CI bar that McMaster sells is fairly hard, probably class 40 iron and is close grained and does not raise so much dust as its softer neighbors; I doubt there is much if any difference between it and DuraBar, you know that McMaster house brands about everything they sell, so theirs may possibly be DuraBar.
 
I am working on a backing plate for a chuck right now. It is DuraBar. Ensure things are coved that you do not want the big chunks in, The fine dust may still get in so you have to clean your system after cutting but nice to work with. Remember it has a thick skin on it that you have to get through to get to the nice stuff. I had to slow the speed down and increase the feed rate, on my lathe.
 
kvt said:
I am working on a backing plate for a chuck right now. It is DuraBar. Ensure things are coved that you do not want the big chunks in, The fine dust may still get in so you have to clean your system after cutting but nice to work with. Remember it has a thick skin on it that you have to get through to get to the nice stuff. I had to slow the speed down and increase the feed rate, on my lathe.
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Yes, that was my experience with DuraBar as well, a chilled outer layer; you MUST get under the skin with the first cut to avoid dulling the cutting tool; when ordering, make sure there is enough oversize to allow this.
 
If you have a carbide tool that's for carbide use it to ruff cut , then go to high speed cast doesn't Do well with flat edge tooling , a little down rake from the top cutting edge helps get under the hard edge. If you tap don't use any cutting fluid it'll gum and bust threads out leaving weak threads.
 
I read that an old HSS cutter should be used to remove the "skin" layer first, then proceed with a good cutter.
Can CI be fly cut?
 
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