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Indexable for interupted cast iron turning

outsider347

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#1
Been using HSS to interrupted cast iron cutting on a SB lathe
Wondering if there might be a index able insert that will work without chipping?
Tks Gents
ed
 

4gsr

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#3
As mentioned above, find a piece of C-2 brazed on carbide tool. The old Kennametal or Carboloy one's were colored either gold or silver. Do not use the copper color looking ones, those are C-6. Try not to put a sharp cutting edge on corner of the carbide. Might even put a slight negative top rake on the cutter at the corner or tip of the tool bit. Run slow in back gear if larger than 2" OD. Try a coarse feed rate, about around .010-.015" and as deep as the tool will let you take. The key to it is get under the interrupted cut as quick as you can. Might have to get a little aggressive and brute with the cuts being made. C.I. comes off best when you can hog it! You think the lathe is fixing to come apart! There's not much more you can do trying to machine a interrupted cut on a 9" SBL. Done it several times in my past when I didn't have access to a heavier beefier lathe. Ken
 

benmychree

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#4
The main thing, as said above, is the C-2 grade, and negative rake on the insert (and holder) and avoid a keen edge on the tool's cutting edge. If the cast iron is not especially hard, there is nothing wrong with HSS with a appropriate cutting speed and lots of feed.
 

Dave Smith

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#7
stellite bits are very good for interrupted machining of cast iron---I found several of mine mixed in with HSS tools that I bought at auctions years ago----the way you can locate them from the HSS bits is to use a magnet---they are not magnetic---some have stellite names on them some don't---Dave
 

epanzella

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#8
I have a cheap indexable carbide set from Grizzly. When I had to face .003 off my faceplate the cast iron was just eating my HSS bit. I tried the carbide and it worked perfectly, despite the interrupted cut over the faceplate slots.
 

Wreck™Wreck

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#9
Since you are asking this question here one must assume that this is a one time hobby project on unknown material. Materials that are commonly called "Cast Iron" may have wildly different properties dependent on alloying elements and method of production.

No one can tell you what the best tool is for an unknown material.
 

Bob La Londe

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#10
Once I finally learned how to grind a decent general purpose tool in HSS I don't use anything else for interrupted turning. However, I would note that I've read a little bit about HSS inserts. That might be something to look at. No cheap carbide insert I've tried has survived contact with the enemy when dealing with interrupted cutting. Can't speak for expensive ones as I don't own any.
 

Dave Smith

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#11
Since you are asking this question here one must assume that this is a one time hobby project on unknown material. Materials that are commonly called "Cast Iron" may have wildly different properties dependent on alloying elements and method of production.

No one can tell you what the best tool is for an unknown material.

stellite and Tantung bits are good for most cast iron and can take the interrupted cutting better than most carbides or HSS tools