What are the best drill bits for drilling into cast iron?
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any sharp bit, if the hole size is large, work up to it, have an assitant on hand to periodically squirt some diluted dish detergent on the cut, slow but sure ..
Why not cutting oil?
Tu stultus esRebuilding my home in Cypress, CAAlso a CRX fanatic!
Look, just send me to my drawer. This whole talking-to-you thing is like double punishment.
It gums up. Cast iron doesn't machine into chips, but rather into "dust". It is best machined dry or with some kerosene or mineral spirits as a lubricant.
"or with some kerosene or mineral spirits as a lubricant"I don't want to say this comes from experience, so I won't... but, you might want to keep a wet blanket or fire extinguisher handy if you use flammable solvents for metal cutting lube! I think the higher flash point is part of what makes "cutting" oil different from "plain ole" oil.-t
Actually mineral spirits is really hard to ignite - it needs to be vaporized first - sort of like diesel fuel. I remember the first time I found this out was when the oil burner repair guy would put out his cigarette in a can of fuel oil.
But, seriously, drilling cast iron gets nowhere hot enough to worry. We always machine it dry since it is much cleaner that way and any oils are tough to remove from the pores in the cast iron if you need to finish it afterwards.
Cutting oils traditionally have a higher sulfur content. Many of the "newer" ones are emulsions of oil and water, with synthetic lubricants.
Cast iron doesn't machine into chips, but rather into "dust"
HUH? my experience is that CI makes nice and easy chips vs. cirlicules. CI is about as easy to machine as wood!
edit - do 100% agree with your 2nd post, gotta have the turning near red hot to ignite any type of oil, even diesel -- although DW has complained about the smell in the house when I've turned 4340 too fast at 1300 rpm with a spray of 10W.
Edited 4/8/2009 7:09 pm ET by junkhound
There are different grades of cast iron. The stuff that we use is still poured in the US and is very fine grained. We generally drill, bore, ream and tap it and unless we really run the ipr up when drilling we get mostly fine powder or dust with maybe the occasional "c" chip. But, then again this is a very costly grade and maybe the stuff used for boiler sections and the like is more likely to produce chips.
I agree, nothing like the smell of overheated lube to overwhelm the nose.
"I agree, nothing like the smell of overheated lube to overwhelm the nose."Maybe that's why they used to use lard as cutting lube. Smells like bacon!-t
cheaper