Pault17 Posted March 10, 2008 Share Posted March 10, 2008 For the last year or so, since my wife gave me a small 10-inch bench-mount drill press, I have been burning the drill bits up like no ones business. After searching the forums here recently, and having seen various comments made (not on the subject of burning drill bits, but of just drilling holes) I realized that drilling dry is no way to go:o you don't need oil when drilling wood! I recently picked up some real "cutting oil" and a little squeeze pump oil can, and WOW!! what a difference. drilling metal is now a whole lot more fun. Thanks for leaning me a new lesson... Now I just have to pick up some new bits of all sizes.. Quote Link to comment Share on other sites More sharing options...
John B Posted March 10, 2008 Share Posted March 10, 2008 Make sure you are not using too high an rpm when you are drilling, the general rule of thumb is: Smaller the diameter of the drill, higher the rpm Personally I normally use my drilling machine on its slowest or next to slowest speed unless drilling small diameter holes less than 1/4" diameter and have no need of coolant or cutting compounds unless doing high volume runs. It also helps if the drill bit is sharp and of good quality, there are some really poor quality drill bits around that work on wood, but not on steel. Using a drill made from the correct grade of material it is possible and practical to drill through files or springs in their working condition. You used to be able to get drills to "drill square holes". (Handy if you are making socket sets) Not used one for a long time though. Quote Link to comment Share on other sites More sharing options...
Jacob Posted March 11, 2008 Share Posted March 11, 2008 Yes, look up the recommended top speed for drilling steel with your desired drill size. The small benchtop drills tend to run very fast. They are usually designed for wood or small holes in light metals. I have an old 21" drill press, intended for metalworking. It has back gears and must turn down to 20 RPM. It's much less than once per second. It was advertised for up to a 1.5" hole. With that machine, there is oil everywhere, so you might as well put some on the tip of the drill while you're at it. Quote Link to comment Share on other sites More sharing options...
Glenn Posted March 11, 2008 Share Posted March 11, 2008 Oil on the tip of the drill to cut into the metal. Is that the same oil you put into your car so you do not get metal cutting into metal? Quote Link to comment Share on other sites More sharing options...
Thomas Dean Posted March 11, 2008 Share Posted March 11, 2008 Motor oil used for drilling holes will harden the material being drilled which in turn will dull the drill bit. Use cutting fluid for best results but if you have nothing else just plain old everyday WATER works good. For cutting stainless you would be amazed at how well Carnation Milk works! Problem with the milk is hot weather....sours! PHEEEW, but it sure works amaizingly well. Quote Link to comment Share on other sites More sharing options...
Glenn Posted March 11, 2008 Share Posted March 11, 2008 So, let me put this in writing. If you drill a hole and use motor oil as a lubricant to CUT the metal, this is the same oil you put into your car engine to lubricate and NOT TO CUT on the metal to metal surfaces, bearings etc. If you drill a hole and for whatever reason (too much speed, dull drill bit, etc) the metal gets hot, the motor oil can act as a quench, hardening the metal you want to cut. The same oil you dip the hot metal into to quench it so it will become REAL HARD. No wonder the industrial cutting and drilling operations FLOOD the cutting surface with the PROPER coolant for the job, keeping the metal both cool and the cutting tool and the cut well lubricated. Quote Link to comment Share on other sites More sharing options...
nonjic Posted March 11, 2008 Share Posted March 11, 2008 glenn, the squirt of oil you place on the drill can not quench the metal (to do this would require taking the metal from above critical temp, to below in a very short space of time). A cutting oils purpose is to prevent the swarf / cuttings sticking to the cutting tool . This should not be confused with a flood coolant (water souluable oil) which main purpose is to keep the cutting tool cool. (you can use plain water, but everything rusts!) The main problem when drilling carbon steels is running the tool too fast, bad quality tools and poor grind geometry (and insufficent feed pressure when drilling, so the tool rubs instread of cuts) Stainless steels will work harden (one of the metalurgists will know why, I dont :) Quote Link to comment Share on other sites More sharing options...
habu68 Posted March 12, 2008 Share Posted March 12, 2008 From "the Modern Blacksmith" 1904 Modern Blacksmithing, 1904 DRILLING IRON: "Every smith knows how to drill, sometimes it gives even an old smith trouble. The drill must be true, the center to be right, if one side of the drill is wider than the other or the drill not in proper shape the hole will not be true. For centuries oil has been used for drilling and millions of dollars have been spent in vain. It is a wonder how people will learn to use the wrong thing. I don't think that I have ever met a man yet who did not know that oil was used in drilling. In drilling hard steel, turpentine or kerosene is used as oil will then prevent cutting entirely. Nothing is better than water, but turpentine or kerosene is not as bad as oil; if you think water is too cheap use turperitine or kerosene. I had occasion once to do a little work for a man eighty years old, and when I drilled a hole, used water. The old man asked if water was as good as oil, and when informed that it was better, said: "I used to be quite a blacksmith myself, I am now eighty years old, too old to do anything, but I am not too old to learn." it ought to suggest itself to every smith that while oil is used in boxes to prevent cutting, it will also prevent cutting in drilling. " A nice little primer on blacksmithing at the turn of the 20th century Quote Link to comment Share on other sites More sharing options...
Thomas Dean Posted March 12, 2008 Share Posted March 12, 2008 habu68, Thanks for the quote from that book. I couldn't remember exactly how he said that as it has been a while since I have read the book. A fun read, especially the first couple of chapters! Wish I had a copy, a friend from out church had loaned his copy to me to read. Quote Link to comment Share on other sites More sharing options...
habu68 Posted March 12, 2008 Share Posted March 12, 2008 here it is in pdf for downloading Modern Blacksmithing, Rational Horse ... - Google Book Search Quote Link to comment Share on other sites More sharing options...
Thomas Dean Posted March 12, 2008 Share Posted March 12, 2008 Thanks! I never think of that...really computer savy here. Quote Link to comment Share on other sites More sharing options...
Dodge Posted March 12, 2008 Share Posted March 12, 2008 I know folks will argue against this but I have been using motor oil, transmission fluid, even wd40 when drilling, for years. (I have Dexron ATF in the pump can currently) At least don't drill metal, dry. 1/4" thru sheet metal, etc, is an exception and I'm sure theres a formula to support this, but the point is, you need a lube or coolant or both. Flood is best, "cutting" oil is desirable, but engine oil is better than nothing at all IMHO. Most important, however, is correct RPM for the drill bit being used. Google it;). I have the fortune of finding a drill/tap reference manual from the Cleavland Drill co. and I keep it near my drill bits. Find and print a chart and keep it with/near your drill press and you will be a happier camper :) Quote Link to comment Share on other sites More sharing options...
brucegodlesky Posted March 12, 2008 Share Posted March 12, 2008 Good advice Dodge. I've ruint more bits by running too fast or chipping them out going too slow with no lubricant. I been using water soluble oil as lubricant/coolant. Really does the job with softer stuff like brass and nickelsilver. Quote Link to comment Share on other sites More sharing options...
MRobb Posted March 12, 2008 Share Posted March 12, 2008 Thanks to all for the great advice. And thanks habu68 for the link on "Modern Blacksmithing, Rational Horse". Can't wait to read it. Quote Link to comment Share on other sites More sharing options...
fat pete Posted March 12, 2008 Share Posted March 12, 2008 feeds and speeds are important....especially cause of all the different alloys....coolants for different applications is important too Quote Link to comment Share on other sites More sharing options...
Pault17 Posted March 13, 2008 Author Share Posted March 13, 2008 Pete, thanks for the links. all, thanks for not beating me to death. I do help my drill speed cranked way down. I have just finished drilling several 1/2 md holes in 1/2 inch and one inch steel with little clatter and no burnt bits:D Quote Link to comment Share on other sites More sharing options...
nonjic Posted March 14, 2008 Share Posted March 14, 2008 I drill a lot without any coolant of any type, no problems (up to 3" dia) . on the radial arm drills we have a squeezy bottle with some soluable coolant in that we squirt at the bit every now and then to cool it off a touch. With correct chuck speeds, and a good solid steady feed pressure you can drill all day without coolant. I do like a proper cutting oil / grease when tapping holes though. 1 broken tap in an important job will cost more than a lifetimes supply of lube! Quote Link to comment Share on other sites More sharing options...
larrynjr Posted March 14, 2008 Share Posted March 14, 2008 A problem that I ran into while making a bunch of wall hooks, I got a good heat on them after they were formed then water quenched them to help get the scale to come off. Not realizing that cooling them that quickly also makes them very hard, I ruined quite a few drill bits try to drill holes through the top of those hooks before I figured it out and reheated them and let them cool slowly. After that they drilled easily. There was a very high pitched squealing noise when try to drill those hardened hooks! Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 14, 2008 Share Posted March 14, 2008 Yup A-36 is *not* necessarily mild steel a lot of tricks that worked with wrought iron or real mild steel will get you into trouble with A-36! Quote Link to comment Share on other sites More sharing options...
primtechsmith Posted March 14, 2008 Share Posted March 14, 2008 Larry. What I tend to do with my wall hooks and S hooks is use the heat to your advantage to descale the material. Light finishing hammer blows at a gray heat will knock off a lot of the scale and having a hand wire brush handy to run over it a few times helps too. Then I just throw them all on the floor and let them cool on their own. I did the "quench before drilling" once. Mike came over and told me that noise was not good...and why. The why is always important! The next day he bought a Drill Doctor to sharpen the drill bits and a new lesson was formed....reading calipers to correctly put all the drill bits back in their proper places after sharpening them. Like Mike tells me: "Experience is a wonderful thing." :-) Peyton Quote Link to comment Share on other sites More sharing options...
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