I am a woodworker who once in a while needs to drill through metal. I never want to use my good drill bits, so I end up using whatever else is lying around and it doesn’t work very well. I’d like to invest in some good bits for drilling metal, but I don’t know what to look for. Any suggestions?
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just go down to the hardware and buy a vermont-american index for $20 and drill away -
I've often looked covetously at the big indexes in the tool catalogs (every fractional size, every number, and metric too!) but a common fractional index serves well, if I break a bit, then I just replace it - if I have a special need I buy that specific drill bit -
do you have a drill press?
Yeah, Vermont-American is generally a reliable brand, yet reasonably priced.
If your view never changes you're following the wrong leader
Unless you're drilling really heavy stuff (1/2-inch steel, cast iron, etc) I'd just get a set of general-purpose drill bits -- whatever is one step up from the cheapest at the local hardware or big box. Set them aside for only metal work, primarily to keep metal shavings and oil off your woodwork.
Trick is to (1) center punch always, (2) use a drop or three of oil, and (3) go slow, to avoid overheating the bit. [And (4) use more pressure than you maybe think you should -- slow with more pressure is better than fast and light pressure.]
Edited 11/19/2007 11:02 am by DanH
I agree with every point but one.
(1) center punch always,
If you center punch stainless steel you just "tool hardend" the work & it turns into a bit eater after that.
"If men are so wicked with religion, what would they be if without it?" Benjamin Franklin
Well, I don't do much work with SS, so can't say. But it sure as heck helps with most other scenarios. In addition to keeping the bit from wandering it gives the bit an initial bite, like a mini pilot hole.
If your view never changes you're following the wrong leader
I learned that one the hard way.
We drill a lot of SS sinks & basins, we predominantly use holcutters View Image
I used to center punch the SS , but noticed my pilot bits were wearing out fast, then an oldtimer educated me on what I was doing wrong.
http://www.hougen.com/cutters/sheetmetal/Holcutters.html
"If men are so wicked with religion, what would they be if without it?" Benjamin Franklin
I use get generic black oxide bits from the corner hardware and have gone though 1/4 steel with them. Slow speed, high pressure and try to keep the springy thingy going.
Also, never use oil on wood. :D
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For a good time, visit MyToolbox.net See some of my work at TedsCarpentry.com
Edited 11/19/2007 10:35 pm by Ted W.
If you buy slit point 135 degree drills there is no need to center punch. They won't walk.
Cobalt, expensive, but great for metal.
Ya, I use cobalt for those difficult situations. They are definitely a step up. You could buy a mid-range index and when you wear out a bit replace it with a cobalt bit. There will be certain ones you use more. It might pay to have those be cobalt.
You can avoid center punching if you use 135 degree split point bits. Cobalt lasts too but proper speeds and feeds are a must with any drill bit touching steel or cast iron.
Even the best 1/4" drill bit will be trash if your spinning it at 2000 RPM with or with cutting oil. BTW don't ever use oil on cast iron.
Coolant (or oil), pull out the bit to remove swarf more often than you would on wood, and learn to sharpen your own drill bits. Takes about five minutes to learn and in one hour you will be sharpening like a pro.Drill press makes it easier.
I've never heard this, but then I am not a machinist.
I have used oil to drill cast iron manifolds. It seemed to help the life of the bit. What did I do to the cast iron?Frank DuVal
I don't remember the technical answer, that's what I was taught in machine shop. I've been out of the trade for over 19 years. Machined, drilled and tapped many a hole in the stuff and never once did I use oil, wear out tooling, or break a tap. Other than being very dirty to work with it was easy machining.Drill speed rounded off is 550/600 RPM using a HSS for a 1/2-13 hole Brass can be machined dry as well but drilling it required a negative edge for best results.
Edited 11/19/2007 3:19 pm ET by RobWes
There is enough of something (I forgot) in cast iron. You never need lube for cast iron.You can centre punch. Just use a small punch. Stops drill from wandering. If your drill bit is sharp it will have no problems cutting through the steel.I was a tool and die maker for four years (a long long time ago). We centre punched every hole. Super small tiny punch.We also bought cheap #### drill bits made in China. Coolant and a proper sharpening job and you can get a whole bunch of holes on one inch steel before you need to resharpen. Need to get your speed right also.
Cast iron is an odd beast. It's low carbon, making it soft, but often includes almost pure carbon (graphite) inclusions on the one hand, and carbide-like (hard) inclusions on the other hand. How much of which depends on the quality of the metal.
If your view never changes you're following the wrong leader
Thanks for that. It has been like 20 years so the brain is full of carbon and graphite.cheers
I once was working on a huge old Russian turret lathe. We were converting it over to modern controls from the amazingly poor Russian electronics. I had to drill a lot of holes for cable clamps etc, and the cast iron was like drilling marshmallows, or steel, or something like Kryptonite. Could be soft to hard in a couple inches. Ended up using a solid carbide twist drill. Some places were too hard to tap. The lathe was formerly used to bore tank engines.
"BTW don't ever use oil on cast iron."How come? Edumacate me, please. I don't ever remember drilling cast iron. I am however thinking about drilling a couple of holes in my drill press table to fasten my aftermarket table to it.
TFB (Bill)
LOL! Drilling wood is easy -- I use the good bits for metal and "whatever else is laying around" for wood. ;-)
Mike Hennessy
Pittsburgh, PA
Yeah, it's a lot easier to burn through wood than to burn through steel.
If your view never changes you're following the wrong leader
You have already gotten some good advice.
I like the Bosch TiN bits, or cobalt, Blue Mol, or Vermont American.
Center punch everything, including drill press work to avoid wandering at the start. Best to pilot any hole diameter over 1/4" diameter - saves your arm and your bits.
Have also heard no oil for cast iron - use water instead -- no idea why.
A tidbit which no one has related re: drill speed vs pressure - you have the right balance of speed and pressure when you are producing one continuous shaving from both sides of the bit - they will look "coil spring - like". The drill speed will be surprisingly slow and the pressure surprisingly high.
I have never produced a shaving as described from cast iron - always produce a gray dust which turns into gray mud with the addition of the water as coolant.
Good luck,
Jim
Never underestimate the value of a sharp pencil or good light.
I get the impression that you are not using oil on your bits. My drill bits last a long time, although I use them for both wood and metal. I have a strict rule that when I drill metal, I oil the bit. You can use cutting oil, air tool oil, motor oil, or whatever. Without oil, you can ruin a bit on one hole. With oil, you can drill hundreds of holes.
No need for special bits for occasional use.
When I have to drill thru a steel beam, I run cold water on it. it make drilling easy.
Use the 135 degre bits and if you're drilling a lot of metal find some Boelube. Best cutting lube to be found.
Good stuff.
And don't grab the bit to change it immediately after you finish the hole....
I used to be a metalworker a long time ago. Now I'm a carpenter. Now, whenever I change the oil in my truck I throw an old bottle in the back with my tools. That way, if I need to drill some steel, I can drain a little oil into the cap and dip my bit into it when I'm drilling steel.
A good center-punch keeps the bit from wandering and speeds the process by giving the drill point a good initial bite.
It helps if you start with a small drill and step up to the finish size, but then the drill bit jams in the hole just as it's punching thru and the drill stops turning and your wrist starts turning. You can stop that before it starts by securely clamping the work peice.
If you need to drill stainless steel, buy the coated bits. Otherwise, for the occasional hole nearly any steel bit will be fine.
Use a pilot point bit - http://www.mytoolstore.com/dewalt/dew02-09.html
Drill 1/2" thick steel - LOL yeah right! Why do that when you can use a Piranha?
Jeff