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#1
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drilling big holes in steel
say, around 3/4'' to over 1''...
whats my best bet for drilling? also, what can i use to chamfer the holes (cut the 90 degree edges off) thanks Last edited by SkaerE; 11-07-2003 at 05:16 PM. |
#2
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How about a mill with a rotary table?
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#3
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how about a cheaper way
seriously... cant afford one yet. maybe one day, but not this day |
#4
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Besides the bits , this takes a mill, mill/drill, or plain drill press with enough oomph to turn the bit, and slow enough to get the speed right for the large diameter. Machinery's Handbook shows 45 fpm for annealed O-1 with HSS bits, or 90 fpm for mild steel (actually there's variation depending on hardness, etc, get a copy of the book...). RPM = 12*V/(pi*D), so the 1" hole in annealed O-1 would require 12*45/pi = 170 rpm. That's pretty slow for most drill presses that folks would have at home. Mine will go down to 250 rpm. With a 3/4 hp motor, the biggest I've done is 5/8 in steel, and that didn't seem like a big strain, so I'll try bigger sometime when I need to. Mass - a big, heavy machine - is a good thing here, because there will be a lot of force involved and so on, and the thing will shake more than you're used to with smaller holes.
Alternatives: Drill smaller holes around the perimeter, then file or grind out the waste to get the size you need. Cut as close as you can with a torch and, again, file or grind for precision. Or, if you forge, punch it. Deburring: I like the little crank type tools, cheap from places like Enco. These holes are big enough to go around with a file, too. Or use a countersink (that's a big one) or a bigger bit (also a big one). Did any of that help? Steve |
#5
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big holes
SKaerE, if the sizes of the hole aren't critical you can buy a hole saw w/ different size saws. I showed a machinist this once and he was setting up on a mill w/ another tool, not even sure what it was but the hole saw saved him about an hour on each piece he was doing. I use them to drill holes for all-thread to hang pipe from instead of the big bits and the mankiller 3/4 " drills. Then you can use a rock on a small die grinder or a rorery file to chamfer the edges. Hope this helps, Mike
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#6
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drilling
What thickness steel are you going to be drilling?. If it,s 1/4" or thinner you can use a standard hole drill with pilot drill on it. After you drill the hole, then smooth it up with a 3/4" or 1" drum type sander on your drill press. to take the edge of use a deburring tool. (hand held type).
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#7
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Have used both a drill press at its slowest (60rpm) and one of the big mill/drills for drilling both stainless and plain carbon stock with 3/4 to 1 1/4 holes. The drill press was 1/2 hp and worked fine geared this slow, the mill 1 hp with 110 rpm). Be sure to use some oil or lube. You can feel the right feed going this slow. Stainless tool stock is pretty hard on the drills even with the slow speed.
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#8
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when you guys say a "regular" hole saw, do you mean the milwalkee bimetal ones or carbide tile saws?
thanks |
#9
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Slow RPM's like on a mill.
A hole saw(Bi metal). Unibit and reamers. Step drilling using three drills.(1/8" hole becomes the pilot for the 3/16" hole, that becomes the pilot for the 3/4" hole) Boring bar in a drill press. You may find a shop with an iron worker and punch the holes. |
#10
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Geno just laid out the options! I have had good success with a hole saw and pilot bit, where the saw is for steel and has carbide teeth. You wont get a precision sized hole but it will be close. Make SURE and clamp everthing down good though, otherwise you will be in a World of Sh*t.
__________________ www.wilkins-knives.com www.wilkins.de |
#11
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carbide grit hole saw
how about one of these?
http://www.harborfreight.com/cpi/cta...emnumber=46151 |
#12
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I have never used one like the Harbour Freight item. The one I have has welded on teeth like those used on metal larthe cutters.
__________________ www.wilkins-knives.com www.wilkins.de |
#13
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Remember to use a coolant with diamond abraisives(water).
They may work slow, but will work. The Bi-metal saw works great and much cheaper too. |
#14
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Another option is a small fly cutter in a drill press. Make sure your your cutting angles are correct for the speed and material.
I've successfully bored 1" holes in 1/8" stainless using plain HSS bits. The main thing to worry about here is cooling the bit and the piece. I use beer! -Frank J Warner __________________ --Frank J Warner Happiness is tight gibs and a flat platen. http://www.franksknives.com/ |
#15
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Typically the best method nowadays for drilling anything over 1" is an ANNULAR CUTTER. MSC and the rest sell these in their catalogs. An annular cutter is nothing more than a hole saw on steroids. Its precise, and very tough.
An annular will bore a very smooth finished hole, and keep the piece much cooler than a drill. It also will put a nice clean hole in metal, and not put a lot of wear and tear on your machine. The days of Silver & Demings are on the way out, and everyone I know who uses an annular will rarely buy another S&D bit again. |
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blade, forge |
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