Cutting 3/4 hole in 1/8" steel?

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I am not at the shop now but guessing the hole I need to drill is about 3/4 of an inch, its the perfect size to fit a 1/2" black pipe through and weld it in. I drilled one with a drill bit and what a chore that was, wondering if there is a better way for my last hole. I do have a plasma cutter and circle guide but don't think I can do a hole that small. Would free hand cutting a hole slightly smaller then drilling it out be better or would you suggest a hole saw?Hoping there is a better option than just the steel drill bit, that was a serious chore.
Reply:Metal that thin is prime material for a hole saw. A good one with an arbor where yu can add the rest of the bits in a series of sizes. A step bit would work good too. The make quite a few styles. Some have steps about equal to 1/8th inch. Some require a predrilled starter hole, some don't."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Uni-bit #4 I think.  Goes from 1/4" - maybe 1 1/4".   Uni- bit will do better than a holesaw on anything less than 1/8".  I'll take a pic if ya need one, or you could google it.My name's not Jim....
Reply:Another vote for a Unibit.http://www.mytoolstore.com/klein/59001.html (scroll half way down page)Get one in 1/8" steps for what your doing. You wont believe how fast you will drill out to 3/4".Millermatic 251Spectrum 300 PlasmaEverlast PowerTig 250EXEverlast PowerCool W300Harris / Victor OACraftsman 13 Speed Drill PressProTools Air/Hydraulic Bender48" BrakeCompressor, Notchers, Grinders, etc.
Reply:My bad, it's a #5.  I get them at menards.  I have a #2, #4, #5.  Those three cover most of my needs.  I could prolly live without the #4 though.  It's just the first one I got and as long as it works, I'm gonna keep using it.My name's not Jim....
Reply:I will admit, those do work pretty darn good!
Reply:These work great, we use em all the time to make some big holes in thing angle iron and the such. They cut like butter, and waaaay faster than stepping up with drill bits. I even use em free handed. Just center punch and go, I usually use some cutting fluid.Watch the video in the link.http://www.amazon.com/Champion-CT7-3.../dp/B0002PS7GW
Reply:Thanks guys some great advice.
Reply:I think 3/4" will be a tad small to fit the pipe in. A standard knockout hole for 1/2" pipe is 7/8", probably 13/16 would work for a really tight fit.I use step bits all the time, very fast provided you have a strong drill and the work piece is secured wellMiller Challenger 172Miller Thunderbolt AC/DC 225/150Miller Maxstar 150 STLVictor 100CVictor JourneymanOxweld OAHarris O/ASmith O/A little torchNo, that's not my car.
Reply:Just find the wright size washer and tack it to a piece of flat bar or angle, make it so you just clamp it to your plate and use the inside of washer as a guide and leave the drill motor on the bench. If you have more than one hole, add washers Attached ImagesI always tried to work with the oldest hand on the job to gain knowlege but now I can't find any.
Reply:Originally Posted by Denny KyserHoping there is a better option than just the steel drill bit, that was a serious chore.
Reply:Rota-broach cutters.  No better option than that for big holes in thin material.These are the ones im thinking of.http://www.hougen.com/cutters/sheetmetal/Rotacut.htmlHave we all gone mad?
Reply:Originally Posted by sn0border88Rota-broach cutters.  No better option than that for big holes in thin material.These are the ones im thinking of.http://www.hougen.com/cutters/sheetmetal/Rotacut.html
Reply:Like bigb said, you want a 7/8" hole.  1/2" pipe wont fit through a 3/4" hole.  I have drilled quite a few of these, takes less than a min on the drill press.
Reply:Hole saw for 7/8" size.  This is the size I use for smoker air intakes.MarkI haven't always been a nurse........Craftsman 12"x36" LatheEnco G-30B MillHobart Handler 175Lincoln WeldandPower 225 AC/DC G-7 CV/CCAdd a Foot Pedal to a Harbor Freight Chicago Electric 165A DC TIG PapaLion's Gate Build
Reply:Could you use the 12 gauge wire cutter?
Reply:Originally Posted by denrepCould you use the 12 gauge wire cutter?
Reply:Unibits actually come in conduit sizes which match the OD of standard pipe sizes.  1/8th inch is right at the upper limit of a Unibit's capacity but it will work.  But, my god Unibits are expensive.  They'll run around $35 a piece for HSS and $90 for a cobalt bit.  Drill bits in that size aren't much cheaper but they also don't work will in sheet metal.  Hole saws are quick and dirty and will work well enough.   Just go for whatever is available in your price range but do shy away from conventional drill bits.  You'll either break bits or break wrists.
Reply:Originally Posted by 76GMC1500Unibits actually come in conduit sizes which match the OD of standard pipe sizes.  1/8th inch is right at the upper limit of a Unibit's capacity but it will work.
Reply:Usually the tip wears the most. They make them with replaceable tips now, I think I'll try one. I use them all the time to punch panelboxes and junction boxes with 7/8 holes to fit my slugbuster in.Miller Challenger 172Miller Thunderbolt AC/DC 225/150Miller Maxstar 150 STLVictor 100CVictor JourneymanOxweld OAHarris O/ASmith O/A little torchNo, that's not my car.
Reply:This is a 1/2" hole punched through 1" steel plate.  It was made with a $39 Harbor Freight low-RPM drill and their cheap off-the-shelf bits.  You can see how big the shavings are when the drill is going slow.  I made four holes very quickly, and the bit was none the worse for wear.If you start with a small pilot bit, I can't imagine a 7/8" hole would be very difficult at all.  The key is that the drill shouldn't be generating heat.  You've got to turn the bit slow in order to drill fast.Here's the pilot hole I drilled:Hougen and Unibits will work, too (especially on thin sheet).  But I'm cheap.Last edited by Jack Olsen; 10-05-2010 at 12:44 AM.Jack OlsenMy garage website
Reply:Originally Posted by denrepCould you use the 12 gauge wire cutter?
Reply:I think I paid like $22 or 25 dollars for my 7/8" bosch drill bit that I use to drill through 3/16-1/2" plate.  I have never had an issue drilling though 3/16" steel with a "normal" drill bit.  Like Jack said, the key is to have the bit going slow.  I think i have my vfd turned down to about 100rpm and with steady pressure it goes right though like butter.
Reply:Originally Posted by denrepCould you use the 12 gauge wire cutter?
Reply:Originally Posted by BoostinjdmConduit sizes?  Where do ya get that?I do up to 1/4" thick fairly often with my big one, just flip the steel over and go in from the other side.  I do up to 1/2" thick with my little one, it has bigger steps.  Uni-bits will also do an excellent job on plastics an wood even.I knocked out a half dozen 1.5” holes in ¼” plate this weekend using a hole-saw.   A technique I learned from this site; is to drill a chip relief hole along the inside edge of the hole.   Go slow and use some cutting oil….  Wamm-bam…thank you mam
Reply:Funny, but no one including the original poster said where the hole is (or did i miss that), with my luck it's up-side-down, and can't be moved, or in some tight spot. lots of ways to drill holes though...........
Reply:For drilling things that can't be put in a drill press I use my Milwaukee 1/2" drive 28 volt cordless drill. Put it on low and keep the variable speed down next to nothing. It just shears out big curly chips like Jack Olson's picture shows and cuts thru in no time, and the bits hold up great. The cordless drill is much easier to control the speed. Right at the end when she tries to lock up I back out a hair, switch to high and push it gently thru while turning fast.Last edited by bigb; 10-07-2010 at 12:29 AM.Miller Challenger 172Miller Thunderbolt AC/DC 225/150Miller Maxstar 150 STLVictor 100CVictor JourneymanOxweld OAHarris O/ASmith O/A little torchNo, that's not my car.
Reply:I use these,2 irwin unibits and 2 craftsman step bits,I put caps on just to protect the point because I use these all the time,plus they take up very little space in the toolbox.Size range for these four-1 1/8" down to 1/8". Attached ImagesMaxus Pro-125 MigChicago Electric 90 amp DC flux-coreLincoln Electric AC 225 tombstoneO/A torchM/O mini-torch10 acres of flatland15 acres of holler
Reply:As one option you inquired about using a twist( regular steel bit) and gradually stepping up the drill size. This is a common misconception. The gradually increasing bit size to achieve a large hole. This plays havoc on the bits and requires much labor. To properly use twist drills, drill the  pilot hole that is slightly larger than the web width of the large bit matching desired hole size. Then drill the big hole. Works much better.Miller TrailBlazer 251Miller HF-250-1Miller MaxStar 150 STLHyperTherm PowerMax 380 plasmaLincoln PowerMig 180Millermatic 252Miller Diversion 180
Reply:Originally Posted by waginAs one option you inquired about using a twist( regular steel bit) and gradually stepping up the drill size. This is a common misconception. The gradually increasing bit size to achieve a large hole. This plays havoc on the bits and requires much labor. To properly use twist drills, drill the  pilot hole that is slightly larger than the web width of the large bit matching desired hole size. Then drill the big hole. Works much better.