Drilling steel

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I have a question and hope you guys can help me out. When drilling through steel  (2 layers of 3/16) with a 5/8th bit is it quicker to drill a pilot hole with smaller bit and widen it or just tough it out with  the 5/8th bit.  I'm drilling under a truck with a 1/2" hand drill. With my drill it took a long time to get through. I'm using the proper bit.  Thanks allot.
Reply:In you case I would have used a smaller bit first, perhaps 3/16 at most, to make a pilot hole, then follow with the 5/8. This will reduce "walking" off the desired center.  If in real tight quarters where I can hardly reach or can't properly apply any sort of lubricant or cutting oil, I would do it in three steps. It isn't faster...  but maintains center better, makes a cleaner hole, and is less likely for the large bit to grab and spin the drill around causing damage or injury.   I speak from experience....  Once upon a time I was under a pickup truck drilling a hole for something or other and had a 9/16 bit snag up and break with the broken end still spinning under power lance through my left forearm.  It wan't pretty unless you really like the color of natural red fluids.-MondoMember, AWSLincoln ProMIG 140Lincoln AC TombstoneCraftsman Lathe 12 x 24 c1935Atlas MFC Horizontal MillCraftsman Commercial Lathe 12 x 36 c1970- - - I'll just keep on keepin' on.
Reply:Originally Posted by Atomik777I have a question and hope you guys can help me out. When drilling through steel  (2 layers of 3/16) with a 5/8th bit is it quicker to drill a pilot hole with smaller bit and widen it or just tough it out with  the 5/8th bit.  I'm drilling under a truck with a 1/2" hand drill. With my drill it took a long time to get through. I'm using the proper bit.  Thanks allot.
Reply:If you went with a large pilot hole (say 1/2" or even 3/8"), you'll probably get too much chatter to be acceptable, but you want the pilot to be about the size of the web in the middle of the 5/8" bit.  The web is the part that ends in a point, which really doesn't drill well at all.  I would say the 3/16" is right on, and 1/4" might work well too.  It should seriously reduce the force necessary to keep the shavings flying.The cobalt advice is something to listen to.  Cobalt bits stay sharper MUCH longer cutting steel, and you need a very sharp bit to get results.
Reply:If you are drilling straight up into the frame a floor jack is the answer.I always tried to work with the oldest hand on the job to gain knowlege but now I can't find any.
Reply:thanks guys exactly the info i was looking for. My problem was more the amount of force i was having to apply.
Reply:A pilot and wax will help.
Reply:Generally the pilot hole is just a bit bigger than the web of the  finish drillA butterfly without wings, is just an ugly bug
Reply:I pilot drill when the hole size is over 3/8".  I make the pilot hole the next size up from the web thickness of the bit I'm going to use for the final hole.  I use a split point bit for the pilot hole.  I lean into it generally as hard as I can, I prefer screw machine length bits because because of this.  When it stops making ribbons, I stop and sharpen the bit, or get a new one.
Reply:By "web", do you guys mean the "dead" center of the twist drill?It doesn't cut"Any day above ground is a good day"http://www.farmersamm.com/
Reply:the best way to take advantage of the pilot drill is to use a 1/4 or 3/8 drill motor which has a much higher rpm than the larger drill motors.
Reply:Originally Posted by farmersammBy "web", do you guys mean the "dead" center of the twist drill?It doesn't cut
Reply:Originally Posted by Static-XJYes.  The largest diameter of the drill that is solid, vs cut away to make the flutes. I actually measure the web with calipers, then grab the next size up (letter/number/fractional) for the pilot hole.  I have even resharpened brand new chisel tips (standard drill bit) to a split point for drilling pilot holes before.
Reply:A word on cobalt. They will hold an edge longer than HSS however they are considerably more brittle. In most shops not used in hand drilling because they snap rather easily.A properly sharpened HSS used with a good cutting fluid will yeild amazing results.I use a Millwaukee Hole Hog for this kind of stuff cuz its compact and has tons of torque.And yes, I would go with a pilot.Our local Ace carries a good sulphur based thread cutting oil that will make life much easier.Another trick I use is to put a sleeve over the drill bit to keep it from pulling thru as the bit exits the hole. Makes for a cleaner hole on the back side.Aloha, LesAloha, LesMiller Legend, Oxy/Acet, HTP Invertig, Metal Lathe, Milling mach.,12'' Baldor grinder, Cinc Tool/Cutter grinder, and tons of other stuff.
Reply:this might sound very noobish, but i'm using silver and deming bits...
Reply:Originally Posted by LesWardA word on cobalt. They will hold an edge longer than HSS however they are considerably more brittle. In most shops not used in hand drilling because they snap rather easily.A properly sharpened HSS used with a good cutting fluid will yeild amazing results.I use a Millwaukee Hole Hog for this kind of stuff cuz its compact and has tons of torque.And yes, I would go with a pilot.Our local Ace carries a good sulphur based thread cutting oil that will make life much easier.Another trick I use is to put a sleeve over the drill bit to keep it from pulling thru as the bit exits the hole. Makes for a cleaner hole on the back side.Aloha, Les
Reply:The last time I had a cobalt bit snap, it was a 1/2" bit, in the drill press.  I opened the chuck with the key, and the bit slipped between my fingers, dropped through the center hole in the table, and hit the floor base, tip first.  The first 1" of the bit, just separated from the rest like it was glass.  I've still got it around, if I ever feel like sharpening a shorter bit.But I'm still not convinced that cobalt is more brittle.  I had an incident with the 5/16" bit from the same high quality set (made in USA), which seriously impressed me about the bit's toughness.  The 5/16" grabbed the workpiece, and ripped the 15lb cast iron vice holding it, from my hands.  When I instinctively jumped back, it lifted off the table (as I had let go of the press handle), and continued to spin until I pulled the plug.  The bit was left with about a 15 degree bend right at the chuck, from the unbalanced weight of the vice.The impressive part, was I put the bit on an anvil, straightened it with a hammer, and although its now got about 0.003" of runout, it still works quite fine.The lesson is that quality bits have heat treatment that leaves the tips harder than the shanks, and are quite resistant to snapping.  HF crap, isn't like that at all.BTW, the term Silver & Deming bits, refers to their size.  Although there is more history to the name, it now refers to a bit that cuts a hole larger than 1/2", where the shank is turned down to 1/2"
Reply:thanks. i read that but didn't quite understand first time around
Reply:But I'm still not convinced that cobalt is more brittle. I had an incident with the 5/16" bit from the same high quality set (made in USA), which seriously impressed me about the bit's toughness. The 5/16" grabbed the workpiece, and ripped the 15lb cast iron vice holding it, from my hands. When I instinctively jumped back, it lifted off the table (as I had let go of the press handle), and continued to spin until I pulled the plug. The bit was left with about a 15 degree bend right at the chuck, from the unbalanced weight of the vice.The impressive part, was I put the bit on an anvil, straightened it with a hammer, and although its now got about 0.003" of runout, it still works quite fine.
Reply:A softer shank also allows the chuck to grip a round shank instead of simply gliding around a smooth, hardened shank.While drilling a series of 15/16" holes in an I-beam at 13-foot ceiling level for a seismic retrofit I was concerned about bit grabbing and either injuring me before I could release my grip or knocking me off the narrow board I was using as a scaffold spanning from the boiler to the storage tanks in the boiler room.  I have had some contusions (but fortunately no broken bones or sprains) from large bits grabbing while using my fixed speed Hole Hawg.My solution was to screw two short pipe nipples terminated with pipe tees into the threaded handle sockets on each side of the drill motor body and slide the straight-through branches of the tees over the smooth shanks of two long bolts bolted to the web of a long piece of 2" channel.  The bit projected through an oversized hole drilled in the web halfway between the two bolts.To set up for each hole I'd clamp the far end of the channel to the I-beam, slide the tees over the headless bolts, and drill away.  The bits usually did grab when breaking through the far side of the pilot hole but all the reaction torque was taken up by the long bolts projecting through the tees.  Worked like a charm for the dozen or so holes required along the length of the I-beam.  No reaction forces at all passed on to the operator.  In fact, the fixture supported the drill motor in position, freeing up one hand to manipulate a lever arrangement to apply drilling force to the drill motor.The beauty of this arrangement is that, unlike using a single long pipe screwed into the handle hole of the drill body as a reaction arm, this symmetrical arrangement had no tendency to tilt the bit to one side when it grabbed.  As I'm sure most of you have experienced, this tilting of the bit off the hole axis compounds the grab of the bit in the hole, messes up the hole, and makes breaking of the bit (or the arm) more likely.Probably not too practical working on your back in the irregular, congested space under a truck but works fine if you have the space.awright
Reply:What I do when I have a situation like this. I live in Detroit, so I drive down to the corner and grab one of the local drunks that really need a drink, offer him a bottle of rotgut when the holes are finished, man you will never have anyone work so fast. The thought of liquor makes the drunk work quicker.If I Can't Weld It!-----It Can't Be Welded!
Reply:And for every hole that isn't within spec he looses one beer.Member, AWSLincoln ProMIG 140Lincoln AC TombstoneCraftsman Lathe 12 x 24 c1935Atlas MFC Horizontal MillCraftsman Commercial Lathe 12 x 36 c1970- - - I'll just keep on keepin' on.
Reply:I have to drill a lot of holes at work. I use a good old Milwaukee 1/2" holeshooter, use a handle if your drill has it. This is usually how I do it.1) Center punch the area you want to drill.2) I usually start with a 1/4" drill bit but you can go with a #21 bit if it walks too much with the 1/4".3) Step up to a 3/8" bit.4) Step up to a 1/2" bit.5) Use your 5/8" drill bit to finish up.It might sound like alot of work but at least for me I'm usually drilling 20+ holes so I just drill them all 1/4" then 3/8"...etc. It'll save you a busted knuckle or broken wrist. As far as lubrication, I usually use Edge which is less messy than cutting oil. If I do use cutting oil however, I would recommend putting some in a container like a plastic bottlecap or spray can cap depending on the size of the drill bit. I drill then dip the drill bit into the cap and drill some more.Last edited by Oxide; 02-21-2009 at 09:23 PM.
Reply:Also slow down when breaking through to avoid bit bite.A butterfly without wings, is just an ugly bug
Reply:I learn a new trick everytime I check a new thread, now I know how to figure the size of a pilot hole To big no good ,just big enough to give tip clearance. Another thing I have found is when drilling stainless ,once it starts cutting ,don't let up until the hole is through the material the drill will heat up very fast , keep the cutting coolant flowing  . I like my Mubea Ironworker  1" hole through 3/4 mild steel in a milisecond.   Keep on Welding Jim.Our local screw and bolt dealers have some drill bits that look like a tapered reamer. Make a pilot hole just a tic bigger than the tip and the will drill a double truck frame like cazy.Tough as nails and damn near as smart
Reply:ThisIs what I use.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:Do you think that is heavy enough to hold a license plate? A butterfly without wings, is just an ugly bug
Reply:Probably overkill for a license plate, but I'll bet it'd work wonders for a pintle hitch"Any day above ground is a good day"http://www.farmersamm.com/
Reply:It will haul a 25Ton Eager Beaver with a Cat 315 on it.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:DO YOU KNOW HOW TO SAY BALZZZZZZ??"Any day above ground is a good day"http://www.farmersamm.com/
Reply:You should see the rest of the truck, on paper it is an 85' Chevy Bruin. In reality it is a hodge podge of parts, a tired non turbo 3208 with a 13 speed behind it, and 2 different axles, trust me you need all 13 gears to get her moving under a load.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:Hey guys, thanks for the help, before. but i have a new question so i thought i'd  bump this up.     What bit should i use to safely step up a hole from 9/16th to 5/8th... and could you post a pic. i believe its a "step up bit"?
Reply:I would just drill it with the 5/8" bit since its the next whole size over 9/16". You can use a hole saw if your drill isn't big or slow enough for a 5/8" bit...BobBob WrightSalem, Ohio  Birthplace of the Silver & Deming Drillhttp://groups.yahoo.com/group/southbend10k/http://groups.yahoo.com/group/sawking/1999 Miller MM185 w/ Miller 185 Spoolmate spoolgun
Reply:I learnt the lesson of pilot holes years ago when I was young and inpatient (as opposed to now, old and impatient )I was drilling 1/2 " hole in 3/16" plate. Center punched it and took to it straight up with the 1/2" bit, which was already a little blunt.  Within 10 seconds I could hear the drill bit screaming and starting to get hot and blunt, and already knew by this stage that bit was now stuffed. But not being an important job I kept at it just to see how hot and what damage would be incurred. I drilled for a full minute and actually "MELTED"  the drill bit into the steel I was drilling through. After removing this melted drill bit, I put my 'sensible hat' back on and tried to start over with a smaller bit and progressively getting bigger, but the steel had now hardened to such a degree that it was "IMPOSSIBLE"  to drill any further. It would not even be scratched with the sharpest of bits, it had gone that hard !!
Reply:Originally Posted by Atomik777Hey guys, thanks for the help, before. but i have a new question so i thought i'd  bump this up.     What bit should i use to safely step up a hole from 9/16th to 5/8th... and could you post a pic. i believe its a "step up bit"?
Reply:well today i picked up a new drill a 7amp 550rpm d-handle, so that should work better... I didn't know the bit howling meant the drill was turning to fast.Last edited by Atomik777; 04-22-2009 at 05:23 PM.