accurate drilling

admin

This may sound like a silly question, but are there any sure fire ways of drilling a hole precisely where you want it to go? I am using a 10" table top drill press (not the best but not crappy by any means). I mark out and centre punch where I want my hole, but occasionally the bit seems to skid out of the punch area  and I wind up with an off centre hole.
Reply:When I have to repeat a bunch of holes accurately, I make a jig that clamps to the drill press and holds the material firmly.  I use split center bits and go slow when I start the hole.  Thats about as good as youre gonna get without spending a good bit of cash.  BobI'm spending my Kids inheritance, I dont like him that much anyway!!!!!!Enuff tools to do the job, enough sense to use em.Anybody got a spare set of kidneys?  Trade?
Reply:I like to use a small bit (1/8") to get a pilot hole done - with a very low vertical travel speed.  Then I switch to the larger bit for the right hole size.Hobart LX235Victor 250 Oxy-Acetylene Rig (welding and cutting)Bobcat 773F-350, 1999, 4x4, 16' 10K# trailerOutdoor Wood Burner - 10 cords/year
Reply:use a pilot hole ,then work up to the size you need if you need a 1/2'' hole start with 1/8 and go up  you don't say you are using one size or doing it in stepsidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:You don't necessarily need to work up in steps, just get a center drill, use that to start your hole, and then your bigger bit will follow the center drilled hole.  Make sure you have a good sharp bit, use some sort of cutting fluid/lubricant and you're good to go.
Reply:If drilling steel, use motor oil or even better thinner stuff liek air tool oil - drip it onto the material/bit while cutting to keep it "moist".  If drilling aluminum go for something thinner like kerosene.Hobart LX235Victor 250 Oxy-Acetylene Rig (welding and cutting)Bobcat 773F-350, 1999, 4x4, 16' 10K# trailerOutdoor Wood Burner - 10 cords/year
Reply:This may help use a center drill (from lathe) to start with.  Some times a small bit can bend and wonder off the center punch mark.  These bits have a bigger body and small tip. You can run the bit down to the countersink part to start a larger drill through bit. Attached Images
Reply:Originally Posted by acourtjesterThis may help use a center drill (from lathe) to start with.  Some times a small bit can bend and wonder off the center punch mark.  These bits have a bigger body and small tip. You can run the bit down to the countersink part to start a larger drill through bit.
Reply:As many have already mentioned, a center drill really helps for making an accurate pilot hole. I've seen them as cheap as $5 each at a local tool store. You may also want to try a stub drill in a good pilot size like 1/8", they're just short drill bits made of carbide. They're also very stiff (like a center drill) and don't wander easily.
Reply:Originally Posted by MechticianAs many have already mentioned, a center drill really helps for making an accurate pilot hole. I've seen them as cheap as $5 each at a local tool store. You may also want to try a stub drill in a good pilot size like 1/8", they're just short drill bits made of carbide. They're also very stiff (like a center drill) and don't wander easily.
Reply:Are you certain your finding the center of the punch mark? I use either a center finder or a super thin (flexible) drill to center on the mark.Is your setup suitably rigid?Center drills will work in a pinch but the small center is fragile and prone to breaking. I prefer single flute spot drills for starting. I also use stub drills when possible which are a lot more rigid than jobber length.A good cutting fluid will also help produce good sized holes. I frequently use Tap Magic.
Reply:Get an X-Y table, T-nuts and clamp set for your drill press, that way you can spell out exactly where you want it to go, like a milling machine or layout drill would haveCrank your table up and keep your quill as far in the drill head as possible.  More rigidity = less likelihood of bit walking
Reply:That's whats happening, the bit tends to bend and walk out of the punch hole. The centre drill sounds like the best bet. thanks all.
Reply:Originally Posted by greenbuggyGet an X-Y table, T-nuts and clamp set for your drill press, that way you can spell out exactly where you want it to go, like a milling machine or layout drill would haveCrank your table up and keep your quill as far in the drill head as possible.  More rigidity = less likelihood of bit walking
Reply:Center punch, pilot/center drill, and work up, or use a mag drill with annular cutters.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:A spotting drill is actually more effective than a center drill and more ridgid. Acceptable work can certainly be done with a center drill, but these were designed to drill hole to accept 60 degree dead/live centers in lathes, dividing heads.Also, watch how you mark your work with a punch. If you come at too much of an angle other than 90 degrees to work surface, you leave a raised burr of metal on one side of the mark which will make your bit wander off to the opposite side.
Reply:Originally Posted by OldtimerExcellent advise. Tap Magic is great cutting fluid like forhire said. WD-40 isn't too bad either.
Reply:Originally Posted by OldtimerTap Magic is great cutting fluid like forhire said. WD-40 isn't too bad either.
Reply:you could also pick up a dewalt pilot point to try http://www.dewalt.com/tool-parts/dri...ts-dw1909.aspx350P 30A spool gun cut master 51  syncro 250 other stuff " take a dog off the street and make him prosper and he will not bite you sad the same cannot be said for man" i didnt use punctuation just to piss you off
Reply:I use a four flute counter sink to pick up the center of a center punch dimple.
Reply:i hate drilling. try a set of thesethey work great Attached Images
Reply:Those edge finders pretty much require an x-y table to use...an accurate one is  very expensive... A less expensive method for really accurate hole making ( which would ideally mean boring but can use a drill )... would involve machinist buttons to locate where you want the hole... Then something like a coaxial indicator ...drill a hole close to where you want your hole.. screw the machinist button on it.. snug but not tight... tap it until it is centered on where you want the hole.... use the coaxial indicator in the drill to locate the drill in the proper place... take the button out.. and drill or bore....http://www.nolansupply.com/superprec...makers+Buttonshttp://www.google.com/search?q=machi...8845393480168fhttp://www.google.com/search?q=machi...8845393480168fhttp://home.iprimus.com.au/stevor/lathehtgage.htmhttp://www.amazon.com/Import-Coaxial.../dp/B002YPA9JGWeldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:All good suggestions so far but I have to reiterate - It is possible to get a good hole with a dull bit, and people win the lotto all the time.Look at the cutting edges on your bits - if there is any difference in the angle they are ground you will get an off size hole or in smaller bits they will walk or worm.  Even the best drill sharpeners get 'off' occasionally - use an angle gauge or  even an old protractor to confirm you are even and centered.When any government, or any church for that matter, undertakes to say to its subjects, "This you may not read, this you must not see, this you are forbidden to know," the end result is tyranny and oppression, no matter how holy the motives.
Reply:If you insist on using a drill bit.... then to get a really good edge and round hole... you can drill slightly smaller than needed and then REAM....for a truly accurate sized hole....Weldandpower Lincoln 225 AC,DC with Briggs 16hp gas engine.WW2 era Miller TIG.
Reply:I have a couple of HF table-top presses and they're a bit sloppy too.  One of these days I may re-bush them so they'll be tighter.  I've had pretty good luck using step drills too:  they're quite rigid, center easily, and pretty much stay centered as the hole gets bigger.  I'm also very careful, especially when i'm starting the hole.  I'll hit the center punch, back off to make sure I'm where I need to be, and either adjust or proceed.  Also, if you're using a vice, leaving it a bit loose when you're starting the hole will let the drill bit move the piece until it has found the center of your center-punch.The other thing I do is cheat.  When I'm making pieces that fit together or tabs or whatever, I'll clamp or even tack weld the pieces together to make sure  the holes line up exactly.  It's easier to get it right once than it is to get it right over and over again, and even if the hole is a hair off, well all the holes will still line up perfectly with their mates (all else being equal).Here are four 1/4" thick thingies tacked together for drilling and shaping.Lincoln Eagle 10000Lincoln 175HDGianttech 520DMiller Snap Start III as well use a center drill when the hole has to be absolutely perfect. The best investment I ever made for my drill press is a X-Y table!  Clamp the part in and then use the table to align it right where you want it to be. You can see a little bit of the X-Y in this pic. I'll never go back!
Reply:Use a scribe  to mark where the hole will go.. take a sharp automatic centerpunch (only like 5 bucks) and run it through the first line you scribed and you can feel the intersection where the 2  scribed lines crossed eachother ..Pop punch it..That will make the tiniest dimple, which you can then enlarge with a normal centerpunch if the drill wont center itself.. When you drill a pilot hole  make it as the same size of the web of the next drill, or slightly smaller.. You can Leave the piece loose on the table, so the drill can center itself in the punch mark..Have a bolt or something in one of the slots on the table so the piece wont whip around if the drill bit gets caught..Or you can have the piece in a vice and leave the bolts holding the vice loose so it can float and the drill will center itself.
Reply:pay some one else to do it
Reply:The best way to accurately drill is with a mill. It is a precision machine and does drill better than just about anything else. To drill accurately with a drill press can be done...to a point.......but the run out of the cheaper drill presses will keep you from any accuracy that is required for precision machining.The tables on many drill presses are not stiff enough to get accuracy....so a mill is the best method. Second best method is get a precision drill press clamp with linear micro adjustment. But the accuracy is still not up to a mill.
Reply:after you've centerpunched the hole's  location, how do you get it clamped to the press table so its directly under the drill?i do something like  described by ak4130 in post 27, run thew drill down into the punch-hole  and then clamp it.Last edited by weldbead; 05-15-2011 at 02:45 PM.
Reply:So I am kind of new to "drill-pressing" as well.  I've found a drill press can make nice, clean, straight holes, compared to hand-held drill.  But I learned something today - they are not much better at preventing bit wander at the start than a hand-held.Case in point:I TIG welded an O2 bung onto an tubular (probably about .065" thick) automotive exhaust today.  The hole was to be drilled after the bung was welded.I offered to drill the hole on my "new toy" - (an old, 300 lb, and having a reputation of having a good rigidity and quality for a drill press, "powermatic" drill press that I'm testing out for the time being..  I used a chunk of wood 2x4 under the pipe to get it in a good orientation, clamping the pipe on the table securely, and set the table height up so could drill without much quill extension too.  Made sure everything was tight, and RPM was set appropriately.Wanting to stay away from the internal threads of the bung, I decided on a significantly smaller bit diameter than the ID of the threaded bung, for a little insurance against damaging the threads.  I figured if my first hole was drilled centered enough, I might take it further with a larger bit I had, and if it was off-centered too much, I'd fall back on using my carbide burr to reposition the hole while enlarging it all the way.I was wondering if I could take a short cut (because of the massive drill press being used) and not center punch, and not start with a small diameter bit or at least a "split point" bit.  It didn't work out so well.  The bit ended up wandering more than I would have guessed.  Almost enough to run into the threads.  (Carbide burr on a die grinder then came out to finish the job of enlarging / re-centering the hole the rest of the way.)Anyway, I think the drill bit ended up wandering because of the following reasons:1.  I did not center punch a spot for the bit to start at.2.  The bit I selected was not appropriate for starting a hole.  It was not a "split point" tip, or an extremely small diameter bit, like a 1/16" bit.  I think to really avoid wander, you need a bit with a tip that engages into the "cone shaped cratered walls" left by the center punch.  That means a small diameter conventional bit, or a large "split point" bit, properly centered in the center punch's "crater".3.  The rounded surface of the tubing further promoted bit wander.So even with a good quality drill press, you can't cut too many corners when it comes to starting a hole precisely.  I am certain milling machines can start holes wherever they want by plunge cutting end mills, but they are apparently entirely more rigid animals.  Drill presses bend sideways all over the place, even heavy-duty ones weighting 300 lbs.  There may be a good bit of sideways bend happening in the chuck itself.  Of course the bit can bend to some degree as well. Attached Images
Reply:Originally Posted by weldbeadafter you've centerpunched the hole's  location, how do you get it clamped to the press table so its directly under the drill?i do something like  described by ak4130 in post 27, run thew drill down into the punch-hole  and then clamp it.
Reply:Originally Posted by BrettA Milling Vise is your freind there http://drillpressmillingvise.co.cc/
Reply:Center punch, use an x-y table, mount a wiggler with a pointer in the chuck and line it up with the punch mark. Start with a spotting drill, finish with the final drill size. if hole size is critical, end with an undersize drill and finish with a reamer.
Reply:Like this. You can see the x-y table and the clamping system. Clamping systems can be had at Enco or any other machining supply house. This was set up for milling instead of drilling, but same methods used. Attached Images