help drilling round holes

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trying to drill some 3/4 holes in 3/16 wall square tube.  tried hole saw, with hand held drill, didn't work to good, walls were not straight.  got a drill press, tried hole saw, not much better.  got a 3/4 drill bit for the press, center punched, drilled pilot, drilled 3/4.  The hole is anything but round.  This shouldn't be this difficult! I know the two responses will be, mag drill and annular cutters, and the best drill press is a mill. but for now out of the budget. what am a  doing wrong that i can't get a mostly round hole?  Thanks for any suggestionsMiller Thunderbolt 225Millermatic 135harris oxy/propane torch
Reply:drill undersize and ream?
Reply:Ya answered yer own question- not that you need a Mill/Drill but your DP isn't good enough.Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:maybe.  I wasn't looking to be that precise.  was hoping for mostly round and about 3/4.  i seem to be having trouble meeting my fairly low expectations!  My results are more hexagon then round,  I've seen others results with a hole saw and i'm not remotely close with the hole saw or drill bit, so I suspect it's me doing something wrong.Miller Thunderbolt 225Millermatic 135harris oxy/propane torch
Reply:With a drill press and bi-metal hole saw (or 3/4" bit with pilot holes) why is the hole not round?  Is there THAT much runout on your drill press???  Is this a $50 HF press?   Or are you not securely clamping the tubing to the table?Lincoln AC225 & MigPak 140, Lincoln Magnum SpoolGun, Miller Spectrum 375-X Plasma, Syncrowave 200 TIG, Millermatic 252 MIG, Miller Digital Elite, General 7x12" horiz/vert bandsaw, 3' box/pan brake, 20 ton press, milling machine, 12x28 lathe, etc.
Reply:it's a 15 inch clausing model 1770 variable speed 3/4 hp.  it's used, but new to me (best i can figure late 60s early 70s), but i can't seem to find any problems with it.  runout on the spindle is about .001 according to my mag base and dial.Miller Thunderbolt 225Millermatic 135harris oxy/propane torch
Reply:Not sure how round you need it to be, or why the holesaw wasn't round enough.  Yeah, the twist dill is a bad choice.  Best bet is to use a step drill, but not many will work well with 3/16" wall stock, because the steps may be too shallow.
Reply:Endmill in the drill press should work if you advance it slowly. Trouble will be to find a 3/4 in endmill with 1/2 in shaft. Also have had some luck before using carbide router bits chucked in a drill press, again need to go at it real slow as the router bits are designed to take a lot bigger bite than an end mill.Lincoln PT185 TIGLincoln 175 MIGLincoln 240 amp AC StickLind Needle Arc plasma welderPlasma cutter, soon???
Reply:I don't know if you tried measure the runout with a piece of round stock you know to be true in the chuck and measure from there.  Maybe you need to replace you chuck if you spindle is true.
Reply:i didn't check the chuck, i just got a new arbor (MT-2) and chuck (threaded) but i didn't check after installing since they are brand new, but i guess i should.Miller Thunderbolt 225Millermatic 135harris oxy/propane torch
Reply:I've had some luck with a one-cutter-lipped counterbore tool.  It stays centered and doesn't bite like a standard drill bit.  Also,do you have any play in the bearings?  You probably have a locking handle for the spindle up/down motion, might want to snug that up a bit...
Reply:Originally Posted by sreachardtrying to drill some 3/4 holes in 3/16 wall square tube.  tried hole saw, with hand held drill, didn't work to good, walls were not straight.  got a drill press, tried hole saw, not much better.  got a 3/4 drill bit for the press, center punched, drilled pilot, drilled 3/4.  The hole is anything but round.  This shouldn't be this difficult! (snip)what am a  doing wrong that i can't get a mostly round hole?  Thanks for any suggestions
Reply:Just a brain fart, but how about drilling a 3/4 hole in a piece of wood as a guide. Clamp the wood guide on top of the metal to be drilled. Maybe this will take out the wobble. My press wobbles but I don't do any drilling that's critical. Hell, I've got a 3/4 bit and it makes sorta three sided holes. Go figure. How a round bit makes three sided holes is beyond me!200amp Air Liquide MIG, Hypertherm Plasma, Harris torches, Optrel helmet, Makita angle grinders, Pre-China Delta chop saw and belt sander, Miller leathers, shop made jigs etc, North- welders backpack.
Reply:Originally Posted by sreachardtrying to drill some 3/4 holes in 3/16 wall square tube.  tried hole saw, with hand held drill, didn't work to good, walls were not straight.  got a drill press, tried hole saw, not much better.  got a 3/4 drill bit for the press, center punched, drilled pilot, drilled 3/4.  The hole is anything but round.  This shouldn't be this difficult! I know the two responses will be, mag drill and annular cutters, and the best drill press is a mill. but for now out of the budget. what am a  doing wrong that i can't get a mostly round hole?  Thanks for any suggestions
Reply:You want to drill a quarter inch hole first. Then a half inch hole. Then I would drill a 11/16" or 23/32"  or 47/64" hole and then a 3/4" hole. If I wanted really nice round accurately sized holes, that are not coned shaped, larger at the top then the bottom. On an aircraft for rivets they used to go up one number sized drill 4 times for the finished hole. To keep it super accurate. The bit at the end gets stuck in the hole. That is how nice a hole it drills. You cannot have slop in your drill press either. Up or down slop. Or the drill will thread through and not cut through.        Sincerely,             William McCormick
Reply:thanks for all the replies, with the hole saw by the walls not straight, i mean the the walls were not square to the face of the work piece, like it was drilled on an angle.  i'll try some of the suggestions and get some pics of the results.  wont be until saturday, taking the day off tomorrow to take the kids to the zoo, should be interesting, my 3 yr old dosent want to go because she is afraid of the lions!! Thanks again to everyone.Miller Thunderbolt 225Millermatic 135harris oxy/propane torch
Reply:How procedure wise did you install the chuck?
Reply:If the hole is not square to the face of the material, you need to check the table on the drill press. Is it square to the spindle? If not, square it up. If you can't (often you can't... a drill press isn't a mill), then you need to square it up with the fixturing. Next, check your fixturing. If the table is square, a decent vise should be able to get the material pretty close IF the vise is well clamped to the table, and the material is supported so that it doesn't deflect the table. If the table isn't square, or you don't have a decent vise, or the material is causing deflection, then you start shimming and leveling the work. This can be done using shims (ranging from cuts of sheet metal for bad cases to shim stock. I keep a couple of beat up feeler kits around for this. I NEVER throw them away when they are damaged), or can be done by using screws (1/2" bolts work well. Drill three holes through the mounting flange of the vise, tap for 1/2" bolt, and use the bolts to level. Then snug the hold downs)If you are clamping directly to the table, same principles apply.The other question is how good the holes need to be. If they need to be nearly dead on, a reamer is the best option. Drill about 1/32 undersize and follow with the reamer. If they only need to be pretty good (say five thou), use a bridge reamer (drill about 1/16 to 1/8 undersize for this). You can also use a three or four flute drill (core drill, used for finishing cored holes in castings. They won't drill without a hole top follow) for a five to ten thou tolerance and very close to dead round. The cheapest and probably most versatile for use later is probably the bridge reamer.
Reply:Use a single-flute Unibit . . . http://www.google.com/products/catal...9936685709799#The steps are only 1/8" but you will be drilling all the way through with the last step . . . 3/4" . . . so it will still work with the 3/16" wall tubing.  Do not be tempted by the two-flute variety sold by HF and others.  They will chatter just like a jobbers drill.  Run it no faster than 300 RPM, use cutting oil and I promise you it will produce a round hole.
Reply:I just recently cut some 1" holes with a whole saw through 3x3x.25" square tubing on a HF drill press my friend has.  I turned down the RPM to 330 and made sure the base plate was square.  Then i cut pretty slowly and added cutting oil every min or so and got a nice square cut.  I think for what you are doing you want 330-400 rpm and a slow down speed.  The big thing is making sure the material is clamped well. I used 2 clamps to attach my tubing.Maybe your outer cutting portion of your whole saw is not true?  Try getting another one, i think they are only like 10 bucks?
Reply:A simple reason a drill bit does not make a hole round is that it is dull or unevenly sharpened.Esab Migmaster 250Lincoln SA 200Lincoln Ranger 8Smith Oxy Fuel setupEverlast PowerPlasma 80Everlast Power iMIG 160Everlast Power iMIG 205 Everlast Power iMIG 140EEverlast PowerARC 300Everlast PowerARC 140STEverlast PowerTIG 255EXT
Reply:I think he wanted very square precision holes. Hole saws do walk. And even a brand new bit in a good lathe will cause a hole larger at the opening then at the finish. If you do not step up in drill size. It is just the amount of friction and drill shavings that have to pass by the start of the hole. Compared to the end of the hole. I do a good deal of machining and I found that this is always true. I get a slightly larger hole in the end I start in then the end I finish in. A very heavy duty drill press moving very slowly, in all fairness does make a sweet hole,        Sincerely,             William McCormick
Reply:It has taken me a while to get back to this, but i finally got a round hole.  I got some bigger better clamps and that seems to have done the trick.  so i guess my entire problem was not enough clamping force on the work piece.Miller Thunderbolt 225Millermatic 135harris oxy/propane torch
Reply:acctuall if you look at a hole made by a smaller bit like  a 3/8 close enough they are triangle shape slightliy and it gets worse the bigger the bit there is a reson behind it and i can not remember what my father and machine shop teacher told me but for most things it does not make a differnce having it slightly out of roundLincoln Pro Core 125Lincolin sp 100Miller Big 40Lincoln Idealarc SP250miller matic 212http://www.facebook.com/hdwelding?sk=wallwww.hdweldingbeds.com