how to cut holes in concrete for Door\ fencing posts?

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I am looking to add some security to my garage for various reasons.  The first step I will tackle is protecting the flimsy access door.  I have chosen 2x4 structural steel tubing for the two posts that will be sunk into the concrete landing.  These two posts will make the frame from which my own fabricated door will hang( either on hinges or perhaps in sliding track manner, I haven't decided yet).  I have never sunk anything as large as 2x4 steel tubes in concrete before.  How does one go about cutting a hole big enough to accept both the steel and concrete fill while providing enough depth for strength and solidity?all I want in my life are....... white castle cheese burgers
Reply:Wet Saw and skill. If you don't know how to use one hire somebody. Another option is a chopping gun with a chisel bit.I.B.E.W Electrician and Damn Proud of It !!!! .Virtus Junxit Mors Non Separabit http://www.shrinershospitalsforchildren.org/
Reply:concrete is hydroscopic meaning it attracts and holds a fair amount of water.  it also has other corrosive effects on steel.  i would suggest welding a plate to the bottom of the 2x4 and bolting it to the concrete.  now there are several ways to secure bolts in the ground, but the easiest is a slip anchor bolt like a redhead.  if you want to after you bolt it down you can tack the threads so the nut will only come off with a torch.
Reply:I needed to set a post out in the middle of my patio to extend my cover. I just marked out a square on the concrete large enough to get a set of post hole diggers in. I drilled a 3/4" hole at each corner and one in between corners with a carbide masonary bit  and a hammer drill. A few licks with an 8# doublejack and I had a rough hole. I trimmed this up with a bricklayer's chisel and 4# hammer. I had all the tools so no cost and it wasn't all that hard to do. I dug down 2' and set the post. The cover has stood up to a measured 93 mph wind so I guess it is pretty strong.
Reply:A hammer drill and either use a redhead like said above or an epoxy set fastener and weld the nut to the threads.  There are many options for and styles to accomplish what you want done, my first option would not be to cut a two by two hole in concrete especially if I had never done it before.  And also like said above the properties of concrete wreak havoc on steel.
Reply:You could use a core drill.  These make perfect round holes in concrete.Millermatic Passport PlusMillermatic 200Millermatic 350P with PythonXMT 304 /w S-64 feeder and 12RCDynasty 300 DXVictor O/APremier Power Welder for my trail junk.
Reply:as pointed out above, you can build  a  gate from hell  but  a thief with an 18v sawzall will cut through a weaker spot. in  my neighborhood they cut out a back wall 5 studs wide to remove the couch and tv...maybe beef up the flimsy  door instead...
Reply:Originally Posted by weldbeadas pointed out above, you can build  a  gate from hell  but  a thief with an 18v sawzall will cut through a weaker spot. in  my neighborhood they cut out a back wall 5 studs wide to remove the couch and tv...maybe beef up the flimsy  door instead...
Reply:Originally Posted by OldtimerI needed to set a post out in the middle of my patio to extend my cover. I just marked out a square on the concrete large enough to get a set of post hole diggers in. I drilled a 3/4" hole at each corner and one in between corners with a carbide masonary bit  and a hammer drill. A few licks with an 8# doublejack and I had a rough hole. I trimmed this up with a bricklayer's chisel and 4# hammer. I had all the tools so no cost and it wasn't all that hard to do. I dug down 2' and set the post. The cover has stood up to a measured 93 mph wind so I guess it is pretty strong.
Reply:I'm a flatwork guy, I've rented core drills several times. they are like hole saws. You can rent them with the drill motor too and the rental place will make sure the drill motor is big enough for the core drill. It's easy just don't try to rush it. And as far as the rusting is concerned, don't worry about it, re-bar is just high strength steel, not stainless, and anchor bolts are just plain non graded bolts. Neither has a problem prematurely corroding in the concrete. your idea of sinking the posts in the concrete is the best and most attractive design, a bolted on mounting plate always looks like an after thought. No offense meant to those who suggested it, it works good in a pinch.
Reply:Your other option could be to check the local rental stores to see if they have a concrete chainsaw, i know mine does and i have used it before, not quite as easy as a core drill, but you can cut a rectangle or a square if you wanted to.Miller Dynasty 300dxSpeedglas 9002XMiller Spectrum 375 XtremeLincoln PowerMig 255xtLincoln PowerMig 140cMilwuakee Portaband
Reply:The chainsaw might be a bit much to do a post hole. I use those to cut 10"-12" conc. walls. They do cut real nice corners, but you will eat a blade fast if you have it buried in the dirt like you would have to to get good corners. For a post I would either use my 14" gas saw with the diamond blade, or the skill saw with the 7" diamond blade. With the skill saw you won't get the corners super good unless you over cut. I usually drill out the corners and then go at it with the big sledge and the chipping gun. As long as you score the top well it will look good. I use the gas saw outside, the skill saw inside usually.Be away there will be A LOT of DUST! A good dust mask is a requirement.  I wet cut whenever possible. It does make a bit of a mess, and you have to be real cautious with water and the skill saw. Works best with two people. One with a garden sprayer or hose on super light, and one cutting. You just need enough water to knock down the dust. Spray the water at the front edge of the blade, and the saw usually drags the water down and eliminates most of the dust.A core drills not a bad idea for small posts, but for that size, you will need a big bit and they get pricey very fast. 8-10" is usually the minimum size to use a post hole digger, 12" is better..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Originally Posted by Broccoli1Seriously? WTF? the TV sure but who steals a couch
Reply:Maybe using wide base plates with four 5/8" x 6" per plate would be easier.
Reply:4421frank is in Chicago, if this is outdoors he can start with any size small hole, and next winter as water collects and freezes it'll heave the concrete and make a hole big enough for two posts! Unless the frost finds it easier to just push the building's foundation in. Seriously, a post set above the frost-line without a footing, will lift from frost-heave and then misalign any gate that's attached to it. If water collects under the concrete through the drilled hole, and can't drain away, the water will freeze and heave or break the whole slab. If the incoming water can drain away, it'll take the base material with it, then the slab will just cave-in. You can't win when putting holes in concrete.It's not unusual for the concrete pour next to a wall to already be weak or undermined. I'm voting for the plate, retained with anchor-bolts in sealed holes.Good LuckLast edited by denrep; 08-28-2009 at 01:40 AM.
Reply:Originally Posted by denrep4421Seriously, a post set above the frost-line without a footing, will lift from frost-heave and then misalign any gate that's attached to it. If water collects under the concrete through the drilled hole, and can't drain away, the water will freeze and heave or break the whole slab. If the incoming water can drain away, it'll take the base material with it, then the slab will just cave-in. You can't win when putting holes in concrete.
Reply:Originally Posted by kenklingermantrue but an extreme example. . . .
Reply:core drill then use fast setting grout in the holeAmerican by birth Southern by the Grace of God
Reply:Thanks for the replies people, very useful, as always.Upon second thought I will go witha professional outfit to do the concrete part of the job.That being cutting the hole to accept the two post for the door posts.  I will call on monday until then I drown my sorrows in the peaty, heavy tastes of a delightful Laphroaig twelve year old, Cheers!BTW the door is in front of of the garage facing my building and not the alley.  Soon though I will have to butt heads with that garage door and protecting it better that, my friends, is for another day............ my supper awaits. Ta for now.all I want in my life are....... white castle cheese burgers
Reply:Try the Knockandoo if you can find it. It is fantastic. Especially with a nice cohiba.
Reply:You are probably making a good decision staying away from the concrete part if you have no experience with it.  Sinking post into the concrete will definitely look more attractive than using an anchor bolt but I don't think I would take something like an ICS concrete chain saw to my wall they can take away alot of concrete quick.
Reply:Originally Posted by allengradingYou are probably making a good decision staying away from the concrete part if you have no experience with it.  Sinking post into the concrete will definitely look more attractive than using an anchor bolt but I don't think I would take something like an ICS concrete chain saw to my wall they can take away alot of concrete quick.
Reply:I would drill holes in your existing concrete floor, big enough to take some concrete "lag" bolts, use those bolts to secure a peice of channel and then weld on to that as a base, if done properly this will be as effective as putting the posts directly in the crete'....this would also save alot of time and money....good luck...."if you are not on fire for God now...you will be on fire one day, and that day will last forever and ever and ever"....
Reply:I'm with all those who said a concrete coring drill is the best tool for making the holes, if you want to sink the posts in concrete.   A 10" diameter hole should do it.Foot plates and concrete anchors would be the easiest way.  If the posts will be inside the garage, this is how I would do it.  Nobody will see the anchors but you and no one outside the garage will see them or mess with them.Cutting open a wall to steal a couch and TV is just plain dumb.   That is obviously the work of tweekers.  Dam fools can't think straight to save their own lives.No matter what you build or how strong you build it, somebody out there somewhere can defeat it.   Taking general precautions of keeping stuff locked up and out of sight and not hanging out with druggies is usually enough to avert most crime.  Keep good insurance for the rest.On the insurance note, I bought an 'inland marine' policy for my tools/equipment that cost only about $45 a month and covers my tools at my home, shop, on the truck or at the jobsite, full replacement value, $100 deductable, up to $30K coverage.   Ask your homeowner's insurance agent about an 'inland marine' policy, which has absolutely nothing to do with boats or water, and they will know what you're talking about.   I took the advice of some here who recommended that to me after one of my machines was stolen and that is probly the best thing I've done for protecting my stuff so far.   The thieves will get it if they want it bad enough.   Only good insurance will fix it after it's gone.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op