Proper Set Up Is The Key To Successful Core Drilling
Core Drilling Many contractors shy away from doing their own core drilling because they have had bad experiences in the past renting rigs and allowing their workers to drill holes with little or no prior core drilling experience. Most of these contractors believe that operating a core drill machine is no different from other drilling operations performed with 1/2″ drills or rotary hammers.
Even though, core drilling is very different from other types of drilling, it isn’t really hard to master. The first thing to know about core drilling is that the set up is vital to operator’s success. The set up may take thirty minutes while the actual drilling operation is completed in just ten minutes. The steps to a successful set up for core drilling are the following:
Be sure to have your holes clearly marked by the contractor and well in advance. Water must be available and a regular garden hose spigot is fine to provide the proper flow however, make sure it is not further away than 150 feet. A power source providing the proper Amperage for your machine must also be available. For that matter, please use a dedicated line for your machine. Do not use jumper extensions for drills, lights etc… Always run a single core (10 gauges) from your machine to the power source (should never be longer than 100 feet). You must have a flat surface on which to anchor your machine. Most machines have leveling bolts, the purpose of which will be explained later because it takes an advance drilling expert to successfully drill on uneven surfaces.
Although some operations require the use of a vacuum pad in lieu of anchoring, I always set an anchor when possible. The exception would be when drilling short penetrations such as 3″ depth for epoxy set railings. I have found that drop in anchors work best because they are flush with the surface and usually are acceptable to the contractor when left behind after the job. I also believe that 3/8″ is sufficient unless drilling over 10″ cores. Once the anchor is in place, I position the machine over it so that the anchor is visible through the slot in the base of the machine. I like to use a threaded bolt with extra length. On the bolt, there is a thick, wide washer more than sufficient to completely catch the base of the stand. Above the flat washer is a slit lock washer and above it a nut threaded between the washers and the top end nut on the bolt. First, the bolt is threaded with washers and second put the nut firmly in place onto the anchor. Then, I spin the inner nut snugly against the two washers and against the base of the core rig. This is a hand tightened action only at this point.
The next point is hard to over emphasize. I wish I had a dollar for every time I approached core driller who said “this core bit must be stuck on something”. The very first question I ask them is: where is your level? In most cases they do not have one! A level is a must for every driller! Some of the better machines are equipped with levels however I still like to use my own because I can use it in several different positions. Get a magnetic bullet level then place it on the column of the rig. Now is the time you use your own leveling bolts. Because you have already hand tightened the anchor bolt, only a slight adjustment is possible. And that should be enough to level the rig. In extreme cases, the anchor bolt may need to be backed off a little. Once you achieve a level base, you can now tighten the inner nut on the anchor bolt with your crescent wrench! You should now be on your way to performing outstanding core drilling.