drill
I'm making some pull up bars with 1 1/8" diameter holes and have some questions about how I should drill the holes:
Right now I'm planning on using spade bits. A drill press is not practical in this situation, but I could use one if I had to. The poles are 6" x 6" x 10', and a small imperfection will span across 5' to magnify. Any suggestions on some sort of portable drill press I could clamp onto the wood to use?
Is there a better tool for this job? Ideally it should be inexpensive/rentable.
Make a bow drill:
Get a block of wood big enough to hold in your hand. Scrape out small hole in the wood. The non-pointy end of the drill bit goes in that hole. This is called the "hand hold".
You're going to use this wood block to push the drill bit against the door.
Make a bow with some strong wood and strong string. Wrap the string around the drill bit, perhaps a couple times to get a good grip on the bit.
Drill into the wood by pushing on the handhold and moving the bow.
You can find more thorough instructions on creating a bow drill for firestarting here:
http://www.wildwoodsurvival.com/survival/fire/bowdrill/pmoc/basicbowdrill.html
Use oil to cool the bit, if oil residue is not a problem. Use water if that will be a problem. Keeping the bit cool is crucial to long bit life. The larger the hole the slower the RPM are to be used to drill the hole. Slow enough it is easy to count the revolutions is a good reference for how slow. When using a drill press the RPM are usually slower, and oil or water should be used there too. If the surface is flat, and water is preferred, an easy way to keep water at the drill tip is put an ice cube beside the hole while it is being drilled. The heat will melt the ice and keep a supply of water while drilling.
Another thing I do that I feel helps the large hole get drilled is using a smaller bit to pilot a hole through the metal first. Watch the last part of the hole just before the drill goes all the way through, the flutes of the drill bit will grab hard into the hole and try to wrench the drill out of your hands. That may hurt....
Best Answer
If you are set on using a hand-drill, there are jigs available that will keep the drill perpendicular to the object being drilled. Alternatively, holding a level against the drill will help you keep it aligned.
I would suggest using a Forstner bit instead of a spade bit. Spade bits can jump around a bit, tear out and are not that precise. They are good for rough work, but a Forstner bit will give you a much cleaner cut.
That being said, a drill press is the best tool for this, and they can be purchased relatively inexpensively. You could also find a "maker" workshop in your area, or a college with a shop where often you can rent time and use their tools.