Need to drill a hole...

[Ron JD670]

Sorry my bad I read this as 1&1/2 inch rather than 1&1/8 so the technique I mention will work but the dimensions mentioned need to be modified. For the smaller hole you would scribe a 1 inch circle if you use a 1/4 inch drill bit. You might want to go with a smaller drill bit say 3/16 inch in this case you need to re calculate the scribed circle and the location of the center punch distance.
You may also want to scribe the 1&1/8 circle before starting so you can grind or file out to this line.
Lastly with lighter and or softer metal you might be able to press out the center after drilling or drilling and breaking some of the remaining web between drill holes.
Ok I hope this clear things up.
RoN

Sounds like the hole does not need to be perfect. Here is a cost effective approach with tools most of us probably have.

Scribe a circle 1&1/4 inch in diameter.
Then center punch on the scribe line every 3/8 inch.
Use a 1/4 drill to around the circle. The 1/4 drill, if sharp, should punch through relatively quickly.
Once you drill out the circle cold chisel the 1/8 remnant between the holes.
Then with a dermal tool or file etc. finish rounding the hole.

Unless you need a 1&1/2 drill bit in the future this is more cost effective. Also, compared to drilling a 1&1/2 at the requisite low speed this may take about the same time.

My shop teacher showed me how punch a big hole this way as a project. Wondered when I might use this again.

Good luck and best wishes
RoN

 

[Baby Grand]

That's the way the man ate the elephant - one bite at a time.

 

[jenkinsph]

If you only have to drill three 1 1/8" holes in 3/8" plate I would use a 1/2" hand drill with the holesaw. Use cutting oil liberally and go slow, won't take as long as setting up a drill press and working out a way to hold the metal in place. I use some small cnc bits to make an initial 1/8" hole then drill out with the hole saw.

When building my landplane two years ago I had intended to use my 1hp drill press to drill the grader blade holes 16 holes through 5/8" flatbar. I figured out pretty fast that it was going to require too much work to rig up for the task. Holding and supporting the large pieces of steel while trying to get the proper alignment was more than I could do by myself. The handdrill and holesaw worked better than expected and I was able to drill out the 16 holes in about an hour.

You should be able to drill out these three 1 1/8" holes in 15 or 20 minutes in a home shop environment. I would use the drill press if the pieces of steel are small enough to clamp down, but for larger sizes it may be faster to use the handdrill.

 

[Short Game]

jenkinsph, how large were your 16 holes and how did the hole saw bit fare through the 16 holes? What kind of hand drill were you using?

My hole saw kit is a Milwaukee and so is my 1/2 inch drill motor. I've had good results with these. It would be good if I had someone pushing on my back when I punch big holes, though.

 

[Den1952]

try strapping a short pry bar to the nearest point and use it for leverage against the drill motor.

 

[Short Game]

try strapping a short pry bar to the nearest point and use it for leverage against the drill motor.

Thanks for that idea! :thumbsup:

 

[bcp]

Several time I've wished my drill had a bicycle seat instead of a rear handle.

Bruce

 

[jenkinsph]

jenkinsph, how large were your 16 holes and how did the hole saw bit fare through the 16 holes? What kind of hand drill were you using?

My hole saw kit is a Milwaukee and so is my 1/2 inch drill motor. I've had good results with these. It would be good if I had someone pushing on my back when I punch big holes, though.

For 5/8" plow bolts and a Milwaukee corded 1/2" drill. Used cutting oil in a small pump oiler can and the holesaw is still in good shape.

I have drilled through lots of heavy electrical panels with 4 5/8" holesaws using a Milwaukee Hole Hawg right angle drill too.

 

[glc24]

For drilling 1-1/8 in a good press Id go max 1/4" for the pilot hole ... plenty of lube and speed under 100rpm.

Most arbors will only accept a 1/4" bit anyway. Believe it or not, we have found blowing air,or clearing the chips very frequently is much better than any lubricant. Seems the oil clogs too much. Might think it's crazy,but it works.We have drilled holes when needed with every size holesaw,up to six inches diameter, through hot rolled and cold rolled steel plate as thick as 2-1/2".:thumbsup:

btw,we don't use anything but Milwaukee:thumbsup:

 

[Short Game]

Thanks for the reply, Steve. Since I have several 5/8" drill bits, I have never thought to try a hole saw at that diameter. Next time...

I like that idea of blowing the chips away. Will try that too.

I have the 90 degree Milwaukee too. I like my old Milwaukee stuff, but was really bummed out when my favorite Milwaukee battery drill motor crapped out with worn out brushes and found they were non-replaceable. I don't mind buying old junk, but I hate buying new junk.