How do I cut a 1 1/4" hole in 3/16 thk angle?

I'm making reinforcements for my body mounts and I need to put a 1 1/4" hole in for the lower neck of the poly body mount. What's the best way to cut this hole? I've tried the most expensive hole saw from Home Depot and drove my wife nuts with all the squealing and screaching (some came from me also) but only managed to get the hole 1/2 way through.

 

Did you try putting some oil on the hole cutter as you were using it?
I've done that and its worked.

 

I drilled a 1" hole through my front bumper with one of these. I was amazed how fast it went through.

http://www.northstate.com/klein/media/59002.jpg

 

X3.

 

someones got to say it so it bout as well be meR) ,,, torch it my man torch it

 

You wanna make sure you're pretty good with a torch. I tried to explain this to my cousin when he torched his holes for his body mounts, and he didn't believe a word I said until he was on a trail and his cab shifted enough that the steering column came apart. For what it sounds like you are doing here though the torch may be good enough for it.

 

You need to be careful about the speed settings of the bit as well.

 

X2- keep it slow. The speed has to be slower with a bigger holesaw.

FWIW- I have cut a 6" hole in a chrome bumper without trouble, but the holesaw was designed for metal.

 

Yeah, use some of that nasty stinky black thread cutting or, or some Tap Magic. The Tap Magic is good stuff to have around anyway, for drilling and tapping.

 

All good info here, make sure the hole saw is a Bi-Metal type, not a cheapy. The bi-metal ones are for cutting metal as the teeth are extra hardened. I use these at work to cut up to 1/4" thick stainless steel.

Oh, yea, very slow cut with lots of cutting fluid.

 

Slow is good. Oil is good. Bi-metal is good.

Slow with *Pressure* is what counts. You want those teeth on the saw digging in and shaving real metal, not just whirring around making heat. If the cutting edges are truly removing steel, they aren't burning up from friction.

That's a big part of why drill presses work so well.

But a hole saw has a lot of teeth and it's hard to bear down against all of them sharing the load. Can you rig some kind of leverage behind your drill, get a lot of pressure on it? A 2x4 and your brother-in-law, for instance?

Of course this then means you also need a powerful enough drill to turn the holesaw "with earnest"...

Good Luck!

Pete

 

If you have a good quality hole saw and drill press, set the RPM on the drill press to 275 or less and use a high sulfur cutting oil. Gear lube works well if you don't have cutting oil.

Speed is your enemy here.

Grandpot

 

Yeah, get a good hole saw, use cutting fluid and keep the speed down.

I was using milwaukee holesaws for a while and they would last a couple cuts. I now use some Sandvik saws and they just keep going. We're talking cutting through some 1/2" plate.

Kevo

 

Cutting oil is a requirement. I use a 75/25 mix of motor oil and STP. Why? because thats what dad tells me to do.

 

All great advise given above, and should be followed. Also, be sure to raise the cutter up out of the groove often to allow the swarf and chips to clear out. I use a crappy brass-bristled brush to accomplish this. No need to turn off the drill, just drag the brush on the teeth while it's spinning. It's messy, but it works.

For a different approach, you could have drilled a 1-5/8" hole in a thin board, clamped it to the piece to be cut and fired up the plasma cutter. (1-1/4" [hole] + 3/8" [plasma tip] = 1-5/8")

 

Thanks for all the advice . I think I see where I went wrong. I assumed I needed high rpms and alot of pressure. I also used (and don't laugh) gun lubricant because it was the only thing I had at the time. I will pick up a new 'quality' hole saw and some real lube tonight and give 'er a whirl (pun inteneded). Thanks again everyone. Excellent advice as usual.

 

I am cutting four 1 3/4 holes in my tube frame 3/16 inch steel as we speak for my shackle reversal. These holes are for the shackle sleeves. And, any good hole saw will work and a slow speed works best. As, for a cutting lube, a fellow I new in California that had a machine shop that built dirt track racing parts said that good old Crisco was the best dilling lube he used in his shop. So, I keep a can next to my milling machine with a little brush in it and smear it on the cutting tips. Has worked so far, so you should be able to cut your holes with no problem and ear muffs help.

 

Re: I did it! I did it!

Thanks for the great advice! I cut the 8 holes this morning on my 20 year old drill press by reducing the speed to the lowest possible (500 rpm) speed and using sulfur based cutting oil. Wow! That was easy! It only took 30-45 seconds per hole using an $11 Home depot bi-metal hole saw. I'm assuming the speed made all the difference. You guys (and gals) saved me a load of time (and $$) trying to figure out how to get these holes in. Now I may be on the road with new body mounts by the end of the weekend! Have a on me!