Making a round hole square.

[Doc2012]

Had this big long thing typed up, and of course, the f**king gov't computers lost internet connection.

Basically, I need to take a 3/8" round hole, and a 1/2" round hole, and make them square.

I know I can buy a broach, but I don't have 137+ dollars to spend on something I'm going to use for this project. (That, and they're like 9" long. I just need to go through some 1/8" plate."

The difference between a 3/8" square and a 3/8" round hole is .08", and a 1/2" round and square is .10". Meaning I'd only be removing .08" and .10" from each corner respectively


My question is:

If I were to take some 3/8" and 1/2" square rod, grind the tip down so it would slide into the hole in the plate, then pressed the rod into the hole, would that it work? Or would the steel be too "weak" and get distorted, not giving me a good hole?

Should I use Key steel, or Tool Steel blanks?


(Yes, I know I can buy a square file and file them, nut I don't have the patience to do 70 holes that way.)

What do you guys think?

 

[GHARP57]

use a jig saw?

 

[Doc2012]

use a jig saw?

Too small of a hole, I think.

And I don't think a jig would be good for the 1/8' thick metal.

 

[GHARP57]

Only other thing I could think of is a dremel tool. mark off the lines and grind it out that way

 

[Doc2012]

I've got a press here at work that I might try out tomorrow with the 3/8" rod.

If that doesn't work, then I'm goingb to have to try the Jig saw or file....

 

[GHARP57]

hope that goes well for you

 

[2014 Warthog]

I've got a press here at work that I might try out tomorrow with the 3/8" rod.

If that doesn't work, then I'm goingb to have to try the Jig saw or file....

Was going to say... a small file and some elbow grease will have that done in short order

 

[nevada]

Had this big long thing typed up, and of course, the f**king gov't computers lost internet connection.

Basically, I need to take a 3/8" round hole, and a 1/2" round hole, and make them square.

I know I can buy a broach, but I don't have 137+ dollars to spend on something I'm going to use for this project. (That, and they're like 9" long. I just need to go through some 1/8" plate."

The difference between a 3/8" square and a 3/8" round hole is .08", and a 1/2" round and square is .10". Meaning I'd only be removing .08" and .10" from each corner respectively


My question is:

If I were to take some 3/8" and 1/2" square rod, grind the tip down so it would slide into the hole in the plate, then pressed the rod into the hole, would that it work? Or would the steel be too "weak" and get distorted, not giving me a good hole?

Should I use Key steel, or Tool Steel blanks?


(Yes, I know I can buy a square file and file them, nut I don't have the patience to do 70 holes that way.)

What do you guys think?

yes, that should work.
the back side of the hole will need to be supported exactly. meaning, it should be the same size square hole, maybe just a fraction larger, to prevent tool from sticking.
otherwise I suspect you will get distortion.


I have seen what you are describing done.

I believe some notches were filed into the side of the tool, to facility cutting the square hole. I will see if I can find the video.

 

[Doc2012]

post

I've watched that video 10 times. Lol.

Only problem is that it's tool steel. "High Speed Steel" is what he calls it, guessing for drill bits.

I'm going to try the normal 3/8" rod, then, if that doesn't work, order a piece of 3/8" "high speed steel" and do it again.

 

[BettysNephew]

I've watched that video 10 times. Lol.

Only problem is that it's tool steel. "High Speed Steel" is what he calls it, guessing for drill bits.

I'm going to try the normal 3/8" rod, then, if that doesn't work, order a piece of 3/8" "high speed steel" and do it again.

I can pretty much guarantee you will have issues if it is made from mild steel. The tool will be about the same hardness as the material you want to work. Even if you flame harden and quench it will not last long. Is there a machine shop that you can get to? If so get an unground lathe cutting tool blank and make it into the tool you need. With the thin metal you will be broaching you will definitely need support on the back side or it will dimple badly. A small die grinder or Dremel with a carbide cutter would do a pretty quick job of this and you would only have to file the very corners to finish.

ETA: Try to find a shop that has a Piranha machine and the die needed. They can punch those holes out in a matter of a few minutes. Sheet metal shop might have one or a welding/fabrication shop. Therenare likely other machines that can punch these out but I am familiar with the Piranha.

 

[KidVermicious]

Mild steel won't work, it'll deform itself and your hole. If you can't get your project to a machine shop, get a set of small square and triangle files and get busy.

 

[Doc2012]

I went and bought a carbide bit for my Dremel and a couple files last night.

Dremel makes quick work of the material to be removed, and the files make a decent job of getting the remailing out of the corners.

Only issue I've had so far, is that the damn corners of the files are already gone. I'm going to see if I can find either a better file, or a smaller carbide bit for the Dremel, and go to work this weekend.

I'm going to have to wear a damn long sleeve shirt, jeans, and gloves(which I HATE) though. That bit doesn't grind the metal away, it chips it away into barely seeable splinters. I spent 45 minutes picking them out last night, and I'm still finding them in my hands.