[How do I?] Square Hole ?

[ELHEAD]

Making a couple of cranks for a DP vise . 9MM hole needed . Any suggestions, short of an expensive broach?

 

[Bob Korves]

Drill hole, file out the corners. Good bench work practice. A triangular file with the teeth on one face and one corner ground off (safe) works well.

 

[RJSakowski]

A small file comes to mind. A small sharp chisel will also work. You can also make a simple broach to square around hole. Harden a piece of square stock and sharpen the cutting edge. It can be pushed through to cut the square with a large vise or press. Use plenty of lubricant.

 

[f350ca]

If the corners don't need to be sharp you can drill out the centre and mill the corners with a small end mill. This on accepts a 1/2 inch socket drive.


Greg

 

[savarin]

Use a Reuleaux triangle drill bit

or

or edm it.
The Vika company in Czechoslovakia still make them

 

[Bob Korves]

Rotary broaches are also an option, expensive to buy, but can be shop made. I have no experience with them myself, but there are YouTube videos about making and using them.

 

[Marc]

Try this.

Sent from my iPhone using Tapatalk

 

[MSD0]

The easiest and cheapest way is to mill a relief in each corner. http://americanmachinist.com/practical-ideas/pocket-milling-gets-some-relief

 

[Andre]

I needed to cut a square hole some time ago. Made a tool identical to a shaper keyway cutter, and used my mill quill to gently broach tiny amounts of material out. Only a little at a time, and rotate the spindle for each side. This is a good way to get the bulk out, then filing for a close fit.

I wouldn't do it this way again, but it did work. If i were to do it again I would make a different shape broach and do it in the lathe using the carriage instead of the quill. But, I didn't have the lathe at the time when I needed that square hole.

 

[pineyfolks]

Drill the 4 corners at the points with a 3/16" drill then mill the square with a 3/16" endmill. It should give you enough clearance on the corners for a square and it will drive on the flats.