Need To Punch 1/4" Square Holes

[rmack898]

I need to punch 1/4" square holes in 1018 steel that is .125" thick.
My first thought was to drill a .25" hole and use a broach but with the material being only .125" thick, the gap between the broach teeth is bigger than the thickness of the material.

Maybe a simple punch and die but Im not really sure how to make one.

I may have to punch about 300 holes so what ever method I use, has to have some kind of tool life.

I'd like to hear some suggestions as there may be an obvious solution that I'm not thinking of.

 

[TommyD]

We used to drill a hole slightly smaller than the finished size then use a very sharp hss lathe bit to nibble the hole square. Take small bites and hold the bit short to stop deflection.

 

[RJSakowski]

Tell us more about the holes: precision required; sharp, square edges required; etc.

If some distortion is permitted, punching hot comes to mind.

For cold work, a rotary broach can be used. randyc did a post on making a rotary broach about a year ago.

 

[francist]

I like Tommy's idea but at, say, 4 nibbles per corner times four corners per hole times 300 holes, that a lot of nibbles! Especially with a hammer maybe. Was thinking of how to rig something fast along the same idea using an arbor press, then started wondering if all the holes were in one large sheet of material? That's gonna affect how you choose to go at it.

Tom Lipton did a video on this maybe two or three months ago. Can't remember what the actual topic was, but he showed grinding the HSS tool bit with a slightly concave end so that the corners of the tool engaged the work first. Then I think he drove the tool into the material using his mill?? Might be worth checking his channel out to see if there's an idea there.

-frank

 

[John Hasler]

he showed grinding the HSS tool bit with a slightly concave end so that the corners of the tool engaged the work first. Then I think he drove the tool into the material using his mill?

That's what I was thinking. Then you could make a multipart die with four 1/4" pieces of HSS. I'd predrill at something like 15/64" .

 

[TommyD]

We did it on a Bridgeport.

 

[TOOLMASTER]

I love my hougen

 

[wawoodman]

I can see why! That thing is a beast!

 

[wawoodman]

I don't know how the finances pencil out, but even buyng a rotary broach tool might be an option.

 

[TOOLMASTER]

I have a smaller version of the one in the vid...still punches 1/2 steel like butter but gets in tighter places. the only setback is the depth of the throat. but for straps ect it rocks

I can see why! That thing is a beast!