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I Forge Iron

1st attempt at making punches...and i had a thought pop up

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(not sure how to ask this question, so please apologize for the ramble. i feel it helps convey what im attempting to ask)

I decided that i needed punches, as the punches i bought at the local hardware store have a tendency to bend and upset when using them to punch hot iron. So i need punches with more girth and strength. I started pounding the steel, with the goal of making a 3/8ths punch, and then i had a question "is there a certain minimum size id need to make for punching through certain thicknesses of material?" for example, If im working 1/4" flat bar, and want to punch a 3/8ths hole, ok, that can be accomplished. But what if im working a 2"x2" block of steel, would punching a 3/8ths hole be ill-advised? or would drilling a hole be better? and if i were to make a punch to punch through 2" block, would 3/8ths be too small? what would be the minimum recommended size for punching a hole through that large of material"


so the question is "is there a rule of thumb for making punches to go through certain thicknesses of material?" Is there a minimum size for thickness?

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It seems another thought would be the taper of the punch from the working end. I have some old handled punches that have minimal taper for up to 1 1/2" from the working end  before they start to thicken up that would be good for the thicker stock. Other punches start a pretty steep taper right away. Shouldn't be a major issue punching 3/8 thru 2" stock, given the proper tool alloy, amount of taper, lube and cooling practice. YMMV


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You are over thinking the problem and putting the horse before the cart. 

The first question is why do I want a hole of any size? You need a hole for more or less two reasons. For joinery or for decoration.

Now you can choose hole size. 2" square? Are you joining two 10' lengths of 2" square? Do you think a 3/8" rivet would hold it structurally? Prolly not.

Are you building a railing with a 2" square nuell post (vertical) and do you want to attach a horizontal length of 3/4"x1-1/2" to it? A 3/4" tenon might work on the end of the 3/4"x1-1/2" horizontal rail. Now, do you want a punched hole with a nice frogs eye? Then simply, you need a punch that tapers at least 2" from ~1/4" to at least 3/4"  at the top of the taper. So the working part of your punch would be a 2-1/2" taper(at least) from 1/4" round to 3/4". Using 3/4" round would be a good material for your punch.

Now you can get into type of steel. 

Easy peasy, huh?  ;)

Design your punch for your job.


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