Slot punching thin stock

[Chinobi]

Hey all,

 

quick question regarding punching holes in thin stock, I will need to use a slot punch, but I don't think the mechanics are exclusive to that vs say a round punch.

 

iv drawn up a small demo project that involves spreading a bar quite thinly to mimic a scallop shell, and then slot punching through the thin part and pushing one side of the slot down and pulling the other side of the slot up to make it a bottle opener.  however, I think I am going to run into difficulty actually punching the slot.  the material will more than likely be between 1/8" and 1/16" thick at the time of punching, my slot punch is an Aspery style 1/8x7/8(plus or minus).  I will not have the opportunity to prototype it beforehand so I need to consult the experts :)

 

am I going to need to modify the process in some way to get it to work?  im thinking the thin stock will cool very quickly and I wont have much working time, but also because it is so thin I don't know if I will be able to get a well defined hole to counter punch and have enough differential in material thickness for the plug to be sheared out.

 

thoughts? should I just hot cut a slot instead, drift it open a ways, and then file off the rag? or punch from one side as much as I can to define the hole perimeter and chisel cut the slug out from the same side?

 

Many thanks.

[Maillemaker]

Punch on the end-grain of a large piece of hardwood lumber.  It won't wick the heat away as quickly.

[Fe-Wood]

Your right that is very thin and will cool super fast. I would definitely try the punching process in thin sheet stock before a demo. Do the homework to get the procedure down. Nothing like working out the details with an audience. Use a pre heated bolster plate.

[Chinobi]

thanks, that would definitely extend my working time.  do you think there will be complications in the actual punching mechanics because the stock is so thin?  may end up benching this one for later then, you are right that would be nervewracking trying to figure something out on the fly with people watching :blink:

[dablacksmith]

are we talking sheet metal? what about punching cold? i use punches all the time for up to 1/4 stock and punch cold.make a bottom die and figure a way to line it up and punch cold . good luck!

[Chinobi]

not sheet, 1/2" bar on the end, blunt taper/flattened out a little and then crosspeined to spread into a scallop shell shape (think shell gasoline logo).  might be able to set something up to allow cold punching, ill have to investigate that a little.

 

thanks for the input :)

[Frosty]

If it's a blunt enough taper it'll help hold heat longer. You still aren't going to be able to dally but it shouldn't be a sprint rush, just a rush. heat a couple few inches behind the punch area to help maintain heat. don't let it sit on the bolster without hitting the punch.

 

I think I'd see about making a spring punch/bolster and put registers on it so I wouldn't have to do anything but stick it in to the stop and hit it.

 

Heck, if the punch zone is flat enough you could make a stout blanking die and do it cold.

 

Frosty The Lucky.

[Alan Evans]

If you are going to make up guided or self aligned tools you may as well make up a shear and forming tool and do it one go...these are tools made up for gates and thus for much larger stock and are aligned by the fly press but illustrate the idea...

Alan

[MLMartin]

Metal 1/16 to 1/8 can be punched cold for a small slot hole like 1/8 by 1. I would forge a punch out of tool steel, then file the end crisp and clean. Heat treat the working end nice and hard, maybe 50 Rc. You can try punching over the end grain of hard wood, or make a bottom die with a hole slightly larger than the punch head out of mild steel to punch over.

[MLMartin]

Metal 1/16 to 1/8 can be punched cold for a small slot hole like 1/8 by 1. I would forge a punch out of tool steel, then file the end crisp and clean. Heat treat the working end nice and hard, maybe 50 Rc. You can try punching over the end grain of hard wood, or make a bottom die with a hole slightly larger than the punch head out of mild steel to punch over.

[Chinobi]

Frosty, Alan, Martin, thank you for your suggestions.  it sounds like im going to have to adjust the project a bit and probably switch the opener to the other side where I have some more meat, and actually forge a church-key type opener ring (think wizard bottle opener) or a curved tab or something.  I was informed of the opportunity to participate in the demo on pretty short notice so it has really been a scramble to get things in order!  as such I don't have enough time to fabricate special tooling :(

 

I could pick up a stout circular punch and punch in a series of holes cold to make a bumpy slot and file it clean.

 

might go with plan B and dish it into a spoon if all else fails

[Frosty]

Forget a round punch, too much trouble and isn't good showmanship. Turn a chisel into a punch and rounding the corners it'll make a drift too. A few minutes on the grinder and it'll look properly blacksmitherly at the demo. If you have a vise available it'll work just fine as a bolster and drift over the hardy hole or edge of the anvil..

 

Heck, tell the audience about it and how making, modifying and improvising is all part of the craft. Folk love that stuff, they like handy people.

 

Frosty The Lucky.

[Alan Evans]

If you do not have the time to make tools but still want to make a bottle opener for your demo...always a good laugh if you open a bottle of beer at the end...The best bottle opener I have used (anthropometrically and ergonomically) is the style that I make and strangely it is the simplest to forge!

The picture shows one of Jan Dudesek's hand grab openers, you should be able to see the fingers and the thumb. My stainless ones are a development of that principle with their cooler, abstracted sculptural form with the facets and all, but without the good humour of Jan's figurative take :)

You should be able to spread and bend the grab in a couple of heats in mild steel with a hand hammer. I take four heats to make mine in stainless steel. One to octagonise one to spread one to bend and one to draw out and bend the handle. Starting point for those is Ø10mm (Ø3/8"). Jan's is from Ø12mm (Ø1/2") and you would need a straight chisel to chase in the fingers and a curved one to cut off the thumb and chase in the thumb nail...

Alan

[Chinobi]

you read my mind Frosty, but I didn't know if it would be safe to heavily reshape and repurpose something like a cold chisel to such an extent.  good call on using the vice as an adjustable bolster too, might need to get a helper to hold onto the stock though, im tall but my crotch cant clear the top of a vice!

 

that's a fun looking piece Alan :) and definitely do-able at my present skill and equipment level too!  I have a lot of friends that are into heavy metal (music, specifically) and I see potential to cut those fingers all the way in and turn it into the horns :D  m/ (>.<) m/

 

thank you both :)

[Chinobi]

picked up a stanley bostich 3/4" cold chisel and ground an inverted V into the point, then put a gentle radius on the outside vertical corners.  i figure the V will bite a little faster and deeper and be easier to keep in the same hole without it bouncing around after every swing.  makes it easier to reset even if it does hop out.  plus i think that shape will shear better and with less force than a flat profile.  

 

 

i tested it a little on a piece of 1/8" flat bar on a piece of wood and my little anvil, but it was way too late in the evening to be sledging away in the garage so i only got 4 or 5 swings off before i felt like i was being a total #### to my neighbor.  i wasnt really giving it 100% either because of the noise =/ you can see the initial bite, on the back the metal was bulged in the same places so i might need to refine the process a little more to get it to shear a little cleaner.

 

 

im thinking put as much of an initial punch in with my slot punch HOT as possible, then quench or let it cool and move to the vice and the cold chisel/punch to take it all the way through

[Frosty]

Using the vise as a bolster and a shear is something that has been done for I don't know how long. I reshape chisels all the time, I pick them and Allen wrenches up at garage/yard sales for just that reason. They're excellent steel for beating on for repousse, chasing, decorative punches, etc. better than spring stock.

 

You'll get it. Glad to help.

 

Frosty The Lucky.

[Chinobi]

thanks frosty :) I might be able to sneak out to the swap meet this Saturday so ill be keeping my eyes open for a number of things!

 

thanks to all who contributed, I have added a few tools to my mental and physical toolboxes :) ill put up some pic's of the results from the demo early next week for you all to pick apart :D 
 

[MLMartin]

Do not quench the mild steel before you try to cold punch through it!  Even mild steel will harden some and make punching harder.  You can hot punch over end grain wood. It will smoke good, or over the vise. Hot steel will shear and punch much easier than cold.

[Chinobi]

Yea, I was kinda leery of quenching for that reason.  ill probably let it cool to black heat or less and then quench.  I don't want to use the new chisel on hot work because im sure I will be distracted and forget to quench it frequently enough.

[Chinobi]

busy week so my apologies for circling back around a few days later than promised.  i didnt end up attempting the original project i mentioned, but i did get to take a swing at the hand bottle opener in the shape of 'the horns'  :) i had a lot more difficulty chiseling the fingers out using the vice than i had anticipated, so it got a little sloppy.  identified a few things to improve on and hopefully the next time i try it i will move a little faster and burn less metal.  i had originally cut a thumb as well, but it looked like a ragged hangnail, so i just cut the rest of the way through and filed off the evidence. :ph34r:  what appears to be a third finger folded down is actually a stretched area that got folded back on itself because the piece slipped in the vice instead of shearing.  

 

had to figure out how to scroll a short taper on the diamond on the spot as well, i made sure that the twist ended up square to the original stock and was quite surprised when i went to do the scroll and was 45 degrees off because i flattened the hand on the diamond instead of in line with the bar!