Small diameter (<1/4") punches?

[Twilight Fenrir]

So, I ran into two projects over the last week that required me to punch a small hole in a piece of hot steel. One was a piece of stainless I couldn't get my drill bits to bite into, and the other was a narrow piece of metal I couldn't afford to lose the material in.

I managed to get them punched, but I ruined my scratch awl in the process :P Anything that small just loses its tempering within 2-3 seconds... I tried using a drill bit, but even that went from brittle hard to bend unrecognizably in about 2 seconds.

So, I got to thinking about what could be done... I know Tungsten Carbide stays hard up past a couple thousand degrees... I was thinking about trying to find a set of rods similar to this: http://www.ebay.com/itm/3mm-12mm-K20-Tungsten-Carbide-100mm-Rod-Boring-Bar-Lathe-CNC-TOOL-MAKER-Endmill-/311156632878?pt=LH_DefaultDomain_0&var=610360690642&hash=item4872616d2e  I'm a bit worried they might be brittle and break, but if I make a steel sheath for them, with a bolt to adjust the length protruding, risk of fracture can be mitigated, I think.

At first I thought it was $9.25 for all 7 sizes, and I was sold... then I realized that's for just the one size :/

Does anyone have any ideas where I could find an assortment of tungsten carbide rods more cheaply? Or, does anyone have any better ideas of what I could use for small diameter punches?

Thanks!

[JoeCB]

Interesting idea you have here.  I would use extreme caution and wear appropriate protective gear in case of shattering a punch. Steel sheath sounds like a good idea. As for a source, perhaps look for broken end mills at the flea market. The shanks should provide some usable length. Another idea, how about try cobolt high speed steel tool bits. These normally come as square tool bits but are also available as round blanks. These retain hardness at red heat, and not as brittle as carbide.   

Joe B

[oldgoaly]

Well I'm no expert but do use TC for embedding into cutting tools like end mills, saw blades, hole saws, drill bit. Rocklinizer is the tool I use to do this. I was thinking how am I going to cut them? they break easy!

[Twilight Fenrir]

Interesting idea you have here.  I would use extreme caution and wear appropriate protective gear in case of shattering a punch. Steel sheath sounds like a good idea. As for a source, perhaps look for broken end mills at the flea market. The shanks should provide some usable length. Another idea, how about try cobolt high speed steel tool bits. These normally come as square tool bits but are also available as round blanks. These retain hardness at red heat, and not as brittle as carbide.   

Joe B

Hmm... I wonder if the DeWalt Cobalt drill bits are Cobalt HSS... This looks promising too, from what research I can do, it seems M42 cobalt HSS is the most heat tolerant. http://www.mcmaster.com/#grade-m42-tool-steel/=xypqb7

Does anyone have experience with just pure tungsten? There are all kinds of rods of pure tungsten on eBay, do they stay rigid at modest temperatures? (modest of course relative to forging 2100 degree steel :P) I imagine the punches themselves wouldn't ever exceed 800 degrees... Shouldn't ever be made to glow at all at least. They aren't much cheaper, but I suspect they'd be less prone to shattering.

[Aunt Phil]

Ramset stud can easily be screwed into the end of a piece of rod.
It costs less than a buck and was made to pierce steel.
When it goes dull it's simple to replace.

[Twilight Fenrir]

A realization occurred today after I ruined a cobalt drill bit... They are differentially tempered... The back of the bit is soft, so chucks can bite into them XD They haven't been losing their hardness, they never had any to begin with!

I've got a few more broken drill bits laying around, I'll try hardening the back myself, and see if that produces any better results :P

[Chillylulu]

Ramset stud can easily be screwed into the end of a piece of rod.
It costs less than a buck and was made to pierce steel.
When it goes dull it's simple to replace.

+1

Great idea - 

3/8" threaded size is the biggest made, and I think the pin may be slightly smaller than 1/4".

Reminded me of an engineer being an idiot and demanding that I get him some 1/2" drive pins. I asked him how he was going to get them to fit the 3/8" sleeve.

But back then we were still shooting high velocity tools. I've seen all kinds of ebay resellers think they are cutting a fat hog when they pick up old ramsets. I always want to be there when (If?) they find out the tools are useless.

I had another dummy sweeping the shop for 5 months while on light duty after he cocked the Ramset against his left wrist and pulled the trigger. The pin went through his wrist and lodged halfway through his watch. That watch was a safety guys best demo.

Chilly

[Aunt Phil]

Just one dern minute there Chilipepper.
I own at least 2 old ramset guns with boxes of powder charges and 1 of the old Hiltis you smack with a drilling hammer to make it happen.  They were fine tools in 1960 and they're still fine tools. 

You can't expect t tool to compensate for a fool playing mechanic with it.

[leg17]

You might try hammering on a piece of tungsten carbide before you spend much money.

[Chillylulu]

Tungsten Carbide is way too brittle, I think.

Chilly

[Aunt Phil]

There are probably more grades of carbide than there are of aluminum.

Most are not impact friendly.

Wear safety glasses when you try hitting any carbide.

[johnsironsanctuary]

Something that Scottg said a while back seems useful now. ALL modern screwdrivers are made of A2 air hardened tool steel. Your sleeve sounds like a good idea regardless of what you make it from.