The Armour Archive

I have a used Whitney Roper punch (not a knock off) and after putting 3 holes in 30 pieces of .050 stainless steel (410) it's getting nearly impossible to punch through.

Do Whitney punches get dull?

Other than buy a new 1/8" set is there anything I can do?

Thanks.

Jovian

Yep, you dulled it. Thought Whitney punch dies and punches held up better than that. Still, if anything is going to dull them, it would be stainless. Or hardened stainless; 400-series is a hardenable springy set of alloys.

If the punch action is still smooth but the punch tools inefficient at getting through scrap mild steel, suspect the punch and die.

Examine the edges of punch and die under 10x magnification under strong light -- compare them with the edges of other punches and dies in the set. See if you see rounding-off or glary shine coming from places in your used dies' edges where it doesn't from more pristine ones.

Resharpening the punch or the die probably calls for chucking them in a lathe and truing the edges up again if they are rounded off. Then finishing the job with a diamond hone. I don't think I'd want to fix them using handheld tools.

A punch has sharp corners with which to cut the slug, the die also has sharp corners. These can dull but punches can also mushroom. Both can be caused by cutting matierial that is too hard and/or material that is too thick. Most of the punches I loose show signs of swelling from having punched metal that was too thick.

One way to avoid this is to use the die from the next diameter up. There will be more stretching and less cutting with the resulting greater need for deburing. It doesn't necessarily keep the punches from mushrooming but it will let a slightly mushroomed punch pass through a slightly deformed die without binding.

Check the punch with callipers to see if it is still the right size. You can CAREFULLY file it back to round. It's how the first punches were made in a day before modern machinging. If you destroy it in the file process... no loss, it was pretty destroyed to begin with anyway.

Luck!
Sean

Yup I had a friend break one punching the Ti lames for his brig. He, of course, replaced the punch and die---why he gets to use my equipment in the first place.

Yeah, I burn through 1/8in bits since I use them more than any other. It's part of why I have three #5 Jr. Punches. That, and the punches and dies are stupidly expensive compared to the price of a whole used #5 on Ebay. If you're getting just a dimple, you might get more punching out of what you have if you tighten the die a few turns.

working Ti for along time says that punches wear out and often break.
I buy punches in tens. the dies last longer.

I also get them wet and gently sharpen them on my grinder making sure they stay cool.
you can do this for both the punches and dies before they need replacing... if you are very careful.

when the point is gone and you do your first sharpening I bevel them a bit which seems to help.

If you hand sharpen them, please use a honing stone. It will take off less material, but give you greater control than a file ever will. If you have a friend who is in industrial maintenance, see if they have a tooling department at work and if he can get the punch/die sharpened for you. (We handle tooling here where I work, but I don't think you want to wait for the tooling to come to me, get sharpened and come back to you.)

If you have access to a lathe I would suggest that route, punches are easy in w2 steel or drill rod.
It takes some time to sand and buff them smooth but not a bad project. You can also turn larger puches down.

Another good option is to upgrade to a larger punch, they seam to last longer.

The only punch I've ever broken was a genuine RW - it crumbled. And I wasn't expecting too much from it - only like 14g mild. It was just a dud. It happens.

It occurs to me that I have a drill press, and I've seen other people do light lathe work in their drill presses.... wouldn't that be the way to go in a pinch? Seems like I'd want to grab a diamond hone, chuck up the punch, run the press at lowest speed, and just hit it for a couple seconds on the face and side each. Maybe hit it with a piece of leather to deburr.
Not sure how I'd do the die... probably just shave off part of the face and let the punch action deburr it.

When making your own punch be very aware of how much gap needs to be built in the punch/die system (Accurate measuring of a new set can help and I do mean micrometer if the values are not available somewhere on the net.)

On using a drill press: How much slop is in your spindle?

Thanks guys! I ordered a set from RW which means I can practice sharpening the old set without worrying too much about destroying it.

Jovian

Thomas Powers wrote:On using a drill press: How much slop is in your spindle?

You put a 6" bit in it and you can see the point wobbling slightly, but I figure that's still more accurate than doing it by hand.

Funny that this should crop up on here, managed to finally wear both my 1/8in punches out punching CS70! Reckon I'll just be buying new rather than try and resharpen them.

i ruined my HF knockoff just trying it on stainless. i drill alot of stainless. use a drill press and slowest speed wuth cutting oil
'

A little trick I do with my Roper-Whitney #8 punches are I hammer the ends of the dies a bit (not to hard) and then take them to my belt sander and sand them smooth in a rocking action to keep the hole from being shaved to far down. I get about double the life from them. The punch is a different story. Buy new ones.

I don't understand that at all, AB. It sounds like you are grinding and rounding the business ends of the dies -- the lower-jaw pieces.

Also Roper Whitney will custom make you a set of hardened dies and punches specifically for punching stainless and hard metals if you ask them. They just dont advertise it.

Valuable datum, that.

The clearances for the regular punch&die is 0.003", I think, and those for stainless are 0.006", IIRC.

Would a 1/8" punch would get dull from punching a large amount of holes in 22 gauge mild steel?

Eventually but that would be a Lot of holes.

ask bobby brown.

(gestures the loathesome, itchy, spotty, Tom K. Ryan pepper pox @ Maeryk)