Punching eyes

[Stormcrow]

My press is intended for all kinds of forging, but the primary job I wanted it built for was to punch eyes in hand tool heads like hammers and axes. I've been working with it a while and just do not have it where it will do quite what I need it to.

My problem is that whenever I go to punch a hole, I end up squishing the thickness of the metal down. It doesn't seem to matter whether the tool is blunt on the end or sharp. If I make it too sharp, it deforms quickly, even if made from H13.

After reading the David Hyde article Grant kindly supplied, I have two theories on solving this: 1.) Use the smaller, quicker cylinder on the press and work it a little at a time from each side. 2.) Make a setup that lets me punch from both sides simultaneously, as seen here:

I'd like to be doing this on a low-level production basis and it's been eluding me so far. I can do the rest of the tool-shaping just fine, but eyes are giving me trouble. What do y'all think?

[monstermetal]

I have been struggling with punching and am in the proses of finishing up my press now... I'll be interested to see opinions on your query... My thought is tool shape and speed are what its going to take, punching from both sides will still leave a hold that needs drifted?

[Nakedanvil - Grant Sarver]

Doesn't need to be sharp, but it should be narrow. At least 2 - 3" of taper I'd say. Pierce 3/4 of the way from one side, straighten it out, and pierce from the other. Then put a bolster plate in and work it open from both sides. I don't like it to be at a real "gooshy" heat, think it keeps it's shape better at a red/orange.

[NeatGuy]

Would adding an accumulator to the top of the cylinder help increase the speed.? I was thinking the accumulator would act kind of like the flywheel of a flypress. The pump would push the cylinder up thereby loading the accumulator. When the operator is ready a bypass valve could be opened and all the energy stored in the accumulator could be released ... Just a thought.

brad

[monstermetal]

Would adding an accumulator to the top of the cylinder help increase the speed.? I was thinking the accumulator would act kind of like the flywheel of a flypress. The pump would push the cylinder up thereby loading the accumulator. When the operator is ready a bypass valve could be opened and all the energy stored in the accumulator could be released ... Just a thought.

brad

The problem with an accumulator is it a issue after the first operation... You have to charge the accumulator so a rapid second operation is not possible... it takes many times longer than if you didn't have the accumulator.... I had thought about having some sort of a ball valve on an accumulator so after the first press you could close it for the second go....


Its a interesting option but would require some effort to get it to work...

[Fe-Wood]

Helmut is amazing!

[Judson Yaggy]

Here's a not great photo (but you can get some ideas from it) of a 2 sided slitting punch for under a punch press. The spring loaded side bars self-center. A second operation is required to drift/push out the rag.

[Stormcrow]

Thanks, guys. Keep up the advice on this. By the way, I forgot to mention that the latest eye punch I've tried can be seen starting at about 3:09 on the forging press details video:

Judson - Thanks for that shot. Is there any way you could get a shot of it looking down the channel?

NeatGuy - I already have a faster cylinder on the left hand work station of the press, which according to the David Hyde article should be powerful enough to do the trick. No need for an accumulator.

Grant - Narrow in which dimension? Are you saying that, for instance, if I was doing an ax blade that needs a long eye, I should use a narrow punch and overlap the punching? I'll try it at a cooler heat and see what transpires. Other than that, I've essentially done what you've said. I'll try to get pictures of the result of what I've done today.

[Mainely,Bob]

Take a look at the business end of Brian B`s punches/slitters on his tools thread and you`ll get a good idea what you need to do with your chisel tooling.
I would modify the one you have to be a double bevel edge in both directions.By that I mean strike a line down the center of the wide dimension of the tool and then taper the tool away by about 1/4-3/8 per inch to start and once you evenly taper it away from center on either side of center,sharpen each side like a cold chisel.
The tool will make contact in the center of the tool first and then start cutting evenly in both directions as it is pressed thru.
As it is the tool is trying to cut all along it`s length at once and that force is more likely to compress the material than a graduated/beveled edge.

Hope this made some sense.

[Stormcrow]

Combining several ideas from this forum and from over at the NWBA forum, I think this is going to be my next attempt:



1. Use the quicker cylinder.

2. Use a somewhat thicker and more tapered punch.

3. Use a bottom jig with bars that will keep the sideways spread limited.

4. Use either a pointed tip on the chisel (like seen in this thread numerous times: ) OR a pre-rounded point.



Umm, I think that was all. I may not do all of those at the same time on the next try, but they are certainly all things I intend to try. I have some scrap 4140 that I'll probably use and save my H13 until I have this thing sorted out.

[bigfootnampa]

Combining several ideas from this forum and from over at the NWBA forum, I think this is going to be my next attempt:



1. Use the quicker cylinder.

2. Use a somewhat thicker and more tapered punch.

3. Use a bottom jig with bars that will keep the sideways spread limited.

4. Use either a pointed tip on the chisel (like seen in this thread numerous times: ) OR a pre-rounded point.



Umm, I think that was all. I may not do all of those at the same time on the next try, but they are certainly all things I intend to try. I have some scrap 4140 that I'll probably use and save my H13 until I have this thing sorted out.

I would NOT do number 3. Limiting the spread in width will just tend to force the deformation in the lengthwise direction and is likely to increase the force needed significantly. Instead drift the slot and then spread the cheeks vertically by forging with the drift in the slot. Brian does this with his hammers and it gives you more metal around the handle plus a stronger connection between two ends of the hammer. With this approach a slight squishing of the blank as you cut the slot will be reversed in the cheek forging step anyway.

[Mainely,Bob]

Combining several ideas from this forum and from over at the NWBA forum, I think this is going to be my next attempt:



1. Use the quicker cylinder.

2. Use a somewhat thicker and more tapered punch.

3. Use a bottom jig with bars that will keep the sideways spread limited.

4. Use either a pointed tip on the chisel (like seen in this thread numerous times: ) OR a pre-rounded point.



Umm, I think that was all. I may not do all of those at the same time on the next try, but they are certainly all things I intend to try. I have some scrap 4140 that I'll probably use and save my H13 until I have this thing sorted out.

I`d like to suggest you try each one individually at least at first.That way you will know for sure which one brought the most/best change,before you start combining.
I know this is asking you to do some R&D for the rest of us but could you also post your findings here so we can see them too?

[Sam Salvati]

http://blacksmith.org/forums/content/280-Punching-with-a-Hydraulic-Press

good article :D

[Stormcrow]

Bigfootnampa - I had tried this before and had some issue with squishing it out of shape. Of course, this was more a lack of control of the press on my part and not necessarily the technique. Maybe some height stops would eliminate the issue... I knew it when I started, but it has certainly been driven home, the press is a very versatile machine but it is dependent upon the tooling you build for it. I need to build more tooling and get more proficient with it.

Mainely,Bob - How dare you suggest that after years of picking other people's brains that I contribute to the knowledge base? Shocking, sir! Sure, sounds good to me. I think I'll start with the pointed Brazeal/Hofi style chisel. Actually, maybe my current punch with the less heated bar a la Grant's suggestion, followed by the current punch with the faster cylinder. Have patience and I'll see what I can do.

[Stormcrow]

Haven't gotten to play with this any yet (been working on paying gigs), but here are pictures of what I had before:

First, the punch itself. Please ignore the bad welding. The bit is H13, and it was ground to a fairly sharp angle. You can see how badly it deformed. I didn't take a measurement, but it's long enough to make a small camp ax eye.





The steel being punched: 1" square mild steel. See how much it squished down?



The hole once it was finally punched. Pretty ragged. I punched back and forth, pushing the biscuit around without it coming loose until I finally took a pointed bar and pryed it out.



And finally, the biscuit I finally removed.



So, in retrospect, having a sharp edge on the punch wasn't too bright. If anything, it should have been cold chisel-ish.

I'll let y'all know the results of further experimentation.

[bigfootnampa]

So, in retrospect, having a sharp edge on the punch wasn't too bright. If anything, it should have been cold chisel-ish.

I think you are right there... for my (hammer struck) punches I give them an edge with a slight center peak (Brazile style) and very blunt chisel facets... halfway between cold chisel angles and just flat topped. Just a slight angle in other words. One thing that I like about that punch profile is that it sticks where you start it better than a flat tipped one. I actually do not see any problem with the amount of squishing that you have there... it'll come right back out as you squeeze the cheeks flat again. It would be nice to get a cleaner slot though.