A Lawnmower Punch Press

[Robo_Pi]

We're not going to let you get away with anything

I think at least half hard would be better, full soft is pretty soft. Half hard 260 blanks pretty nice, I've never punched full soft. Full hard punches about like 1020 steel. I'm an old tool & die make too, built a lot of punching and forming dies.

I am certain that you are way more experienced than me. No doubt about it. My experience was back in my early 20's. Back in the late '60's. I worked "tool and die" in my brother-in-law's father's machine shop. He was teaching me the tool and die trade. I did make some punches and dies. He had a lot of business making tiny tin masks for an automotive parts company. We punched out the tin masks. These were then placed on things like plastic dashboard knobs so they could chrome them using a process they called "Luster Coat".

In any case, as young as I was I was often given a full project. I was handed the knob and told to make the punch and die to form the mask. Of course the boss gave me all the detailed clearances etc. All I had to do was draw up the punch and die, by hand, and then machine them. He would then have them hardened. And then I would need to set them up on punch presses so his female employees could sit there and punch them out all day.

So it was limited experience to be sure. None the less, it was experience. I did learn how critical clearances were, and various ideas about relief and cutting edge angles. Far from an expert to be sure. But it was still a valuable experience.

If you say half hard 260 blanks will work well, then that's what I'll do. I'm sure you know what you're talking about.

And hey, I was guessing at half-hard too. So gotta give me credit for a lucky guess.

 

[Cadillac]

The crankshaft on a engine like that will have journals around 1". The block will be useless for you in that the "bearings" are aluminum. No bearings machined into the block. Forces the crank can handle? That's debatable I know for a fact they don't like the blade hitting something sticking out of the ground. I've replaced acouple cranks and side covers from people hitting the buffalo box water valve or such bending the crank like a banana. I would think in this application if properly laid out it could work but the crank is one of many moving parts to this equation. I think the flywheel weight would be the ticket.

 

[Robo_Pi]

The block will be useless for you in that the "bearings" are aluminum.

I figured that would be the case. I'll just grab the crank, connecting rod, and piston. And build the rest from old farm equipment. I kind of figured that I would need to make my own bearing blocks. So that was already expected. I took a picture of the whole lawnmower, but I'm really only talking about using the crank, connecting rod and maybe the piston just to take advantage of the existing wrist pin configuration. I expect I'll need to modify the piston extensively. Possibly even remove it altogether and just use the wrist pin on an entirely new punch holder.

So I may be down to only using the crank, connecting rod, and wrist pin.

I will use the original flywheel, but only because it mates to the shaft already. I'll actually bolt a much larger and heavier flywheel onto the original for the inertial momentum I'll need for getting through the entire punch stroke.

Building this punch press will deserve it's own project thread.

But I won't start a project thread for this until I make more progress on it. I don't even have time to disassemble the lawnmower right now.

 

[Superburban]

Have you considered a manual press? The crankshaft is likely between 1 to 2 inches of stroke, If I remembver things right, a 2 foot lever would yield you about 12 to 1 advantage. Yea, doing 260 manual punches is not simple, but neither is all the fab work to make up a power source, the clutch, if thats the plan, and all the control pieces.

 

[Cadillac]

Shop press air over hydraulic ram with your parts would be no time at all.

 

[rwm]

I like your idea but I have some concerns. I don't understand how you are going to get the individual blades of grass into the punch mechanism and align them accurately? They are too variable in size and shape?
Robert

 

[Firstgear]

if you make something, make sure you are very aware of any safety issues...good way to lose some fingers quickly!

 

[Robo_Pi]

I know. For some reason punch presses always make me squirm because I imagine getting my fingers punched off. There are obviously other many other places on the machine where you can loose a finger as well. But this is really true of most other machines as well. In fact, when I watch a shaper running it makes me feel just as nervous.

And what we often don't think about is that the lawnmower itself is actually quite dangerous. Typically when we mow the lawn we don't think about what would happen if our foot slipped and went under the mower. But that wouldn't be pretty either.

Life is dangerous. In some ways a punch press should be less dangerous than a lawnmower simply because you can visually see the danger more easily. But yeah, I plan on building a clear plexiglass guard around the die to make it impossible to stick anything in it other than the thin brass sheet.

If you want to have some nightmares watch this video.

These people think they have a better safety solution. I'm not convinced of that.

The compound die I'm hoping to build will most likely have a very tiny opening in it when fully open. You probably wouldn't be able to fit your finger in it if you wanted to. None the less I'll still build a guard around it leaving just a small slot large enough for 0.6 brass sheet to slide through.

But yeah, safety is always a major concern when using any power equipment, even the lawnmower itself.

In fact, I run a chainsaw pretty much daily. Talk about a dangerous tool! You can hurt yourself with a chainsaw pretty easily if you aren't paying close attention to what you are doing. My cousin is a professional logger and he put a running chainsaw blade through his forehead. Long story, and fortunately he wasn't seriously injury. Just resulted in some ugly looking scars. But I'm sure it didn't feel real great.

I slipped and almost feel off my tractor the other day too. Had I fallen I could have been seriously insured as the tractor would have kept going and run over me. In fact, I hear that farming is one of the most dangerous professions.

Yep, life is filled with extreme danger. Gotta watch your back to be sure. And even then you aren't safe.

 

[Creativechipper]

manual punch, this looks makeable

anyone ever make something similar to this

 

[Shootymacshootface]

You could pick up a used reloading press. The toggle system that most use can make a tremendous amount of force. The die bodies are almost always 7/8-14 so they can accommodate .50 cal or larger projectiles. You can even buy die blanks and make whatever you want with them. Production wouldn't be an issue either. Lots of people have automated presses that the designers never would have imagined would be.