Mini Press Brake

[JimDawson]

I have 600 of these pieces to do. I had the H-sections laser cut, so all I have to do is fold them up. 5 inches long, 3 inches wide. 16ga HRMS The bend is 45 deg.




I have a broach press that I made out of a Chinese 7 ton, electric wood splitter. So all I needed to do was build the tooling to fit what I have.




First the punch holder. 2 inch, 1018 CR shafting

Drill and Tap a 1’’-8 thread to match my ram arbor. Here I am redefining power tapping, an impact wrench makes a great large tap driver.
The gear box was in neutral for this operation, and I was holding the chuck with my hand, I didn’t want transfer the shock load to the gears.


First, make a 0.625 x 1.5 deep slot for the punch. The old ‘’two vice trick’’. This holds the part very securely, and allows the next operation with minimum setup. (those nasty looking cavity’s in the jaws are on purpose, those are sacrificial aluminum jaws, and that was a fixture for another project.)



Drill, tap, and counter bore for the securing capscrew. For this operation all I had to do was locate the hole. Just by flipping the vice over the hole is 90 deg to the slot.




The Punch.
A chunk of 5/8 A36 structural steel I had laying around. Pretty nice machining stuff. Not the best material for a punch, I hope it lives for 600 pieces.
Milling a 40 deg included angle to be able to over bend the part a bit




The Die
Thank you to all of you who replied to my post asking about the die for this project http://www.hobby-machinist.com/show...-Brake-Tooling?p=243552&viewfull=1#post243552 and a special thanks to pineyfolks for pointing out a better die design. This die is based on his suggestion.

3.375 x 10.375 x 1 Unknowdium Steel, it machined really nice, maybe 10Lxx?
Milled a 0.375 x 0.400 deep slot to clear the tool, then chamfered the edges with a 22.5 deg carbide laminate trim router bit. I use carbide router bits on metal quite often, especially aluminum.



The punch & die installed in the press. I added a couple of dowel pins in the die for part location.




Part way through the bend




Bend complete. It actually over bent a bit because I didn’t have any height control at that point. It didn’t spring back as much as I thought it would



I added a shim in the slot to provide a depth stop, and then the bends came out perfect. (well almost perfect, this is not for NASA)

 

[pineyfolks]

Nice job on the die and great use of the HF wood splitter. How did you set up a limit switch on it?

 

[ecdez]

Good stuff Jim.

I like the upcycling of the log splitter!

 

[chuckorlando]

Awesome

 

[JimDawson]

Nice job on the die and great use of the HF wood splitter. How did you set up a limit switch on it?

Thank you.

There is no limit switch. I just put a shim in the bottom of the slot and allow the tool to bottom. I just release the pressure as the tool hits, it's pretty easy to tell when it really starts working hard. There is also an adjustable pressure relief valve on the hydraulic pump, so if needed, I'll reduce the pressure a bit.

Thank you again for suggesting air bending.

 

[Smithdoor]

Looks great

Dave

 

[gr8legs]

Great job!

The re-purposing of a log splitter is way cool!

I am fascinated by your use of an impact wrench to do tapping. Having never tried it, I keep thinking about the many taps I have snapped off by being a bit too aggressive when hand-tapping (or occasionally power tapping using a cordless drill motor but with much smaller i.e 5/16" or 3/8" taps).

Putting the brute force of an impact driver onto a tap just seems like a recipe for fracturing/failure.

Now that I've seen it, I will have to give it a try!

Thanks again

Stu

 

[CoopVA]

Well done!


Sent from my iPad using Tapatalk

 

[JimDawson]

Great job!

The re-purposing of a log splitter is way cool!

I am fascinated by your use of an impact wrench to do tapping. Having never tried it, I keep thinking about the many taps I have snapped off by being a bit too aggressive when hand-tapping (or occasionally power tapping using a cordless drill motor but with much smaller i.e 5/16" or 3/8" taps).

Putting the brute force of an impact driver onto a tap just seems like a recipe for fracturing/failure.

Now that I've seen it, I will have to give it a try!

Thanks again

Stu

Thank you !

You are correct about a fracture failure of the tap. I have never had it happen, but it could. I have never tried an impact wrench on less than a 3/4 inch tap, so I'm not sure what might happen with a smaller tap. I do a lot of power tapping with a drill motor or a machine tool under the right conditions, all the way down to #6-32, and have had pretty good luck.

In many cases when hand tapping, the reason the tap breaks is because of the bending load on the tap from our inability to put a balanced rotation on the tool.

 

[brino]

Brilliant!
-brino