Off Topic - Sweet Custom Press Break

[Joe Jones]

May I make one friendly suggestion about your design? I see only one potential problem with it, and it is easily corrected. But then ... I am not an engineer, and I do not play one on TV, so ....

Joe



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[SegoMan DeSigns]

Just cleaning up server space to give Joe more room for his rants, hijacks and non documented posts..

[Joe Jones]

Other than the hole thing is a pinch hazard, What did you notice Joe?

Have you ever seen a spark plug blown out of an engine block?

The design itself is great. I am tempted to build something like this myself, using this design concept, after I finish a thousand other half-completed projects around here.

However, you have a huge ram (3" ?? 25,000 LB ???) at the top of the machine that pushes against the RIGHT black cam arm which rotates on a bolt to provide the force multiplier for downward pressure at that end. That part of it is fine. I am just GUESSING that you are producing about 60,000 pounds of downward pressure through the RIGHT cam assembly.

The part I see as a potential problem, is that this massive force is shared by what is essentially a turnbuckle, two threaded rods that mate to a steel tube with internal threads, presumably to provide some adjustment to the dimension of that side of the parallelogram. I won't even pretend to be able to guess the number of pounds of force that would be required to shear those threads, but you basically have two threaded cylinders, each maybe 1-1/2" wide, connecting the other black cam arm via the threaded rods. This means that the full force of the ram is not only pushing against the right cam, but it is also pulling the left cam, and the only thing holding that link together are the metal threads inside of the two ends of that red cylinder.

For the purpose of the mechanical movement, it will work fine, and the geometry is sound. However, if you bend something that requires more than (n)% of the ram's hydraulic force, I am not confident that those threads will be able to match the force of the ram pushing the right cam. I see that threaded steel cylinder failing, as the threads are sheared by the lateral force. There is no DIRECT downward force on the left Z mechanism, so the force is reversed. The material is pushing UP against the short moment arm as it resists bending, and the only thing trying to overcome that, is the right directional side pull of the threaded cylinder. I fully admit I could be completely wrong!

If you are only bending light gauge sheet metal, then this design is absolutely BEAUTIFUL! But if you try to bend some wide 1/4" plate or something substantial, this is where I am concerned about this link.

I would replace that setup with a solid steel bar with a hole at each end. If an adjustment is needed, use an offset bushing that can be rotated to adjust the distance between the center points of the two pins. In that way, one hole or the other would need to be ripped out of the bar to cause a failure.

That is the only thing I saw that worried me. Relying on those THREADS in that (Chinese?) turnbuckle, with the (also Chinese?) threaded rods, which are normally used to take up slack between two rods or chains, etc., and handle a minimal amount of shearing force. I don't know ... maybe those threads CAN match the force of the hydraulic cylinder being applied to the other cam arm, but I have to wonder ... If one of the threaded rods was mounted to something solid, and you used that ram to pull the other rod out of the threaded cylinder, which would fail first ... the threads, or the ram?

Joe

HOMEMADE BRAKE MARKED.jpg

[Joe Jones]

I would really be interested in finding some SolidWorks genius who could draw up this mechanism, and do some virtual testing of bend forces, just to see if my theory is correct.

You know, YOU are a very strong person, but if a broom handle falls between your front door and the door jamb, and YOU push hard at shoulder height to close the door anyway, you will rip the bottom hinge out of the door, or the jamb, or both, because the leverage of the RESISTANCE to closing at the broom handle is stronger than YOUR force to close the door. You would think that the broom handle would be sheared by the closing gap of the door, but the reverse is true, because there is no DIRECT closing force at the intersection of the broom handle and the door jamb. The resistance force comes back up through the door to your hand.

Cops and door-to-door salesmen know about this. It is why they can prevent you from closing your door by placing their foot in between the door and the door jamb at the bottom. Your closing force against the door four feet off of the ground is LESS than the resistant force of their foot in the jamb that is working against you. Otherwise their foot would simply be cut off as you close the door, right?

In theory, the downward pressure of each cam mechanism for your blade is equal, but if you were to find a way to measure the force on each side, I believe you would discover that the left side is substantially WEAKER.

Joe



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[SegoMan DeSigns]

Just cleaning up server space to give Joe more room for his rants, hijacks and non documented posts..

[sonbakler]

OK, now that's awesome! Wow you build some trick looking stuff SegoMan!!!!!!

[Joe Jones]

That is an interesting video! Okay, I accept your premise that this joint is sufficient for the intended purpose. We will assume that the steel used to create the nut and bolt are of similar strength to that of the steel used to make the threaded link on the machine. I doubt that the bolts used in the video came from CHINA though. The "metal" they use to make hardware is so soft and weak. A friend in L.A. is an aircraft mechanic. He calls CHINESE hardware "Tootsie Rolls." He says they have about the same resistance to bending, stretching and breaking.

I can strip a 3/8" CHINESE bolt with a six inch combination wrench, and I can't count the number of CHINESE 3/8" bolt heads that my little DeWalt impact gun has twisted off of the shaft as I tighten them. I hope that the components used in this link were not purchase at Harbor Freight Tools!

I certainly do like the design concept of the brake though. If only I had the time to create something like that.

Joe



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[SegoMan DeSigns]

Just cleaning up server space to give Joe more room for his rants, hijacks and non documented posts..

[Joe Jones]

Given your dual rotating cam design driven by one ram, I guess the question is, could you not make that machine much wider and use four cams, or even five or six to give you a brake that can handle 10 or 12 foot bends? I realize that the longer the material is, the thinner it must be in order to achieve a long bend. The basic design of the machine is awesome. I like the simplicity of it.

Joe



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[SegoMan DeSigns]

Just cleaning up server space to give Joe more room for his rants, hijacks and non documented posts..

[Joe Jones]

Generally in that case you go thicker & wider on the jaw plate and increase the ram size and numbers.

If / when metal prices drop I might consider doing a 12' wide version of what's in the video below. Time & Money wise, you would be better off finding a used one. Go to all the auctioneer sites around you and sign up for their news letters.


https://youtu.be/uvKJcf4z13c

That is a nice machine. I do not do enough heavy metal stuff to justify an expense like that, but I came close once. A local company in Tennessee was going out of business, and had a nice 14 foot 190 ton press brake for $9,000.00. I don't have three-phase power, or it would be sitting here now. I spoke with my local welding shop that HAS three phase power and asked, "If I buy this thing and park it HERE at your shop, and make it available for your unlimited use, will you maintain it, and do free bends for me whenever I need them?" He was absolutely willing, but when I went back to buy the machine, it has been sold out from under me. The delay was, it had to be moved NOW, and it needed a 16" thick concrete pad to rest on. I would have had to hire a contractor to create the pad first, before I could have it moved.

Joe


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[SegoMan DeSigns]

Just cleaning up server space to give Joe more room for his rants, hijacks and non documented posts..

[SegoMan DeSigns]

Just cleaning up server space to give Joe more room for his rants, hijacks and non documented posts..

[SegoMan DeSigns]

Just cleaning up server space to give Joe more room for his rants, hijacks and non documented posts..

[cutnweld]

Ok.. so what are you doing for tooling for top and bottom? Did you build your own or is there some standard stuff you can buy someplace??? Did you use t100 or mild steel? I'm always thinking that I would use 1 1/2" t100 for the the top and bttom supports plus make some auto crowning program... still thinking tho!

[SegoMan DeSigns]

Just cleaning up server space to give Joe more room for his rants, hijacks and non documented posts..

[SegoMan DeSigns]

Just cleaning up server space to give Joe more room for his rants, hijacks and non documented posts..

[adbuch]

Those are some nice looking bends on those brackets. Judging from your photos it looks like you are a full-on production shop. Several years ago I build a small press brake using the Swag Offroad kit with HF press and some parts from several other sources. I did add digital readout for repeatable bends, and upgraded to their air-over-hydraulic bottle jack- but mine is a toy compared to yours. Mine has come in quite handy for some of the little projects I work on here at my hobby shop, and for the cost and effort involved I really can't complain..
David

[adbuch]

Here are some photos of mine.
David

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[acourtjester]

here is a similar build from a welding site.
https://weldingweb.com/vbb/threads/7123 ... ress+break

[adbuch]

here is a similar build from a welding site.
https://weldingweb.com/vbb/threads/7123 ... ress+break

Nice!!

[plasmanewbie]

Awesome build David! Did you flame cut those dies or are they plasma cut?

[adbuch]

Awesome build David! Did you flame cut those dies or are they plasma cut?

Thanks Plasmanewbie! I purchased the hemming dies and gooseneck dies from Swag Offroad. They are cnc laser cut and come with tabs between the dies as shown below.

hemming dies.jpg

gooseneck dies.jpg

You cut them apart and grind off the tabs, then stack them up and weld together to create different die widths.

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I also purchased their flat top which allows for doing more detailed work. I made some adapters so I could use some thinner/narrower dies from one of my Grizzly bench mount brakes.

grizzly dies with adapters.jpg

I borrowed the upper dies from this mini brake.

Grizzly 12 inch mini brake.jpg

And the lower V-dies from this one.

Grizzly 14 inch bench top press brake.jpg

[plasmanewbie]

Ah I see, thanks David. That's pretty cool, I had no idea you could buy something like that. I am used to super expensive dies that I could never justify buying but have used in the past on other peoples breaks. Will keep those in mind

[SegoMan DeSigns]

Just cleaning up server space to give Joe more room for his rants, hijacks and non documented posts..