Ed Nauman found that using a hydraulic press to straighten a piece of material involved guesswork. You apply the force and then gradually increase it with each successive try. You usually track the appropriate force by counting the number of pulls on the pump handle. That's not very scientific.
Nauman created a gadget that indicates the actual force being applied. The goal was to make the process of using the hydraulic press quicker and more accurate.
Now, that's a really practical device a lot of shops can actually use. I'd love to see the source code but I can understand it not being there. You could actually market the device. What transducer did you use? I like the fact that you made it look good by putting the lettering on the front panel. It shows you didn't just make it for yourself. Good work.
The schematic was drawn in Sunstones free printed circuit board design program, PCB123. PCB123 does not allow any format other than theirs. The only way to transmit the schematic to design news was via a screen capture and a JPG conversion. If you want an electronic version, I will be happy to email anyone a copy. But PCB123 does not allow any format other than theirs, so you will have to download PCB123 to be able to open it. If you are interested, email me and I will send you a schematic and the code for the PIC. If you plan to build one, I would be happy to program the PIC for you if you don't have the means to do so.
I agree. Seems like a very practical idea. I'm curious, though. In hydraulic ram press applications in the past, how was the force calculated? Mr. Nauman mentions counting the number of pumps on a handle. Was the calulation really that crude?
The force is simply the hydraulic pressure times the surface area of the cross section of the ram. The pressure transducer was calibrated in the laboratory and the instrumentation amp gain is set to allow maximum range for the A/D converter in the PIC. The PIC does the simple E.U. conversion to provide the LCD display with actual pounds force exerted by the ram.
In the "old days" a pressure gauge was used, located similarly to the pressure transmitter in this application. On some rams, the gauges were calibrated in lbs (or Tons), rather than psig, or sometimes both. I don't recall ever seeing one with a settable pointer, but that would be an obvious useful feature.
I needed a set of jacks made with pressure gauges like this once. We used them to check the compression force of springs on packaging equipment in several plants. We planned on calibrating them so we knew the force/PSI reading, and then using a table. But a little work by our supplier let us select a hydraulic jack that had a cylinder area close enough to 1" that we could just take the gauge reading in PSI and read it as lbs force. We confirmed it with a force gauge in the shop, and it was bang on.
The one I built has a pressure gauge like the one shown. The pressure on the gauge directly correlates to the pressure applied to the component being bent/mangled/distressed. The gauge displays psig which can be fairly easily converted to lbs of force. If I was developing a process and had to train someone else to use this device, I think this display would be much more useful. Good idea.
In case you missed it: "We have 38 hydraulic cylinders. We want to avoid running hydraulic piping to each of them, because that would be heavy, so we have electrovalves embedded in the wing to actuate the hydraulics. But if you had two wires, positive and negative, running to each electrovalve, your wing would look like a PG&E substation, and that's heavy too, so we use a CAN-bus [controlled area network] with far fewer wires. Still, it's incredibly complex.
"We wind up with lot of hydraulics," Cayard says, "and the America's Cup rules don't allow stored power, so two of our eleven guys—we think, two—will be grinding a primary winch all the race long. Not to trim, but to maintain pressure in the hydraulic tank so that any time someone wants to open a hydraulic valve to trim the wing, there will be pressure to make that happen."
If the only object is to straighten a piece of metal, then shouldn't we just apply enough force to "overbend" the workpiece to allow for springback and then measure the piece for straightness? Then, if necessary, hit the piece again and re-measure as necessary. It seems we just need a press with sufficient force to bend the metal.
I had the damaged journals of of a race-engine crankshaft welded and the rebuild shop did just as I described above to straighten the shaft before machining and grinding the journals. The press operation was done by "eyeball",and precision measurements were made with a dial indicator to check concentricity. That crank lasted several seasons with many sprints up to 9.000 rpm with no problems. Unless there is more to this story, I'm not sure why a force gauge is required.
I am with you Myron. In my years in the shop I straightened dozens of shafts, just as you describe. You put a block under the shaft/plate or whatever, at each end of the distortion, bent side up, and then apply pressure until it overbends. Measure with a straight edge and dial indicator, aplly that lesson and try again If there is a formula for how much over bend is required I have never seen it. This is also a problem I run into quite often in pressforming shallow bends. It may take many tries before you get to the right point of elastic deformation and it stays where you want it to be.
This device would have to be recalibrated everytime one of the points of contact has been changed. I can see where it would be usefull on a repetative operation (same shaft/same offset), but for just general arbor press bending, I think it would be a toy that would end up in a corner somewhere while work was being done.
I made the front panel. I used BobArt (from BobCAD) to generate the engraving artwork. I have a 10x54 3 axis CNC vertical mill in my garage that I used to cut the panel and engrave it. I also use the mill to make my own Printed Circuit Bords.
enauman, What a nice analog and microcontroller application. I like the look of the front panel and I think it's impressive you made your pcbs by use of a milling operation. I definitely share this video with my Microprocessor & Microcontroller students at ITT Tech. Also, is there a clean circuit schematic diagram and software code available for this project?
The schematic was drawn in Sunstone's free design software "PCB123". Since their software is free, it limits the type of file outputs available to their native format. The schematic appears so poor because the only way to get an electronic copy is to do a screen capture and paste it into something that will allow saving to a different file type. Not the best way. If you go to Sunstone's website and download the program, I will send you the file so you can open it. I use PCB123 because it is a pretty good PCB design program and Sunstone's circuit board prices are reasonable. When I mill a board myself, I use PCB123 to draw the schematic and layout the board. But then I have to redraw it using my CADCAM program in order to get the tool paths. It is a tedious process, but for me, it beats spending $10K for PCB design software. And, for moderately populated boards, I can go from the first "back of the napkin" schematic to an assembled prototype in a day. Send me your email address and I will send you the schematic file and code listing.
This is cool. I built my own 50-ton shop press using old fork-lift rails and would love to have this gadget.
However - Seems like there's some confusion here over relatively simple concepts. Such as equating the number of pumps on the handle to force? Doesn't the number of pumps equate to the volume of oil going into the ram which would equate to distance of ram travel? I would have simply gone to Excel; created a nice laminated graph correlating pressure to force and taped it to the press.
Adding a device to precisely measure the travel distance of the ram could be useful.
The comment about the number of pumps on the handle was editorial and has nothing to do with the calibration or operation of this system. I was trying to relate how one goes about straightening something on a press that has no force indication or pressure gage. In which case, the only way to crudely estimate the force applied between successive 'trys' is to count the pulls on the handle.
While designing electronics has been a career for me, when it comes to spare time, I don't cannot envisage spending the time and effort to build such a device when simple $15 old fashion dial pressure gauges are readily available in a wide variety of full scale ranges.
To convert psi to pound force, you simple multiply the square inch area of your piston by the psi reading of the gauge. Let's say you have a hydraulic cylinder with a 1.5" bore (1.77 sq. inches) rated at 10 tons (20,00 pounds). The pressure at this rated load would be 11,299 psi. In the stated application, all you want is repeatability, so the actual units don't matter.
I've used a cheap 10,000 psi mechanical gauge on my press for over 30 years and it's still doing the job well. I can guarantee you that in 30 years your creation probably won't be in service and the parts used definitely won't be available, while commodity pressure gauges will still be available cheap. Such is the sad story of electronic devices.
However, if you have a need for automation, then electronics is king.
Boy, some people can take the fun out of anything... The caveman's wheel will still be around when your car is rusting in a junk pile or has been melted down for scrap. But I'll bet you don't drive the cave wheel.
I didn't realize the article was about having fun. Sorry, but try as I might, I don't see the fun in your solution. Is there something I'm missing?
I look at these sorts of articles as examples of an efficient engineering approach to a stated need. In my over 40 year engineering career, cost effectiveness has always been at the top of the list, both in cost and time. Elegant solutions is the name of the game, at least when it comes to public presentations. And believe me, working on a solution that's elegant is a great deal of fun, at least for me and our crew. It's the joy of engineering. The quicker and more efficiently you can finish a job, the quicker you can get on to the next challenging project. I especially like the projects that other people had given up on.
A caveman's wheel will not do the job of a car in most people's minds, while a mechanical gauge will do the job in measuring your hydraulic force.
If on the other hand the need is for automation, then an electronics approach is the way to go.
I do have a suggestion for an addition to your project that would make it a lot more fun. If you hook up a $20 digital caliper to your press to measure displacement, you would begin the makings of a "universal testing machine." Most digital calipers have a digital interface which can be readily interfaced with a PC (just Google it). If you then interface your pressure sensor with your PC, you can then have your PC display a stress versus strain graph displaying the elastic and plastic properties of your sample. It would also be very useful for getting your workpieces perfectly straight as you could read the displacement to the nearest thou.
Actually, I made a modification similar to your proposal except I used a string pot instead of a caliper for more travel. I have found a number of uses for the press, since making these additions to it, that couldn't be done with a steam gage. I appreciate what you said about elegant solutions and all. I was a senior instrumentation engineer for Lockheed's Skunk Works Flight Test Division for 30 years. In Flight Test instrumentation, the job consists of an endless stream of unique measurement problems that require unique solutions. I like to think that most of mine were elegant.
I think the spirit of the Gadget Freak contest is in the interest of having fun rather than solving the world's toughest engineering chllenges. After all, most people would consider my Computer Controlled, Pneumatic actuated, Vacuum Assisted, Beer Can Crusher a hopelessley impractical, but fun creation. It sure makes people drink a lot of beer at my parties... :)
Very professional looking. You used your mill to engrave the panel and added color. I never thought of using a mill to engrave a PCB. I have used the photo transfer stuff for prototypes, but programming your mill is so elegant. I personally think the orange wire is a nice touch ;-)
The final showdown is under way in our first-ever Gadget Freak of the Year contest. Who will win an all-expenses-paid trip to the Pacific Design & Manufacturing Show? It's up to you, dear readers, to tell us.
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This discussion will examine what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.