Sun 5 Feb 2012
Ironworker Update- Ready to build!
Posted by Brianna
Last week I said I’d have the complete OSE proposal and Sketchup done for the ironworker by Friday. I didn’t get it done by then, but I am prepared to start building next week. I finished the majority of the OSE Proposal, see it here. I’ll be posting my engineering calculations onto the proposal when I get them scanned in. I also generated a Bill of Materials with most of the costs listed. I’m waiting on the quotes for the steel; these should come in Monday morning. I plan on having all materials purchased by Tuesday, and begin building as soon as I get materials to work on.
I’ve updated the sketchup model to include the support frame, shown in the picture below. It’s now color coded: green means it will be 1018 steel, and red means I’ll have to surface grind it. A few small changes still need to be made for the model to completely match what I’ll be building. The frame isn’t completely updated with all its bolts and holes yet, and the stripper needs to be re-done to be a bit stronger and out of the way of the punch.
Everything shown and written here is a work in progress, so forgive any inconsistencies. Feel free to comment on any changes or errors you could have found. See my personal blog for more frequent updates.
If there are any engineers out there looking to help on a project, I could use some help analyzing the punch element for the machine. Here’s an excerpt from an email I sent explaining the issue. Contact me at brianna (at) kufadesigns (dot) com if you can help. I have a couple of weeks before I need to build these parts. If I don’t get an analysis, I’ll build it as is. If anything deforms, it will be really easy to replace because of the modularity of the design. Here’s an image to accompany the text.
“Could you help me analyze the punch on the Ironworker?
We need to insure the alignment tube won’t warp, and that the nuts welded to it will be enough to resist the pressure, and resist stripping (up to 45 kips on each bolt) while stripping the punch.
Note that the pressure (45 tons) will be distributed about the perimeter of the hole being punched, and the size of the punch will be a 1″ Diameter when the machine is under most stress.
I did shear calcs, and everything is OK except the bolt connections, which may need to be more, but I’m not sure I understand math behind these- bolts will have clamping power which will pull down with friction, so bolts won’t be entirely in shear… I’m planning on putting 3/4″-10 SHCS bolts there. (These bolts are what attach alignment tube assy to the lower arm at the back of the table).”
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4 Responses to “ Ironworker Update- Ready to build! ”
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February 11th, 2012 at 10:34 pm[...] Kufa, and Yoonseo Kang, two of which are currently off-site. The active projects include: the Ironworker Machine (build started), open source Tractor (modification field testing), CNC Circuit Mill (build almost [...]
February 5th, 2012 at 1:31 pm
The google doc needs to be shared.
February 18th, 2012 at 12:47 am
Hi there. Layman with practical work experience. Your problem with the work hold-downs is understandable. First, when you weld a nut to a large bit of metal there is a huge thermal mass difference going on which, though can be managed, will still cause heat distortieon to the inner threads possibly warping the nuts, or cause a weak weld due to the aforesaid mentioned heat difference. Besided if your punch is off by a tiny bit (dull or cocked sideways a smidgen) the punch tool will start jerking around the work piece and you’ll find those nuts too weak to do the job. May I suggest 1.create a threaded tube instead of nuts or use two nuts on either end of the tube and braise those on to the guide, or 2(best) make two lobes on the guide that are tapped for threads and run the bolts through those. One piece is usually stronger than any weld.
Concerning the bolts holding the guide to the main body, their job is to manage light sheer pressures. I think you’re fine there. As for the guide deforming, a longer tube, a longer stroke will help ensure less “rattle” of the tool in its guide as it has more surface area to be guided by.
I used to run a pnunatic press similar to what you’re working on, in a factory, once upon a time.
Hope this helps.
February 21st, 2012 at 3:56 am
Regarding shear at the mounting bolts — could you take the stress off the bolts by seating the upper rear edge of the guide bracket against a backup lip welded onto the vertical support? Banking against a fixed surface might also help ensure the guide doesn’t slip out of alignment under load, as could happen if the bolt holes have some diametral clearance.