Ironworker Prototype II Design Update

Hello world,

This is an update for the Ironworker prototype 2.

By next Friday, Feb. 3, I will have completed the remainder of the sketchup design, and the official OSE Proposal, and will be posting both in another blog post. This will include my calculations for the machine sizing, a design rationale, an overall project plan, a bill of materials and a budget. I’ve been designing the ironworker for months now, and the design stage is finally nearing completion. See the latest sketchup model. The design is not quite finished, but will be within the next week. Major things which are missing from the design are the frame to suspend the machine, and a clamp for the flat shear. Everything else is pretty much done, except that a few bolts and holes, as well as the pins need to be fixed.

I’ll be building the ironworker in my grandfather’s fabrication shop in San Diego. I’ll be doing the majority of the fabrication, however I will have to hire his fabricators from time to time to help me maneuver the steel. The main arm will weigh about 650lb.

This design builds on the first ironworker prototype, which had only the hole-punching function. Prototype II adds a flat shear and angle shear function. OSE’s first prototype was successful up to 1″ holes in 1/2″ thick metal, at which point there were signs of pin linkages egging. Since Prototype I is still in use until the second prototype is built, we have not performed destructive testing to determine its maximum hole punching capacity. I am designing for a punch of up to 1″ holes in 1″ thick metal, flat shear of up to 1″x12″ mild steel, and angle shear of up to 5/8″x5″x5″.


I based the design on a Piranha P-3 Ironworker that we had in our shop. Since I had it on hand, I could closely inspect it and get detailed measurements. See the study sketchup model I created of it. This is very different from the initial Scotchman-like design I proposed in prior blog entries, because I realized how impractical it would be to design after a machine I didn’t have access to. Unfortunately, the GrabCAD challenge didn’t yield very useful results, as the Pirhana design is much simpler.

See my personal blog for daily updates on ironworker progress.




  1. James Bunny

    Looks really good! Can’t wait to get this on the list to build here. 🙂

  2. Marcin

    More technical notes on Brianna’s blog:

  3. Dick Weber

    I bought a Piranha P-3 in 1979 and used it in small production runs of different types of auto-related parts. It was an amazing machine, safe, excellent repetitive accuracy and economical to purchase ($9,800 including a standard set of dies. Eventually we made our own punches and a top table with spaced tapped holes that made fabricating a breeze. It is relatively silent compared to flywheel types and it required absolutely no maintenance during the six years I had the shop. It will be a great copy!

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