First Draft analysis of Sketchup

After posting the blog on OSE yesterday, I discussed my design in depth with Marcin. We decided to make the main arms and main linkage from 1018 steel if it is affordable. This will guarantee that the machine will cut more than the 1×6 flat capacity that we are already expecting.

After discussing with Marcin, I discussed it further with my grandfather. Less changes needed to be made than I thought! Here’s what I got out of it:


  • For the 2.5″ pins, a 1″ threaded rod will work for “clamping” the pin together. 1.5″ is overkill.
  • The easiest way to attach the threaded rod to the pins will be to drill an oversize hole (maybe 1.5″ Dia and 1/4″ deep) and plug weld around the base of the threaded rod. This insures a strong connection which will not interfere with the threads.
Upper arm:
  • For inserting the bushings, we will not weld them, we will mill out a hole .02″ smaller than bushing OD. We will then freeze the bushing so it shrinks and insert it. This insures a perfect fit, and will minimize any warping which would come from welding or torching. This also means that we will not have to fit with the machine in place.
  • The portion of the upper arm to be welded will work, and should not cause any warping.
  • I need to add bushings for the punch linkage, and the top hole for it should be slightly smaller.
  • The attachment for the punch guide will work, despite prior worries about not being able to drill and thread holes for the attachment. I’m just gonna have to learn a new technique or two. =)
  • The die holder needs a set screw on the outside to prevent it from pulling up when stripping.
  • The stripper should be 1/2″ thick
  • The alignment tube should be welded in place to insure a perfect alignment.
  • Table can be bolted or welded to lower arm.
  • I need to move the backstop so its not in the way for shearing.
  • For cylinder attachment to lower arm, the easiest way will be to torch away the section which the cylinder attachment will attach to, and weld the attachment in place.
  • Grease joints are well placed.

Materials handling:

  • We will torch the 3″ plate on our pano-graph torch (uses a camera to follow a drawn line to torch).
  • We will grind down most of the torched surfaces by hand, and surface grind the necessary ones.
  • For the angle shear assembly, we can mill the half-moon pushers; DOM is both un-necessary and impractical.
Things I need to update or change in model:
  • Add holes for Punch guide attach 
  • add set screw for die holder 
  • increase size of punch pressing plate , add bolts for it.
  • Update all pins so they are the right length, and have the right size TR.  
  • Add bushings for punch linkage, update hole location.
  • stripper nuts size needs to be updated.
  • Add guide slot for vertical linkages.
  • Add pin for punch (shaft to pusher)
  • Add bolts to attach table to lower arm.
  • move backstop
  • simplify curves; we don’t need this to be aerodynamic.
  • update lengths so all possible lengths are in increments of 1/4″. (increases ease of fabrication)
  • Color-code all surfaces to be grinded. 
  • Color-Code all steel by type (A-36, Chromoly, or 1018) 
  • Add support frame (to be done with G-daddy tuesday
  • Add flat clamp
  • Remove DOM from angle shear assembly 
  • Stripper: will it bend at center? Are welds strong enough to hold nuts? may need to weld the nut into a larger part. this is not too critical, as this part will be cheap and easy to access and beef up in case of failure.
  • Punch guide:  can this resist bending moment from shaft and stripper (yo mama couldn’t…). Are the bolts strong enough to hold to frame? Only critical thing is that  threads do not strip on lower angle shear.
  • Motion: can we get full capacity of angle shear? this could prove difficult…
  • Motion: place slot on lower arm for vertical linkage.

Things which will be updated when I receive parts:

  • Angle shear assembly
  • Angle shear mount bolt holes and location

One response to “First Draft analysis of Sketchup”

  1. marcinose says :

    Five new open techniques to the world coming from Open Source Ecology documentation here: surface grinding, panograph torch, milling, freeze fit, threading large parts. I love it.

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