Prototyping & Reverse Engineering

Fun @ Work

At work I have the pleasure of people walking up to me with hand drawn blue-prints of items they would like fabricated.  I call these “Prototype” projects.

I’m also handed existing objects that need modifications or are broken and need to be remade.  I call these “Reverse Engineering” projects.

Using 3D CAD software, I build the project so parts can be cut, bent, drilled, welded, sand-blasted, powder-coated, assembled, etc…  It’s a lot of fun.

So, what exactly do I mean by “Prototyping”?

A prototype is anything original that hasn’t been built before.  A TV stand may not be original, but a TV stand that you designed to fit in your living room is.

Here’s a recent drawing that I was handed.  Joe (The Hander) explained it to me for a minute, I asked a few questions, and less than an hour later I had created the parts, assembly file, drawing file, DWGs, and emailed it all to Joe for approval before he created nesting files for the plate laser and printed off the drawings for the welders to fabricate it.

DVR Flat Screen TV Stand - Prototype Hand Drawing

DVR & Flat Screen TV Stand - assembly drawing

Flat Panel TV & DVR Stand

And what about “Reverse Engineering”?

Most of the time I don’t have to deal with extreme-precision pieces, other than CNC Machine parts, meaning: as long as it’s within a 16th or 32nd of an inch, it’s good.  But sometimes I have to reverse engineer something and have no idea if it was originally designed in metric or standard, and when I’m measuring it, my micrometer may say a length is .129″ or 3.277mm.  So is it supposed to be 1/8in, or is it 3 1/4mm?  Or am I not squeezing the object tight enough/too tight with my micrometer?  Should I consider the fact that it’s a plastic piece that may flex or deform as I measure it, or consider that it’s powder-coated metal and the paint layer can add to a measurement?

Then I tell myself to chill out and just take measurements and type them in.

When you’re reverse engineering something more complicated than a square plate with bolt-holes in it, you’ve got to come up with a plan.  Take time to turn the object over in your hands (if it’s small enough), or walk around and study a larger object.  3D CAD applications are often based on extruding solids and cuts, so you’ve got to think about:

• which plane to start your drawing on?  Which flat side of the object (if there is one) will be easiest to make into your initial extrude?
• Would it be less work and more sensible to find the symmetry of the piece or feature, draw half and then mirror or pattern the other half?
• Are you going to have to insert a lot of reference geometry and planes?  If I can avoid some of this by starting a model a different way, then it saves time.

Here’s one of those tough-to-measure projects.  It’s a piece of pliers used to tag livestock animals’ ears.  It is manufactured in plastic, but the person who uses it breaks it often (and it’s inconvenient and expensive enough to replace) and asked if we could make a metal version so it would be more durable.  I didn’t have the whole apparatus, just the little piece, so I was unable to completely understand how it operated mechanically.  I had to create a model in SolidWorks so I could make a drawing dimensioned to 4 decimals for the CNC machine operator to mill the part.

Set Screw Pliers Part, Livestock Tagging Tool

Set Screw Pliers Part, Livestock Tagging Tool

Set Screw Pliers Part Drawing