sub frame: part II

I’ve been rethinking the sub-frame assembly. Originally I had planned on notching the longitudinal and latitudinal extrusions together, but this may have compromised the strength of both.

Lapping them together with L-shaped extrusions top and bottom may be a better solution. This allows the longitudinal and latitudinal assemblies to float independently of one anther until final assembly – allowing me to pick-up any tolerance build-ups I may encounter.

emerald city comicon

I went to the Seattle Comicon today. I was hoping someone there might have a Master Replica Falcon on display. No such luck – but there were a bunch of Stormtroopers surrounded by latex-clad bunnies. Um, ok…

AT-AT on the horizon

Today my wife an I took a trip out to one of Seattle’s surrounding islands to visit Keith – the guy with the mill. We enjoyed the sun and ferry ride, and Jenn even put-up with my ‘pew-pew’ noises as we passed buy the container cranes…

sub frame

Here are some of the aluminum parts I’ll be using to assemble the sub frame. I’m still in the planning stages, but you can kind of see where it’s headed.

It’s mostly 1 inch square extrusion that will be notched at the intersections to make the whole thing 1” thick. Two large 0.060” ABS panels in the basic silhouette of the craft will be attached to the dorsal and ventral sides of the sub-frame and the wedges to to those.

With all the CAD work I’ve shown so far, I thought it’d be good to show something in the physical world.

The black block in the upper left is one of my ABS chunks that eventually will be the wedge of the saucer the has the radar dish on it, among other parts.

The little aluminum hex rod in the upper right is my mounting post. This will be part of the stand I’ll use to hold the model up while I work. It threads onto an old camera tripod.

pumpin’ CAD

To prep the model for machining, it needs to be broken-up into smaller chunks. Well, my original plan was to make it all one part, but that ended-up being cost prohibitive. So smaller chunks it is.

first blood

A friend of mine just bought a new CNC mill. He eventually plans to offer machining services as part of his product development firm – but in the meantime, he wanted so practice. That’s where my little project comes in.

This was a practice cut. It’s the rough-in for one of the upper dome wedges. The parts are milled with consecutively smaller an smaller bit’s to capture more detail. This is pretty rough at 1/2” diameter. The interior of the parts are designed to be cut with a 1/4” cutter.

The Material is MDF – but the final pieces will be ABS.


I liked these scribbles in my Moleskine. I’ve kept it on my desk in front of my keyboard as I’ve transcribed dimensions from photos to CAD. Solving the geometric equation that results in the right shape an proportion has been a lot of fun – for me at least.