Day 95 - The light cages and the eye

I spent a productive day working on the light cages and the eye piece.  Back in February of this year (2014), my plastic parts from Plastruct were delivered to me.  Prior to that, in November of 2013, I had a local maker shop laser-cut the parts for the light cages.  Assembling these was another task I was afraid to tackle, mainly because of the cost of the ABS plastic, and the cost of the laser-cut acrylic.  In addition, I had no back-up pieces in case I screwed up.  I hadn't ordered any glue from Plastruct, either, so I didn't have a means of gluing them together.


I had, however, obtained acrylic cement from TAP Plastics, and so I started there, with the light cages.  First, I drew a square, with the sides being the same as the diameter of the bottom part of the light cage.  I drew diagonals to find the location where the light cage struts were to be cemented, and lightly scored the acrylic with my box cutter blade.

Afterward, it was essentially a breeze to cement everything together.  The cement applicator has a needle nose, and, while holding the strut to be glued in place with one hand, I gently dragged the needle along the base.  The capillary action of the cement allowed it to draw itself directly under the piece.  After holding it in place for several seconds, a secure bond had formed.  I repeated this for all the remaining pieces, and eventually, I had to lovely (unpainted) light cages assembled!  In 24 to 48 hours, the molecular bond of the welded pieces will reach maximum strength.

(Of course, I would prefer to have aluminum light cages, but so far it's been prohibitively expensive for me to do that.  Maybe someday!)

Next up: Cutting up the stepped cone for Rainier's eye.  I took the smaller of the long tubes and sat it in the cone to find where I was going to cut it.  I marked out the spot and made a test cut one step higher for practice.  It wasn't too difficult of a job; I mainly just gently scraped the razor along the "L" of the step, over and over again until it was free.  Then I repeated that on the marked line once I was confident.

The resulting piece needed to be cut into two sections.  I again marked the places that needed to be cut, and soon I had both pieces ready to assemble.

I also needed to get the tubular sections of the eye piece cut to length per the plans, so I used my miter saw to do that on both the small tube and slightly larger one.  The miter saw wasn't my first choice for this, but I didn't have a miter box for a handheld saw.  Very carefully, I cut until I couldn't lower the saw further, then rotated the tube, continued the cut, and soon the job was done.  Some light sanding using 120-grit paper, and I had the pieces I needed.

Now, how was I going to glue all of this together?  I went to the web and googled what the proper bonding agent for ABS plastic was.  I ran across several videos where people demonstrated making their own glue using acetone and scrap pieces of ABS.  Eureka! I thought, and decided to give it a try.  Heck, it made sense to me—use ABS as a means to weld other ABS together.

First, I chopped up the scrap rings from the cone I had cut, and threw them in a jar.  I added a small amount of acetone to it, screwed on the lid, and let it sit for about an hour.  When I came back to check on it, it was all pretty much melted.  I gave it a good stir with a stick, and was very satisfied with the consistency.

After flipping over the two front eye pieces and placing them in their final position, I took a cotton swab, dipped it into the goo, and ran it along the edge of the seam.  I made sure a good amount of the slurry covered the piece.  Then I let that sit for about 30 minutes or so.  I was very pleased.  It was still slightly malleable, but, like the acrylic cement, it should be nice a solid once the acetone has completely evaporated.  I then added my glue to the edge of the smaller tube, and pressed the eye front onto it.  I repeated this for the larger tube edge, and squeezed the back eye hemisphere onto that.

Now they're both curing, so I'm going to give them all the time they need to dry.  Later, I might add another layer to the front piece and to the interior joins of both the tubes, just to make sure everything is nice and secure.