Bender's Head - eye shroud

The fiddliest bit of the project - the shroud which goes around Bender's eyes.
I first planned on building this part using slices of extinguisher and simply flattening the round section onto a mold/pattern/former, and then cutting and welding it on - sounded good in theory, but nearly impossible to do in practice without resorting to heavy equipment, or forging temperatures. - sorry no photos of that attempt - all evidence was taken to the tip months ago.

The second (and successful) attempt was to use a "built up" approach. I split some of the pipe I used for the arms and legs longitudinally, and inserted pieces of sheet in between the pipe halves to form up the shroud. In the photo below the two halves of a shroud are seen on the left, and a completed shroud on the right.

I didn't bother making the sheet the same length as the pipe halves since I knew the pipe had to go back to the centre line of Bender's head, where as the sheet did not. In the next photo the marking for the intersection with the head has been marked with a cheap whiteboard marker. (I grab the cheap ones whenever the discount store is in town - I use them for marking metal if I need to have contrast, or the ability to erase the lines (if on smooth metal) - I basically use whiteboard markers like chalk on rusty metal, or prussian blue on smooth. - I do use chalk as well, just whatever suits, or is within reach at the time)

The waste material is cut away, and the shrouds are ready for fitting to the heads.

A sharp observer will notice I have not cut the corners at the back of the shroud too accurately, and have instead commenced thinning the metal from the inside. Knowing the pipe has wall thickness of around 4mm (just under 3/16"), it knew a smooth transition would require the metal to be thinned considerably.

Fitting the shroud to the heads was fairly straightforward. I attached an eye-plate to the head, and then labeled one head "A", and the other "B". I then marked each shroud with a corresponding letter, and marked the top surface of the shroud so the shroud would always be placed on the same head, the same way up. I then worked around the seam touching up grinding, thinning, and contouring until the fit was less than 1mm (~1/16"). I also marked the head so the indestructible red paint could be ground away for the welding.

A note about the red paint... I don't know what NuSwift used, but that paint is amazing. It prevented rust for over 20 years, is hard to remove, and doesn't burn very well. In the welding photos a margin of only 1/2" can be seen between the weld, and the unburnt paint. I weld salvaged material a lot, and the epoxy paints favoured by local industry burns to a margin of at least 1" when I weld comparable thickness metals. The interior of the extinguishers had another paint inside which was pretty good at well... a thin grey paint which was found failed in only 3 of the 40 extinguishers I cut open.

Back to fitting the shrouds on...
Once fitted, the shrouds were welded in place (see photo below), and I then ground and rewelded to try and build a neat consistent fillet.
The fillet is just visible in the photo below. I placed the eyes on the plate, and bolted it in for testing the fit and look - perfect!!


The next thing to do was the liberal application of bog (automotive body putty - "bondo"), and a lot of sanding and general clean up of welds, fits, and general appearance.
I didn't take photos since the amount of dust generated from the process coated everything with a lovely dust, and I didn't want the camera filled with it.
My approach to the preparation for painting was to sand back all rust, and paint, and then apply a skim coat of bog, and then sand back so the surface was smooth. I predominantly used a flap wheel on my grinder for the aggressive work, and used files, knives, and sandpaper for the finer work.

Looking back, I know I missed a few spots here and there - I'll be the first to admit I simply wanted to get this project finished, and weighed the effort for perfection, versus the return on my time. As I said a few times to people, "it's a lawn ornament, not a show piece. I can always go back and strip him back to metal and refinish him if I change my mind."

Next article... painting. I'll discuss the colours I used, and masking the "fiddly bits"

Bender's failed eyes

I won't go into too much detail on this aspect of Bender's construction, but it was something worth trying, and it may be of use to someone.
I had this one gas cylinder, it was from inside a pressurised water extinguisher. The bottom of it was a perfect hemispherical shape, and the diameter was perfect for Bender's eyes... the problem was I only had one of them.



I decided to use this one cylinder as a positive pattern, and make molds so I could replicate the hemispherical end. I cut up a scrap piece of 4" pipe for flasks, and using common packing tape to close off the bottom, half filled the pipe segments with sieved clay mixed sand. I tamped the sand down as I put it in the flask, and tamped the sand around the pattern as I sprinkled more sand in. Effectively I was creating an "open face mold" for each eye. I created six molds as shown in the photo below. The long 1/2" bolt was used for tamping the sand.

Now I had the hemispherical shape of Bender's eyes sorted, I needed a way to attach them to the rest of his head. I'd designed the use of an "eye-plate" which would bolt to the rest of his head, and essentially be a carrier for the eyes. This design made fabrication easier, and allowed for other features such as "clip on eyelids". To attach the eyes to the eye-plate, I made up some fixtures which were basically a 1/4" bolt, with some heavy wire welded to it. One leg of the wire was bent parallel to the bolt, and presented 15mm (~5/8") away from the bolt centre. This leg was to stop the eye rotating around the bolthole when fixed to the eye-plate. The rest of the wire was simply bent in a loose loop to be encased in the eye casting. The photo below shows a row of bolts, having their heads welded to the wire loops, holes drilled in the aluminium extrusion maintains the spacing of the bolt and the wire prong.

The molds were then filled with "post mix" cement, and the bolt/wires fixtures were inserted. The cement was left over from another job, and used pretty much straight from the bag, but I'd sieved out the larger aggregate so it'd flow better in the molds, and not have any inclusions.

Once the cement had cured, I removed them from the sand molds, and cleaned them up, and sealed them with sealer undercoat paint. I had a hiccup when two of the eye rolled whilst the paint was drying, and stuck to the benchtop, when I pulled them off, the paint pulled out of the cement - this was a warning of what was to come.

Maybe the cement was old, maybe removal of the aggregate did something, maybe the phase of the moon was wrong, maybe the mix was too wet, maybe, maybe, maybe - whatever the reason, the eyes were too fragile. I found I could "cut" them with my thumb nail, and I accidently dropped one of the eye-plates when it was loaded with the eyes, and the eyes flew apart. (see photo below)
Based on that, I decided cement eyes were not going to work. I retained the eye fixtures, plates, and started looking for a better method. What worked was only a minor deviation from this plan, but it worked well.