Bender Gets Religion

Given that smoking isn't something I encourage in our house, I thought it fair to give Bender a good behaviour. He was quite well behaved when he had religion in "Hell is other robots" so I made him a Robotology symbol.

I started by drawing up the symbol, tracing around a 20cent piece for the dots, and scaling everything else so it looked in proportion.



I then traced it onto a piece of sheet aluminum from an instrument case in the scrap bin. To trace the design I painted the aluminum with cheap white paint (for contrast), and coloured in the back of the paper with the design with red pen, I then went over the design from the front, transferring the red ink onto the white paint. I then went over the marks with the red pen to contrast it better.



The shape was cut out with shears, hacksaw and filed to shape. I then primed the shape, and glued some magnets to the back with rubber cement.

A second coat of primer on the front to smooth any drips, and soften the edges a little


I then sprayed the symbol with a "cold galvanising" spray called Zinc-It. It's a CRC product one of the boilermakers from work put me on to. My Dad used to have a paint on version he used when making gates, so when I was given a can of spray zinc, I use it on all my work where I want it to last. Here I only used it for the colour, and the fast drying aspects. - The finished result...



One well behaved Bender

Next installment.. eyelids

Building Bender's body - part 4 - the door

The door needed to be hinged so things could be placed inside the chest cavity. I did consider using normal hinges, but I didn't want them visible from the outside - I was trying to follow the cartoon as accurately as possible. The hinges seen here were made from the same 4mm galvanised sheet I used everywhere. I made up two pairs of them, bolted them together and shaped them as one block using the grinder, files, etc. after seperating the parts, I put them back into their sets and welded in one half of the bottom set, placed the door in place with spacers (shim steel made from pallet straps) and commenced welding in the other hinge parts.



This photo shows how the door hinges inside the cavity somewhat by having the door parts of the hinge flush with the edges of the door, and the chest parts above (or below as appropriate) so there is clearance. A washer is used to maintain the spacing as put in by the shims.


Although we rarely see the knob on Bender's door used, it's always drawn in, so I made it a functional part of this model. The knob was made by welding a disc of 1/4" plate on top of a small bolt. This was then chucked in an electric drill and spun up against a bench grinder for rough shaping, and removal of the rough edges. I then chucked the knob into my lathe and turned the disc to 30mm diameter (1 1/4") and slightly domed the top, and severely undercut the bottom.
I then cut out a segment of the welded bolt head so there was a tangential flat for the catch to engage with. I turned up a brass flanged bush with a clearance hole which matched the small bolt shaft, and filed away a part of the bush to mate with the tangential cut in the bolt head. The brass bush was made with 5mm (3/16") of section which was passed through the hole in the door. The flange then prevented the bush pulling through the door, but allowed some "slop" in the knob/catch to compensate for the curvature of the door.



The catch (striker) on the inside was fashioned form more 4mm scrap. A clearance hole for the bolt shank, and a small "tongue" cut in the plate to engage with a corresponding slot in the flange of the brass bush, provides the rotational rigidity. A single nut holds it all together. The operator turns the knob on the outside of the model, which turns the brass bush, which turns the catch. Probably harder to describe than to see... I'll see if better photos, or a drawing is needed.



Here is the finished door - cut, hinged, and with the working catch and knob.

In case you're wondering, the door was cut out with a 1mm cutting disk in my grinder, and the corners finished out with a hacksaw blade operated in "pull cut" mode.

Building Bender's body - part 3

The chest door was marked and cut out, and the shoulder holes marked and cut. I cut the door out early so I had more access to the internals, making it easier to make welds and measurements.
Then the shoulders were welded in place (details on the shoulder/arm joint in the arm page) - the shoulder is essentially the bottom of a 2.5Kg (5lb) DCP extinguisher, with the footring cut away for the curve, and then a plate inserted at the extreme of the curve so a flat joint with the arm. The curve will be cleaned up with "bog" (automotive putty, "bondo") after all the welding is completed.


The crotch plate was made from some scrap 4mm plate/sheet I had. The four holes are for the leg/waist joints, and will be discussed in the page discussing the legs. The crotch plate was cut very slightly oversized so the plate would sit inside the body about 2 mm higher than the bottom, giving me the chance to ensure it was level, and then trim the bottom edge to straight, and level.

The crotch plate was welded in place internally, and externally. In this above photo, and the next one, you can see the legs are already welded up, and the body placed on them for testing of fit, and stability.



The next page will cover the hinging of the door, and the catch.

Building Bender's body - part 2

So after cutting out the two panels from the propane cylinder, and butting them against each other on the welding table, I welded them together along the seams - pretty heavy tack welding since I expected to have to adjust the fit as the bottom was rounded out.

I tried thumping the body with various sized hammers, I tried swearing up a blue streak, but nothing worked satisfactorily... what to do?...

I carefully marked out some radially spaced lines on the lowest half of the body (to part I wanted to curve the most) and scored them with the angle grinder using a 1mm cut off wheel. I then used a spare automotive screw jack to crank the curve in the direction I wanted. This got it reasonably close to round.
What finally got it to round (unfortunately no photo) was laying the body in a piece of 4" (100mm) channel, and bashing the body from the inside with my "ugly hammer". The "ugly hammer" is something I found in my travels - I suspect it's a railway tool (based on local industry) and is essentially a piece of 3" (75mm) diameter steel shaft - about 350mm (14") in length, with a fairly long 30mm (1 1/4") pipe handle welded at right angles at one end - sorta like a demented golf club. I'd suspect it was used to permit striking things in recesses, based on the marks on it... for me it's a 15Kg (30lb) sledge hammer based on the japanese blacksmith's hammer

Here you can see the tapered body resting on the other half of the cylinder, with the original top section resting above that.
Now that's close to round!!! It took about 6 hours of cussin' under my breath, and hammering/grinding/ rewelding, etc to get to this point, but I was quite pleased with the result


Part 3 of "Building Bender's Body" will cover welding in the crotch plate, and cutting, then hinging and fitting the chest door.

Designing the model of Bender

As I mentioned at the beginning, I was initially inspired to build a model of Bender when sitting at the front step one day, gazing tired at some of the scrap metal, and noticed a familiar shape. I sat there for several minutes looking at the top half of a fire extinguisher which was being used to cover the valve of a propane cylinder - the domed top, the straight sided extinguisher, and the rounded top of the propane cylinder looked familiar, but I couldn't place it. It was the head and shoulders of Bender.
I'd admired the work done by Simon Jansen at http://asciimation.co.nz/bender/index.html, and knew I'd never have the spare time to build what he had, but after seeing the shapes in my own scrap metal, I started making plans.
I collected a few images off the web - copies shown here - if there's a copyright issue - sorry - they're images found by Googling, and used them as a starting point.

These side and front view images were found somewhere - I believe a fan had done up a 3D model of Bender and rendered these based on that.
I sat down with my own models (a diecast model, and one of the tin walking models) and recorded every dimension possible. I then built up a spread sheet of these dimensions, and scaled them to suit the diameter of a propane cylinder, and a NuSwift DCP fire extinguisher. The NuSwift has an outside diameter of 187mm. All dimensions were scaled to the relevant sizes, and recorded. As you can appreciate, there was some range in the eventual sizes, so these were tweaked based on pipe sizing, and "how it looked".





This is a photo of the "plans" I used when working on Bender. All dimensions have ranges on them, and there are small notes to myself here and there about things I expected to have problems with. Not shown are the other 16 pages of notes, designs (rejected, or used) and other ideas I had whilst doing the design.

For the construction notes in this blog (still getting used to that word... I think I'll betray my age by calling this a website, with pages) will be broken into the following pages;
Body, Base/Feet/Legs, Arms, Hands, Head, Eyes (good and failures), Antenna, Progress shots, Painting, Assembly, and then I'll do the Accessories and a few more finished shots.

Building Bender's body - part 1

Bear with me, I'm still learning how to use these blog tools. Building the body started with cutting up this damaged/condemned 44Kg (100lb) propane cylinder. If you look closely, you can see the neck ring is damaged, and the valve has been removed. I had let it sit vented for over 6 months for another project, but that project got shelved so it was donated to this cause.
After cutting away the rounded top (to become the top of Bender's shoulders), the next step was to mark out the cuts based on the amount of taper I wanted in the body. Thankfully the length of Bender's body worked out to be 6mm (1/4") above the welded seam. I then calculated the reduction in circumference at the waist, compared to the shoulders, and split it evenly on each side of the two side seams. I also calculated the minor changes in level of the top cut, compared to the tapered body once the two halves would be joined - this resulted in a 5mm (3/16") sliver being cut at the top edges tapering to nil at right angles to the side seams. The 1mm sliver at the base was ignored until welding the floor in.

The removed pieces were cut out first...


and then I commenced cutting around the bottom of the body. I cut in this order to keep the panels attached to the rest of the cylinder for stability - I hate it when steel moves around whilst being cut. The flat red dome piece on the ground is the removed top section - the red paint is probably overspray from something else... I used the cylinder for holding up things being painted for months until I cut into it.

The two panels butted up against each other on the welding cart. From the top (Bender's shoulders) the two panels form a circle with the same diameter as the removed top piece. At the bottom (facing up in this photo) - Bender's waist - the two panels form a pointed ellipse shape due to the intersecting circle segments. Making this round was quite a chore.