Friday, April 9, 2010

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.

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