It occurs to me now, that I was building a jig, but it has turned into a fixture.
A fixture is something you bring the work to. It supports everything off the floor.
A jig is something you bring to the work, which is otherwise supported or self-supporting. When a jig becomes big enough to require hoisting, it becomes a "fly fixture". You fly it in and put it on the work.
I started out doing trusses and walls, but my second pro job in engineering was designing jigs and fixtures and programming the tube benders. 1979 it was...
I cleaned off the 9 UGLY decals and the silver goose looks much nicer now, But looking at this Mongoose frame, you can see several tiny dingleberries in the paint.
Weld spatter that didn’t get chipped before painting. Clearly it wasn’t sanded. They sprayed it with hot trichloroethylene and applied thick plastic paint to conceal (ineffectively) the lack of love they applied.
Never would you see such a thing on any bike made in 1970 or before US bike companies all went Asian.
I could be cutting up a 1930’s Rollfast instead of this Giant-made Chinese ‘goose. If the guy drops his price I may do both.
That 20” Huffy has some interesting pressed tubing. I wish the headstock was bigger. I think this was achieved by putting the tube in a mold cavity and applying hydraulic pressure from the inside, But I have never seen this process done myself.
I may have the ability to develop those kinds of hydraulic pressures.
The tire that I bought is a Subrosa, Probably made by Kenda, but it doesn’t say. At least it wasn’t one of those bloody folded things. This is not the sort of tread pattern that I wanted but I think it will provide plenty of functional traction.
Anyhow here it is mounted onto the 20” Huffy wheel. Biggs and Littles, as they say.
I was thinking to mod a skirted blank “HD” fender, but it is all wrong.
I thought many times about using fiberglass but this is just not in the cards.
This is intended to be a structural member so that I can eliminate the seat post.
I had envisioned a pressed steel fender with embellishments and hidden reinforcements inside the fender and under the seat, the seat pan actually being a structural reinforcement to the fender itself.
If I have to build the rear fender 100% from scratch this means a wood buck. I came up with a strategy that will get me out of making most of the lips to reinforce the edge. It means a multi-piece design.
The best laid plans of mice and men . . .
Meanwhile I am still not happy enough with my jig to start welding it up so I continue with the modifications. .
I bought this blank trailer fender from Tractor supply company. It’s about four times as thick as your average fat bicycle fender and about twice as wide as I need.
This should be plenty of metal to create a rear fender. In fact I’m gonna throw lots of it away, which is good because it’s heavy.
The idea is that this fender will be both the seat pan and the seat post meaning that this bike will only have the fender to attach everything to that would normally come to the seat post.
Because it is so thick I am going to skeletonize it. The center section needs to be essentially a built-up tube, but the rest of the fender could be swiss-cheesed.
I want to start cutting this up but I promised myself no cutting and welding on the project bike until I fix my clutch. I should also do some work on my truck, so if I disappear for a few days I didn’t die in a bicycle crash.
I dropped my seat post down inside the frame on the mongooose, and it went down hard and wedged in. I could not pull it out with pliers or internal expanding pliers. I was yanking the bicycle off the ground.
I had to make a long rod that I could pull from my little slide hammer. Then Tappy-tap-tap
Only bummer was that I could not find a piece of threaded rod long enough and a coupling nut would not fit through the post. I took the 2 foot piece of 5/16 rod and threaded the ends. I put a small washer and a nut on the bottom.
As you can see I jammed it in place with an old screwdriver. Two smacks & she popped right up.
I found a bicycle shop in town that was sort of obscure but they sell fancy chrome plated Lowrider stuff and also I found a banana seat. It’s not a Schwinn.
It’s made by Lowrider of ShunFeng or somewhere close by. It looks faithful enough that I can use it. I would’ve made up the sissy bar by now but I spent hours fishing that stupid tube.
I really didn’t know how this fender was gonna work out but it appears to be pretty close to the size I need.
I’m wondering what’s going to happen when I cut it into pieces. This is a roll formed sheet and it may try to un-form itself. Well if it doesn’t work out I’ve only wasted $65.