Forum whore
I could I spoze. I wanted to try with the cheap stuff for the buckets. Then make a Chromo frame for the 300 F3 bike when I have my eye in so to speak. I have seen some of your fabrication work. Any tip on poor mans pipe bending?Originally Posted by jasonu
Low personal B.M.E.P.
Yeah, minimal bending, small dia tube, knock one up in the lunchhour...
Been discussed to death here previously. Mainly straight tube, I'd use mild.
Hardcore Biker
Try and let everything you can distort from welding and then very carefully fit and weld in the last critical bits.
I've had reasonable luck with starting at the steering head and adding the swing arm pivot bushes as the very last thing. Other people work the other direction, fitting the steering head in as the last piece.
cheers,
Michael
Forum whore
Where I worked we bought in the bends and hand cut them to fit. They were mandrel bent and not cheap...
Forum whore
10 charact
No8 Wire Extraordinaire
So to the important question; what colour will the jig be.
Don't you look at my accountant.
He's the only one I've got.
Forum whore
One of the many things you should try to avoid in a frame is bent pipes.
If you want light, use 25 x 1,25 mm tubing from head stock to swing arm. Than you can omit most of the cross members on the sketch below.
It saves material and, at least as important, it saves welding across the main tubes which should be avoided whenever possible.
Funny story on the side: the first drawings done by the guy who later became a multiple German champion on this machine, showed a lot of bent pipes, both in horizontal and vertical planes. When asked why, he answered that he had tried to follow the shape of the tank. Explaining my view on the matter may have taught him some German four-letter words that even he had never heard before.
(actually, German four-letter words are always at least 12 letters long, 8 of those being consonants, and larded with never less than three exclamation marks).
You don't even need seamless. Use furniture tubing.
Anorak
Chairs Frits
Some more pics. They might look familar to you
Kinky is using a feather. Perverted is using the whole chicken
Low personal B.M.E.P.
Agree with Frits - simplicity is king.
Agree re emphatic German too - the old man had a pretty good command of idiomatic German after 4 years as a POW. More than once i heard him let loose on someone....lot of moisture flying during that.
In my experience what will take longest Rich, will be machining up the hollow bosses for tube junctions at points like the swingarm. Mild steel is fine for those.
Colour scheme of my jig Dave, is nicely patina'd light rust....
Fair weather rider
The rear shock attach to the frame appears to be offset to the right down tube for pipe clearance,am I seeing that correctly?Nice frame design!!
Forum whore
Yes for sure. Just like making pipes. Next set of pipe I will make the mounts nozzles and spring retainers first. I was thinking the same way with the frame.
Thanks Frits. Ok KISS it is. Shape of tank is so my style as well.One of the many things you should try to avoid in a frame is bent pipes.
If you want light, use 25 x 1,25 mm tubing from head stock to swing arm. Than you can omit most of the cross members on the sketch below.
It saves material and, at least as important, it saves welding across the main tubes which should be avoided whenever possible.
Funny story on the side: the first drawings done by the guy who later became a multiple german champion on this machine, showed a lot of bent pipes, both in horizontal and vertical planes. When asked why, he answered that he had tried to follow the shape of the tank. Explaining my view on the matter may have taught him some german three-letter words that even he had never heard before.
(actually, german three-letter words are always at least 12 letters long, 8 of those being consonants, and larded with never less than three exclamation marks).
You don't even need seamless. Use furniture tubing.
Although I do love these things.
I want to draw the version of this I have in my head. Now that laser cutting is so cheap and the materials. I'm sure with some smart design a mono frame could be made. Not sure how much Ali moves around when welded.
Low personal B.M.E.P.
Mock it up in cardboard. I get card sheets from a packaging co - top sheets in a pack are often dirty and unusable for packaging, ideal for our use. Cheap too.
Not sure these days on Monocoques. With single shocks you finish up with a short box and a structural seat either in glass or alloy. Any tank should be separate too, either welded or a bag tank. Is this any better than a tube frame ? Some torsional flex is required if only to give the chassis some feel when laid over.
If you do a Monocoque, it doesn't have to be welded. A basic folder and then glue and rivet works fine.
Hardcore Biker
Robin Drury's Foale TZ twin, with Tony's lightweight LL fork. I spotted this on FB and there was no photo credit given for the period photo.
cheers,
Michael
Forum whore
I started with the steel butterfly below. Cut it, fold it, weld in the head stock and the bottom sheets and you're done.
I used 2 mm mild steel because I had no aluminium welding equipment at the time (1972). Not many laser cutters around then either, so I cut it by hand.
2 mm steel sheet may sound heavy, but I had the lightest, lowest, narrowest and simplest 500 cc bike in Holland; not much bigger than its 50 cc cousin.
Forum whore
Nearly spat my coffee all over the screen then. (500) Holy crap. Do you have any pictures of that bike? Sounds a little mental. In the best possible sense of the word.but I had the lightest, lowest, narrowest and simplest 500 cc bike in Holland; not much bigger than its 50 cc cousin.
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