fork of sheet metal

J.A.W. said:

David Warren, inventor of the B/B flight data recorder was Australian, & dont go bringing bloody SS/Nazi rocket scientists into it.

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Interesting to read that Warren's father died in an airplane crash. Makes a person want to know what happened, eh?

As for Von Braun the rocket scientist, good thing his passion was for the science and engineering.

J.A.W. said:

Actually they killed the 1st Apollo crew by fire after specifying oxygen instead of air for the capsule..whoops.

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Yes, but not so simple, had to do with ignition source, flammable materials, pure oxygen atmosphere, hatch design, emergency preparedness, proper risk assessment, appropriate risk management and probably a few other issues.....

Apollo crews expressed serious concerns leading up to the accident, just like a few have expressed concerns over fitness for use of this metal formed steering yoke we are supposed to be discussing....whoops.

"concerns with fitness for purpose"

Hmmmm...

Any reports of one of these failing?

(just to possibly bring some perspective into the discussion)

grandpaul said:

"concerns with fitness for purpose"

Hmmmm...

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Not sure who you are attempting to quote here but you bring up an interesting point. Perhaps the fabricator is creating these for show.

grandpaul said:

Any reports of one of these failing?

(just to possibly bring some perspective into the discussion)

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From what I can tell from the website, at the time of publish the fellow had made two and no telling if any were put into service or what type of service.

From his website:

"As I mentioned earlier, this is just the first piece to an amazing puzzle. The key features here are the ability to create a product which will allow the adaptation and re-use of virtually any set of forks I come across. They will also serve as an excellent tool for developing fabrication skills, which will be essential when I join forces with those looking to learn the trade.

The first clamp took over 3 months and 9 attempts to refine and complete. The second clamp took around 7 hours:"

The craftsmans intended purpose is rather cryptic.

I guess I get my shorts in a bind when I read about someone expounding on the virtues of something they really don't know anything about. My bad and perhaps I should tone it down a bit.

The yokes are truely beautiful. Hopefully we will learn more about them soon.

Between the quality seal of approval "Made in China" and those fabricated pieces, MY choice is easy to make. There are a number of aftermaket triple trees made from billet aluminium ( http://www.pro-one.com/Triple_Trees_s/55.htm http://confederate.com/development/?p=142 http://www.streetchopperweb.com/tech/06 ... index.html ) they look good too, but do they have that all important liability insurance? I wonder if Paul Dustall had these concerns when he made his go fast goodies :?:

I think cottage industries have come a long way since the seventies, information is easier to obtain and they make products that are better than what the factories used to come up with, especially a radically different product. When I look back on my brother's Honda CD175, I can remember many places where the wrong material was used, fortunately it was stolen before anything important broke. At the time, his Atlas looked to be better built, everything was beefier just because they had the time to add metal to parts that would break in use, compare that to the early Commando with its "widowmaker" frame, new design, no time to test it fully before release to the general public. I don't know if lives were lost as a result of that "mistake", but I sure hope not.

At any rate, I will leave you with your doubts about handcrafted MC parts and I will continue to admire the work of craftmen like him.

Jean

PS I always thought FDR were a Canadian invention, google gave me some good reading after I took my foot out of my mouth.

Apparent examples of Rob North work from triples online which include his yokes.


http://www.triplesonline.com/racing/frame.asp

Some of yoose guys may have a burr in the saddle or home life with the harshness of the counter points and cautions. Main point of the post is to point out that the strongest lightest construction method known in yoke and similar hi load bearing things, is use good grade of just thin enouhg Steel sheets in biggest OD size that can be fit in space available.

As far as similar race run examples, I have yet to see anything like this. The Rob North triple clamps were not hand formed; from recollection he used flat sections welded together. Apples to oranges.

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The prior surviving examples I've seen in sheet metal yokes were the slab sided safely over built enough method Dance's points out. But consider that auto makers and rocket scientists know that adding curvatures and contoured ridges adds to the rigidity of thin sheets, so its possible that Smiths yokes with his crafted shapes is stronger/safer way to do this method yokes. Lesser fatigue resistant material like Al or Ti must be made thicker or braced more to stand this vibration cyclic load application but then the weight and or cost advantage goes away. Should not ignore the extra toughness created by the cold work hardening of forming sheets beyond relaxed flats.

Here's more on cold formed sheet steel structures, like the famous Norton that loved to drift turns in era the rest were still slowing up to point before shooting.
http://en.wikipedia.org/wiki/Cold_formed_steel

I'm a bit of a student of the occult sciences, so know that it was politics and financial influence that caused the O2 cabin fire, the cold brittle o-ring seal failure in solid fuel booster and the adhesion failure of ceramic blocks missing on reentering death flight and that Van Braun was indeed a NAZI war criminal occultist more than a physicist as main motives. Here's tip of ice berg but realize SS Troops were more an occult initiation clan than just drafted military troops
http://www.v2rocket.com/start/chapters/vonbraun.html

hobot said:

Main point of the post is to point out that the strongest lightest construction method known in yoke and similar hi load bearing things, is use good grade of just thin enouhg Steel sheets in biggest OD size that can be fit in space available.

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You can make this statement but you cannot back this up. This is my main point. My question is, how could the world wide motorcycle industry miss this important point? Probably the same reason they transition from steel connecting rods to aluminum connecting rods in certain high load high performance applications.

Not a burr under a saddle but an intolerance for strong buckets of fertilizer when I hear it or read it. The fellows craftsmanship looks superb and was never in question in my mind.

In absolute terms strongest and lightest is a big maybe but from a practical standpoint, what you put forth is difficult to manufacture (make) and certainly delicate to maintain. I think you miss the point that structures do not necessarily scale up and continue to perform well. The Honda Dream was apparently successful with various pressed steel components. Unibodies and monocoque construction are other good examples when properly designed.

There are certainly those that want to believe. I am saying that a healthy level of skepticism and some simple testing can save a lot of skin.

Mass production/selling items at profit [with attendant liability issues] vs purity of design/performance...check out some G.P. bikes where cost/benefit is an order of magnitude removed, & items are 'lifed' prior to being consigned to research, museums or simply crushed.
If Valentino wants a sheet metal crafted triple clamp, Valentino gets a...

J.A.W. said:

Mass production/selling items at profit [with attendant liability issues] vs purity of design/performance...check out some G.P. bikes where cost/benefit is an order of magnitude removed, & items are 'lifed' prior to being consigned to research, museums or simply crushed.
If Valentino wants a sheet metal crafted triple clamp, Valentino gets a...

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You are correct regarding mass production versus one off assuming you get purity of design and performance!

My concern has been what purpose is it suited for.

Perhaps Valentino does not want a sheet metal crafted triple clamp.
Is he on to something? :roll:
What the heck does he know anyway. :roll:

Going from forged steel triple tree bottoms and cast aluminium tops to billet aluminium can save a few pounds, a sheet metal fabrication may be even lighter. Mass production without any WOW factor is cheap and heavy, billet has the WOW factor and can be easily made on a CNC mill on the other hand, a fabricated one is not easy to make, but it does have that WOW factor that even a CNC machined piece can't match.

If you want to sell a one off bike and you are a fantastic welder, then what he is doing makes perfect sense.

Jean

Jeandr said:

Going from forged steel triple tree bottoms and cast aluminium tops to billet aluminium can save a few pounds, a sheet metal fabrication may be even lighter. Mass production without any WOW factor is cheap and heavy, billet has the WOW factor and can be easily made on a CNC mill on the other hand, a fabricated one is not easy to make, but it does have that WOW factor that even a CNC machined piece can't match.

If you want to sell a one off bike and you are a fantastic welder, then what he is doing makes perfect sense.

Jean

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+1

I am still intrigued with the concept of a plate aluminum welded construction or a cnc machined and welded construction set of aluminum yokes.

Dances with Shrapnel said:

I am still intrigued with the concept of a plate aluminum welded construction or a cnc machined and welded construction set of aluminum yokes.

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IMOHO, a welded plate aluminium yoke woud distort and require machinig after welding whereas a CNC machined one would just drop in IF it was properly programmed and machined.

Jean

Or a master-smith's hand forged wrought unobtainium item, plunge quenched in the blood of a virgin princess & cloaked in the finest shimmering samite...fit for Conan hissself.[L.O.L.]

The whole discussion of liability and protection of the public from irresponsible manufacture is very interesting. I think it has more to do with culture than anything else. Some might say that there is a moral absolute on this subject either written or somehow knowable in our hearts. To me it comes down to culture and what we have come to expect. (From government unfortunately.)
I don’t see a lot of race bikes coming apart on the track or Indy type cars with stuff just breaking and falling off. But that is where this type of technology gets tested. If we demand full liability from a manufacturer then progress will come to a complete halt. You can read up on how architects were in a virtual fight with inspectors about the strength of materials in building tall buildings in the early parts of the 20th century. If the inspectors had won then we wouldn’t have any buildings over about 10 floors.
Personally I am for a “buyer beware” system with the possibility of punishment if it can be proved that the manufacturer knew that a product was probably going to dangerously fail. But if you agree with me about this don’t be a hypocrite and expect the government to pay for your medical when you hurt yourself.
My opinion of the triple clamps in question is that they would be plenty strong and have the added advantage of bending before they totally break. Steel is like that but cast iron and aluminum will all just snap as your first indication that there is a problem. Of course, as has been pointed out, a certain amount of testing can be done by stressing the units and measuring deflection and loading. Destructive testing on a unit this size could also be easily done.

The tin ones in the link look great, as has been pointed out strength is unknown. For all the effort and expense Im not sure if they would be any lighter than the al items on the Gsxr front end I used for my vincent special. They are light as a feather and have been tested in racing plus crash tested on the roads by a zillion young heroes.
A
One sees a lot of bent and mangled front ends on wrecked Sport bikes, but broken fork yokes are rare. I once toured the Icbc (the Insurance Corp of BC)wrecking yard and had a good look at several rows of severely damaged motorcycles, maybe 3/4 were sport bikes, 1/4 cruisers.
Almost all had front end damage, but only recall a few with smashed yokes. And for those few it probably would not have mattered what the yokes were made of.
It was a sobering experience.

Glen

Jeandr said:

Dances with Shrapnel said:

I am still intrigued with the concept of a plate aluminum welded construction or a cnc machined and welded construction set of aluminum yokes.

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IMOHO, a welded plate aluminium yoke woud distort and require machinig after welding whereas a CNC machined one would just drop in IF it was properly programmed and machined.

Jean

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Yes, absolutely, machine, weld and then final machine.

I can imagine a yoke with underside webbing finely machined out and then capped (welded) with plate aluminum pieces cut to fit within the webbing ends. This would be a closed form construction. Final machining would be required. Bit of a pipe dream on my part.

If the triple clamps gives one pause, it might be best I don't show anyone the accompanying frame rail:



...which is made in 3 pieces and welded at both sides:



...and connected to the clamps via the steering head made of expanded DOM tubing:



But being a Norton specific website, it may be more appropriate that my first post pertains to Nortons, so here's an aluminum primary cover for a Commando:



If anyone is interested in how this particular piece was constructed, here's a link to a breakdown of the process:

http://coopersmithingco.com


This is a great site, I have some poking around to do!


Joe Cooper

Love your work Joe!

CooperSmithingCo said:

But being a Norton specific website, it may be more appropriate that my first post pertains to Nortons, so here's an aluminum primary cover for a Commando:

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Holy guacample, nice stuff! Welcome.

The primary cover is beautiful, there must be a lot of hours in. Did you keep track of te time that went into it?

Ive considered making a sheet aluminum primary for my Vincent project bike which has a belt drive. I expect there is more work in making the primary cover than there was in the alloy tank which took me roughly80 hours to complete.

Glen