Featherbed frame design went against all engineering princip

Re: Featherbed frame design went against all engineering pri

Hydroforming is done industrially, usually with dies - there are several utube clip showing this.
Small scale producers of 2t expansion pipes usually just do it as described - again there has been a utube clip.
The trick is getting the development right.

The Porsche 917 was well known for being pressure tested for cracks in the space frame. Late 60's on.

Re: Featherbed frame design went against all engineering pri

hobot said:

I'm testing Peel's OIF with vaccum and pressure from out in sun heat which did open up pin holes to weep or drip so had to JBW some more in many cycles so far. I've wondered about pressurizing a box structurea to stiffen it but don't know if that also makes more prone to fracture. Peel's boxed Al swingarm has 100 PSI in it planned. Showed it to a few retired engineers and active machinist who say should be fine. They make gas tanks by welding two or more flat sheets together then inflate with water pressure till splits, weld more and repeat till ends up the desired shape.

Click to expand...

When I had my Rickman OIF repaired the finished article was tested with air pressure, in a water bath like you do with an inner tube!

Pressure was taken up to 250psi no problem. 1 1/4" OD tubes in Renold 531, bronze welded.

Re: Featherbed frame design went against all engineering pri

That bronze welding interests me. When we made the Egli replica we used gas flux with nickel bronze. However I believe all the original Seeley frames were done with tobin bronze. Any ideas about what might be best ? I've actually got a steel TIG welder however I'm reluctant to use it on frames because of the doubts I have about the metallurgy, and the necessity for a close fit-up. I'm still interested in making this frame :

Re: Featherbed frame design went against all engineering pri

Roger Titchmarsh uses Sifbronze 101, a bronze filler rod with manganese added, for his replica Seeley frames. Seeley also used a Sifbronze rod, but it was probably the older Sifbronze No. 1 rod, which was similar, but without the manganese. That was the rod used by Rickman, Seeley, and pretty much anyone else who built bronze welded frames back in the '50s, '60s and '70s. It was the original Sifbronze rod, and was just referred to in the literature at the time as Sifbronze rod, with no number. 101 was a later development, with added manganese and tin, and was promoted as better for use with gas fluxers, which I think Roger uses. I don't think you can call either of them Tobin bronze, as I think that generally refers to a straight copper/zinc bronze with minimal or no additives.

The attraction of nickel bronze rods is their higher tensile strength, and for other uses its hardness and wearability, but it's doesn't flow as well as the 101, and I'm not sure it offers any advantage in frame construction. It also has a higher melting point, so the risk of overheating the parent metal is greater. If it was me, I'd use one of the locally available rods with similar characteristics. I've used Harris No. 15 silicon bronze rod for frame modifications and swingarm fabrication, and been quite happy with the results.

Lots of good information on history of Sifbronze here

http://www.weldability-sif.com/pages/home.asp

Ken

Re: Featherbed frame design went against all engineering pri

Tobin bronze is just zinc/copper like you say = common old brass, which can't be puddled or built up into fillets.
Useless for frame building, the welds would all look like they'd melted away.
(Great for lugged frames though, precisely what is needed, wicks into the lugged joints)

This is about the 10th time this has been covered here....

Re: Featherbed frame design went against all engineering pri

Better tell moderator to delete and prohibit all these on and on repeated threads that annoy you enough to write about it.

Back to the Featherbed frame, it sure made a lasting name for itself so why was that if so badly conceived? There's a number of pleased riders with isolastic Command power inserted so Norton could of too. Is Commando frame easier less costly to make time after time? I was surprised opening the spinal tube to find the middle tubes aren't just welded to spine exterior but continue straight though.

Re: Featherbed frame design went against all engineering pri

One of my Clubmates raced a Featherbed Atlas, (Manx frame for <weight) at the old Westwood mountain course in Vancouver back in the sixties. For awhile he held the lap record there with it. When the Commandos came out in 68, British MCs, the Vancouver Norton dealer, sponsored him.
He told me that the Commando frame is a better handling frame than the featherbed. He could lap faster on the Commando and found it much less tiring to road race with than with his F'bed. When he told me that, I dropped the idea of building a featherlastic. Seems Dr. Bauer et al got it right.

I like em both, but there are no flies on a good Commando.

Glen

Re: Featherbed frame design went against all engineering pri

If you've ever ridden a rigid framed bike, you'll know why Nortons plunger framed bikes became popular when they appeared.
Riding a rigid framed bike - merely on the road -for a few hundred miles is hard work....

And when swingarm framed bikes appeared, you'll know why the old plunger framed bikes died a quick death.

And, I am told, telescopic forks were a similar improvement over the old girder forks of old.

Folks just don't appreciate the huge quantum leaps that have appeared in motorcycle over the decades and centuries. ?
The story goes that "featherbed" was coined when Harold Daniell (was it ?) took one for a spin,
and was sooooooooooo impressed with how easy and comfortable it was to ride....

Re: Featherbed frame design went against all engineering pri

Glen that's music to my ears as few of us would have much to do with each other except for Norton bringing on Dr. Bauer genus. Still the most dangerous motorcycle to go around fast for me is the isolastic Commando, so I never do no more. Wonder if me-we could come up with a better isolastic after market frame, though likely would be shot down by regulations.

Some flex, compliance and energy storage and release w/o rebound is needed to solve secure racing so its only and always the pilots fault not a surprise from the cycle behavior control loss. Current concept is weakening the ends of the frame, stem forks, swing arm, I say better to be soft in the center hard on the outside. I'd call it the Goldie Locks box frame.

Re: Featherbed frame design went against all engineering pri

worntorn said:

One of my Clubmates raced a Featherbed Atlas, (Manx frame for <weight) at the old Westwood mountain course in Vancouver back in the sixties. For awhile he held the lap record there with it. When the Commandos came out in 68, British MCs, the Vancouver Norton dealer, sponsored him.
He told me that the Commando frame is a better handling frame than the featherbed. He could lap faster on the Commando and found it much less tiring to road race with than with his F'bed. When he told me that, I dropped the idea of building a featherlastic. Seems Dr. Bauer et al got it right.

I like em both, but there are no flies on a good Commando.

Glen

Click to expand...

I can beleive this but in the hands of "the man on the Clapham omnibus" a featherbed is a much easier frame to stay safe on.

Its very hard to make a featherbed handle badly.

Its extremely easy to make an isolastic Commando handle badly.

I have done both!!

Re: Featherbed frame design went against all engineering pri

johnm said:

worntorn said:

One of my Clubmates raced a Featherbed Atlas, (Manx frame for <weight) at the old Westwood mountain course in Vancouver back in the sixties. For awhile he held the lap record there with it. When the Commandos came out in 68, British MCs, the Vancouver Norton dealer, sponsored him.
He told me that the Commando frame is a better handling frame than the featherbed. He could lap faster on the Commando and found it much less tiring to road race with than with his F'bed. When he told me that, I dropped the idea of building a featherlastic. Seems Dr. Bauer et al got it right.

I like em both, but there are no flies on a good Commando.

Glen

Click to expand...

I can beleive this but in the hands of "the man on the Clapham omnibus" a featherbed is a much easier frame to stay safe on.

Its very hard to make a featherbed handle badly.

Its extremely easy to make an isolastic Commando handle badly.

I have done both!!

Click to expand...

In my humble opinion the issue is the height of the engine. A single can sit quite low between the frame rails on a featherbed but a twin like an Atlas or Commando has to have the engine higher which compromises the handling.


Edit: Maybe there's a commercial opening for someone who can make a featherbed with wider lower frame rails so a twin can sit lower.

Re: Featherbed frame design went against all engineering pri

wakeup said:

At the risk of moving even further away from featherbeds, I remember reading somewhere that the JPN "space frame" had a tyre valve inserted somewhere so that the frame could be "pumped up" with an airline to a known pressure, then routinely checked for any drop in pressure, which would equal at best a crack somewhere.

Click to expand...

Just a question here......the space frame was not OIF.......but to be useful each tube joint would need a hole to allow the inside of the frame to become one chamber....did they really do that?

IOF frames of course you have to, but generally they are made of less individual tubes.

Featherbeds.....must be something going for them if you look at various Japanese race frames that were described as 'Mini featherbeds' that used the same principles.

Dr Bauer may have rejected it, but clearly thousands haven't....and thousands also do not accept that a Commando frame can handle better.....what does that mean?....

Two things. Few have ridden a Commando frame and suspension performing at its best! And a lot of people feel more comfortable on a Featherbed.

Why would that be? Well it is easy to understand the first, most bikes need a suspension set up to suit a rider, but do not need the frame itself to be set up!

The second? There is a difference between handling, roadholding and comfort, and expectation! And a difference in rider style that Dr Bauer may not have considered important when building for the mass market.

Some have noted that the Manx frame used lighter tubing, but that tubing also has different flex and resonance characteristics to the road bike mild steel, and the replica frames being made today have different tubing again, and are used with different tyres, suspension and geometry.

Whatever Dr Bauer thought the basic featherbed design has proven over time to meet rider expectations of a good handling frame in various applications and various implementations and developments have allowed them to fit the riding style (and tyres) of the day!

The featherbed has been adapted. In most cases a rider has to adapt to a Commando to get the best from it.

Re: Featherbed frame design went against all engineering pri

SteveA said:

Featherbeds.....must be something going for them if you look at various Japanese race frames that were described as 'Mini featherbeds' that used the same principles.

Click to expand...

It is important to note that the theoretical aspect that was initially criticised about the featherbed was the multitude of curved tubes involved.
Nothing else.
If the design had been morphed somehow so that all those tubes were straight, there would not have been a murmur in this direction. (?).

We mentioned earlier too that it had been reported that Jim Redman organised an actual new manx to go to Japan,
for them to explore the frame design...

Dr Bauer's objections need to be explored separately ??

Something that needs to be born in mind is that featherbeds are quite a smallish motorcycle,
and the US market had/has a lot of larger riders.
Just making the bike suit larger riders was quite a mission in itself. ?
And wow, have we seen that in some of the present day offerings....

Re: Featherbed frame design went against all engineering pri

Rohan said:

SteveA said:

Featherbeds.....must be something going for them if you look at various Japanese race frames that were described as 'Mini featherbeds' that used the same principles.

Click to expand...

It is important to note that the theoretical aspect that was initially criticised about the featherbed was the multitude of curved tubes involved.
Nothing else.
If the design had been morphed somehow so that all those tubes were straight, there would not have been a murmur in this direction. (?).

We mentioned earlier too that it had been reported that Jim Redman organised an actual new manx to go to Japan,
for them to explore the frame design...

Dr Bauer's objections need to be explored separately ??

Something that needs to be born in mind is that featherbeds are quite a smallish motorcycle,
and the US market had/has a lot of larger riders.
Just making the bike suit larger riders was quite a mission in itself. ?
And wow, have we seen that in some of the present day offerings....

Click to expand...

I may not have good recall of the story, but Redman rode for Honda, who I understood were a bit dismissive of Redman's effort and less than pleased with Mike Hailwood's involvement with Ken Sprayson.....

But someone in Japan took note and ironically some of the featherbed design that was copied on the TZ Yamaha and its road siblings, YDS7 etc. was the multiple curved tubes!

Excellent point about rider size, I am a Brit but I am around 6' and have longish arms. I have never been comfortable sitting on a featherbed...it is just too short for me, even with clip ons, rear sets etc.

The Commando with flat bars and standard rests or clip on bars/rearsets is much better for me, but my Rickman errs toward too long....hence I have had slightly shorter tanks made for it (though this is as much about shifting weight forward over the front end as it is about comfort)

The Rickman has fewer curved tubes than the featherbed, but some criticise it for being too stiff, frame stiffness is a fine line also dependent on how much power/tyre grip you are twisting it with...

In most cases the 'improved' race frames of today work because of increases in both power output and grip.

Note that most prefer a stiffer version of the MkII Seeley for a Commando engined racer today, whereas in the '70s they were made with the potentially more flexible MkIII frame.

Re: Featherbed frame design went against all engineering pri

First thing i noticed about the feather bed frame is it GRACE ,STYLE , forget all that stress and stuff! the frame just looks bloody great, have you seen another that looks so good on a triton Cafe racer in Willow green? The GB access Manx [1951] Goodwood bike with its light green frame and polished Alloy bits looks a Million Bucks. Good enough to lap the IOM at 100mph says it all..

Re: Featherbed frame design went against all engineering pri

john robert bould said:

First thing i noticed about the feather bed frame is it GRACE ,STYLE , forget all that stress and stuff! the frame just looks bloody great, have you seen another that looks so good on a triton Cafe racer in Willow green? The GB access Manx [1951] Goodwood bike with its light green frame and polished Alloy bits looks a Million Bucks. Good enough to lap the IOM at 100mph says it all..

Click to expand...

Would be bloody difficult to build a Triton without a featherbed! :roll:

Re: Featherbed frame design went against all engineering pri

SteveA said:

john robert bould said:

First thing i noticed about the feather bed frame is it GRACE ,STYLE , forget all that stress and stuff! the frame just looks bloody great, have you seen another that looks so good on a triton Cafe racer in Willow green? The GB access Manx [1951] Goodwood bike with its light green frame and polished Alloy bits looks a Million Bucks. Good enough to lap the IOM at 100mph says it all..

Click to expand...

Would be bloody difficult to build a Triton without a featherbed! :roll:

Click to expand...

Unless its a isolastic? any seen one?

Re: Featherbed frame design went against all engineering pri

pommie john said:

johnm said:

worntorn said:

One of my Clubmates raced a Featherbed Atlas, (Manx frame for <weight) at the old Westwood mountain course in Vancouver back in the sixties. For awhile he held the lap record there with it. When the Commandos came out in 68, British MCs, the Vancouver Norton dealer, sponsored him.
He told me that the Commando frame is a better handling frame than the featherbed. He could lap faster on the Commando and found it much less tiring to road race with than with his F'bed. When he told me that, I dropped the idea of building a featherlastic. Seems Dr. Bauer et al got it right.

I like em both, but there are no flies on a good Commando.

Glen

Click to expand...

I can beleive this but in the hands of "the man on the Clapham omnibus" a featherbed is a much easier frame to stay safe on.

Its very hard to make a featherbed handle badly.

Its extremely easy to make an isolastic Commando handle badly.

I have done both!!

Click to expand...

In my humble opinion the issue is the height of the engine. A single can sit quite low between the frame rails on a featherbed but a twin like an Atlas or Commando has to have the engine higher which compromises the handling.


Edit: Maybe there's a commercial opening for someone who can make a featherbed with wider lower frame rails so a twin can sit lower.

Click to expand...

I think there would be a problem because of the diameter of the flywheel and the crankcases. I don't think it is ever possible to get the same weight distribution with a twin motor in a featherbed frame, that the single cylinder engine gives. I've ridden what was an extremely good 650cc triton and also an extremely good 1961 model 500cc Manx. The manx is streets ahead, it gives much more confidence to the rider because of it's feel. If you get off-line with it, you simply give it more stick. I've never raced an isolastic Norton, however a featherbed frame with the wrong diameter wheels can be exhausting to race over more than a few laps of a tight circuit. I don't believe the ability of the rider makes a bad bike go much better. More like a good handling bike creates a better rider.

Re: Featherbed frame design went against all engineering pri

pommie john said:

johnm said:

worntorn said:

One of my Clubmates raced a Featherbed Atlas, (Manx frame for <weight) at the old Westwood mountain course in Vancouver back in the sixties. For awhile he held the lap record there with it. When the Commandos came out in 68, British MCs, the Vancouver Norton dealer, sponsored him.
He told me that the Commando frame is a better handling frame than the featherbed. He could lap faster on the Commando and found it much less tiring to road race with than with his F'bed. When he told me that, I dropped the idea of building a featherlastic. Seems Dr. Bauer et al got it right.

I like em both, but there are no flies on a good Commando.

Glen

Click to expand...

I can beleive this but in the hands of "the man on the Clapham omnibus" a featherbed is a much easier frame to stay safe on.

Its very hard to make a featherbed handle badly.

Its extremely easy to make an isolastic Commando handle badly.

I have done both!!

Click to expand...

In my humble opinion the issue is the height of the engine. A single can sit quite low between the frame rails on a featherbed but a twin like an Atlas or Commando has to have the engine higher which compromises the handling.


Edit: Maybe there's a commercial opening for someone who can make a featherbed with wider lower frame rails so a twin can sit lower.

Click to expand...

I think there would be a problem because of the diameter of the flywheel and the crankcases. I don't think it is ever possible to get the same weight distribution with a twin motor in a featherbed frame, that the single cylinder engine gives. I've ridden what was an extremely good 650cc triton and also an extremely good 1961 model 500cc Manx. The manx is streets ahead, it gives much more confidence to the rider because of it's feel. If you get off-line with it, you simply give it more stick. I've never raced an isolastic Norton, however a featherbed frame with the wrong diameter wheels can be exhausting to race over more than a few laps of a tight circuit. I don't believe the ability of the rider makes a bad bike go much better. More like a good handling bike creates a better rider.
I suggest that every budding road racer should try to get a ride on a 500cc manx, even if they have to pay for it. The bike is a benchmark - something from which to judge the performance of other bikes.

Re: Featherbed frame design went against all engineering pri

SteveA said:

Some have noted that the Manx frame used lighter tubing, but that tubing also has different flex and resonance characteristics to the road bike mild steel, and the replica frames being made today have different tubing again, and are used with different tyres, suspension and geometry.

Click to expand...

Did the Manx frames have bigger diameter tubes? If not and all other things being equal they would flex more than the road frames.
With respect to the original suggestion that design was flawed with curves, it must also be remembered that there is an engine and gearbox bolted in the middle of it all. Then if you look at the load paths the curved sections are probably not very highly loaded or are gusseted.