Tubing Bender

[Titan performance]

We tried to create headers for Gt500s and 750s with the orange one. We were using 2" stainless, and to be honest we didn't even get vaguely close. It just folded the tube right away.
As it goes, we found a machine shop with a mandrell bender, and the results from that are outstanding.

 

[sasquach]

OK I decided not to buy one and have it sent out instead . Now the big question Who bends tubing in the Pittsburgh area ?

 

[Cafe-XV750]

Check out pro-tools.com. Many different versions/cost levels of quality benders.

I have one of their HMP-200 rolling die benders and hole-saw notchers and am very satisfied with the results. Use it to make small batches of 1" and 1.25" formed tubes for a car product I sell. Also used it to make the rear subframe of my XV750.

 

[NortonGuy]

An interesting thing I read a bit ago. Colin Seeley, manufacturer of Grand-Prix racing motorcycles in the 1960's, built the frames for his first bikes using only an electrician's hand-bender. I worked as an electrician for many years and made thousands of bends in thin and heavy wall tubing, probably nothing with a radius tighter than 5"-6" though. But if you design your frame with that in mind you may be able to get away with very simple equipment.....

The Seeley frame was mostly all straight tubing except for the front down-tubes that had a large-radius around the engine, something that is not hard to bend with simple equipment. Later on Seeley axed the front radius down tubes and had most of the motor just hanging out there in front.

Exhaust is a whole different game, with very thinwall tubing that often has very small radius bends, but you do not have to worry about it because you can buy ready-made bends to weld into your pipe where you need it.

A frame made with straight tubing is going to be stiffer than one that has a lot of bent tube elements. Modern frames are all triangulated straight element frames. The famous old Norton featherbed frame had a lot of bends in it that were tied together with gussets, engine plates and the engine. Without all those parts tying it together it would have been a piece of shit, it did a good job with the skinny tires and 50-60hp engines of the day. The same design with a modern 100-200hp engine is way out of it's league....

 

[Hoofhearted]

NortonGuy. Featherbeds don't use the engine as a stressed member. Its a wrap around frame and the only gussets apart from the swing arm gussets are around the steering head which are not on the Manx frame. As far as doing a "good job" it was in its day the standard by which all other frames were judged. Might I suggest you change your name to BSAGuy?

 

[NortonGuy]

NortonGuy. Featherbeds don't use the engine as a stressed member. Its a wrap around frame and the only gussets apart from the swing arm gussets are around the steering head which are not on the Manx frame. As far as doing a "good job" it was in its day the standard by which all other frames were judged. Might I suggest you change your name to BSAGuy?

An essential part of the stiffness of a featherbed Norton frame, is the plate/mount that is bolted between the cylinder head and engine. This stiffens the steering head considerably and transfers some of the forces the steering head is subject to into and through the engine to the rest of the chassis. The three points by which the Norton engine, gearbox is attached to the frame, at the rear, at the front and at the top of the cylinder head form a triangle, which "triangulates" and considerably stiffens the entire chassis in that plane.

Basically, you are saying that having the bolts holding the engine-transmission in the frame loose and/or missing is not going to affect it's handling, which is not only laughable in respect to the Norton chassis, but to almost any motorcycle chassis ever designed in history.....

If you don't mind, I will keep the engine/transmission and head-steady bolts of my genuine Norton Manx, and my other five featherbed Nortons, tight and fitted with precision....

 

[Hoofhearted]

I will keep the engine/transmission and head-steady bolts of my genuine Norton Manx, and my other five featherbed Nortons, tight and fitted with precision....

Well ya got me beat there. I only have one featherbed and its only a land speed record holder. I feel so inadequate.

 

[scm]

So you admit NortonGuy is right with his statements about the featherbed frame?

 

[Basement rat]

I understand what they both are saying, The engine is'nt stressed like a modern sport bike but it helps stiffen it too. The reason I'm interested in the Featherbed frame is because of the two hoops that make the most of it. I'm not looking to build a serious racer or a complete clone. I just want to eventually build a frame up bike based off of it. Its interesting for its time because there is less welding involved (compared to other frames) reducing the risks of cracks. Sure, to modern standards, its a wet noodle.

 

[Hoofhearted]

So you admit NortonGuy is right with his statements about the featherbed frame?

Nah! It was my attempt at sarcasm. True the head steady runs from the steering head to the engine head. And they are necessary. But to run to the engine is not necessary. My Norton has a Weslake 500 in it at the moment. Weslakes have no provision for a head steady. I run a small alloy brace from the head to the crossmember.

"Basically you are saying that having the bolts holding the engine-transmission in the frame loose and/or missing........". No, I didn't say that. I said the engine is not a stressed member. Huge difference. Anyway this is a thread about tube benders and lets get back to it. I don't want to hijack a thread and turn it into a pissin match.

 

[NortonGuy]

I don't want to hijack a thread and turn it into a pissin match.

You did , and you are wrong.....

When you say "the engine is not a stressed member", then you are saying that none of the stress the chassis sees in it's intended use is channeled through the engine/transmission unit. That is, it could be suspended by rubber bands or springs and not affect the handling or performance of the chassis at all, which is dead wrong.

The Norton featherbed as designed had it's head steady attached to the top of the engine, and it's engine/transmission bolted rigidly in place exactly because stresses from the normal use of the chassis were transferred through it.

If all Norton wanted to do was to contest straight-line speed trials with it's motorcycles, then it never would have needed the Featherbed frame at all, it could have gone on using the primitive rigid or garden-gate plunger frame. But Norton was involved in World Championship Grand Prix road-racing, which as everyone knows involves closed circuits with combinations of stresses from turns, braking ,acceleration and uneven road surfaces.

For their road racing machines, the Manx, and the street bikes they sold with the Featherbed frame, they incorporated the parts necessary to brace the steering head to the engine of the machine.
Just because here and there over decades oddball private owners leave pieces of the frame off or modify it for other uses means nothing at all...

 

[t71ford]

I think Hoof was referring to the stressed member by its definition, though, where a "Stressed Member" engine actually uses the engine as an essential and completing part of the frame structure, which the Featherbed does not. While it does contribute to the frame stiffness, the frame is complete without it, unlike in a stressed-member frame as in a modern sportbike. So while the Featherbed frame uses the engine to contribute to frame stiffness, it does not use the engine as a stressed member.

...as if it matters :

 

[borzwazie]

This is a stressed-member frame:

so is this:

This is not:

Neither is this:

And neither is the featherbed. My CB450 uses a head steady but the engine isn't a stressed member. My bike and the Norton will run just fine without the head steady, if less precise in corners.

 

[joeyputt]

Those are good examples of what some may consider to be a stressed member frame by definition however in theory all motorcycle frames, or most any other motorsports frames for that matter, are stressed membered frames to an extent. I do not want to get in to a large debate here so I will keep my explanation very basic.

Anytime that you connect one frame rail to another by bolting something to or in between them that piece becomes a stressed member and greatly influences the dynamics of the chassis, this holds true for something as small as a bracket that is simply mounted between two seperate frame rails, or the same frame rail, and bolted on each end and for this discussions purposes certainly holds true to greater effect for an engine which is mounted to the frame at several different points therefore connecting all of these frame points.

A racing kart chassis for example is a great example as there are no suspension components such as shocks, forks, etc. so we can remove them from the equasion. A kart chassis itself acts as the suspension and running the floorpan, bumpers, body, seat, etc. bolts loose or tight greatly affects the way the chassis reacts to different forces, pressures, and torques and can be finely tuned for flex by the location of mounting points as well as how they are mounted individually, it is very common practice to run individual components bolted loosely or tight at different race tracks to fine tune the chassis itself and the same could and does apply to motorcycles. Even something as simple as exhaust mounting locations that tie different areas of the chassis, or the engine and the chassis, togethor greatly influence the dynamics of the chassis so in theory an engine that is bolted to a frame in several different locations is most certainly a stressed member of that frame.

All motorcycle frame designs take into account the rigidity that is added by the engine bolted tightly in place as a stressed member which greatly affects chassis flex and motion and could they be ridden with or without the engine in place they would without question handle not only differently but at opposite ends of a comparison scale just the same as if you were to run them with the engine mounting bolts loose or tight for comparison.

 

[NortonGuy]

All motorcycle frame designs take into account the rigidity that is added by the engine bolted tightly in place as a stressed member which greatly affects chassis flex and motion and could they be ridden with or without the engine in place they would without question handle not only differently but at opposite ends of a comparison scale just the same as if you were to run them with the engine mounting bolts loose or tight for comparison.

Wow, someone in touch with reality, how the hell did that happen? Thank you joeyputt.

I took issue with Hoofhearted's rhetoric aside from it's mean-spirited intent, because I was afraid it might let youngsters think that they can leave out or cut out parts of their Norton or other motorcycles chassis that were an integral part of it's design and get away with it. This is at least irresponsible advice.

The Weslake speedway engine that Hoof uses in his bike has many decades of tuning information that can be drawn from when putting it to use.

Taking the Weslake out of speedway competition, where amazing skill is needed to master the style of riding added the close proximity of other competitors, is as unimpressive as taking a chassis designed for Grand-Prix motorcycle road racing and using it to ride only in straight-line speeds that a thousand teenagers achieve on public highways on Jap sportbikes every week.

It is great that this gets someone out from in front of the television, but it does not mean that anyone who does it is a chassis engineer or any better a human being than anyone else....

 

[Chivatty]

Crap, how many pages do I have to go back to find the tube bender opinions??

 

[Hoofhearted]

Wow, someone in touch with reality, how the hell did that happen? Thank you joeyputt.

I took issue with Hoofhearted's rhetoric aside from it's mean-spirited intent, because I was afraid it might let youngsters think that they can leave out or cut out parts of their Norton or other motorcycles chassis that were an integral part of it's design and get away with it. This is at least irresponsible advice.

The Weslake speedway engine that Hoof uses in his bike has many decades of tuning information that can be drawn from when putting it to use.

Taking the Weslake out of speedway competition, where amazing skill is needed to master the style of riding added the close proximity of other competitors, is as unimpressive as taking a chassis designed for Grand-Prix motorcycle road racing and using it to ride only in straight-line speeds that a thousand teenagers achieve on public highways on Jap sportbikes every week.

It is great that this gets someone out from in front of the television, but it does not mean that anyone who does it is a chassis engineer or any better a human being than anyone else....

Sorry Chivatty. I feel a need to answer this post.

If you read my posts I never advised or advocated running without a steering head brace on a featherbed or leaving off anything else. I did say the Weslake in my Norton has no provision for a head brace but I run a steady from the steering head to the top crossmember.

Many decades of tuning information? Weslakes started off as pushrod engines. The early model became known as the long rod. The next model had a shorter rod which is how the earlier model got its name. After that came the SOHC. Followed by the disasterous DOHC. As soon as another manufacturer build a better motor the old models were dropped like hot potatoes. Some Vee twins in pushrod and OHC forms were made but only in small numbers. Tuners keep their secrets close to the chest. There is little or no tuning info available.

The next paragraph is amusing. I'm not sure I understand the why using a speedway engine for some other purpose or a Norton frame for something other than road racing is unimpressive. I guess Les Archer taking a modified 500 Manx and winning the 1953 European Motocross Championship is equally unimpressive. True, any modern 600 or liter bike will make my speeds look silly. But thats not the point. Were pure speed the only reason there wouldn't be 566 entrant at Bonneville SpeedWeek or any other speed event. I run LSR now for a simple reason. I'm too old to road race. My Norton was road raced from the late 60s until the mid 90s. I returned home but didn't want to stop entirely. Willow is the closest track and it doesn't seem to run many classic races. So LSR fill the bill nicely I never claimed to be a chassis engineer nor would I be so bold.

By weslake at 2011-09-13

 

[teazer]

Borwazie and Hoof are correct. The issue is not whether or not an engine contributes to stiffness or even the degree to which it does so. It's a term which is used to describe frames in which the motor was designed to substantially contribute to the integrity of the frame.

In fact it really means that there are significant frame stresses put through the motor and that the motor has to be stiff enough to withstand those stresses. The term really relates to the motor rather than the frame.

Joey and Norton guy are both correct that all engines tend to contribute some stiffness, but the rubber mounted engine in my GT750 has very little frame stress through it, though it makes a minor contribution to the plot.

It's just a term and it has a common usage, so let's try to be a little tolerant and flexible - just like many of our old frames.

A really good point is that we don't want people cutting bits off frames to look cool when they have no idea how badly that might end.

Now what was the answer on that bender?

 

[Basement rat]

I feel the need to say I'm sorry I started this. All I said was if I couldent bend a frame like a featherbed with a bender, then its useless to me. Thats all.

Good cheep benders?

 

[NWDragRacer]

I feel the need to say I'm sorry I started this. All I said was if I couldent bend a frame like a featherbed with a bender, then its useless to me. Thats all.

Good cheep benders?

The orange one shown in the first post is a pipe bender. Pipe is used for water and fluids and is all about the inside diameter. Tubing is different. You cannot expect nice, wrinkle free tubing bends from a pipe bender.

Here is a cheap solution to build a decent bender on eBay http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=190576833124