Race chassis

[WilDun]

Must be a work of art because no self-respecting technician would even dream of such improper use of steel tubing.

Nothing which looks "proper" will ever attract the hordes with their dollars, Harley honed that philosophy down to a fine art! .......... well, maybe John Britten had the ability to make "improper" looking stuff but managed to combine it with reason! - however, he didn't wait to see it through.

[philou]

Hello,

I am search information on the bending of extrud aluminum frame spar

[Grumph]

Hello,

I am search information on the bending of extrud aluminum frame spar

Putting it very basically - a little at a time, under a press.
If you can locate a copy of Bradley's book "The racing Motorcycle" Volume 2, there's a good description of how to do it in there.

[philou]

3 years I seek it

[F5 Dave]

I find a job goes much quicker if you don't try to do it properly.

[Ocean1]

Hello,

I am search information on the bending of extrud aluminum frame spar

Assuming you've got a suitable alloy, there's still quite narrow limits as to how far you can do that, mostly based on thinning out the outer bend radius wall thickness.

I can't help as far as Mr Bradley is concerned, but I'd like to know his technique.

What works for me on similar projects is: making inner and outer form tools to control expansion distortion, (bulging) and packing the extrusion with fine, dry sand, (with welded caps) helps control collapse of the walls.

I've used both a workshop frame press and a hydraulic pipe bender. Nice and slow and releasing the pressure occasionally has, for me helped reduce the liklihood of cracks. That, and keeping the whole assembly, (including form tools) warm.

It's almost certain that even if you don't stuff up the first attempt you'll learn how to do it with better results, so I'd suggest getting your hands on enough material to do a few. And make that your first operation, so when you bin it you haven't thrown away too much time...

[chrisc]

Go to 1.46 mark of this video for a glimpse of how Oral Engineering/Kymco did it for their Moto3 frame.

[F5 Dave]

Engine looks overly complex and heavy for a small racebike.

[chrisc]

Engine looks overly complex and heavy for a small racebike.

I know right Dave, for one, they have these weirdly complicated valve things and it fires only half as often as it could. Weird. Must be a Chinese thing?

[Pumba]

Engine looks overly complex and heavy for a small racebike.

It's ok Dave. It will never catch on.


Sent from my iPhone using Tapatalk

[Flettner]

I'm late to this thread so possibly already talked about?
A mandrel tube bender is what you want. It can be made to bend all sorts of shaped tubes. It uses an outer and an inner shape, also a 'slug' in the middle held with a long rod from an anchor point down the straight unbent bit. Where the bend takes place, the tube is supported all around. Alloy tube is best softened (T 0) it will work harden a little at the point of bend, this helps it hold shape as it's drawn off the mandrel. After finishing and welding the frame it will need to be heat treated to T 6 again. Assuming you are using 6061.

[Grumph]

The problem with that Neil is that what frame sections can be obtained (in Europe) are odd shape and have internal divisions making mandrel bending difficult. Not impossible, granted. Plain rectangular tube is, by contrast, easy, as well as in plentiful supply.
The dedicated frame sections are also usually in a 7000 series air/time hardening alloy which means no heat treatment post weld.

I haven't yet seen the vid ChrisC posted, next time I'm on broadband I'll have a look. Bradley detailed the bending of frame spars in the book which was done in multiple bends under a press, going to around .020in deformation each press. Form tools were used too.

I'm actually suffering withdrawal symptoms, the book is on loan.....

[husaberg]

I haven't yet seen the vid ChrisC posted, next time I'm on broadband I'll have a look. Bradley detailed the bending of frame spars in the book which was done in multiple bends under a press, going to around .020in deformation each press. Form tools were used too.

I'm actually suffering withdrawal symptoms, the book is on loan.....

If you rub a bit of bar soap on the tube when it turns black its but about ready to dissolve into a puddle.
http://makeagif.com/i/udEI7l

[Flettner]

The problem with that Neil is that what frame sections can be obtained (in Europe) are odd shape and have internal divisions making mandrel bending difficult. Not impossible, granted. Plain rectangular tube is, by contrast, easy, as well as in plentiful supply.
The dedicated frame sections are also usually in a 7000 series air/time hardening alloy which means no heat treatment post weld.

I haven't yet seen the vid ChrisC posted, next time I'm on broadband I'll have a look. Bradley detailed the bending of frame spars in the book which was done in multiple bends under a press, going to around .020in deformation each press. Form tools were used too.

I'm actually suffering withdrawal symptoms, the book is on loan.....

Bike frames (pedal) were made from 7000 series but it's fatigue resistance was not as good and older 7000 alloy bikes were not worth owning, they all cracked sooner or later. On the other hand 6000 series frames, although a little heavier, have much better fatigue resistance. many early units are still operating.
I wouldn't bother with 7000 series frames, just (expensive) trouble waiting to happen.
Interesting to note that all our Gyro Copter rotors, rotor heads and frames are all still made from 6061 T6. Frames and Rotor heads are bolted together with the rotors being bonded (and bolted at the hub also)
6061 T6 is good all round performer.

[husaberg]

Bike frames (pedal) were made from 7000 series but it's fatigue resistance was not as good and older 7000 alloy bikes were not worth owning, they all cracked sooner or later. On the other hand 6000 series frames, although a little heavier, have much better fatigue resistance. many early units are still operating.
I wouldn't bother with 7000 series frames, just (expensive) trouble waiting to happen.
Interesting to note that all our Gyro Copter rotors, rotor heads and frames are all still made from 6061 T6. Frames and Rotor heads are bolted together with the rotors being bonded (and bolted at the hub also)
6061 T6 is good all round performer.

Honda MX Frames are 7005 and it says to use a 5356 welding rod (According to HRC)
they are age hardened after welding.

Yamaha had a lot of trouble with their MX frames as well not the tubes and forgings but actually the welds