HeadSmess
Well-Known Member
- Local time
- 10:17 AM
- Joined
- May 17, 2010
- Messages
- 3,048
i need to go get some superglue...another point to procrastinate over.
dont do it kids, its a filthy habit! just get up and do it!
been modelling up pipes for the nsr150 the past few days, mainly to try and prove the point that you DONT need anything more sophisticated than scissors, aerosol cans, a blowtorch and patience...
the aerosol cans might be a but too thin for the size of this pipe, and the number i have to cut up...im just going for a particularly flimsy galvanised toolbox lying around. saves having to prep any joins as well. the point remains the same. its thin enough to cut with heavy duty scissors.
brazing the majority and welding just the header section...all 29mm of it.
but, thats irrelevant. the main point of this thread is to lay out some maths required for hydroforming.
once i have this section modelled up in paper i can squash it and measure all the new angles...
the basics are simple. start with a straight cone, and the length wont change...but the diameters will be flattened, becoming half the circumference each.
if you make a cone bent through 180 degrees... you have to figure out what the bend will straighten out to when "flattened".
figure out how to use a freakin spreadsheet and i could find the relationship between diameters and angles...
then its no more rolling cones and cutting paper but just lay out two profiles, seam weld, and inflate.
seriously, using 240gsm paper (stiff) you can go through a full ream before getting to the stinger... amazing how much difference just 2 degrees can make.
so far it looked like a 36:63/340mm cone bent through 130 degrees flattened out to 56:100/340mm at 90 degrees... unfortunately that bend needs to be expressed as a radius...
backtrack. (56*2)/pi= 35.7... about right.
(100*2)/pi=63.7ish.... also close enough...
i also have to find how the inner and outer radius varies from the main or central radius. thats a function of the diameters/degree of taper... hmmms.
there is no way im ever going to contemplate spinning one! (trumpets...)
dont do it kids, its a filthy habit! just get up and do it!
been modelling up pipes for the nsr150 the past few days, mainly to try and prove the point that you DONT need anything more sophisticated than scissors, aerosol cans, a blowtorch and patience...
the aerosol cans might be a but too thin for the size of this pipe, and the number i have to cut up...im just going for a particularly flimsy galvanised toolbox lying around. saves having to prep any joins as well. the point remains the same. its thin enough to cut with heavy duty scissors.
brazing the majority and welding just the header section...all 29mm of it.
but, thats irrelevant. the main point of this thread is to lay out some maths required for hydroforming.
once i have this section modelled up in paper i can squash it and measure all the new angles...
the basics are simple. start with a straight cone, and the length wont change...but the diameters will be flattened, becoming half the circumference each.
if you make a cone bent through 180 degrees... you have to figure out what the bend will straighten out to when "flattened".
figure out how to use a freakin spreadsheet and i could find the relationship between diameters and angles...
then its no more rolling cones and cutting paper but just lay out two profiles, seam weld, and inflate.
seriously, using 240gsm paper (stiff) you can go through a full ream before getting to the stinger... amazing how much difference just 2 degrees can make.
so far it looked like a 36:63/340mm cone bent through 130 degrees flattened out to 56:100/340mm at 90 degrees... unfortunately that bend needs to be expressed as a radius...
backtrack. (56*2)/pi= 35.7... about right.
(100*2)/pi=63.7ish.... also close enough...
i also have to find how the inner and outer radius varies from the main or central radius. thats a function of the diameters/degree of taper... hmmms.
there is no way im ever going to contemplate spinning one! (trumpets...)