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 [GP 125 & 250] Why hydroforming is not as good as welded cones?

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AuteurMessage
koenich



Nombre de messages : 108
Localisation : Germany
Date d'inscription : 07/02/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 13:57

wow frits, everyday there is sth new to learn!!! gonna be a long night, but worth it! thanks...

may i ask which program you are using to do those graphs and so on? is it just a basic plotter with your formulas in the background or sth engine related?
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Frits Overmars

Frits Overmars

Nombre de messages : 2131
Age : 70
Localisation : Raalte, Holland
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 14:18

koenich a écrit:
wow frits, everyday there is sth new to learn!!! gonna be a long night, but worth it! thanks...
Your girlfriend will hate me...
Citation :
may i ask which program you are using to do those graphs and so on? is it just a basic plotter with your formulas in the background or sth engine related?
I started writing my own physics programs around 1970, so over the decades it became quite a collection. They are not available to the public. Because I wrote them for personal use only, they are rather user-unfriendly and distributing them would cause an avalanche of questions that would completely rob what little time I have left; I would not be able to visit this forum any more Wink.
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koenich



Nombre de messages : 108
Localisation : Germany
Date d'inscription : 07/02/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 16:47

Frits Overmars a écrit:
your girlfriend will hate me...

or love you, cause she got rid of me for some hours

Citation :
I started writing my own physics programs around 1970, so over the decades it became quite a collection. They are not available to the public. Because I wrote them for personal use only, they are rather user-unfriendly and distributing them would cause an avalanche of questions that would completely rob what little time I have left; I would not be able to visit this forum any more Wink.

ok, very interesting! i was always wondering which program it is...I am at the moment compiling an excel file with the calculations I find useful - lets see where it'll lead me.

on the topic of exhausts fabrication, i just stumbled over this vid. could be also a method to get some nice cone. especially it seems to be enough to have a wooden cone and spin the metal over it.



though i do not know if it works with stainless on a small machine, somehow i doubt it.

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Frits Overmars

Frits Overmars

Nombre de messages : 2131
Age : 70
Localisation : Raalte, Holland
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 16:57

koenich a écrit:
on the topic of exhausts fabrication, i just stumbled over this vid. could be also a method to get some nice cone. especially it seems to be enough to have a wooden cone and spin the metal over it. though i do not know if it works with stainless on a small machine, somehow i doubt it.
Stainless will be extremely difficult, and titanium quite impossible. And then you would still have to curve the header....
There is something to be said for hydroforming if you can get the dimensions to within 0.5 mm, as Howard claims.
The object on the picture below is hanging on my wall. Everybody recognizes it as a work of art. In fact it was my first attempt at hydroforming, in 1978 or thereabouts. The pipe curved a bit more than I had expected (now I know why). And notice the little hole? I thought that torching the stubborn areas would soften the material. It did...
[Vous devez être inscrit et connecté pour voir ce lien]


Dernière édition par Frits Overmars le Jeu 12 Juil 2012, 17:06, édité 2 fois
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koenich



Nombre de messages : 108
Localisation : Germany
Date d'inscription : 07/02/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 17:00

Frits Overmars a écrit:
koenich a écrit:
on the topic of exhausts fabrication, i just stumbled over this vid. could be also a method to get some nice cone. especially it seems to be enough to have a wooden cone and spin the metal over it. though i do not know if it works with stainless on a small machine, somehow i doubt it.
Stainless will be extremely difficult, and titanium quite impossible. And then you would still have to curve the header....
There is something to be said for hydroforming if you can get the dimensions to within 0.5 mm as Howard claims.

yeah titanium should be impossible, but stainless should probably work if the machine has the right specs, maybe you need to countersection header and so on in 2 or 3 parts. regarding the header you could just spin in as one part, cut it with an angle it in lets say 5 parts, turn them a 180° and weld it. thats how a friend of mine does it...
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Frits Overmars

Frits Overmars

Nombre de messages : 2131
Age : 70
Localisation : Raalte, Holland
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 17:11

koenich a écrit:
[regarding the header you could just spin in as one part, cut it with an angle it in lets say 5 parts, turn them a 180° and weld it. thats how a friend of mine does it...
That's how I do it with a conventional rolled header. Cut over it with a 7° angle, rotate it 180°, weld it, hammer it, etc... But hydroforming gives an infinitely nicer result.
[Vous devez être inscrit et connecté pour voir ce lien]


Dernière édition par Frits Overmars le Jeu 12 Juil 2012, 17:21, édité 2 fois
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koenich



Nombre de messages : 108
Localisation : Germany
Date d'inscription : 07/02/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 17:15



so when are you starting my exhaust? just kidding...i am looking for a way to do my own, but roll them seems to require someone that can fabricate you cones cheap
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Howard Gifford



Nombre de messages : 136
Age : 62
Localisation : Ottawa Canada
Date d'inscription : 01/05/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 17:22

My firewall will not let me post images from work (yes I have a day job) Is there someone I can email a before and after picture of hydroforming that will post it for me?
Howard
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Haufen



Nombre de messages : 55
Localisation : Allemagne
Date d'inscription : 23/12/2011

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 17:33

koenich a écrit:
Frits Overmars a écrit:
koenich a écrit:
[regarding the header you could just spin in as one part, cut it with an angle it in lets say 5 parts, turn them a 180° and weld it. thats how a friend of mine does it...
That's how I do it with a conventional segmented header. Cut over it with a 7° angle, rotate it 180°, weld it, hammer it, etc...

so when are you starting my exhaust? just kidding...i am looking for a way to do my own, but roll them seems to require someone that can fabricate you cones cheap

What exactly do you mean by "fabricate cones cheap"?
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koenich



Nombre de messages : 108
Localisation : Germany
Date d'inscription : 07/02/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 19:20

if u fabricate them "normally" you need sth to bend header, diffusor, belly and reflector. and it needs to be the "negative" - so it must have the inside shape of the cones u want. and the negative part needs to be massive steel - but if u do not own a turning machine you will not be able to fabricate them.
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Haufen



Nombre de messages : 55
Localisation : Allemagne
Date d'inscription : 23/12/2011

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 19:43


Don't worry, you can bend cones around anything that is round or close to round. Neither do you need an exact negative nor does it need to be made of steel. :-)

When I bent the cones for my first pipe, all I used to bend the cones around was two different sized tubes and the gas bottle (and it's end cap).

Today, I use a wooden cone with one angle and 3 different sized tubes. I do have a round bending machine also, but rarely use it, as I have found it not to be a big help when turning cones with bigger angles, anyway.

For your first pipe, I'd recommend to pick thin blank sheet metal (0,8mm, no stainless) and to split the differnet sections into several pieces (if they're shallower, they're far easier to bend)


Dernière édition par Haufen le Jeu 12 Juil 2012, 19:53, édité 1 fois
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koenich



Nombre de messages : 108
Localisation : Germany
Date d'inscription : 07/02/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 19:50

@Haufen: so you do not have a machine like this: [Vous devez être inscrit et connecté pour voir ce lien] you are bending them by hand around sth round?

ok - thats worth a try though, then I just need to learn welding. ah and get a welding machine silent
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Haufen



Nombre de messages : 55
Localisation : Allemagne
Date d'inscription : 23/12/2011

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 19:57


I do have a machine like that, but it's quicker the other way.

Send me a personal message, maybe you're located nearby, then I could help you out concerning the welding machine.
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GrahamB

GrahamB

Nombre de messages : 3457
Age : 56
Localisation : Lyon
Date d'inscription : 19/08/2011

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Jeu 12 Juil 2012, 21:28

koenich a écrit:
I just need to learn welding. ah and get a welding machine silent

Oxy is fine for making chambers. By the time you've made a couple, you'll know how to weld :)
(My first one fell in two pieces while riding...)
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Frits Overmars

Frits Overmars

Nombre de messages : 2131
Age : 70
Localisation : Raalte, Holland
Date d'inscription : 12/10/2010

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Ven 13 Juil 2012, 06:17

Haufen a écrit:
...Send me a personal message, maybe you're located nearby...
Yeah, Germany and Allemagne are not that far apart Wink. This is what I like: forum members helping each other out
By the way: I have built more exhaust pipes than I care to remember, but I never used a roller; only a couple of tubes, like Haufen says.
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koenich



Nombre de messages : 108
Localisation : Germany
Date d'inscription : 07/02/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Ven 13 Juil 2012, 08:38

Frits Overmars a écrit:
Haufen a écrit:
...Send me a personal message, maybe you're located nearby...
Yeah, Germany and Allemagne are not that far apart Wink. This is what I like: forum members helping each other out
By the way: I have built more exhaust pipes than I care to remember, but I never used a roller; only a couple of tubes, like Haufen says.

if the master says it, i am fine
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Haufen



Nombre de messages : 55
Localisation : Allemagne
Date d'inscription : 23/12/2011

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Ven 13 Juil 2012, 09:04

Howard Gifford a écrit:
My firewall will not let me post images from work (yes I have a day job) Is there someone I can email a before and after picture of hydroforming that will post it for me?
Howard

Here are the pictures of Howard's work art


[Vous devez être inscrit et connecté pour voir ce lien]

[Vous devez être inscrit et connecté pour voir ce lien]

[Vous devez être inscrit et connecté pour voir ce lien]

[Vous devez être inscrit et connecté pour voir ce lien]

[Vous devez être inscrit et connecté pour voir ce lien]

[Vous devez être inscrit et connecté pour voir ce lien]

[Vous devez être inscrit et connecté pour voir ce lien]
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Mic



Nombre de messages : 62
Localisation : Denmark
Date d'inscription : 12/02/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Ven 13 Juil 2012, 10:07

This process [Vous devez être inscrit et connecté pour voir ce lien] would also give some nice and smooth pipes. I also think the accuracy would be quite high.
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GrahamB

GrahamB

Nombre de messages : 3457
Age : 56
Localisation : Lyon
Date d'inscription : 19/08/2011

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Ven 13 Juil 2012, 11:32

Beautiful !

Otoh, there is one reason Aprilia Corse would not have used hydroforming... I don't think you can do it with titanium Sad



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koenich



Nombre de messages : 108
Localisation : Germany
Date d'inscription : 07/02/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Ven 13 Juil 2012, 11:41

GrahamB a écrit:
Beautiful !

Otoh, there is one reason Aprilia Corse would not have used hydroforming... I don't think you can do it with titanium Sad




they are great! and by keeping in mind that they are homemade, it is even more great!!!

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Howard Gifford



Nombre de messages : 136
Age : 62
Localisation : Ottawa Canada
Date d'inscription : 01/05/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Ven 13 Juil 2012, 13:26

I have never worked with titanium sheet so I can't comment. I can tell you that the amount of weight saving versus the enormous cost and the fact that titanium is not easily "field repaired" would deter anyone from using titanium except for those people or companies that have very deep pockets and need to shave ounces off the total weight of a race vehicle. In snowmobile racing several trips are made to my race trailer every weekend to weld a cracked header or weld a silencer back on. Aprilia had a full time staff developing the RSA so a small advantage like a lightweight pipe was a big deal. The cost was not.

My investment in making a pipe is extremely low compared to a CAD designed stamp. A sheet of white cardboard is under a dollar and is what I invest in the template. My time of course is an investment but I would rather design a pipe than sit in a pub drinking beer complaining. I was taught how to hydroform by a very good friend by the name of Alex Mayes. He was a craftsman and reminds me a lot of Frits. Unfortunately he had a bad heart and he was a chain smoker. When he suddenly died I was left to either find another pipe builder or start making my own. By the way frits your first try at hydroforming looks surprisingly a lot like my first attempt. I have got very wet a few times and it took about a year before I could say my pipes were as good as Alexes pipes. I have probably made 200 sets of hydroformed pipes since and every time I finish a pipe I get excited to try it. I will gladly answer any questions if anyone wants to attempt it.
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rgvbaz



Nombre de messages : 4
Localisation : UK
Date d'inscription : 18/02/2011

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Ven 13 Juil 2012, 14:19

Hi all, first post on the Pit-lane forum, been lurking and looking at the RSA thread for a while now .

I am from the UK and race 50cc 2 stroke bikes. I have been making pipes for a few years now but I probably average 1 maybe 2 a year. I use rolled cones for my pipes and have been put off hydroforming as it does look tricky to get the pipe to the right dimensions. Also trying to get supadraw sheet steel in the UK is difficult if you only need a small amount and I'm not sure if CR4 grade will form very easily?

Howard, I love the pictures of your pipes, they look real nice and sounds like they go well too!


Howard Gifford a écrit:
I will gladly answer any questions if anyone wants to attempt it.

I do have a question. For example, the diffuser, do you make the diffuser with definate angle stages or are they a constantly changing angle?

Regards

Dave
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koenich



Nombre de messages : 108
Localisation : Germany
Date d'inscription : 07/02/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Ven 13 Juil 2012, 14:20

a first question from me Wink what do you use in order to obtain the high pressure? from what i saw till now most people used high-pressure cleaners with a modified frontend.

great atmosphere in here with people from all over the world sharing their knowledge!!!
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Howard Gifford



Nombre de messages : 136
Age : 62
Localisation : Ottawa Canada
Date d'inscription : 01/05/2012

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Ven 13 Juil 2012, 20:10

The difuser usually starts out as a 3 stage straight cone design because that is what my software spits out and that is how nmost pipe designs begin life. I make a full size straight line drawing of the actual finished pipe. I then use a french curve to blend the intersecting cones so as to make a smooth transition. Sometimes I blend the cones almost 1/3 of their entire lengths to make a more or less parabolic curve. I have found that a straight cone difuser at near the center section delivers the best powerband. A more parabolic continuous curve gives a more peaky power band with a little more peak horsepower. Just to let you know the template drawing is typically 1.5" smaller than the finished diameter. The metal stretches that much. That is the secret to getting very smooth finished products. Also to achieve high pressure in the pipe I use sleeves that exactly match the finish diameter of the center section. This only works on pipes that have a defined straight belly section. THe pipe expands into the sleeve allowing me to build pressure in the rest of the pipe to remove any ripples or dents. For a pressure source I use a standard piston type pressure washer with a standard wash handle fitted with a hydraulic fitting. It is vital that the handle be leak free and is able to control the flow. it is also vital that there be no pinholes. A lot of the time is spent with a pressurized pipe on your lap hammering away with a small ball peen to dolly out the ripples. With about 300 - 400 psi in the pipe it allows you to work dents and ripples by tapping around the dent. It is also vital (and may save your life) that you ensure there is no air at all in the pipe when blowing it up. Even a small trapped pocket of air can store enough energy to do serious damage if it were to rupture. With no air the rupture gets you wet, thats it! People ask me about the weld. If you can't weld then dont try to blow up a pipe. Practise and get good at welding with acetylene first. I have tried several types of filler rods and the best I have found by far is 19 gage "Mechanics" wire. Yes the stuff used to twist things together. it is cheap and most importantly it is malleable even when welded. The outside seam actually shrinks quite a lot so you need a soft weld that will shrink with the metal.
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Haufen



Nombre de messages : 55
Localisation : Allemagne
Date d'inscription : 23/12/2011

MessageSujet: Re: [GP 125 & 250] Why hydroforming is not as good as welded cones?   Sam 14 Juil 2012, 10:32

Thanks for the insight, Howard!

Do you use any special steel, like deep drawing steel or something like that? Which material thickness are you using? How do you prevent the header and diffuser section from getting oval? When tapping the wrinkles, do you heat the corresponding areas?
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