How Are These Pipes Made?

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theredbarron
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Re: How Are These Pipes Made?

#76 Post by theredbarron » Thu Oct 13, 2016 4:22 pm

We brazed all of the expansion chambers we made for the guys that were building racing outfits, that was probably 30+ years ago on the old GT750 suzuki engines. As you can imagine to TIG weld all of those joints with no filler the fit of all the parts would have to be spot on, by the way the technique where no filler is used is called "autogenous".
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Re: How Are These Pipes Made?

#77 Post by Smoker » Sat Oct 15, 2016 1:38 pm

Talked to Roger at Exclusive Welding. Not that his opinion is better than anyone elses, but he does incredible projects for Disney, JPL, NASA, and tons of artists. Not just the welding, but the complete fabrication.

He said "no" on using stainless rods with mild steel to mild steel, and "Yes" for the TIG brazing. He said- "You know all those sculptures I do? All TIG brazed." I asked if he could make dimestacks with TIG brazing- "Sure, no problem."

My latest idea is to use machined stainless exhaust flanges and brackets, and the first single section of pipe would be stainless (engine side) - all TIG brazed to a mild steel pipe. Then polish the stainless parts. The mild steel would be TIG welded. Might be a cool/different look.

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Re: How Are These Pipes Made?

#78 Post by theredbarron » Sat Oct 15, 2016 2:11 pm

Hi Smoker, the front Stainless parts would look great polished up, stainless polishes up and looks like chrome until you use the bike then the stainless will discolour. Learned this many years ago after spending hours polishing s/s down pipes on a honda vfr.
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Re: How Are These Pipes Made?

#79 Post by Smoker » Sat Oct 15, 2016 7:28 pm

As long as the fabrication idea is sound, I'm happy.

Would be cool just to try something different.

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Re: How Are These Pipes Made?

#80 Post by Smoker » Sun Oct 16, 2016 7:44 am

Okay, can anyone help with this one?

Can titanium be TIG brazed to mild steel?

Need to check the temperature for color anodizing of titanium vs. The temps of tig brazing.

Also have a great idea to make heel guards for the pipes, like I did on the WR. The bungs could be TIG brazed after the pipes are finished. The guards could be titanium and gold Ti nitrided.

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Re: How Are These Pipes Made?

#81 Post by theredbarron » Sun Oct 16, 2016 7:57 pm

Hi smoker, in my opinion the answer would be no you cannot braze Ti to Mild steel due to brittle intermetallic phases, visually you could get a presentable looking joint but in service i suspect the joint would fail.
When i was at The British Welding institute a few years ago they were working on a project there using vacuum brazing technique to join S/S to Ti but not sure what the outcome was. If i have time this week i will experiment with flame & TIG brazing a couple of joints out of curiosity. :smt003
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Re: How Are These Pipes Made?

#82 Post by Smoker » Sun Oct 16, 2016 9:27 pm

Good stuff redbarron.

My thought that was because brazing is done at a lower temp than welding, maybe a titanium piece could have TiN coating before brazing. Didn't take long to remember that the metal needs to be red hot before the rod is applied- so not a good idea.

Back to stainless.

I was associating those silicon bronze dimestacks with tig welding, not gas welding.

https://youtu.be/nSIOgI2NDCw" onclick="window.open(this.href);return false;

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Re: How Are These Pipes Made?

#83 Post by RuZty » Mon Oct 17, 2016 1:42 am

That's beautiful. I watched a reproduction Lotus 21 frame being built that way years ago. The acetylene was percolated through the liquid flux on it's way to the torch, looked like an industrial bong.

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Re: How Are These Pipes Made?

#84 Post by Smoker » Tue Oct 18, 2016 3:47 pm

RuZty wrote:That's beautiful. I watched a reproduction Lotus 21 frame being built that way years ago. The acetylene was percolated through the liquid flux on it's way to the torch, looked like an industrial bong.
Was reading about this setup.

Evidently, the best way to go for braze welding. The flux is delivered through the acetylene hose, so you don't have to interrupt the bead to dip the rod in flux.

Anyone know the name of this setup? Now, I can't find it.

Is flux not used for TIG brazing?

If complete pipes have been made by brazing, I'm assuming that brazing can withstand temps of the engine exhaust ports.

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Re: How Are These Pipes Made?

#85 Post by theredbarron » Tue Oct 18, 2016 6:24 pm

Hi Smoker, the answer to your first question is as far as i know called a "gas fluxer" very old set up, i havn't seen one for 20 years or so. When TIG brazing you do not use any flux as you would with Oxy-Acet. The brazed joints will easily cope with the temperatures generated in the exhaust system.

"The recumbent bike forum" has a feature on "gas fluxers" may be of interest :smt002
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Re: How Are These Pipes Made?

#86 Post by Smoker » Sun Oct 30, 2016 2:44 am

Thanks to everyone for the good info.

I found a journal article related to welding TiN coated titanium. Long, boring study, unless you're very interested in this topic. Here's a small bit:

"In this work, two commercial purity (99,8%) titanium sheets with
dimensions 30 x 20 x 2 mm were welded. One face of each sheet was
coated with TiN using PDV (Physical Vapor Deposition) generating a
hard coating of 2 µm thickness. The TiN coating showed an elevated
microhardness value (~ 2300 HV) and the titanium substrate showed
a quite low value (~ 180 HV)."

"Under normal conditions, i.e. rectangular pulse, the laser heat-
ing is not sufficient to dissolve the TiN coating which is presented
as a fine dispersion, inoculating the liquid with solid particles and
creating the dark region visible in Figures 3a and 7a."

"An improved weldability of titanium nitride coated titanium
was obtained by a pulse-shaping mediated laser process. The energy
distribution of the laser beam was divided in three consecutive steps:
a high power short pulse where the titanium nitride was dissociated,
a long pulse which allowed thermal penetration and a quenching
slope to decrease the residual stresses. The pulse-shaping process
has shown effectively transfer of nitrogen to the melt pool and de-
creased cracking on the top part of the seam."

Appears that regular laser welding won't work well with TiN coated titanium. I'm guessing that TIG welding won't work, either. I'm not going to start looking for a pulse laser welder to make pipes, so TiN coating would be after welding.

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Re: How Are These Pipes Made?

#87 Post by Smoker » Fri Jan 13, 2017 3:52 pm

Another photo of some outstanding looking pipes.

Just curious what the technique is to fabricate pipes like these.

Image

Almost ready to start cutting stainless tubing for some custom stingers.

I'm going to contact Unobtanium Welding to see if the stingers can be TIG brazed and anodized like these Ferrari pipes:

Image

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Re: How Are These Pipes Made?

#88 Post by Smoker » Thu Aug 31, 2017 2:23 pm

Jim Lomas

Image

Lomas Factory Tour:

https://m.youtube.com/watch?v=v-6HQvguUu0" onclick="window.open(this.href);return false;

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Re: How Are These Pipes Made?

#89 Post by Smoker » Fri Nov 03, 2017 6:36 am

What would be the proper thickness for making exhaust cones out of titanium?

What grade of titanium plate should be used?

Please post or pm me. :smt006

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Re: How Are These Pipes Made?

#90 Post by BigGuy » Sat Nov 04, 2017 10:46 am

Smoker wrote:Jim Lomas

Image

Lomas Factory Tour:

https://m.youtube.com/watch?v=v-6HQvguUu0" onclick="window.open(this.href);return false;

Thank for posting this. I enjoyed watcing these guys do their art.
Shake "N" Bake!

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