Metal choice and welding.

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mk
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re: Metal choice and welding.

Post by mk » Wed May 18, 2005 9:16 pm

Dave wrote:[...] but I also get the feeling that the quality of the welder (both human and machine) plays a part in the equation. [...]
Oh yeah, definitely. My low-cost MIG welder (50%/50% split) is a headache sometimes! Wire speed changes -- rather becomes too low -- when it gets too hot internally, what results in ugly spots and unsealed, ugly welds. Then you know it's time to let it rest a few minutes or seconds and rather start cutting, rolling or finishing another piece. On warm summer days it really eats you up!
Thus my split becomes building when the weather is cold and ugly and running the engines when it's nice and warm outside.

But, well, it's a compromise you're getting used to.

After having it tried for myself a LITTLE bit, I can tell: TIG is pretty cool!
But I think MIG still is the one amateur pulse-jetters -- and not only they -- can face a lot of upcomming welds with. Thick to thin, thin to thin, thick to thick etc. at least when refering to sheet metal 0.8 to 4mm. Small things of thicker material aren't a problem, too, as e.g. spark plug mounts for "Steve" sized ones.

And, Dave, the first 5kg of welding wire (MIG) are the thoughest! Just try to weld something once every one or two months, not even a whole engine, but just to keep your skills at hand.
Last edited by mk on Thu May 19, 2005 9:28 pm, edited 1 time in total.
mk

Dave
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re: Metal choice and welding.

Post by Dave » Thu May 19, 2005 9:35 am

Good points Marten.
Less talking, less typing and more welding = engines.
Now I just have to go do it.
Dave

mk
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Re: re: Metal choice and welding.

Post by mk » Thu May 19, 2005 9:26 pm

Dave wrote:Good points Marten.
Less talking, less typing and more welding = engines.
Now I just have to go do it.
Dave
Ha! If it would be just THAT simple!
Good point, Dave.
mk

steve
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re: Metal choice and welding.

Post by steve » Thu May 19, 2005 9:39 pm

Speaking of which, Dave, how are your experimental FWE/Reynsts comming along?
Image

Bruno Ogorelec
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Re: re: Metal choice and welding.

Post by Bruno Ogorelec » Thu May 19, 2005 10:10 pm

steve wrote:Speaking of which, Dave, how are your experimental FWE/Reynsts comming along?
Yes, let's hear about them!

hagent
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re: Metal choice and welding.

Post by hagent » Wed Jun 01, 2005 8:55 pm

Hey what about oxyacetylene with stainless steel ?

What type of rods work best?

Thanks,
Hagen Tannberg

targa2
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re: Metal choice and welding.

Post by targa2 » Wed Jun 01, 2005 10:26 pm

The Maupin PJ download plans show the body construction
having solderd seams. The only solder i can find is CupSol
soft solder which is specific to stainless. However the melting
point is 296 deg C. Is there a suitable solder out there or was
the life expectancyof the Maupin measured in seconds??

Mike Everman
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Re: re: Metal choice and welding.

Post by Mike Everman » Wed Jun 01, 2005 10:54 pm

hagent wrote:Hey what about oxyacetylene with stainless steel ?

What type of rods work best?

Thanks,
308 works great on that and oddly enough, mild steel.
Mike
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larry cottrill
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re: Metal choice and welding.

Post by larry cottrill » Wed Jun 01, 2005 11:28 pm

Type 308 rod was recommended to me for welding both 304 and 316, and sure enough, I have actually welded a Type 304 fitting to a Type 316 cone with it, with reasonably smooth results and no problems during the welding. This was with Chromalloy flux on both sides of both pieces and coating the filler rod as well.

L Cottrill

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Re: re: Metal choice and welding.

Post by hagent » Thu Jun 02, 2005 2:45 am

Larry Cottrill wrote:Type 308 rod was recommended to me for welding both 304 and 316, and sure enough, I have actually welded a Type 304 fitting to a Type 316 cone with it, with reasonably smooth results and no problems during the welding. This was with Chromalloy flux on both sides of both pieces and coating the filler rod as well.

L Cottrill
Thanks Larry and Mike,

Is this what I need?

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... eName=WDVW

Can you use 308 electrowelding rods for oxyacetylene use?

Sorry I'm really green when it comes to welding.
Hagen Tannberg

larry cottrill
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re: Metal choice and welding.

Post by larry cottrill » Thu Jun 02, 2005 3:31 am

The 308 rod I had was intended for TIG welding, I guess. When I said I was going to weld it with oxyacetylene, the guy behind the counter looked at me like I had come in through a time warp. They were reasonably impressed with my sample welds a few days later, though.

It was 1/16-inch diameter x 36 inch long rod that I bought. Of course, they expected to sell me an even pound of it, but gave me a break and sold me half a pound when I convinced them that, being over 50 years old, I couldn't use up a pound in my remaining lifetime. It was pretty expensive, as was the flux [over $15 for a 1 lb can of powder].

L Cottrill

ed knesl
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re: Metal choice and welding.

Post by ed knesl » Thu Jun 02, 2005 6:32 am

Standard packaging of welding rods is 3 lbs. I went thru such box in
pretty short time. Now I got 10 lbs of .035 rods very suitable for thin
24 and 26 ga ( $125). Yeap, welding is pretty expensive procedure.

I am still afraid that oxy acetylen welding of SS will not produce desirable
quality for such harsh enviroment of pulse jet engine. Heat and vibrations
can break any substandard weld in no time. Any aircarft application X- rated weld on SS can be done on TIG only because of continuous argon gas shielding and back purging. Oxygen contaminates the weld and surounding
base metal at its molten state, and substantialy reduces its strength and
ductility, becoming brittle. Vibrations and reheating do the rest. The weld may look good, however internal structure is damaged.

Ed
...Nobody is right, nobody is wrong...

El-Kablooey
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re: Metal choice and welding.

Post by El-Kablooey » Thu Jun 02, 2005 7:31 am

Man, not trying to be a smart-ass, and I don't mean any disrespect at all, but A friend of mine welds pipes for a DOW Chemical plant here in Georgia. I'd be willing to bet that Dow is as strict as Boeing when it comes to weld inspections, most of these pipes he welds are meant to carry large amounts of very volatile chems, & gases. Everything he does is x-rayed and inspected by 3 different inspectors. He does most all his work with an arc-welder.. Also, weaker weld joints may not be such a terrible thing in p-jets, especially larger ones. From what I understand it is possible to make one explode, whereas a weak spot might just save your #%@, spltting a seam would be a heck of alot less violent than an actual metal shredding, shrapnel slinging explosion

Bruno Ogorelec
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Re: re: Metal choice and welding.

Post by Bruno Ogorelec » Thu Jun 02, 2005 9:28 am

El-Kablooey wrote:From what I understand it is possible to make one explode, whereas a weak spot might just save your #%@, spltting a seam would be a heck of alot less violent than an actual metal shredding, shrapnel slinging explosion
Wrong. Not a single pulsejet in history has been known to explode. In fact, they often _implode_ and go flat. There are pictures to prove it and people in the forum who have had it happen.

Mark
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re: Metal choice and welding.

Post by Mark » Thu Jun 02, 2005 3:18 pm

Except for all those target drones. I suppose if you gased one up with some pure O2 or acetylene it might shrapnel, or if you were trying some unorthodox constricted design and didn't use very thick steel you could fire the head off or something fun like that.
Mark
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