New build, not 1:30 anymore...

[wolfdragon]

I checked the thermal expansion and stresses before I put it together, being 304 Stainless and 0.035" thick, it gets mildly stressed, but nowhere near the yield point. I figured I would have to account for that since I couldn't figure out a good way to bolt in the flame tube to the housing without adding another huge flange and 1/8" Stainless is way more expensive than the 0.035". I really like the look that the front half pipe ring gives to the combustor, which was also the only way I could see getting the good swirl around the flametube (and thus inside it). I'll see how it goes, but for now, this whole setup is a first crack, I'm sure the next one will have a few changes after I see where something needs to change.

Also, what isn't readily apparent, the seam for the flametube (made it out of rolled sheet) is not totally zipped up. It only has 75-80% penetration tack welds, they are farther apart near the primary zone, so if it really wants to move, it has an avenue for that excess force to go to.

As it is, she lightly clicks and pops a little bit after a hard liquid propane test burn (that reminds me that I need to go get my tank refilled), nothing like an old hot rod after a dyno run, but that was one of the test points I was looking for.

Additionally, since that fuel injector plate gets to and stays at 500 or so degrees F, now I know what materials I need to look for as a sealing gasket.

Now if I can only get those oil pumps in for myself and metiz... I'm calling that place on Monday to find out where they are

[stoffe64]

hmmm , i hope that would work for you,i have seen photos of such flametubes where there were not enough expansion room and they got qite buckled,if you get a really bad hotstart it can expand qite severely,ask John Wallis about it, i sure hope it works for you though!

[wolfdragon]

If it breaks, I'll just make a new one

won't know till I try...

[stoffe64]

that is soo true wolf!,i sure hope it works for you though

[wolfdragon]

I look at it this way, this is my first crack at it with a less than well known turbo at it's heart, I'm probably going to blow that turbine just learning how to get it going let alone going well.

Every other turbo I have found would need a bigger combustor, so if I need to make a new setup... step one will probably be to break out the plasma torch and disassemble everything to see where what all happened.

It helps that I found a place to get stainless from that doesn't charge a terrific amount for thin sheet.

[metiz]

Jun 20, 2011 16:14:32 GMT -5 wolfdragon said:

It helps that I found a place to get stainless from that doesn't charge a terrific amount for thin sheet.

The scrapyard? 2€/ kg and top notch stuff to. Found a shitload of .5mm sheet, in almost perfect condition, to bad I can't weld that or else I would've taken it. Can't beat that price XD

[wolfdragon]

lol nah onlinemetalsupply.com has 0.035" x 12" x 48" for just over 20USD the sheets are meant to be kitchen backsplashes...

0.035" is about 0.90mm, I wouldn't try to weld anything significantly thinner than that, it gets very difficult to find the right diameter filler wire (and the arc distance at less than 20 amps, which that stuff would want 12-15, is already too freaking close)

[cnctech]

over the years i found that welding thin metal ( in your home shop) is best done with a small torch set, with a little pratice you can weld metal as thin as .010 . check out the "smith little torch " it is mostly used for jewlery repair i think i paid less than 150.00 for mine. you can use tic flux to help the filler rod flow better and anti flux to keep it off of the parts you want to protect. the tips are aprox 1 inch long and the hole is fitted with a ruby that has a .001 to .005 hole drilled in to the ruby.

[wolfdragon]

Yeah but when you start getting that thin, the filler and materials get expensive, and you start losing significant strength due to the lack of thickness

Case in point, doing just a rough calc on hoop stress for my combustor housing as it will get rather warm and have to hold back P2, I have a yeild stress limit of about 100 psi for P2, rupture is still higher

And I'm fairly certain my wife would kill me I'd I bought another welding rig, as it is I have a tig, mig, and plasma torch

Not a bad suggestion though, unfortunately I like the added control that a tig has over a torch, and I can always try an 0.020" tungsten if I really wanted to try and weld 0.010, but I know I am not that good...

[cnctech]

your right filler is expensive. i just use small rods that pulled through a draw plate to get smaller size rods the draw plate cost me 20 bucks. # 1 rule never never never tell your wife how much you paid for tools . if she asks why you need more than 2 or 3 welders just say for the same reason you need 30-- 40 pairs of shoes or more than 3 or 4 golf clubs . trust me no good can come from telling your wife about tools you have bought. dont lie just dout tell

[Richard OConnell]

I like the "I found it" excuse, or the "I've had it for a while now" one. A "friend gave it to me" works too.

[metiz]

How about "It's my money, I'll do whatever the hell I want with it"?

[wolfdragon]

All are good suggestions, but the problem is that I (engineer) married an engineer, it's almost impossible to slip something by her...

But she doesn't protest when I have a fully backed reason why I need a tool, problem is that she knows what my current tools are as well as their capabilities...

[metiz]

Hey look at this - brand spankin' new doorstop! and guess what? you can weld with it too, added bonus!. What? you said you wanted a doorstop right? ;D

[cnctech]

dam your in a tough spot. when ever i tryed to lay out a new plan for building turbines and planed costs tools ect i could never find a good reason to build one . this made me unhappy now i dont try to justify building and this makes me happy . dealing with a wife thats a engineer. sorry bud your on your own LEN