Tig welding stainless plate, will it work?

[Sean350]

I'm looking at having a buddy (former welder for Seven) tig weld up a frame for me. I'd like to do the chainstays out of stainless plate. What kind of thickness do you all think would work? I'm attaching some pics of examples I'd like to imitate. Both of these examples use the plate as a pivot, which mine will not as it will be a hardtail. I'm primarily doing it for aesthetics (the steps for the chainring on the La Ruta are about the coolest thing ever, imho). I can't see any reason not to use stainless, do you? Is it more likely to break? Thanks in advance.
-Sean

[potus]

how are those bullet looking things going to work in your design?

[Revtor]

I guess youll have someone machine the bullets to fit the tubing and plate.. How big a boy are ya? Are you going to be pounding on the thing? riding serious trails? Or mainly street?

id use 1/4" plate.

-Steve

[eurotrash666]

i was also thinking 1/4". might be flexy, though. use austinetic (300) stainless for flex, or martensitic (400) for rigidity. try welding with ER80SD2 or Stoody Versalloy when joining stainless to cromo.

[potus]

if you use 1/4" plate my guestimation is it will be heavier and flex-ier than traditional tubes. which leads me to ask, why?

[Seggybop]

i was also thinking 1/4". might be flexy, though. use austinetic (300) stainless for flex, or martensitic (400) for rigidity. try welding with ER80SD2 or Stoody Versalloy when joining stainless to cromo.
wouldn't the heat from the welding kill a lot of the heat treatment that produces the martensite/austentite?

[Peterpan1]

Doesn't anyone make flat plate drops already for track bikes or something? Do they bother to boost them up?

[SoonerLater]

How big a boy are ya?
-Steve

Steve, are you related to Roy D. Mercer? ;)

[Revtor]

Steve, are you related to Roy D. Mercer? ;)


Good call!!! R. D. Mercer is my favorite prank caller by far! lol

good luck with the plate stays!!! If youre going to go with something like this why not try and mimic the castellano (sp?) design or Kleins version and add a bushing for an inch or so of cushion? you cant really see down there, so doing it for purely aesthetic reasons seems like maybe kinda a waste.... ymmv of course!

-steve

[Sean350]

Thanks for all of the replies.
I would be following the Fango design for the most part, but I really dig the idea of the stepped area for the chainrings from the La Ruta. I never planned on using the bullet ends from the La Ruta.
I weigh anywhere between 155 and 165 depending on the season.
I'm going with stainless so I can shine 'em up purty like.
Keep the tips coming, please.
Thanks,
-Sean

[potus]

here's a few pics of a cool design by wade @ http://vulturecycles.blogspot.com/

kinda, sorta, similar to what you're doing

[eurotrash666]

wouldn't the heat from the welding kill a lot of the heat treatment that produces the martensite/austentite?


it's the main body of the piece that is of concern, not so much the joints. you should know the differences in elasticity between the two.

as for your comment:
1) austenite is stable when chromium and nickel are alloyed proportionately.
2) martensite does not transform when quenched with water after welding- if allowed to cool slowly, then yes, it will become pearlite. the idea here is not to allow carbon to precipitate out of the compound while cooling. a water dip stops this.

my father was a welding process metallurgist. he wouldn't let me slip by without learning a thing or two about burning metal together.

[Revtor]

that vulture design is pretty cool looking but it looks like it might be a bit flexy side to side..

Sean you want ideas, but you never even told us what kind if bike this is going to be or what kind of riding you want to do??

stv

[Sean350]

that vulture design is pretty cool looking but it looks like it might be a bit flexy side to side..

Sean you want ideas, but you never even told us what kind if bike this is going to be or what kind of riding you want to do??

stv

I asked nicely didn't I? :) Anyhow, It will be for a 29er/cyclocross/commuter fun bike. Some gravel, some road, some singletrack. Nothing crazy aggressive.
The Vulture gave me an idea. Would it be possible to start the chainstay flat (parallel to the ground), and then twist it perpendicular similar to where the vultures plate/tube junction is? I know it would look interesting, but how about the structural integrity?
Thanks again for the input
-Sean

[eurotrash666]

get as creative as you want, it will certainly LOOK cool. my only comment is that bike frames are built out of tubing for a reason.

[Sean350]

get as creative as you want, it will certainly LOOK cool. my only comment is that bike frames are built out of tubing for a reason.
Is there any reason to believe that this is going to somehow be unsafe? The Fango design is pretty well proven, and mine wont even involve any suspension. What's the thinnest plate you all think I should use?
Veering slightly off topic... how much are a set of 953 stays (maybe not as cool looking, but easier, right?) running right now?
Thanks again!
-Sean

[Peterpan1]

OHH you are making the whole stay out of plate!!

It's not that difficult to work this out. I went into an aicraft factory that made wooden planes. They tested their wood samples for their spars with this rack of metal that held a stick of wood over the top of a bathroom scale. The used a pulp jack to bend the wood a given amount and then read the result off the scale. From that they calibrated the modulus of samples. A bit complicated, but the point is that if you want the same stiffness just get some and do a little deflection testing. clamp one end to something and hang a known weight off the other.

[Thylacine]

Um, you can't just make some or all of the chainstays out of plate without doing the same to the seatstays or having some sort of shock in there.

If it's just for you, why not copy the Fango's say design? Castellano has FEA'd that sucker so you know it will work.

Personally though, I don't know why you'd bother. If you know a competant welder that can fab a frame up for you, just get a regular frame made. Heck, if he's not charging you for the labour, get TWO made!

Forget 953. Stays aren't long or strong enough for 29er application.

I reckon the best chainstays if you want to introduce a bit of vertical compliance are these Dedacciai stays

http://www.anvilbikes.com/gallery/data/media/11/jasonsdiscrouting.jpg

[MarkWW]

just throwing out an idea, but if you wanted the stays to be more rigid, you could possibly weld two pieces together per side to make an L shaped or maybe even a T shaped cross-section. I guess if you really wanted to go crazy, you could even have a + shaped cross section. or I beam? it'd definitely be more rigid.

[eurotrash666]

i would respect thylacine's recommendation, considering his experience. find something you like, specify the perfect geometry, and add tinsel to the tree if that's what you want. best bike i ever had was an amazingly stiff fillet-brazed custom that fit me like a glove. it looked pretty plain, but it perfomed like perfection. after realizing that you were trying to do the whole stay in plate, i began to visualize the loads and dynamics. i think you would get some pretty strange flex effects out of it, as well as put enormous strain on your seatstays. it's cool to dream, but when dreams cost lots of money, you better hash it out over a cup of strong coffee before signing over the check.

[Peterpan1]

This would all be so easy to do with a chopper frame. It's not a deal breaker if it comes out at 40 pounds or 100, you can dream up whatever you want.

[Revtor]

yeah pete, and thats what it comes down to here in bike land. weight. sure he could work it out with all plate, but in order to get plate to perform as well as tubing (stiffness/strength in many directions) it will weigh more.. might weigh alot more.

But if the desire for plate stays is strong enough and if they will encourage you to take the bike out more, then by all means go for it.. if the welder is your friend and he has his own equipment then maybe he would let you experiemnt with cutting and shaping pieces for him to weld, you might have to go through a few variations but you could work this out, yeah. FiniteElementAnalysis software would be a real time saver here if you had access to it and someone who knows how to use it.

thylacine, that gold frame is beautiful!!!

steve