Power Kite Forum

BUGGYS, Stainless or Mild Steel?

bigkid - 17-2-2012 at 07:56 AM

I have one of both and then some. Rust or no rust. Beach or dry lake bed. Repaint or polish.

Got to ask the question, Has anyone ever had there buggy rust to the point of not being able to use it?
Is Stainless better than Mild Steel, or Mild Steel better than Stainless.
Or who cares?

WELDNGOD - 17-2-2012 at 08:22 AM

stainless is way stronger than steel. But it is likewise heavier. I have built several out of aluminum.And it will corrode if not kept preserved w/ etching primer and paint.

Scudley - 17-2-2012 at 10:30 AM

How were you defining stronger?
304 stainless YS 33000 PSI
1020 hot rolled YS 55000 PSI
4130 normalized YS 63000 PSI

Even though stainless is not as strong, I think it is better a material for a buggy in some ways. It is easier to check for cracks.
304 will be easier to bend, but harder to weld.
For for free style and no salt waler, a bug made of 4130 might be very nice. Strong, light with some spring.
Any thoughts on brazing the 4130? Norton frames were brazed as are lots of high end bicycle frames. Norton felt the softer filler was less likely to crack than a hardened weld.
S

BeamerBob - 17-2-2012 at 11:12 AM

If I was going to ride at Ivanpah the rest of my life, regular steel would be fine with a good powdercoat job. But knowing I'll have beach riding in my future, I just don't want the hassle of rust that come from the inevitable chips and cracks. It's stainless only for me.

bigkid - 17-2-2012 at 11:55 AM

Quote:
Originally posted by BeamerBob
But knowing I'll have beach riding in my future, I just don't want the hassle of rust that come from the inevitable chips and cracks.

So you are saying your choice is cosmetic?

awindofchange - 17-2-2012 at 12:20 PM

Stainless is harder to bend than cold or hot rolled steel. Stainless is also stiffer / stronger. Not sure what the PSI ratings are but working with it myself, I can for sure say that Stainless takes a lot more force to bend than the same sized steel. Stainless also has much more deflection (spring back) than steel does.

awindofchange - 17-2-2012 at 12:30 PM

As far as a buggy rusting beyond use... that would take a ton of rust. Even the old Rockwell buggies that are true rust buckets are still useable. The chrome plating job on those is so cheap that it rusts right through the chrome. There are a couple here that people use and there is more rust on them than chrome any more.... And we are not on the beach. I would hate to see what would happen to them in the salt air / wet beaches.

The way that the steel buggy is prepped / powder coated / painted will determine just how long it will last before rusting out. If it is just spray painted with basic primer, rock chips will be very common and the rust is going to be much more than a buggy that is properly prepped. The quality of paint will also make a huge difference in how long it will last. Spray paint is not nearly as durable as automotive type paints and will effect the quality of the coating and its longevity.

Powder coating is the same. If not done properly it can chip or flake off easier than if done the right way. If the metal is not properly prepped before the powder goes on, it will not properly lock into the metal the way it should. Powder coating is much more durable than any form of paint and also has a much higher gloss rating.

Of course you could always powder coat or paint stainless - which would give you the color options without the chance of rusting.

That being said, even poor quality stainless can rust depending on how much impurities are in the stainless. Also, if stainless is welded with the wrong material it can inject impurities into the stainless and cause it to rust at the welds...which will also be weaker or will fail.

I am sure Weldingod can give much more input on the welding techniques....but that it getting somewhat off topic here.

Hope that helps.

bigkid - 17-2-2012 at 01:33 PM

I have an old Kite Trike that was chrome and is now brown, but still is as solid as it was when it was new, just a different color and texture.
I had a powdercoated buggy that was rusted in all the weird places and had more chips than a bag of Fritos. But as with the Kite Trike, still works and still solid, just looks nasty.
I have a stainless bug that has been painted grey and no rust and no chips.

Is anyone better than the other? Does living on the coast cause a problem. For me the answer is NO. Rust is rust no mater where you live. If it comes down to Stainless or Mild Steel, I will go with Mild Steel. Cheaper cost, anyone can weld it, and as far as powdercoating, I will not do that again. No way you can add a weld or change a hole or anything with out screwing up the finish and having to redo the complete part. Get out the wire brush and the rattle can of black and it looks as new as the day it came home.

I do very much appreciate the time, effort and pride that is put into a bug as one of Popeye's. It would be hard to go out and not ding it up. I came to play, not pose. Throw the bug in the back of the pickup and head to the beach, when the bearings freeze up and the seat rips and it doesn't hold my butt in it any more, and the rust ate through the side rail, I will be long dead and gone to worry about how the bug looks.

indigo_wolf - 17-2-2012 at 02:32 PM

I expect you would not be totally averse to posing if there were tats and free kites involved. :lol:

ATB,
Sam

bigkid - 17-2-2012 at 02:49 PM

Quote:
Originally posted by indigo_wolf
I expect you would not be totally averse to posing if there were tats and free kites involved. :lol:

ATB,
Sam

I hope to live long enough to die with out certain things engraved on my tombstone. :shocked2:

Scudley - 17-2-2012 at 02:55 PM

Kent can you provide a reference on 304 stainless being stronger and stiffer than 1020 other than personal opinion. a couple of specs sheet or something. I could not find anything other than the number I quoted. The stiffness numbers were close enough that it would be hard to tell the difference without instrumentation: 304 is about 7% less stiff than mild steel. Sorry to put you that trouble.
S

crazymanme2 - 17-2-2012 at 03:19 PM

Quote:
Even though stainless is not as strong, I think it is better a material for a buggy in some ways. It is easier to check for cracks.
304 will be easier to bend, but harder to weld.



I weld stainless every day,& different grades,& it all welds the same.304 welds no different than say 316,mild steel ,or even chrome moly.
I'm in the process of building a buggy & it will be 304 polished.As soon as I'm far enough I will post some pics.

jellis - 17-2-2012 at 04:08 PM

Scudley are you saying stainless is not as strong as steel in the same temper and thickness? I still think steel is stiffer size for size and like Libre does, zink coat and then powder coat. Less expensive, stiffer (stem doesn't twist over under power as much, frame is not as springy), the material is easier to work with and no rust. As far as welds breaking , I have seen lots of pls and some stainless axles on rickys buggies break.

Cheddarhead - 17-2-2012 at 07:49 PM

100% carbon fiber buggy would be the cats ass, but MUCHO expensive!!!!

WELDNGOD - 17-2-2012 at 07:56 PM

TITANIUMMMMMMMmmmmmmmmm.......$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
But the 4130 scud mentioned has a higher Ultimate tensile strength...... And braze it like a bike.......scud might be on to somethin here.

RonH - 17-2-2012 at 08:28 PM

Have you ever seen one of those old timer's fillet braze weld a bike frame? Talk about art!

WELDNGOD - 17-2-2012 at 08:40 PM

I was taught how to braze by an old school shipyard welder, he had the magic touch with that torch. I learned quite a bit from him. He's gone now , but a little bit of him still lives in me. :wink2:

BeamerBob - 17-2-2012 at 09:12 PM

Quote:
Originally posted by bigkid
Quote:
Originally posted by BeamerBob
But knowing I'll have beach riding in my future, I just don't want the hassle of rust that come from the inevitable chips and cracks.

So you are saying your choice is cosmetic?


Yes cosmetic is an issue for me. I wouldn't want to ride a rust bucket. I know stainless can get some spots on it but that just rubs off. If I've paid good money for a buggy I'm proud of, I don't want rust on it and I want a uniform finish. Patches, recoats and other blemishes would drive me crazy. That's the reason I've only ever owned stainless.

That being said, I also don't mess with the finish on my buggy beyond hosing it off from time to time. I toyed with re bead blasting my Apexx but it would be lots of trouble and wouldn't improve anything enough to be worth the effort.

Scudley - 18-2-2012 at 06:46 AM

Quote:
Originally posted by crazymanme2
I weld stainless every day,& different grades,& it all welds the same.304 welds no different than say 316,mild steel ,or even chrome moly.


I am not welder, a metallurgist. I thought you had to be much more careful about shielding when welding stainless. Can you gas weld stainless? I know that when making stainless they are yery careful about oxygen content compared to more conventional steels.
Donny, why look at UTS? If you are worried about bending, YS is the important number.
Jon, it is hard to compare three such different alloys in the way you were talking. They respond to working and heat treatment so differently. Austenitic stainless is far more ductile than ferritic steels. They do not work harden the same way. An annealed piece of 304 has a yield strength of a little over half that of annealed 1020 or 4130.
Stiffness is marginally lower for stainless, around 6% less. Stiffness of a part depends to a huge extent on geometry. If you are really interested, pick up a copy of Gordon's "Structures or Why We Don't Fall Through the Floor".
S

crazymanme2 - 18-2-2012 at 09:50 AM

Quote:

Can you gas weld stainless?


I tig weld everything which uses argon as a shield.

Don't believe you can gas weld stainless other than brazing.The disadvantage of brazing, however, is that the heat is hard to control and, in effect, can cause annealment and brittleness. This can make the stainless steel tubing lose its corrosion resistant element.

You can stick weld stainless but the flux is doing the shielding.

van - 18-2-2012 at 11:54 AM

ok, i'm gonna give my opinion base on an engineer and a buggy builder's perspective. I don't see any one best metal but I do think mild steel is the most economical for what we need. Stainless is more bling than anything for our application. There is no need for strength comparison for the average rider. I hear all this talk about having a strong buggy and all then I see everyone going 20mph on the playa. Worry about how the buggy is design, not what type of steel. It is harder to drill stainless because of the way it transfers heat, no hardness. So as a builder I prefer mild steel.

awindofchange - 18-2-2012 at 07:29 PM

Scudley, I don't have any physical hard core data, but I know that when I bend stainless tube, it takes much more force than bending the same size and thickness of steel tube but not quite as much as bending 4130 chrome moly. The same goes for the spring back. Stainless will spring back nearly double that of steel when bent. This leads me to assume that stainless is more resistant to bends than steel. This is only my own assumption which could obviously be wrong.

Having worked with both, I feel that welding stainless is actually easier than welding steel, it is much brighter to weld because of the reflection but it seems to flow better....but that may just be my mind playing tricks on me. I use a Tig for all my buggy builds. I may use stick or mig for other projects depending on what I am building at the time.

As for strength on the buggy, I use .120 wall tubing on everything so there is no way it would ever fail structure wise. Compared to the PL Standard buggy which uses .032 tubing and the XR+ which uses .068 tube.

I am not a structural engineer or a metallurgist....so I may be way off point here, just going by what I feel when I fabricate each type of metal tubing.