Mr Whippy
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| posted on 11/1/08 at 12:13 AM |
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Mig welding a motor bike frame can it be done?
yes another post from that mad man...
I’ve been looking over some sites about how to weld up a simple chopper frame as a bit of fun. Many sites go on about TIG welding and how great it is,
no doubt that’s the case but I struggle to believe that it’s the only thing to use, after all it’s really only recently that TIG’s have come down in
price, but still not low enough for me. Yet that is what some are saying and that MIG welding has little place in frame construction.
I have seen some DIY sites that are using MIG’s and although the welds are not as attractive, certainly seem fine for the job. I intend on using
nothing more than a (don’t laugh) 250cc (I said don’t…laugh) engine so have little fear that it might rip apart from the awesome torque and was going
to use swing arm rear suspension, so even less stress on the frame and also my arse.
I’m sure there will be many naysayer’s out there who declare I have too little knowledge to risk the lives of my fellow brit’s by attempting this
death machine. But I want to have a go.
So any idea’s from this great reservoir of knowledge?
[Edited on 11/1/08 by Mr Whippy]
Fame is when your old car is plastered all over the internet
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blakep82
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| posted on 11/1/08 at 12:21 AM |
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i think they like tig because it look neater, and chopper frames are largely on show? maybe?
________________________
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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locogeoff
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| posted on 11/1/08 at 01:28 AM |
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I agree on the aesthetic reasons for the chopper frames, also bike frames, at least old british ones anyway) tended to be made out of high spec steel,
or at least high spec for the day, and for that reason they tended to be lugged, pinned and brazed (possibly bronze welded cannot remember off
hand).
I would be a bit concerned about creating stress concentrations around the mig weld due to the profile of the weld.
just my tuppence mind
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skodaman
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| posted on 11/1/08 at 02:01 AM |
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I'd copy the basic dimensions from something modern that handles well. What engine are u planning on using? I remember the welds on my
1980's Jap bikes being like piles of pigeon pooh so shouldn't be that difficult to make something better. Throw in a single rear shock
and a brembo caliper on the front and u could have something pretty good. You'd be hard pushed to make something as bad as a Harley anyway.
Skodaman
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Fred W B
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| posted on 11/1/08 at 08:24 AM |
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Welding is welding is welding.
Fred W B
You can do it quickly. You can do it cheap. You can do it right. – Pick any two.
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Bluemoon
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| posted on 11/1/08 at 08:33 AM |
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You could think about braising?
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JAG
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| posted on 11/1/08 at 09:06 AM |
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Loads of people have welded their own chassis for their Locost - I can't see any difference.
I am assuming you are planning on using steel for this chopper chassis of course.
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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D Beddows
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| posted on 11/1/08 at 09:52 AM |
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Not at all mad this one  I know a fair few people who've made their own hardtail frame using a MIG welder and none of them fell apart.
Obviously being hardtail ie no rear suspension the shock loads are higher as well.
You could probably argue that MIG welding isn't ideal for the application but in the real world it works.
There you go you see, I'm not against all your mad ideas
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02GF74
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| posted on 11/1/08 at 10:00 AM |
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quote:
Originally posted by Bluemoon
You could think about braising?
you mean like putting the frame in a large saucepan with some vegetables and lamb stock and leaving it in the oven for 2 hours, gas mark 3?  I
don't think that will be very effective.
quote:
Originally posted by Mr Whippy
I intend on using nothing more than a (don’t laugh) 250cc (I said don’t…laugh) engine so have little fear that it might rip apart from the awesome
torque and was going to use swing arm rear suspension, so even less stress on the frame and also my arse.
put it this way, a bicycle will have less power than yer engine and will have a much lower top speed, I can tell you you would not want to be on
one at even 20 mph when the frame gives out!
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tks
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| posted on 11/1/08 at 10:24 AM |
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you say that tig is expensive i partly agree with that.
on fleebay prices are as low as 200euro for an Tig welder. i'm with you that that doesn't buy you a gas bottle and regulator etc. etc. BUT
lower as 200euro for a 140AMP HF unit you aren't gonna pay.
also if you think that with TIG the result will be better/nicer or more secure then i wont try to save those 200+euros.
anyway if you can weld MIG wy doubt??
To build a bike you need to be sure of your welding quality. sow it looks like you aren't that secure... after all WELDING = WELDING.. and its
just down the quality wich you generate = strenght.
so my advice spent those 200euros on a TIG unit and weld the chasis that way.
you are looking to doubtfull about your own MIG welding quality and building then a bike is in my eyes a to high risk.
(imagine you ball head rips of or the steering etc. etc.)
if i'm wrong i appolozise its just a question wich comes down (for me) to confidence.
regards,
Tks
[Edited on 11/1/08 by tks]
The above comments are always meant to be from the above persons perspective.
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Peteff
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| posted on 11/1/08 at 10:35 AM |
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I've mig welded bits onto an existing frame for a friend who is building one. I don't like choppers personally but if they are done right,
not these tarts handbag things with tassels on the handlebars and forks 10' long, they are o.k.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Hammerhead
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| posted on 11/1/08 at 10:49 AM |
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Here is a good website, you can even download plans for the frames.
http://www.chopperhandbook.com/
I watch American chopper and biker build off quite a lot and have noticed that they tend to tig weld the frames and use mig on non structural parts.
They seem to use the mig to tack everything in place then finish off with the tig. I guess as stated before this may be for looks.
I wonder if the rollcages made by MK, mac1, mnr etc etc are mig welded?
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Bluemoon
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| posted on 11/1/08 at 10:59 AM |
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I never could spell!
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kikiturbo
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| posted on 11/1/08 at 12:07 PM |
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Ducati frames are mig welded, nothing wrong in that, especially if you go for mild steel...
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trikerneil
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| posted on 11/1/08 at 12:50 PM |
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MIG's OK
Have a look at a Japanese motorcycle frame from the seventies to see how bad the welding can be before you get trouble.
My Trikes are MIGged
Neil
ACE Cafe - Just say No.
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locogeoff
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| posted on 11/1/08 at 01:29 PM |
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quote:
Originally posted by trikerneil
MIG's OK
Have a look at a Japanese motorcycle frame from the seventies to see how bad the welding can be before you get trouble.
I would say a 70s jap bike frame was an example of how badly you can get it wrong, though to be serious a lot of the problems they has where due to
putting massively over powered engines into a woefully inadequate frame, rather than the quality of the welding
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Mr Whippy
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| posted on 11/1/08 at 02:28 PM |
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well that's good to know and the web site is very good, cheers.
Fame is when your old car is plastered all over the internet
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Coose
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| posted on 13/1/08 at 05:57 PM |
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quote:
Originally posted by locogeoff
brazed (possibly bronze welded cannot remember off hand).
I would be a bit concerned about creating stress concentrations around the mig weld due to the profile of the weld.
just my tuppence mind
Brazing and bronze welding are one and the same - the correct term is actually bronze welding! 
Stress concentrations around the weld are a possibility, but 95% of motorbike frames are MIG welded! Even on aluminium frames such as Fireblades etc.,
the only TIG welded bits are those on show. Have a look under the seat and it'll be MIG'd....
Spin 'er off Well...
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