Ever designed your own?

Woodmonkey

Weren't alu frames originally joined with silver solder?

rockmonkeysc

MiG is very easy to learn to use as long as you only need a weld that looks nice and has a little strength. If you want a mechanically good weld it's actually easier to learn to use TiG or MMA (stick).
When I used to build pressure vessels we used to TiG weld in the root of the joint to get the penetration and good fusion and then blast in a really hot MiG weld just to fill it up. And for pipe work (simila to bike frames) TiG or gas welding is actually easier to do properly than MiG.
Silver solder can be very strong when done well (not easy) and so can brazing.

bluechair84

can you use gas welding and welding rods on alu? Or just steel?

rockmonkeysc

I have never gas welded aluminium but it can be done. I would have thought its very difficult. With TiG it takes ages to heat up then you have to move quickly or it will melt and burn through, especially with thin aluminium. I always used TiG with a foot control for the amperage to keep control of the heat.

bluechair84

Well, cheers for all this. I'll start to read up on gas welding and see how expensive it is to try. I won't be able to give a project like this a try until I'm in a new place with a bigger yard but I'll have plenty of time to learn and plan.

rockmonkeysc

Try a evening course at your local college. Gas welding kit is expensive, TiG is probably cheaper, I have seen 200A TiG welders for about £200, plus rental of a bottle of argon, a second hand grinder, a few tungsten tips and some wire.

bluechair84

Yeah I'll look into a welding course I think. I don't want this to become a financially explosive passtime though. I thought TIG was the expensive option? I'll keep looking into it. If TIG is cheaper than gas, and it creates stronger, neater welds, it would be the obvious avenue to go down.

dmorton

How about this, pricey though:

http://www.downlandcycles.co.uk/frameBuilding.htm

bluechair84

dmorton wrote:

How about this, pricey though:

http://www.downlandcycles.co.uk/frameBuilding.htm

Cheers, steel only though. I'm reading lots of mixed messages on various places, some suggest that self teaching alu isn't that bad, but most agree that getting it professional quality is extremely hard. But I'd like to go down the alu route really

jairaj

hmm might be tricky finding a frame building course for Alu. Might be better of going on a frame building course and then going on a Alu welding course and combine the knowledge from both courses.

rockmonkeysc

I wouldn't bother with home brew aluminium frames. There are good reasons why manufacturers don't use plain round tubes.
Also distortion can be a bigger problem with aluminium, you will need to get the frame heat treated affter welding (which can cause more distortion) and aluminium dust from grinding, cutting and sanding can cause some pretty nasty health problems.
Aluminium frames use very thin tubes (1mm ish) and thin aluminium welding is very difficult.
Stick to steel for home brew.

bluechair84

Oh. Well, I wanted to play with making a full suss bike and create a roller that carries the chain to the pivot location. I could do it out of steel to as it's only a muck about, but, it does loose some of its attraction. I suppose it'll have to be steel tubing if I want to teach myself a few new things.

bluechair84

Damn it, Jeff Steber must have read this thread as there is now thisarticle explaining the difficulties of making alu frames strong. I think he was concerned about the competition to be honest...
Looks like you can't just weld up an alu frame and expect it to be strong. The whole thing needs to be heat treated which, without decent jigs throws out the allignment.

philxx1975

Did anyone ever follow any of this up ?

I was speaking to a chap about a week ago who does this kind of thing and it really did interest me to learn more,I own a couple of custom frames and would like to design and make my own.

Thanks Phil

bluechair84

I got chatting to the guy who designs and owns Empire bikes. Turns out, you can weld up your alu frames and send them off to a company to heat treat them. Both Empire and Orange send their frames away to be heat treated at the same factory so that will make designing your own frame easier.

philxx1975

bluechair84 wrote:

I got chatting to the guy who designs and owns Empire bikes. Turns out, you can weld up your alu frames and send them off to a company to heat treat them. Both Empire and Orange send their frames away to be heat treated at the same factory so that will make designing your own frame easier.

Hi Bluechair84

I solved my problem and managed to find the chap who runs the bike company in Sheffield I had actually got details on twitter but never use it.

Hopefully I may be able to learn a few bits and bobs there.

YeehaaMcgee

bluechair84 wrote:

I've got an itch, to knock together my own frame! Let's see... I can't weld, I don't know the geo of my current bike, and I know nothing about linkage kinematics. How badly could it go wrong?

Very

bluechair84 wrote:

Such a project is really just me mucking about and wanting to teach myself new skills such as how geo affects handling.

Get some more experience of riding a variety of bikes in all terrains, there is no path to being an instant expert since many changes have counter intuitive or unforeseen results

bluechair84 wrote:

Is welding actually that hard to get right with some practise?

Yes. Very.

bluechair84 wrote:

How easy is it to get tubes with very specific diameters, like the headtube and seat tube?

very easy, but unless you're ordering on an industrial scale, economies of scale make it very expensive.

bluechair84 wrote:

Can tubes be easily manipulated into curves?

If you're asking such rudimentary engineering questions, then maybe building a bike is slightly beyond you right now

No harm in having an interest, however. Have a look at some engineering / manufacturing night classes nearby. Most of them are fairly open to letting you experiment using their equipment to facilitate learning, and will have a decent set of (EXTREMELY expensive) tooling to fiddle and tinker with.
You never know, you could be the next Jon Whyte - but be prepared to put a lot of learning time into it.

bluechair84

YeehaaMcgee wrote:

bluechair84 wrote:

Is welding actually that hard to get right with some practise?

Yes. Very.

This is my biggest barrier really. I've since started looking into carbon manufacturing techniques and though it isn't as simple to produce due to the lay-ups, I think this will be what I make my prototype out of.

YeehaaMcgee

Carbon is very hard to get right, even the big manufacturers with all their expertise and experienced crews have struggled, hence the stigma of carbon frames.
worth remembering also, that GT switched from carbon to aluminium for the Fury DH, because prototyping the changes in carbon was too slow and expensive.

bluechair84

It would likely be quicker than learning to weld alu though which I've heard is a dark art. And I know of a few 'shed' projects in carbon which by all accounts have gone pretty well. It's risky - and welding would be my preference, but it really does look like CF would be the better material for me.
I doubt I'll get many volunteers to test ride it though...

bennett_346

I don't know that i'd trust a home made carbon frame. How will you verify how strong it is?

Good luck though, woould be really cool to see it work.

cooldad

Try one made of bamboo.
Then sell everything, buy some sandals, grow a beard and live in a cave.

YeehaaMcgee

bluechair84 wrote:

Oh. Well, I wanted to play with making a full suss bike and create a roller that carries the chain to the pivot location.

Hmm, just saw this.
Are you wanting to get the chain near the pivot location? or above or below it?
A lot of designs have tried various things over the years, some of them pure "blue sky thinking" that ultimately... didn't work well at all. (spoiler alert, having the chain pass at the pivot attains nothing useful)

Sonic had a pretty comprehensive write up of suspension designs in WMB a while ago, which, if memory serves, goes into this kind of thing.
If you ask nicely and maybe offer him a biscuit, he might have a link, or a copy for you.

bluechair84

I've worked on a design using Linkage that uses an Alfine at the pivot location. It would be similar to a Zerode - but would have genuinely no squat characteristics. The advantage would be that there is no chain restricting the movement of the wheel, but the chain wouldn't be used to counter act pedal-induced bob either.

YeehaaMcgee

bluechair84 wrote:

I've worked on a design using Linkage that uses an Alfine at the pivot location. It would be similar to a Zerode - but would have genuinely no squat characteristics. The advantage would be that there is no chain restricting the movement of the wheel, but the chain wouldn't be used to counter act pedal-induced bob either.

It'll bob quite badly.
To put it simply, the accelerative force from the rear wheel will be trying to drive the rear wheel forwards, and the inertia of the rest of the bike will want to stay still, with a net result of the wheelbase tending to shorten whenever you pedal.
Depending on the rear wheel path, this could mean squatting under power, or extending under power.
Sorry.

bluechair84

Yeah... I think you're right. But I'm not trying to create a suss which is especially efficient at pedalling, I want to create something which prioritises handling and bump munching. It will be an experiment... and like I said, I'm hoping to pick up some new skills with the project.
Cheers for the input so far

YeehaaMcgee

I don't mean to discourage you, like I said, you may turn out to be the guy who turns the bike world on it's head. However, I will politely (hopefully it comes across that way, I'm not the most articulate) discourage you from things that have already been proven as blind alleys, so to speak.
If you're interested in bikes that prioritise bump munching over pedalling, then DH bikes are a good place to look. Trek's Session just seems to get faster over every bump it encounters!

However, efficient pedalling and bump munching often come together.
For example, a lot of bikes use a rearwards axle path to reduce the deceleration from a bump. However, this also gives chain growth, which assists in creating a stable pedalling platform.

YeehaaMcgee

For some interesting reading regarding suspension...
http://members.home.nl/vd.kraats/ligfiets/pa/index.htm

bluechair84

Don't take this the wrong way, but this is the politest I've ever seen you disagree with someone 8) All ideas are very appreciated and I'll consider them as I go on developing it. Can't access the link at work, will have a look in future.
I read somewhere that the new crop of Monarchs don't use platform damping, but instead increase the spring rate by something in teh region of 20% which sounds like it could be more appropriate for this frame which will naturally be an elephant turd of a climber. Then, top of your descent, fully open. In my sig is a link to the design - it's changed since as there is area in the frame, but you can see I'm aiming for a higher than normal pivot location.

YeehaaMcgee

bluechair84 wrote:

Don't take this the wrong way, but this is the politest I've ever seen you disagree with someone 8)

I'm not actually disagreeing with you at all, just offering a little guidance!

It's fools I don't suffer gladly, adventurous people are fine. I wish everyone looked a little more critically at things!