Aluminum frame?
- Thread starter KEG
- Start date
On here it is not usual to make one of Brads designs in aluminium .
The main reason sited is that the act of welding changes the structure of the aluminium at the weld site and to avoid these areas failing the whole frame needs skilled heating and cooling to achieve maximum strength.
If you are after the perceived weight saving , it tends to be reduced in actual life as due to aluminium's lack of fatigue resistance it tends to be of a heavier section than the equivalent steel
However we are open to anyone coming along and proving us wrong , however we expect to see photographic proof
The main reason sited is that the act of welding changes the structure of the aluminium at the weld site and to avoid these areas failing the whole frame needs skilled heating and cooling to achieve maximum strength.
If you are after the perceived weight saving , it tends to be reduced in actual life as due to aluminium's lack of fatigue resistance it tends to be of a heavier section than the equivalent steel
However we are open to anyone coming along and proving us wrong , however we expect to see photographic proof
IMO, you can build an aluminum frame bike without heat-treating using 7000/7075 alloys but the material here in the USA will cost 6-8 times what steel will cost. Using .049 wall round 4130 steel will reduce weight and if engineered correctly will be light but then you are still dealing with higher cost material and welding. If weight is really important then go carbon fiber but be ready to really open your wallet. Building a bike from the AZ plans will produce a long lasting, proven ride.
Welding any kind of metal (not just aluminum) causes changes to the crystal structure of the metal in the HAZ (heat affected zone). It's a complicated topic.
Heat treatment is not required if you select the right type of aluminum.
One problem with welding aluminum is the welding equipment required to weld it. Forget about stick welding because there is no flux covered electrode that does a decent job. You need either:
Mig for steel is not too expensive but for aluminum you also need a spool gun which is expensive
Tig is far less expensive than Mig but requires considerable skill and practise to get good quality welds.
Heat treatment is not required if you select the right type of aluminum.
One problem with welding aluminum is the welding equipment required to weld it. Forget about stick welding because there is no flux covered electrode that does a decent job. You need either:
- Mig with a spool gun
- Tig
Mig for steel is not too expensive but for aluminum you also need a spool gun which is expensive
Tig is far less expensive than Mig but requires considerable skill and practise to get good quality welds.
aluminumwelder
New member
"Heat treatment is not required if you select the right type of aluminum."
Really? what alloys do not require heat treating to regain strength?
Aluminum does regain some of its strength by aging. But that takes months to years. i have seen a couple of bolt together aluminum builds, and while they do require a lot more hardware weight I would guess they are still 10-15% lighter than a steel build. It is amazing how heavy steel can be.
Really? what alloys do not require heat treating to regain strength?
Aluminum does regain some of its strength by aging. But that takes months to years. i have seen a couple of bolt together aluminum builds, and while they do require a lot more hardware weight I would guess they are still 10-15% lighter than a steel build. It is amazing how heavy steel can be.
Why do you want heat treatment?
Heattreatment changes the steel but it depends on the use if it is needed. It makes the steel stiffer but it can also break faster.
So it isn't Always the way to go.
Bolded aluminum frames are not Always that much lighter. The amount of extra hardware and aluminum parts, make that the frame becomes as heavy, if not heavier.
Yes steel is heavier than a bike you buy, but as you want a light frame, then you need to weld aluminum or use he materials that bike manories use. It is a lot more expensive than steel and you save a few kilo.
My frame isn't that heavy. It becomes heavy mainly by what i have put on to it, but the main frame isn't that extreme heavy. It depends on the frame you buld and the matterials you use.
Why weld aluminum when it can be bolted together without compromising the strength of the metal?? This is not my site or idea.......I found it in a YouTube video
aluminumwelder
New member
I am NOT talking about steel. I am talking about aluminum. Specifically previous poster said some alloys of aluminum do not need heat treatment which I think is incorrect. I have seen youtube diy builds that do not heat treat aluminum frames, but they will be stronger if heat treated.
I have seen that. I looked ad it before i went for steel and my first design was for aluminum.
But what i calculated, the frame wouldn't be that light or i had to go for more expensive aluminum. Than you can go thinner without that you have to be afrait that it would bend and use less tubes.
Now i have my steel frame almost finished, I looked how i could improve my current design and one of the things was still aluminum but then on an other wat. Only 2 round tubes and the rest steel. But the price is higher then steel. For now i stay with my current frame.
Saving money for e-assist on it.
But what i calculated, the frame wouldn't be that light or i had to go for more expensive aluminum. Than you can go thinner without that you have to be afrait that it would bend and use less tubes.
Now i have my steel frame almost finished, I looked how i could improve my current design and one of the things was still aluminum but then on an other wat. Only 2 round tubes and the rest steel. But the price is higher then steel. For now i stay with my current frame.
Saving money for e-assist on it.
You buy the quality you want with aluminum. The stronger it is, the higher the price. As you do heat treatment, then you need also cool it the right way, els it will make that you get weak spots. As it cools, the aluminum can crack as it isn't colled evenly and it can bend.
It isn't easy to do ad home, especially not with tubing.
When i designed it, it was about as heavy as a steel frame and i did't put everything on it because i stopped workingon it.
Those bolds ad a lot of weight but also the aluminum isn't that much lighter because of the amount you need and the thicknes as you go for such a design. Only as you use the way more expensive aluminums, then you can go ligher, but then still i would weld it. Else the bolds make that it is still not much lighter.
aluminumwelder
New member
Wow you designed the bolt together aluminum frame? very nice! How did the wheels pivot on your frame? The way AZ tadpole trikes are welded together by guestimate is less than desireable. A bolt together design might be more easy to replicate with out needing to make custom jigs.
I wanted to use the part from a bike and keep one tube on it that slide in the aluminum tubing and bolted togheter.
But I didn't finish the design.
Also the wheels had to be mounted to it and that part I wanted to let cut or make it like the warrior Trike plans. I was planning to ask a company to make it for me.
Welding the frame, made it easier to make a frame.