# Project: Failure is always an option (Frame No.1)



## PISTON (Jan 6, 2008)

Hello guys! 
It is my first post here in the frame building forum, but recently built a frame, and I want to show you a litte bit of what I've been through.

The whole idea started about 5 years ago with some CAD drawings (which I am not showing you, because they are just to silly )

The thing got more serious about 2/3 years ago when the designing got a bit more organized.








First the basic concept was defined, and after many hours of calculating and looking for better solutions the details were set. At least that is what I tought back than.
Along with this there were also some "paperwork" for school that was done...








After that I began searching for a suitable material. Spent many months searching and yet did not found what I wanted.

I was also planning to get everything done by local machineshops, which soon prooved to be an impossible task, so changes in the design were needed (cost and machining complexity - you can immagine the shapes an inexperienced engineer with a CAD software can produce ). Now everything was designed to be cut on a waterjet. The material bill was shortened drammaticaly.















Some machining still needed to be done on CNC machines.








Later on I bought a small lathe and milling machine, so producing parts became much easier.

The welding was done by a friend of mine (I have to thank him again), so no many issues there 

I was ready for assembly...








and the bike was finally finished...








... or so I tought

about 15min of "just riding along" around the house and disaster...








I knew that the material wasn't the best, but I just did not expect such a drammatic failure so quickly (the broken piece wasn't the problem, the bent chainstay worried me the most).

It was back to the drawing board (I did spend countless hours calculating the strength of every single detail, yet I forgot the most important one ).
Anyway, I managed to find the mistake I made, and begin to design a new rear end.

This is just some random "homemade" measurements to assess the extent of the problem.








After some 100 hours of designing (the results now are more optimistic) and machining the new rear end is made, and ready to be tested...








This time no major problems. The bike survives the "around the house" test.
Since then a few local rides were done. There are still some minor issues to be solved, but all in all the bike rides very well, and most important, it rides very close to what it was expected.
The feeling during the first rides is just amazing - guess only who built a frame himself can understand this .



















































Believe I still owe you some spec about the bike:

-Changing the shock mount it can take shocks from 200x50mm to 241x76mm. (right now I use a 200x57)
-Travel ranging from 130 to 175mm (right now cca 145mm)
-Adjustable geometry 1. 3 positions of the shock mount (bb height 0, +-5mm, head tube angle 0, +-0,5deg. )
-Adjustable geometry 2. Head tube 1.5" (headtube angle - with homemade angleset i should have +-4 deg window)
-Adjustable geometry 3. Dropouts (bb heigth, chainstay length (up to 5-10mm shorter).
-Fork axle to crown from 520 to 565mm (140-180mm - right now 545mm @160mm)

Other requirements:

-Standover as low as possible
-Continuous seat tube
-Shock mounted as low as possible
-Mud clearance
-Progressive suspension ratio (maybe even a bit too much)
-Some details about axle path, and squat characteristics compared to the actual bike

Geometry (basic, based on 545mm atc fork):

-Head tube angle: 65deg.
-Seat tube angle: 72deg. @780mm from bb
-seat tube length: 480mm
-Horizontal virtual: 615mm
-bb heigth: +10mm
-chainstay: 435mm
-mWheelbase: 1200mm
-weight (w/o shock): cca 3,3kg (version 1: 3,1kg)

I could go on for a lot more, but will stop here. Hope you like it. If there are any questions do not hesitate to ask.


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## TrailMaker (Sep 16, 2007)

Well...

Pretty ambitious. What series alloy did you use?


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## murf99 (Dec 12, 2010)

I think its great...nice job dude :thumbup:

Sent from my SCH-I535 using Tapatalk 2


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## Walt (Jan 23, 2004)

Needs to be anodized purple!

Great job!

-Walt


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## PISTON (Jan 6, 2008)

TrailMaker said:


> Well...
> 
> Pretty ambitious. What series alloy did you use?


Since the 7000 series could not be found anywhere I ended up using the 6000 series.
I am still trying to find some better material, meanwhile I hope this one will hold up enough abuse to show anything that is wrong.
Will keep updated if there will be anything new 

@Walt, for the moment I'm gonna stick with the "black and white" scheme


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## unterhausen (Sep 28, 2008)

Pretty cool project

Many aluminums in the 6000 series are a much better material if heat treated. You can assume that the welds have returned the material to the annealed state. 

Looks to me that some of your parts are not designed from a fatigue resistance point of view. Inadequate edge distance and sharp corners are going to lead to failure. Note that fatigue failures occur when loading is far below the yield stress of the material. So just figuring out what the static load limits are will lead you to failures sooner rather than later


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## PISTON (Jan 6, 2008)

I wanted the 7000 (7005) series, since it does not need heat treatment so badly, but I just couldn't find anything that wasn't overseas and in industrial quantities. I than had to go with the 6000. And still did not get what I wanted - so the material is acctualy wrong "twice".

I honestly never considered heat treatment too much - It would get me some problems I am not sure I am able to solve at a reasonable cost.

As for fatigue resistance... The calculation acctualy took in account fatigue life (It was done according the iso 4210 standard (hope did not mess the number up), with some minor, but important changes) - a lot of time was spent doing this - I obviously made a big mistake in the first run, and there are probably some other mistakes I still cannot see, and some I saw after the failure of the first swingarm, but basicaly decided not to bother 

I'd be really glad, if you could point at the spot(s) you think is(are) problematic. Maybe I have a reason for that, maybe I just screw up... there is still a lot left to learn.

I honestly ignored fatigue in the design of the new swingarm. Since the strength near the weld was very low (yield strength was acctualy just a little bit above the expected fatigue strength), I tried to create the whole swingarm in "one piece" - to avoid welds (remember, 6000 series alu, no heat treatment), and the shape is "rough" so that it could be (easily) produced on a small milling machine I have at home.
I speculated that the weld-free design (in this case) is such an improvement, that fatigue is not all that fundamental - I mean, everything else should fail earlier than the part that was not designed with fatigue strength in mind.

Explaind like this, I have to say the project might seem pointless... but I still believe it was worth it :thumbsup:


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## TrailMaker (Sep 16, 2007)

Hmmm...

I would not say it was pointless. There are definite points there. As a design exercise it is great, and the execution is pretty impressive, but as a rideable machine it must be limited to some unknown degree. In terms of failure, it will be very hard to tell what is a design flaw and what is related to material strength, or lack thereof. There may be some correlation still, as what fails will fail no matter the material state if it is of less than adequate design. Hard to say, and that would be my point.

You might have created a backwards bike. Strong everywhere that you really don't need it, and "weak" where you do. Having some minor experience with heat treated aluminum, in both its natural and annealed states, I would watch that frame very closely.


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## Walt (Jan 23, 2004)

60 series + no heat treat = death wish. Pull it apart and heat treat it.

-Walt


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## PISTON (Jan 6, 2008)

Walt, now you scared me 
Joke, I am aware that as far as mechanical propreties goes I am not even close to where I should be. Sadly.
I am playing about some different material options, but since it will probably take eternity to build another frame, I will research the options I have for heat treatment again.

The biggest fear is I am not only going to loose alignment of the frame, but also the circularity/cylindricity of some holes (head tube, BB as the greatest fear...). Anyone have experience with that?


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## TrailMaker (Sep 16, 2007)

Hey;

All I can tell you is that annealed T series aluminum is EXCEPTIONALLY soft. Whether you will die or not I can't say, but if you continue to ride it, you will find such limits out for yourself, undoubtedly!


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## Eric Malcolm (Dec 18, 2011)

Hey, really cool project.

You can find heat treating processes for the various grades of aluminium throughout the internet, so study the topic there. Sources of suitable ovens include Glass Artists as they use large ovens. You have to look beyond yourself for this task. Depending on the alloy, it will have to be quenched. With a frame, this means dipping it into water immediately when you remove from the oven. Do this vertically. That is: rear drop-outs first submerging to pivot, Seat-tube to head-tube. If you lie in shallow water on its side, the dropouts will bend to touch each other. The main frame will cup/curve. I'm passing this info/method from a friend who did make alloy frames, and we often joke at his 'master piece' first attempt, I know the glass maker as well. He took all care, but no responsibility for the result.

Eric


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## car bone (Apr 15, 2011)

PISTON said:


> Walt, now you scared me
> Joke, I am aware that as far as mechanical propreties goes I am not even close to where I should be. Sadly.
> I am playing about some different material options, but since it will probably take eternity to build another frame, I will research the options I have for heat treatment again.
> 
> The biggest fear is I am not only going to loose alignment of the frame, but also the circularity/cylindricity of some holes (head tube, BB as the greatest fear...). Anyone have experience with that?


Have a look at Online Materials Information Resource - MatWeb they specify most stuff about most materials there. 
I heard 2000 series alu is maybe a bit weaker than 70 and 60 series but the fatigue resistance is like double.

Also consider making high stressed parts out of steel, like heat treated 4130 or similar weldable material.
you have much higher margin dead/not dead with steel since its at least 3-4x stronger to begin with.

ALL alu needs heat treatment imo. T6/T651 condition is very common with all alu.

60 series will bend before cracking when overloaded, its corrosion resistant.
70 series is stronger and will crack most likely, less corrosion resistant than 60.
20 series is weaker than 70series and needs to be painted or anodized due to corrosion, high fatigue resistance. Not sure if it will crack or bend.

There is an american company that sell 410stainless tubes for bikes, this is a much better material than all kinds of alu and can be welded with dc, does not rust and is like 3-4 times stronger than all alu. No HT needed. And I'm guessing its a lot cheaper than other stainless bike tubes.


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## car bone (Apr 15, 2011)

If you wanna get a good alu frame I suggest starting with alu that only needs like 200-300C to get hard. Because then you can send it to a powder coater and have it HT'd.


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## PISTON (Jan 6, 2008)

@Eric Malcom
Thanks. Useful bit of information. Residual stress is the issue...

@car bone
Steel is an option, but the whole frame would need to be completely redesigned.
Which alu needs only 200-300 C to get hard?

Usually the factor fatigue strength/yield strength is higher on softer materials (at least steel works like that)...


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## car bone (Apr 15, 2011)

PISTON said:


> @Eric Malcom
> Thanks. Useful bit of information. Residual stress is the issue...
> 
> @car bone
> ...


Ok first you need to deciede what alu to use and in what temper, and if its even weldable. afaik 7050 and 7075 is not weldable, these are the strongest alus except Li/Al alloys ans Sc/Al.

Aluminum Tempers - AlcobraMetals.com
Aluminium alloy - Wikipedia, the free encyclopedia

6061 aluminium alloy - Wikipedia, the free encyclopedia
7075 aluminium alloy - Wikipedia, the free encyclopedia
7005 aluminium alloy - Wikipedia, the free encyclopedia
2024 aluminium alloy - Wikipedia, the free encyclopedia
2014 aluminium alloy - Wikipedia, the free encyclopedia

Metal, Plastic, and Ceramic Search Index
Metal, Plastic, and Ceramic Search Index
Metal, Plastic, and Ceramic Search Index

Aluminum (depending on the alloy) is taken up to solution temperature, quenched and then aged (tempered). 
Most of the aging ones age at under 200C if not all of them. The most common alu for bikes is 6061/7005 and maybe 7020/6066 this is definitely because they have a relatively uncomplicated and cheap process to get it in usable strength, the cheaper the better. Alu isn't really that cheap and easy to work with if you don't have a factory and make thousands of them imo.

When you have found an alloy you like then just search for xxxx t-whatever, tempering temperature or aging temperature or process or whatever there might be and see what you find. I would look for makers of bike specific tubes and just go with what they recommend.


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## Eric Malcolm (Dec 18, 2011)

I studied this subject a few years ago and found this site from Easton to be useful in general regarding 6061 vs 7005.

www.eastoncycling.com/bike/wp.../fab_instructions-7005_6061.pdf (site won't come up) Edit.. I can get onto it from Google: 6061 vs 7005 ageing.

Its better than data sheets as it is bike specific. Ageing details are given to a limited extent.

Pizza ovens are also useful. The key is even and accurate temperature control that a home/domestic basic oven will not achieve.

I concluded that 7005 is much easier to use if you can get it. Nova Cycles sell Bar and Plate in 7005, but this gets expensive when International freight comes into the picture.

Eric


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## afwalker (Apr 26, 2012)

I'm getting a 404 page not found
maybe this: http://www.eastoncycling.com/bike/wp-content/uploads/2010/04/fab_instructions-7005_6061.pdf
cheers
andy walker


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## Eric Malcolm (Dec 18, 2011)

Thanks Andy 

Thats the right one.

Eric


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## threebikes (Aug 27, 2007)

Progressive suspension ratio (maybe even a bit too much)

What does it start at and what does it finish at?


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## PISTON (Jan 6, 2008)

I read a lot about that topic, yet I didn't found any exact data. That is why I (at that time) decided not to bother 

Some say that it will get back to T4 all by itself after some time (for 6000 series), others say you need artifical ageing (@2-300C), and some talk about quenching (520C or so) and than ageing back to T6.
That easton link also says it needs to be quenched first...
A lot of research needs to be done to se if it is possible

Anyway... It sadly isn't (wasn't) about choosing the material I wanted, but about making in with the material I was able to get...

@threebikes:
Guess you want to know the leverage ratio at the beginning and at the ending of the stroke? Will provide that data as soon as I get home.


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## car bone (Apr 15, 2011)

What 6000 series do you have? There are like 50 different ones and they all require different temperature. matweb says 160-177C for t6 and 6061.


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## PISTON (Jan 6, 2008)

I have a 6082/6060 combo.

@threebikes. The ratio (travel/stroke) goes from about 3.2 (beginning), to 2.2 for 145mm of travel with 57 stroke shock. Drops further with longer stroke shock.


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## ssalmons (Apr 15, 2008)

That is a cool bike and super awesome job. Go ride and be proud of your creation.


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## car bone (Apr 15, 2011)

PISTON said:


> I have a 6082/6060 combo.
> 
> @threebikes. The ratio (travel/stroke) goes from about 3.2 (beginning), to 2.2 for 145mm of travel with 57 stroke shock. Drops further with longer stroke shock.


the 6060 seems to be a tighter spec 6061 (very lax chemical composition standard), basically 6060 fits inside 6061 except for 1 or 2 elements, mangesium I think so i would just heat treat it as 6061.

I find this *Ageing Treatment* Various ageing times and temperatures can be used to obtain good mechanical properties. However the ageing conditions generally recommended for 6060 alloys for production operations are 6 hours at 185 +/- 5oC. 
Rio Tinto Alcan - Alloy 6060

but this could be t-whatever

and so could this

*ageing Treatment* Various ageing times and temperatures can be used to obtain good mechanical properties. However the ageing conditions generally recommended for 6082 alloy for production operations are 8 hours at 175 +/- 5°C. 
Rio Tinto Alcan - Alloy 6082

6060 from a pdf from "wilsons" Aluminium Alloy - L112 T6 - 6082

Heat Treatment:
Forging Stock:Cast billets & slabs for hot working & extruded
bars,sections and hot rolled plate for forging shall be supplied non heat
treated.
Forgings:Unless otherwise agreed in accordance with BS L100,Forgings
shall be supplied solution treated and precipitation treated.
Forgings shall be heat treated as follows:
Solution treat by heating uniformly at a temperature between 510-
540C and quenching in water at a temperature not exceeding 70C.
Precipitation treat by heating uniformly at a temperature between 165-
195C for 3-12 hours.
This specification cover forging stock and forgings of aluminium-
magnesium-silicon-manganese alloy,solution treated and precipitation
treated, suitable for welding.
The titanium value shown in the Chemical Composition applies to
titanium and/or other grain elements.

I'm sure there are more exact times and temperatures to be found but I found this in about 2 minutes.


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## threebikes (Aug 27, 2007)

Thanks PISTON nice job.


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## PISTON (Jan 6, 2008)

The bike is still going strong, so I tought it was time for some update. :thumbsup:

I studied the issue of heat treatment, but gave up. With the oven I could use it seems it would be just to hard to get it right...

First I had to make new pivot axles and bushes. Changed slightly the dimensions and tightened the tolerances to get rid of the play that developed on the last set.
Not yet sure how long is this set going to last, but after some 20h of use they still feel good - the first set got play much earlier.

For the bushings I use some self lubricating plastic. I was told it is the right material for my case, but it feels just too soft. What do you use or suggest to use?

The second update are some new dropouts for the rear wheel.
With this new set I shortened the chainstay length by a massive 15mm (so it now it sits at some 420mm-ish).














As you can see, the tyre its just a bit to close to the swingarm and the derallieur, but for what I am trying to do it is just fine. (just really need to avoid mud:thumbsup.
Also the tire section had to be reduced (from 2.4 Maxxis to 2.35 Schwalbe) - mainly because of the derailleur (wonder how does spec get their cs length to 419mm?!)
However 15mm does really make a difference to how the bike handles. It has now just lost all that lazyness that it had before.


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## PISTON (Jan 6, 2008)

Well, for a long time there was nothing new to show, just lots of hours spent in the workshop...

But now I've got a some updates...

First there is a new bash (25g), and a new chain device (18g). The chain guide is basicaly just glued to the frame. The future idea however, is to screw it to the frame, but at this stage I just didn't fancy the idea of drilling holes in the chainstay (nor did I had the space for them)
I used some oilon plastic for the slider. It is a bit louder than the roller, but nothing drastic - probably I would be better off with something a bit softer...








And then there is the new seatstay...







Handmade cf tube, and aluminum inserts for the pivots... nothing too exceptional, but somewhere you just have to begin 








...next probably the replacement of the front triangle...


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