Kenny--Trials
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Posts posted by Kenny--Trials
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7 hours ago, Dman said:
BSD passenger as an example.
26 minutes ago, Paperclip said:They're heat treated because of the thinner tubing or they would be pretty heavy.
That thing looks as if its going to be damn heavy anyway because it looks as though its stainless steel.
Also, whats the need for the tapered headtube?
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50 minutes ago, Pít said:
I like it too!
Whats the geometry? Seems pretty short and high.
I haven't measured it off the bike but it should be 995mm wheel base, 350mm chainstays and +95 bb height
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On 11/22/2015, 10:25:59, David Biddle™ said:
looks good Kenny didn't realise you were gonna make your own frame.
cheers biddle
3 hours ago, ItsMatt said:looks a bit messy but functional, good work.
it is messy because i haven't done much aluminium welding yet but i hope to make another better one in the next few years
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It's finally finished!! So here it is...
So far it rides fairly well but the rear brake makes the frame flex so much and so I definitely need a booster
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Ah right, no im definitely not high class enough for an oven that size
I was speaking to my boss today and he said that hardening isnt that expensive so i think ill look a bit more into it. And you're totally right about the design/hardness problem.
ill have to do a google search of which rods it is then
it has been a really great project and i really want to make another one now i know what went well and what didnt
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it really wouldn't fit in a domestic oven so id need to take it to a specialist to get it hardened which may or may not be worth the time/money. Because this is the first frame ive done, im expecting to have to re-weld it at some point which would remove the temper in a large area around that and im expecting that to get it hardened would be fairly expensive. I have used special magnesium alloy welding rods which are much stronger than the ones what we would normally use for aluminum tig welding.
I think im just going so see how age hardening goes as i do want to make a few more frames so it wouldnt be the end of the world if it did break and ill be much better at alu-tig welding then anyway
Also i just had the idea that it might become brittle if it was too hard, thoughts?
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It might not harden fully anytime quick, but im pretty sure that a significant part of it is done in the first week of it being heated, possibly the first few days
EDIT: Been looking on aalco's website which is the aluminium supplier we have at work and it states that age hardening works on 2000 series, 6000 series and 7000 series
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Great work
Got someone to do the heat treating for you?
Thanks
I asked one of my friends at work about that and they said that it doesnt need to be heat treated at all because aluminium hardens over time (after being heated) and will go back to its original temper from when it was made
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Nice.
Is the dent in the top tube intended for gusseting? And the bottom chain stays join really central on the bb, another gusseted area?
Spoze I could wait and see.. but where's the fun in that
I was really hoping nobody would notice the dent haha, but yes it is.
And yeah the bottom bracket is also somewhere I'm going to gusset to hell.
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Nice, it'll be interesting to see how long this holds up compared to other home made frames we've seen.
To be honest i dont have masses of hope for it because it feels waaayyy too light but we shall see
I'm impressed- it looks very nice indeed
thanks
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Update: I'm so close to finishing now! It's all welded up, just got to put a few gussets on and make the brake mounts and it's done!
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i plan on running duel maggies, what do you mean carrying the welds on past where they normally end?
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4130 is much stronger than the carbon steel (which im assuming is just a form of mild steel). 4130 tubes are also extruded from a die (cold drawn) when they're made where as the mild steel ones are most probably rolled hot from sheet to save a fair chunk of money. But, mild steel is much stronger than the 6061 or 7005 grades of aluminium most commonly used in trials frames. So, personally, i dont really see the need in spending the extra money for 4130 when chances are that if it did crack, it would crack on the weld anyway.
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i had those places in mind but i was just wondering where exactly, like is it the welds that crack or is it just next to them?
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The frame is almost done, just have to cut the top chainstays in and sort out the dropouts but I'm now thinking about strengthening plates. So where is the most common places for frames to crack so I can make sure I make those areas as strong as possible
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t-poo's are great to learn on just because they're so terrible. If you got a new 'modern' geo in like a years time its like gods greatest gift. Also, they're built like brick s**t houses and so you'll never break it.
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Got the bottom chainstays and most of the jig done today
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It was definitely Ot Pi. He revolutionized trials by climbing many stairs
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when we order in tubing at work we order it in pre heat treated and when you weld it up it looses that treatment. That's why I just assumed it was just the welds that need treating but I may be wrong
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6082 is the uk equivalent of 6061, far lower strength than 7075 that most trials frames are made from.
you'll buy at t6 temper presumably but after welding will be at t0 at the haz ( heat affected zone ).
Without heat treating the area around the welds will be significantly weaker due to the rapid cooling of the metal resulting in the crystalline bonds in the metal not aligning correctly.
Pretty sure I'm right in saying that.
im almost certain that frames arent made of 7075 because 7075 is virtually impossible to weld without it cracking due to it cooling so quickly in relation to the rest of the material. i did look into making it from this but it just wouldnt work. it wouldnt be that hard to heat treat the welds would it?
Well, they'll possibly still fit but they won't run particularly smoothly. That's why BMX frames almost all have post-weld machined BBs and head tubes. I've used a press-fit frame in the past that didn't have that, and the bearings would feel silky smooth just in your hand, but as soon as they were pressed into the frame they felt poop. I managed to sand the shell so it wasn't quite as ovalised and that made things better, but it still wasn't ideal.
the proiblem is that i dont have access to a lathe big enough or a cnc machine to do that haha
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if you know someone with a tig welder you could weld a T bar to the top and try and get it off like that but a smaller socket is probably the best way to go
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Which grade is that?
i think its 6082
ive found some press fit ones but ive been advised not to use them by co-workers because as i weld it up it will just distort like hell and then the bearings wont fit in
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It was bearing precession I was thinking of...
I don't know what stage you're at, but you could maybe just try buying some pre-built BB shells? Companies do sell ready-made parts like that which might help you out if you're struggling.
I cannot find anywhere which sells pre tapped aluminium shells in the grade that i want is the issue
Would be pretty difficult to tap a thread that large nice and square , as above get hold of a bb she'll or ask a machinist to screw cut one for you
tapping it square isnt the issue because of the way the tools are designed. the machinist idea is pretty good though but i feel like it would be quite easy for them to get it wrong
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either way im still trying to find someone to tap the threads for me. ive messaged a few companies but they all said that they either dont have the taps or wont do it because they only use them for chasing the threads
Hope Oil
in Trials Chat
Posted
Hi peeps,
Does anybody know if there's any difference at all between specific bike brake oil and car brake/clutch oil? Dot 4 and dot 5.1 just seems a fair amount cheaper from somewhere like halfords than chain reaction
Thanks
Kenny