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Houseface
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hey,

i was thinking today and got confused about all the different stuff that you get?

so,

what is the difference between cnc'd and not cnc'd?and what so good about cncing? :S

also,what are eyelets? :S

thanks :-

steve.

CNC is just a machining process. It pretty much involves a computer cutting out shapes from metal stock. What's so good about it is that it's a big buzzword right now, but also just that you can make intricate shapes with it and do neat designs, as opposed to just using standard tubes and welding stuff to them with traditional bike frames.

Eyelets are stainless steel spoke hole reinforcements. They can help with the spoke pulling through the rim itself.

With eyelets link

Without eyelets: link

Look at the difference in the spoke holes.

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cnc stuff is cut from a block which makes it nice and strong, also stiff

eyelets are clips of metal that reinforce the spoke holes on rims, allowing you to to have tighter laced wheels without the danger of spokes pulling through, used more in downhill rims like the mavic ex729 which has "double eyelets" which are small sleeves that join the two walls of the rims making it uber strong :)

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as said forging is stronger than cnc'ing because the grain of the metal can be realigned to resist the forces that are applied to it. but you dont see it much in trials bits because of the cost of the machinery involved. and the fact that the process is a lot onger, due to most parts being forged to as nearer end shape as possible and the final bits are machined into the final shape.

cnc'ing isnt quite as strong as the grain in the billet that the final peice is cut from flows in a uniform direction and the cnc mill/lathe will cut through the grain, meaning that the forces applied through the peice wll not be dealt with by the metallic grain in the same way the the forged peice will. :)

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What they've said plus its a great way to make lots of high quality components with a minimal (unnoticable) differance.

Edit:Its also Cheap, it would take a man a day to make one bottom bracket yoke in a milling machine, thats if you could find someone experianced enough!

A CNC machine can churn out things in minutes, seconds depending on the detail and tolerance, and once its set up, you dont even need to pay it.

Edited by jake1516
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also while we are on the subject of metals..........my frame is made out of U6 alloy, this i have never come across?

neither has the metalogist where i work at rolls royce, or my college tutuor?

what is so good about this material?

is it a 6000 series alloy? what does the 'U' indicate

any help would be much appreciated

cheers ash

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also while we are on the subject of metals..........my frame is made out of U6 alloy, this i have never come across?

neither has the metalogist where i work at rolls royce, or my college tutuor?

what is so good about this material?

is it a 6000 series alloy? what does the 'U' indicate

any help would be much appreciated

cheers ash

http://www.observedtrials.net/vb/showthrea...highlight=alloy

(Y)

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so basically the u6 is just another name for t6 which is the heat treatment grade? or am i mistaken?

most of the trials frames are now claiming to be made out of this u6 alloy, is it just say 6061 t-6 but with the u6 name?

cheers ash

U6 is a trade name. I think it's supposed to be similar to 6061-t6 maybe, but that thread will say better. But yeah, U6 is just a trade name, like plexiglas or teflon.

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Edit:Its also Cheap,/quote]

Not really, over-all? For example, with the Hi-Fi/XTP style CNC'd headtube, it costs more 'cos there's more waste material created 'cos instead of having 3 tube welded at angles, it's one big f**k off bit of alu creating one tube and part of the other two tubes, so there's more waste, hence it costing more. Equally, it's more to have the machine to do it, and to train people to use CNC machines and so on? Either way, it's not cheaper...

The whole thing is though is that you can create the optimum component. Basically, with a tube of material, there's different forces acting on it. That's why there's butting 'n' stuff on frames, 'cos - say - at the centre of the tube it's got less force than at the ends, so it can be thinner 'cos it doesn't need to take as strong a load. With tubing, you're limited to butting stuff, or using an overall thinner wall. However, with, say, a BB or the head-tube config. they've got on the XTP/Hi-Fi, you can fully get rid of whatever your FEA says is un-stressed material, and make an ultra strong join or part of a frame. Because you can also manufacture i-beams (capital i looks like l :() into products, it means you can get stiff-as-f**k bits for seat-stay/chain-stay joins too, so it's all good. Either way, it's not "pointless" and "just to make money" as people seem to imply.

An eyelet is a ring of metal that, when used on rims, spreads the force of the spoke pulling through the rim out so it's less likely the spoke'll tear the rim a new arse. Think of it like a little dinky round gusset.

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For mass production, in the long run, CNC is cheaper.

You cant compare welding and CNC as they are not nearly the same process, like I said above a more fitting example would be that of a milling machine.

When any bike company decides to use CNC machining they dont turn round, and train someone who hasn't used cad before, they will simply employ a cad operative who whould be able to knock up a machining program within a week.

If CNC isnt much cheaper/better, then why is it at the forefront of engineering??? I doubt its because its expensive and crap.....

Equally, it's more to have the machine to do it, and to train people to use CNC machines and so on? Either way, it's not cheaper...

If by this you mean the cost of the machine makes the process more expensive, then yes, for a one off your right, but were talking about mass production.

Like I said above, there not gonna train anyone, there gonna employ one CAD guy who should be able to do all the drawing of the components aswell as making the machining programs.

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I stand corrected, I guess. Just for the record though, I was saying throughout that entire post that CAD was awesome, by the way :) Just referring to

If CNC isnt much cheaper/better, then why is it at the forefront of engineering??? I doubt its because its expensive and crap.....

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CNC'ing is a more expensive manufacturing process than producing a product with welded tubular components. its relatively slower and more costly due to the amount of material waste that is produced. the reason you find cnc'ing on a lot of bike components and frames is due to like you said before the flexability with how you can modify the material when compared to a simple tube. at places like the bb yoke it is a viable alternative to welded tubing, due to the extra strength that is gained i.e. you can have what material you need where you need it and no where else.

apart from the extra strength gained and weight lost due to using cnc parts manufacturers use it because us consumers think it looks god damn good!

its practical and beneficial to us; stronger product less breakages and warranty replacements for them and aestethically (sp?) it differentiates "some" bikes from others.

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