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Middleburn Bashring Project


Alex Dark

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Can you get some pictures, bradford's a bit of a way from plymouth.

I certainly can :) I'll get some as it gets made anyway.... probably a video too.

http://www.velosolo.co.uk/shopdisc.html

Their design looks usable, you think the bash could hold this configuration?

Yep quite possibly, depends on the diameter of their bolt holes....I suppose it would be 46mm like a standard disc hub? If so then maybe not....as the inner ring ( lockring ) on some burns is 42mm...

It would nearly definitely work with a custom cnc'd / routered one however :)

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Ha i'm lookin forward to seeing how this turns out.

It might just be a case of putting the lockring on before adding the sprocket.

Simple solution?

It's more of a problem of the bolts interfering with the lockring...even with the cloud 9 the sprocket has to be removed before the actual bash, and thus lockring can...

I have an excellent idea for another project now though ^_^

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It's more of a problem of the bolts interfering with the lockring...even with the cloud 9 the sprocket has to be removed before the actual bash, and thus lockring can...

I have an excellent idea for another project now though ^_^

i have a thought for you alex seeing as you seem to be looking at middleburns...

would it be possible to make a set of burns accept a FFW with a bit of CNC'ing and modding?

or

make an adapter that fits like a middleburn bashring which can accept a FFW

;) I has ideas....CAD model ahoy when I get home :)

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Righto! Got an update...decided to really get on it and nearly finished me little project. Used the lathe, mill, and pillar drill to get it sorted. Just need to do some cosmetic machining, and drill the cog and tap the bash. Super high (12.2 ) tensile bolts came in the post today, sooo I should have the whole thing on the bike and in testing by the weekend?

post-11254-127257053454_thumb.jpg Here's the bash before I buggered around with it...pretty bashed up but structurally gravy. Actual weight at this stage was: 223.7grams

post-11254-127257041414_thumb.jpg Just after lathing the first 2mm off

post-11254-127257044502_thumb.jpg Here it is after milling the other side down a bit more, 10mm thickness now.

post-11254-127257086829_thumb.jpg Milling the side down, decreasing the diameter from 104mm to 89.5mm to just cover the new 18t cog.

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Weight at this point was 114.2gr....almost halving the original :)

post-11254-127257102009_thumb.jpg Here shows the conversion from full to half ring...hacksawed roughly to remove most of the material, then finished off with a 6mm cutter.

post-11254-12725730756_thumb.jpg Same as above, but shows bash bolted to rotating bed.

post-11254-127257312162_thumb.jpg Here is the final picture for now....bash has been milled and lathed to give a fairly nice half bash shape, the 'flick' at the end of the bash needs milling, along with the slot on the upper side. Also the spider mounts need removing, leaving enough for the cog to rest on ; eliminating the need for spacers :)

Hope you guys like, the final product will be all fly cut then milled to give a nice cd like finish :). Aiming for around the 85 gram mark, bash only

really interested as to how this turns out mate, might have to give you one of mine plus some dollar to have a play (Y)

Yeh man I'd be up for that, tell me what foot forward and anything you want done to it :) Really sussed out how to do everything now, could probably make the next one more accurately and in half or less of the time. :)

Yeah man, looks cool so far!

I miss being in a job where I get to use a lathe, Such a good tool to work with.

I can't wait to see this done

Cheers dude :) They're ace, I'm still pretty much a complete novice, but love working with machines like this....

Should be finished byt tomorrow * fingers crossed * then I'll have pictures on the bike too.....Just need to drill the bloody cassette cog, standard HSS bits just aren't cutting the mustard / cro-mo :P

Any tips? Maybe Cobalt cutters?

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Well got the bash finished today at long last....I reckon it looks pretty good, think im going to skin another 2mm off the top face ( still 10mm thick now..so wayyyy over kill in my eyes. Damned light though, bang on target at 74gr bash only with a good 10grams of material still to be removed.

The Hi-ten bolts and now drilled sprocket ( another 5 holes still to go in ) weigh in at 82grams....so hardly weighty. At the moment the whole bash with bolts is grams.... compared to the cloud9; pretty damned good!

The Tnn alloy set-up is 39g, pretty amazing, but alloy ring which I personally wouldn't trust my face with :S The steel set-up is 120g so I guess that's the target for mine :)

Have to consider that mine is over twice as thick as the TNN! Same as the Cloud9 really... I know that I can comfortably get it to around high 50gr, and the cog down to around 70 something.

Anyway, enough jibber-jabber....pictures are below :)

post-11254-127273529098_thumb.jpg

post-11254-127273531131_thumb.jpg

post-11254-127273536436_thumb.jpg

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Nice project!

With reference to the FEA plot, I would take that with a very large pinch of salt. Firstly your peak stress is on a corner at which the stress will tend towards infinity as the mesh in that area gets refined. And if I remember correctly, Solidwork's inbuilt FEA creates its own mesh with little or no user input, which is pretty rubbish for knowing the level of error in the results (and believe me, the wrong mesh settings can give you errors of over 20% in the results) let alone correcting for it. As far as putting up an impressively "pretty" picture, it does the job, but you're better off doing what you are doing and making a prototype to test rather than relying on Solidworks to tell you if it'll break or not :)

Fail....I can't stress test an assembly at home, but I can assure you nearly all the force is acting through the splines... Erm, I have this...but I don;t think it really shows anything as the crank isn't mounted, and the force is only perpendicular, not a cyclical torsional force.

post-11254-127236456702_thumb.jpg

Got a picture below of the latest revision, but without the drilled holes, only the large scoop :)

post-11254-127236459518_thumb.jpg

Cheers

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