RADBMX.CO.UK
BMX General => BMX Chat => Topic started by: Peter J on December 19, 2008, 12:24 PM
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I’m currently building up and O/S race bike for next season and I've looked round for a stem I like, but non float my boat. So I got to thinking why don't I make one, I've got the software to design it I've got access to CNC millers, CNC lathes, finishers etc.......... and a very good chrome plater and powered coater
First Idea: Was to make a design based loosely on my hutch stem and engrave a special logo (with kind permission from Stodgy :daumenhoch:) on it....
Second idea: I've made a 3D CAD of my first Idea the "special logo" will go the front where the recess is....
(http://www.radbmx.co.uk/archive/albums/a253/the1carper/PrototypeStem.jpg)
Any feedback please guys ;)
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how will you get the bars in the stem?
apart from that looks ok
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The bottom bit under where the bars fit comes away (you might be able to see that the hole towards the back is not completely round) the bolts go from the front of the stem all the way through. I've run the design though an FEA (Finite element stress analysis) package and its strong enough.
I also put it thorough a product life cycle test package and with type of shocks/hits/vibrations a stem would take it will last around 60 years before it breaks :daumenhoch:
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peter.
if that bit comes out and clamps the bars upwards it might not go up enough for the bolts to line up that come in from the front. I'm assuming there's some angle bolts underneath.
need an exploded view and multiple angles.
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So do the front 2 bolts go right thro? So the bit at the bottom is just a spacer with clearance holes for the bolts that thread into the main body?
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Good Luck ;) looks like its gonna be one cool stem :daumenhoch:
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So do the front 2 bolts go right thro? So the bit at the bottom is just a spacer with clearance holes for the bolts that thread into the main body?
Yep :daumenhoch:
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So do the front 2 bolts go right thro? So the bit at the bottom is just a spacer with clearance holes for the bolts that thread into the main body?
Yep :daumenhoch:
Is there anything to stop the "spacer" rattling around? If it actually gets clamped in there, then the bars wont be tight.
Also, wont there be quite a bit of twising across those 2 long bolts (from the leverage of the handlebars)?
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There are only two bolts holding it together, the front gap on the stem is large enough to clam the handlebars firm and still leave enough clearance.
I've designed this stem for a specific set of bars (for which I will be forever grateful to the sound bloke I'm buying them off ::) ) although I’ve used a pair of GT's for the bar diameter
The mechanics of the design will work I have no issue with that (I would be out of a job if I didn’t know that much) I just wondered what people thought of the aesthetics
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Twisting won’t be a an issue due to the material used for the stem :daumenhoch: and theres a key way for the spacer to fit in. Its only designed for old school racing not freestyle or mass production