Before I go and waste all my money, would any of you mechanical types know why
this wouldn’t work? I am building a unicycle and the only problem I have is the
bearing holder. I am thinking of putting together a lollipop type from a heavy
duty BMX bottom bracket cup and welding an aluminium rod to it. The OD of the
cup is the perfect size. I’m thinking of putting it together then drilling the
holes to attach to the fork. Thoughts, concerns??
-Mary
Re: Will this work
Mary Wrote:
> Before I go and waste all my money, would any of you mechanical types know why
> this wouldn’t work? I am building a unicycle and the only problem I have is
> the bearing holder. I am thinking of putting together a lollipop type from a
> heavy duty BMX bottom bracket cup and welding an aluminium rod to it. The OD
> of the cup is the perfect size. I’m thinking of putting it together then
> drilling the holes to attach to the fork. Thoughts, concerns??
What a great plan!
Here are my thoughts/concerns.
Material compatibility: there are lots of types aluminium and not all of them
are weldable, especially those that are cast. Check first. Distortion: Aluminium
distrots badly when welded (again depends partly on material and whether it is
billet, cast, machined, etc). Do you have the facilities available to dress the
bearing surface? There are some clues as to how badly it will distort, if the
material wall is greater than 1.5 x weld depth distortion will not be too bad.
If the wall is less than 1:1 than I would have though you will definatly need a
meathod of dressing the bearing surface. There are techinques to reduce
distortion when welding, look at one of these… too many to mention. Welding:
make sure you give a good weld prep on the rod. I learnt this one from
experience! 5x5 chanfer on a 25mm bar is not extreem. Mexhanical fix: on my Mk2
CF uni I machined a bearing housing then drilled and tapped m8 hole. Spot faced
surface. Machined, stepped and tapped the bar. Srewed together with perminent
lock tight. This is not a bad solution, it has failed once in 4 years. You could
consider a combination of the 2 methods. Mechanical then tack the thread to hold
it. Hope this has helped
Roger
The UK's Unicycle Source <a href="http://www.unicycle.uk.com/">http://www.unicycle.uk.com/</a>