maanantai 19. lokakuuta 2015

Replacement bike parts? Print 'em!


I can be cheap bastard at times with things that might seem so very insignificant, which might be reason too - when something small, stupid and, well, insignificant is broken I don't really want to pay for it.

Case in point: my bicycle's side stand (I'm not sure this is the proper term for it, but I'll use it for now) is essentially but a hollow two-part metal tube (two-part due to adjustable length) that originally came with plastic at the end to distribute the load on ground. Over time (fairly quickly, actually) plastic wore out, and not very surprisingly hollow tube doesn't hold even bike's weight very well when on a gravel, grassy or otherwise less firm surface, making the stand pretty useless as bike will just fall over. Plastic part is still there but since it was so difficult to rip off that I just left it there.

On recent bike ride the screw holding two parts together came loose. Fortunately this was at stop so no parts were lost so instead of spending some 20€ (or something around that, haven't checked exact prices) and some ten minutes of my time (to take old out and put new in, ignoring time needed to drop by a shop) I chose to waste some 15 minutes of time to draw and print a new end piece. Printing of course took longer but since it's hands-off I don't really count it.


Drafting the part in openscad took just few minutes (I've grown used to it by now so small things like this are trivial), but maybe I shouldn't have drawn it first thing on the morning. I measure the opening at the end of metal tube, which was about 6.5mm. Then I draw a cylinder (well, cylinder stack actually) with r=6.5mm and commit print (I think print time was one hour or so)

When prints start I usually check that is started well, but typically I don't bother but occasional quick check mid-print (I moved the printer to another room as the noise gets annoying next to my desk when trying to do something else so I don't watch it all the time anymore).

After printing finished I go to check it out and immediately see what went wrong. Radius of 6.5mm. Stupid me.

Modify model and start over.

If you've been reading my posts you might remember that I pretty much consider USB unusable for any  job that requires any reliability. As it turns out, that list would include 3D printing. Mid-print I hear usual USB disconnect noise (for no reason apparently), printing stops and it's ruined. Close Repetier, unplug cable, plug back in, and restart. Another 30 minutes (of print time) wasted.

Try again. And then I get the part printed.


Now to see if it does the job. Angles don't match the original but hope it's good enough but then again, I can modify it and print it again anytime if it doesn't. Possibly with a different material, as PLA most likely isn't the best material for the job (didn't feel like switching material just for that).

As a side to, the more I use the 3D printer the more I start to find it useful for many small, even tiny things like this. Some small part that broke, or some small thing that would be useful (like wedge-shaped spacer for between shelves and wall to distribute load), toy repair like mentioned before... Anything. Draft it quickly and print it. Parts aren't necessarily pretty but who cares, they get the job done well enough.


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