Saturday, June 17, 2006


Never estimate something you've never done before. Sarah's bike hasn't made it to the painter yet.

There is progress. The plates on the the top of the seat-stays are now polished, and look pretty good. The edges of the plates aren't as sharp as on stays that I've done without polishing. It looks like there's something more to learn about polishing to the edges without rolling them.

The seat-tube is reamed and honed, and a seat post tested in it. The keyhole on the back is cut out too. Rather than use several hacksaw blades taped together, I cut the slot with a Dremel metal-cutting wheel. The wheel has sort of a bayonet mount on its shaft for quick changes. This also allows it to flex on it's shaft - so be careful and don't force it. Anyway, it produces a nice clean, quick cut. Recommended.

The head-tube is milled and faced. The bottom bracket is chased and faced. And, generally, everything is done but polishing the head-tube.

I started by trying to sand the larger surfaces of the tube using a palm sander, hoping that the random sanding pattern would avoid scratchs and make subsequent grits easier to do. Instead, the pattern left by the sander hid any blemishes in the surface of the tube.

Practice shows that parallel strokes leave a surface that's easier to read for blemishes. Working through a grit, I use several directions of sanding before finishing with strokes parallel to the axis of the tube.

Even with this trick, it can be hard to recognize deeper scratches in the surface until one gets to a level of grit that can in no way take it out. So, I've been starting with 120 grit and working my way through 220, 320, 400, 600, 1000 and 1500. Except everytime I go down 2-3 grits, I find a scratch that forces me to move backwards through the grit.

Having done that several times now, I tried buffing the surface using a Dremel mop in the flex-shaft tool. The problem is that the mop is too small and its possible for the chuck to touch the tube. Ouch! Back to the 120 grit.

So, my challenge now is to find a bigger mop and get the tube polished. And on to the next project.


mal said...

interesting problem. You may be beating the sanding to death here. Depending on what your intentions are for finishing, you best bet may be to prime it and wet sand with 400 grit. Depending whether you are going to have it wet painted or powder coated, you will be adding a minimum of .003 or more in paint. This will go a long way to hiding any small scratches you may have.

I have taken my beater down to bare metal twice and really had no issue with the small nicks and braze lines that were apparent when I was stripping it.

my 2 cents worth. If you have specific questions, please feel free to E mail at the address on my blog

Rick Guggemos said...

Thanks for the feedback.

Yeah, I should have been clearer here. You'd have to read the various other posts to know that I'm polishing the head-tube because it's stainless steel. The end result should be a chrome-like finish, which will be clear-coated, but just to protect the decal.