Getting going & building a jig.

Posted: February 16, 2012 | Author: | Filed under: Uncategorized | Leave a comment

Ok, So I need a jig to tack my seat tube into the bottom bracket shell.

I had all these bits..

I found all this stuff down the back of the sofa..

Then I said the magic words, “jiggy-wiggy-wamma-jamma”.

And the Wilk-O-Matic ST1 jig was born.

Complete with Park stand clampability.

Nearly got this one in focus..

An adjustable parallel is used to shim up to the height of the seat tube just as it exits the BB shell. The base is a precision straight edge. I had this side of it clocked at work at less than 0.1mm error over 1 metre.

The screws lock the adjustable parallel at this height. I had to make sure the tube was sitting flat on the top of it.

Then I moved the parallel to the other end of the tube and insert it into the slot I cut to allow it to sit on the flat surface. I close the toggle clamp after adjusting its set screw and locknut to give the correct downward force and travel.

Another view

Detail of angle bracket with brazed reinforcements. I stuck some cushioning clear rubber, the type you use to protect bike frames from cable friction or chain rub, underneath the bracket to protect the flat surface. It's self-adhesive and stuck to the bracket.

I had just enough room to double-check along the top with my surface gauge.

Both ends matched for height.

I made these rectangular washers out of some 3mm stainless bar so they would sit in the gap and raise the nut above the flat surface, thus protecting it. I filed the edges off to leave them slightly rounded.

At the other end I made a double washer with 2 holes for the bracket bolts.

All in all, I’m happy with the jig, but I have to be careful not to drop the adjustable parallel on the concrete floor.  Perhaps I can improve the design in this respect.

I brazed my fork crown to the steerer today.

I took this shot while filing away the excess steerer tube and silver.

I cleaned up the crown and filed the points to be crisp and sharp.

Next I mitred the seat tube with a half-round second cut file.

My tubing blocks came in handy.

Checking the mitre against the BB shell. The "ears" need to come down a bit.

View through the down tube socket. I've filed the points and the edges of the socket walls to sit at 90 degrees to the tube.

Good old John milled my dropout faces down by 1mm and gave them a near-mirror finish.  Then it snowed.

Now the track faces are nice and shiny. I've cleaned up the brass and started to shape the edges to more rounded chamfers since these pictures were taken.

I had to show off the Winter Viburnam.

Plenty more to come. Bye for now.

Matt