Rack Building Basics -- Eyelets
It's been a long time since I've posted a Rack Building Basics entry, but I still have some in the queue.
Today's photo series is about making the eyelets that connect the rack to the fork or frame. There are a couple of ways of doing this, but this series focuses on doing it with brazed in tabs made of flat stock. This is similar to how dropouts are made.
The first step is making a slot in the end of the tube for the tab. I draw the slot and then use a hacksaw and a thin file to make it:
Now we need to cut a piece of flat stock to fit. I purchased 3' of 1" wide 4130 which is perfect for this purpose. You only need to make a single cut. I use the tubing as a gauge to how wide it should be.
The tab is the same width as the tubing:
Brazing just the tab in is probably strong enough. Note that I filed the end of the tube to slope the tubing towards the tab:
I like to fill the whole end of the tube with a "plug" of brass. To do this you heat the whole end of the tube and draw the brass around below the tab. I'd do a few tests first and cut them apart to see how well you do at pulling the brass in. It is a bit hard to see in this photo, but the whole end of the tube has brass in it.
After removing the flux I do a little work with a round file (12" round which is about 10mm or 3/8" in diameter) to make a nice clean scallop. The tab has also been bent to match the angle needed for this rack:
A bolt hole is drilled and a file is used to ease off the edges:
A final photo showing where this tab is used on the rack. It connects the stays to the fork blades:
At the start of the entry I mentioned that there are other alternatives. A nice and easy one is to braze a piece of tubing perpendicular to the stay and run the bolt through it. 5/16 x 0.035 tubing is a nice fit for an M5 bolt. This is an especially good idea if you need a spacer to clear part of the fork blade. In this example the tubing is extended on the inside so that the rack can clear the fork blade even if the fenders aren't installed. This is from the first rack that I built:
Another option is to simply flatten the tubing in a vise and drill a hole through it. I think that this looks a little less refined, but it is strong. Sorry, I don't have any photos of this approach.