The Right Tool

After a long holiday weekend full of family, I was ready to get back to working on the bike.  After getting the blades bent, the next step is to slot and dome the blade ends.

There are two types of dropouts - socket and slot style.  The socket style is easier to work with by far, simply slide it on the end of the fork blade and start brazing.  Some of them even have small recesses where you wrap the solder wire around; slide it over the blade and heat the joint up, and the solder will flow from its holding spot into the joint.

I went for the slot style because Talbot recommends using them for your first frame (for some bizarre reason).  There is significantly more work involved, and it seems much easier to screw things up.

The process of slotting the fork blades involves cutting a slit down the smaller end of the blade (this is the round end if you have oval blades) and then filing it open to accept the dropout.  You can perform a variety of finishes on the end of the blade; Talbot describes how to dome the blade, but there are other versions that he does not describe. 

The first step is to cut the slit.  The cut must be lined up with the bend in the fork blade or else the dropout will be installed askew.  Install two blades side-by-side in your hacksaw, and then carefully cut a 1/2" length slit at the narrow end of the fork blade.  I found this very difficult to get started, since the saw kept chattering and the two blades were bowing against each other.

After the slit has been roughly cut with the hacksaw, you must now start filing.  If you don't have a warding (flat) file, now would be a good time to get one.  I spent about two hours with a small flat needle file before I gave up - the needle file is simply not designed to remove the amount of material that was left.  The hacksaw produced a slit about 2.5 mm thick, while the dropout is 4.5 mm thick; I managed to open the slit to about 2.8 mm before I gave up.

The next day, I stopped by the local hardware store and picked up an 8" flat file with a double-bastard cut.  The file is about 3.5 mm thick, which works out perfectly for this application.  It took another hour and half or so to open up the slit from 2.8 mm to a size that would accept the dropout snugly.  You will be filing for quite a long time; turn on some music and drink plenty of water.

The next step is to press the slit closed and reopen it by once again cutting and filing.  Here is where I've currently hit a wall.  Talbot uses a vise to close the slit; I don't have one, so I tried for about 15 minutes to close it with a large cast iron C-clamp.  The clamp, unfortunately, has way too much play in it - the side of the clamp attached to the screw tends to skew, and it's attached to a ball joint that allows the flat part to slide around the blade.

I got the slit closed maybe a fraction of a millimeter, but this method simply isn't working. I tried closing it using the split tabletop on the workbench and a ratchet clamp, but only succeeded in putting  a dent in the MDF tabletop and breaking the ratchet in the clamp.

I'm going to have to buy a vise to finish the fork blades.  I shouldn't need to mount the vise on anything to get the slit closed, but this is a good excuse to get a workbench to install the vise on.

No pictures yet, but when I get do the other blade I'll document it better.