I finished slotting and doming the fork blade and successfully brazed the dropout in to the blade over the weekend. Without actually logging the time, I think I spent about 10 hours over a week and a half sawing, filing, sanding, and filing some more. I hope that I learned enough to cut that time down significantly for the next blade.
Is this worth it? I think it's a good experience, but in the future I'll be going with the socket-style dropouts. For the sake of continuity, I'll probably use slotted rear dropouts, but future frames will be socketed.
It was very encouraging to find out that I can braze with bronze using the hand-held torch. I'm sure that I'm eating up fuel like nobody's business, but in a pinch it's very capable.
Step-by-step walkthrough with photos will be forthcoming once I start the second blade later in the week.
Monday, July 19, 2010
Tuesday, July 13, 2010
More Right Tools
I purchased a "light-duty" vise from the local Ace Hardware store. It weighs about thirty pounds, and I carried it home in a backpack (with an extra canister of MAPP gas) on my Raleigh.
It is also completely covered in grease. I can understand lubricating the moving bits, but this thing looks like it was dropped in a vat before shipping off to the store. The screw, both handles (for the jaw and the rotational lock), jaws, and the flat surface on the anvil were all coated in a thick ooze.
After a quick wipe-down (now I need to go back to Ace and get more rags), I used the vise to pinch the slot on the fork blade closed. It was much easier than trying to use the C-clamp, but I encountered a few issues-
First, the vise is just resting on my workbench. I still need to hold on to it if I need to apply any sort of torquing force to it, such as trying to turn the handle to close the jaws on a stiff piece of steel tubing. This is just going to be unavoidable for now, but I may drill some holes in the workbench to semi-permanently mount the vise. I'll need to be able to remove it if I want to move the workbench around.
Second, the slot did not close evenly. One "tang" on the end of the blade moved much more significantly than the other. I don't think this is a huge deal, but it does mean that the end of the fork blade will likely be a little uneven. When I opened the slot up again with the file, it took more material off of the less pinched side of the slot, so maybe it will even itself up if I try to close it up again. I may be able to adjust the position of the blade in the vise to favor the unbent side of the slot.
Work has become difficult because a) we've hit full-on New England Summer and it's hot as balls and b) there is zero ventilation in the basement. Sweat just pours off me and there's no air circulation to help it evaporate. The file is frequently binding in the slot, making it slow going to get it opened up again.
Slowly but surely, work moves on. I'll take photos of the second blade as I slot it.
It is also completely covered in grease. I can understand lubricating the moving bits, but this thing looks like it was dropped in a vat before shipping off to the store. The screw, both handles (for the jaw and the rotational lock), jaws, and the flat surface on the anvil were all coated in a thick ooze.
After a quick wipe-down (now I need to go back to Ace and get more rags), I used the vise to pinch the slot on the fork blade closed. It was much easier than trying to use the C-clamp, but I encountered a few issues-
First, the vise is just resting on my workbench. I still need to hold on to it if I need to apply any sort of torquing force to it, such as trying to turn the handle to close the jaws on a stiff piece of steel tubing. This is just going to be unavoidable for now, but I may drill some holes in the workbench to semi-permanently mount the vise. I'll need to be able to remove it if I want to move the workbench around.
Second, the slot did not close evenly. One "tang" on the end of the blade moved much more significantly than the other. I don't think this is a huge deal, but it does mean that the end of the fork blade will likely be a little uneven. When I opened the slot up again with the file, it took more material off of the less pinched side of the slot, so maybe it will even itself up if I try to close it up again. I may be able to adjust the position of the blade in the vise to favor the unbent side of the slot.
Work has become difficult because a) we've hit full-on New England Summer and it's hot as balls and b) there is zero ventilation in the basement. Sweat just pours off me and there's no air circulation to help it evaporate. The file is frequently binding in the slot, making it slow going to get it opened up again.
Slowly but surely, work moves on. I'll take photos of the second blade as I slot it.
Wednesday, July 7, 2010
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.
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.
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