The North American Handmade Bicycle Show is just around the corner, a true highlight of the year for the builders, suppliers and riders. The pressure has been on to complete booths, products and projects, so the weekend of the 2nd to the 4th of March will be a massive relief and an environment conducive for a party. Paul Brodie will be there, with the reproduction of an 1888 Whippet bicycle he has been revealing step by step to the readers of Cycle EXIF over the last week.
He goes on: “The Whippet rear hub was made of bronze on this original bike, and also had radial spoking, which I did not expect at all. I ordered a short bar of bearing bronze, and took a few cuts. I did make a quick drawing on a piece of cardboard”:
“Here, the shape is being “roughed out”. This is Machinist Talk. Also, if you can use a lathe, but are not too skilled, you’re a ‘rough turner’”:
“The hub shape is finalized, and the thread cut for the freewheel”:
“I took a short piece of 6061 aluminum, and cut an internal thread to go onto the freewheel threads. This will allow me to hold either end of the hub in future operations. Here, the threads are being cut with a very small tap. I start the mill, and switch it off. When the spindle has almost stopped, that’s when I bring the tap down and start the thread. The mill head has been angled to 6 degrees”:
“The first side is done, so a machinist square is used to layout where to start drilling the holes on the other side. You can see the fine red felt pen marks. One side is offset from the other”:
“For each hole, you center drill, tap drill .600″ deep, go half way with a plug tap, then all the way with a bottoming tap. If you break a tap, you will never get it out, it’s too small. Best just to take a break and order more bronze… It’s a very time consuming process, and with 2 hubs there are 64 threads to tap”:
“Cutting off the excess bronze in the vertical bandsaw”:
“The 6061 aluminum is now holding the hub in the 3 jaw, and a small carbide tool bores the hub for a sealed bearing. The dial indicator is my ‘stop’”:
“The finished hub looks a little lonely without a freewheel”:
“How exactly do you put a BMX micro drive freewheel into a custom block chain sprocket?”:
“First step is to bore it out”:
“Second step: the freewheel was 14 teeth, so I cut 14 notches using a 1/4″ carbide endmill in the rotary table. If I remember correctly, that’s one cut every 25.714 degrees…”:
“I belt sanded down the sprocket teeth a bit, and then I had a good fit”:
“I made a little stainless steel cover, held on with 5 Allen screws. This will secure the freewheel and sprocket. You can’t space 5 screws equally around a 14T sprocket, in case you wondered”:
“Mounted in the rear stays of the Whippet frame”:
“Felt good to finally get the wheels built. My list is slowly getting shorter, as NAHBS gets closer…”:
In an email last night, Paul quietly let slip that the finished Whippet will actually be FOR SALE at the Show, but I will assume that any of the world’s bicycle museums, collectors or eccentric millionaires will realize the worth of this creation and snap it up before I can write out a check.
Paul teaches Framebuilding 101 at the University of the Fraser Valley. For more information on the course, where you can learn how to build a steel framed bicycle using Paul’s original jigs that have built over 4000 frames, visit the UFV website.