A custom, hardtail, V-twin chopper
A chopper is any of a variety of modified motorcycles, but specifically one that has been simplified structurally and mechanically. Compared to a production motorcycle, choppers have fewer mechanical parts. When building yours, you might just want to replace your rear shocks with rigid struts, or you might want to weld in a new rear end. The possibilities are endless.
Deciding What Kind of Bike You Want
This Harley Softail is designed to resemble a hardtail; no shocks are visible in the rear.
The equipment you need to build a chopper depends largely on whether you’re starting from scratch, assembling a bike from a kit, or modifying an existing bike. Building a kit bike requires the least equipment, because all of your parts will come largely pre-assembled. You’ll probably need to weld on some brackets, but you won’t have to shape sheet metal. If you’re modifying an existing bike, you may not need to much equipment–unless you’re exchanging a suspended rear end for a rigid one. But if you’re building a bike from chromoly steel tubing and 18-gauge, cold-rolled sheet steel, you’ll need a whole bunch of equipment. Below you’ll most of the critical tools to aid you in all your fabrication needs.
Getting proficient at TIG welding is very important for successful metal fabrication.
Steel and aluminum require different welding setups. If you’re modifying your frame, you’re dealing with steel. Steel can be welded using oxy-acetaline (gas welding), MIG (automatic, wire-fed, shielded-gas arc welding), or TIG (shielded-gas, electric torch welding). Oxy-acetaline is the most finicky of these three types, and the least advisable when you’re dealing with a frame. MIG welding is the easiest to learn, and though a MIG weld can be very strong, it’s the least aesthetically pleasing; a MIG bead is thick and raised, and looks something like a slug. TIG is the cleanest type of welding, and it produces the prettiest weld if done right. You can weld aluminum with a TIG welder, too, so investing in a good TIG set up and becoming proficient with your machine will pay you the biggest dividends. To prepare your tubes for welding, you will need a tube bender (manual or hydraulic), and a saw or drill press to notch your tubes. It also helps to build a jig to hold the tubes during welding, but you can make a jig out of wood.
Sheet Metalworking Equipment
The compound curves on this gas tank were created by machine, but they could be made by hand with the right tools.
If you’re building a kit bike, you might not need to actually shape sheet metal. But a custom-built gas tank, oil tank, or fender can really set your bike apart from the others parked on the curb. All tanks and fenders start out as flat pieces of metal–steel or aluminum–before someone (or some machine) molds them into compound curves. To cut out your flat stock so that you can work it, you will need snips or a plasma torch. Snips are cheaper, but a plasma torch can cut much thicker material. Next, to achieve a compound curve, you need, at the very least, a polyurethane hammer and a block. A good polyurethane hammer needn’t be heavy; in fact, it should be light with a head-curve radius of an inch and a half. A block is a malleable anvil–usually a leather bag filled with deer shot or similarly sized ball bearings. You want a malleable anvil when manually shaping sheet metal so that you can assign your work a specific shape. To finish work that’s pounded out by hand, you can use an English wheel or a planishing hammer. In fact, you don’t need a block and hammer if you have a planishing hammer. A pneumatic planishing hammer is both a hammer and an adjustable anvil. For serious metalworkers, this tool is a very necessary investment.