4. Making FOSMC Parts
If you are having Fictiv, or another CNC machine shop manufacture the aluminum parts, the parts should arrive ready to use and only needing minimal preparation. Each part should be thoroughly checked for burrs and sharp edges. The two large side plates will be drilled for use with 10mm engine mount bolts as is common on early 90s era Ducati's.
If you are using a newer engine with 12mm engine mounting bolts you will need to drill out the mounting holes. A slightly oversize hole (12.1~12.5mm) is recommended.
The final task is to place some protective tape on the CNC parts. This will protect the parts from scratches and nicks during the assembly process.
Using the design template as a guide (or from the CAD models) you should estimate the length of each tube, then add 3 to 4 inches extra length to be trimmed later. The FOSMC is designed so that each individual tube will only have one bend.
Using a marking pen, place a mark where the bend will begin along the longest leg of the tube. Add a inch to the length to allow for final trimming later.
The bending techniques describer are using a Pro-Tools 105 manual tube bender. The technique should be similar with other brands of benders.
Note: the manufacturer will suggest permanently mounting the bender to a concrete floor. Some people may not have space for permanent installation or may simply want the convenience of a movable mounting location. A good alternative is to mount the bender stand to a large steel plate. 2’ x 4’ x ½” thick is a good size. This allows the user to stand on the plate while making bends.
Once your bender is set up and ready to use (follow the manufacturer's instructions for setup and use) you will need to zero the degree indicator. This process will need to be done for each size of tubing. With a piece of tubing in place ready to bend, apply ample pressure to the lever so to take out any free play and apply enough pressure to slightly bend the tubing but without permanently bending it. The technical term for this is _elastic deformation_, where the tube bends slightly, but will return to straight when the pressure is taken away. At this point is where you want to set the degree indicator to zero.
If you are using CREW (cold rolled electrically welded) tubing, you will see a thin weld line on the inside of the tubing. When placing CREW tubing in the bender, the weld line should be oriented on the neutral access of the bend. On a Pro-Tools 105 bender the neutral axis is facing either up or down.
The bend mark should align with the edge of the die (beginning of where the bend will begin). Now you are ready to bend the tube. Follow the operating instructions for your specific bender. It is highly suggested that you begin with a scrap piece of tubing to get a feel for the process. Once you are comfortable making bends, you will want to prefect the accuracy and consistency. The most important thing to notice is that you will need to bend the tubing a little farther than the desired angle. This is because the metal will come back slightly after the pressure. This is referred to as spring back. In other words, you will need to bend the tubing a few degree more than desired. Use the design template to double check each bend.
With the design template on a flat surface, use squares and/or 90-degree blocks to compare the bent tubes to the drawing. If a tube is not bent enough, you can carefully put it back into the bender and bend slightly further. Sometimes it is easier to bend a new piece from the beginning and increase the bend amount slightly. For obvious reasons, if a tube is bent too far, it will need to be scrapped. Some trial and error may be required and consistency getting matched bends is the most important goal.