The first project began after some cheap plastic mirror brackets broke. The old ones looked like metal, but they were actually plastic with a metallic paint on them. The old brackets were fairly “agricultural” in appearance, but I wanted the new brackets to look like they were professionally made.

The first project: Truck mirror brackets

^Grae-Tech 

I had to re design the brackets to allow for stronger wind loading and more vibration. The material of choice was aluminium because it was readily available and fairly cheap. I used stainless steel fasteners to prevent rust.

 

Cad drawings (Computer Aided Design.)

I use siemens solid edge for all of my 2D cad drawing, I personally find it easy to use, I can now make up a cad design like this in about half an hour after some practice.

 

I use several different “layers” and assign the different features of the part to a new layer. Later on when in the CAM package it is a lot easier to assign a tool and cutting instructions to everything in one layer, and different cutting tools and feed rates etc to different layers.

 

For example, The first layer is the part outline. This will be cut with a slot drill in a series of several passes each cutting deeper into the 25mm thick slab than the one before it. Another layer may be all drilled holes, That layer will have a different cutting tool and feed rate. 

 

Another layer is the inside pocket for the oval shaped part– which is an adjustment point for the mirrors so that they can be made to hang vertically on the truck door.

 

           Importing the design into CAM (Computer Aided Manufacturing.)

 

I had to make blanks before I could turn each blank into a swing bracket. The blanks were another design altogether including two mounting holes so that I could fix them to a jig for machining. Then, each blank could be cut to make the above part. I used a cold saw to cut the blanks from the bar, and proceeded to put each one onto a jig, which was mounted in the mill vice.

 

 

 

Cutting the outline

I used a 12mm slot drill to take four passes of 6.5mm depth per pass. The feed rate was 160mm per minute  with a spindle speed of 1600 RPM. I left a finish amount of 0.75mm

 

Finishing pass

The second operation was the finishing pass at the full depth of 25mm, feed rate of 60 mm/minute to make a very fine surface finish. 

Base brackets:

I used a similar approach to make the base brackets, although the machining required a lot more operations. I designed the base part, cut several from stock and then fixed each of the blanks to a jig for finishing.

CAD design of base brackets

CAM tool paths for base brackets

Finished two part truck mirror bracket