Wednesday 11 July 2018
A while ago I showed you how I had upgraded an older workbench for the WPP workshop by cladding it in birch ply. At the time, I wanted to fit bench dogs for workholding but I didn't have the time to do it just then. Now I have finally got around to making a very practical cheap method of installing bench dogs.
I had a length of 20mm diameter aluminium rod, which I bought some time ago. I teamed it with a 20mm diameter '3D' bit and started by cutting the rods to the right length: two to go in the bench top and a shorter one to go in the vice jaw facing, which was quite thick. The ends were filed flat and the edges bevelled.
I marked two lines of dog holes on wide masking tape strips. This avoided drawing on the bench top itself. They are placed 100mm apart and centred across the top so, if it is ever flipped over because the top is too worn, the holes will hopefully still line up. A mains drill and stand proved to be the best method of ensuring perpendicularity. However, I had to kneel on the base of the stand to keep it in place!
The 3D bit wouldn't go quite through the very thick top so I used a 20mm diameter IRWIN bit to follow through, which also helped to ease any tightness when the dogs were fitted.
I decided to use tiny ball catch inserts as the method for holding the dogs so they wouldn't fall through the holes when in use. First, the drilling positions were marked with a punch.
The outer collar receiving hole is drilled using an 8mm diameter drill to match the ball catch. Next, the inner barrel hole is drilled at 6mm diameter. I found it useful to drill a small diameter hole right through as it allowed me to knock the ball catch out if the fit was too tight and therefore needed easing.
The tiny ball catch is ready to be tapped into the hole – the brass collar must sit within the profile of the aluminium. Do not use excessive force as it will damage the brass surround and prevent the ball bearing from sitting properly.