One of the posts in my saw build along series showed how I squeeze the slot closed so that the blade is held in the back by friction. Although this works well for me, it requires the use of a hydraulic press that is not likely to be found in most workshops. The method shown below requires nothing more than an ordinary machinist’s or mechanic’s vise and two short pieces of aluminum angle.
Before squeezing the slot closed, I now chamfer the edges of the blade slot slightly. I use an old needle file to cut the chamfer, but any file with a sharp corner will work. This chamfer, along with the roundover on the edge of the blade, makes it easier to install the blade into the back.
To squeeze the slot, I line the jaws of the vise with aluminum angle to prevent the steel jaws from marring the brass. I had some 3/4″ x 3/4″ x 1/8″ angle laying around, but the actual size is not too important.
To concentrate the force on a shorter section of the back, I cut one of the pieces to 1″, which means that you will need to squeeze the blade in 1″ increments along its length. I also trimmed one of the legs to a 3/8″ width so that I could keep the force at the edge of the back (first picture below).
There are a few things to keep in mind when doing this:
- The force required to close the slot in a brass back is much greater than that for a bronze back.
- The slots in brass backs will spring back open when the vise is opened, and may require multiple squeezes before it takes a set.
- If you are unable to generate enough force to close the slot up, try a bigger vise. Or, cut the angle shorter; by halving the length of the aluminum angle, you effectively double the force applied to the back.
- A set of feeler gauges is invaluable in measuring how wide the slot is. These have many uses around the shop, and can be had for short money at most auto parts or hardware store.
- Aim for a slot that is about 0.002″ – 0.009″ narrower than the blade (the thicker the blade, the more you can close the slot up without getting in trouble). This difference generates enough friction to securely hold the blade without making it overly difficult to install the blade. For the math averse, I have included a short table at the end showing the slot widths that I use for various blades.
- Above all, take it slowly. It is far, far easier to squeeze the
bladeback (Corrected 28 Feb 2014. Does no one proofread these entries? – Ed.) a little more than it is to try installing a blade into a slot that is mashed shut.