Marking the hole positions
Note: If you are making a new handle for the Spear and Jackson 9500R read the following:
This is the time to put the saw blade on top of the handle and mark precisely where the holes need to be drilled. The design has these points marked on it, but they might vary slightly in position for your saw blade.
If you are making your own saw, you can do this the other way around and first drill the holes in the handle in a position where they look pleasing to the eye. Then proceed to mark the location of the holes onto the blade when it is positioned in the slot of the handle.
Drilling the Holes for the Nuts and Bolts
How to approach drilling the holes depends on what nuts and bolts you will use for your saw. There are a few places online where you can buy them, you could make some yourself on the lathe, or you can reuse nuts and bolts from an old saw.
When it comes to drilling holes, there are some general strategies that will help to get fitting holes for the nuts and bolts you will use.
What to Aim for when Drilling the Holes
A.To be able to fit the nuts and bolts properly and flush with the side of the handle, the center of the hole needs to be in the same place on both sides of the handle. A good way to achieve this is to first make sure the two sides of the handle are indeed parallel. Secondly to use a drill press or any drill guide that makes sure a (pilot) drill goes in at right angles to the surface.
As a pilot a wood drill bit with brad point will help avoid wandering during the drilling. Keeping the length of the drill bit extending from the chuck short will also help if you are using a thin drill.
Alternatively, it is also an option to use split nuts with oversize bolt heads and sand or file them flush after installation. This is the historical way split nuts were installed on saws and this needs much less accuracy.
B. The parts of the holes need to be fairly concentric when there are stepped diameters for the head and the shank. Most of this is achievable by planning the order of different drills to use. When the head of the bolt and part of the nut need counterbores, you can ensure concentricity by first using a pilot drill.
When using Forstner bits and Brad point drills, a small pilot hole that accommodates multiple size drills can be helpful. The sequence of drills could be; 1,5mm pilot hole, head diameter Forstner drill, thicker part of the nut diameter, shank diameter Brad point drill.
Alternatively it also works to use the small 2mm drill after the Forstner and big Brad point to get to the other side of the handle.
C. The hole for the shank of the bolt needs to be slightly oversize for the bolt to go in easily. A little filing with a round file or a tapered reamer will make it easier for the shank of the bolt to go through.
D. The sunken parts which fit the heads need to be drilled to the right depth. With the drill press it’s possible to use its depth stop to drill to the right depth for the heads of the nuts and bolts to end up flush with the surface. Drill a hole on a test piece or cut off from the handle blank with the same thickness to set the depth on the drill press.
It’s possible to make depth stops from scrap wood and drill collars if you have a drill press (or have a friend who has one) after which you can use the depth stop itself to drill at right angles with a hand drill.
It’s also possible to drill to depth by eye and use calipers to measure the depth. a mark on the drill bit at the right depth can help. There is one catch (!) its easy to mar the edge of the hole if you have to reinsert the drill bit to drill deeper. On the other hand, a hole that is too deep can be filled with some sawdust to bring it to the right depth.
E. Many bolts have a square part right under the head to stop them from spinning in the hole. A square part will often need to be cut with a small width chisel to accommodate a good fit.