Invent Design Make

We are getting there now, and have a working up-down saw type device – I couldn’t resist testing it on cardboard at this point.  We want the saw to cut on the up stroke, so that the motor is pulling the blade rather than pushing it.  If it were pushing it might well bend up and do other unpredictable things. So we need to arrange the teeth as shown, the pointy cutty vicious looking things directed upward.  Now this is all well and good, but it does present two slightly awkward issues: 

1. Every up stroke of the blade will try and lift the work piece up off the flat work surface. One could maintain extreme vigilance and hold it down at all times, but that would quite frustrating. What we need to do is bring the existing presser foot into operation.

2. As with all sawing there is the problem of splintering edges where the cutting teeth of the blade exit the wood, sometimes tearing fibres loose, making a rough splintered edge.  This can be minimised by using a sharp blade, but we can do better and eliminate this almost all together, again, by using a modified version of the presser foot.

Using some transparent polycarbonate (the kind of material they use for safety goggles), we can fabricate a functional splinter guard.  Any of you that read my blog will know the ironic string of failures I had trying to get this right… I will show the way that seemed to finally work.

Basically this involves cutting into a piece of the plastic with the scroll saw. This piece of plasti will become the ‘hold-down splinter guard’, and the slot we cut  in it will be exactly the correct size for the blade.  See the photos for a further description of what to do.  This splinter guard is kinda optional, you might find the presser foot on its own, with a sharp blade is enough.

Go on, treat yourself, have a test on some cardboard… Take care to hold it down well though.

Scavenged, grubby goggles. These look like a fine donor. Don’t cut up your nice ones… you’ll need them when creating your master-works later!

Squeeze out the polycarbonate sheet, and size up. The material cuts with tinsnips, but if you are careful to hold it down super tight, you can cut it with your up and coming scroll saw.

Once you have cut a section out, you are going to cut a straight slot down the middle, to about half way along. Be very careful to hold it down tightly or the saw will lift it off the cutting table. Now turn off the saw and retract the plastic a smidgen. Then keep it in place.

Lining everything up, you want to attach the presser foot, to the new splinter guard. A few dabs of super glue do the trick. I had fun trying all sorts of stupid other ways.

Fine crisp edges.