Ok so not unplugged, but it’s made of wood and shop built by me. It was built about five years ago and is still going strong.
I always planned on remaking it using the lessons learned from this build, but it works fine so I never got around to it.
I posted the original build on Lumberjocks.com. You can see that post here. It’s had over 11000 views and generated a few requests for more information over the years. I’ve recently had more questions, so I’ve stripped it down and taken some detailed pictures of how it works to help explain it.
This is what it originally looked like. Since I built it its had a coat of paint and varnish, but it’s unchanged mechanically.
It’s made from scraps of Ash and plywood I had in the wood shop and about £20 worth of skateboard bearings and coach bolts.
As I don’t use a scroll saw often enough to warrant buying one, I decided to utilise my lathe to power a home made one.
A lathe is a great source of power in the workshop, it’s got a powerful motor and is designed to run for long periods with consistent speed. It’s also quiet, so no banshee screaming when you use it!
All you need to do is figure out how to transfer the rotation into linear motion effectively.
I took inspiration from this post on Lumberjocks and my basic understanding of engines and created a crank shaft that would power the scroll saw.
The lathe chuck holds a round wooden disc with a bolt inserted in the disc slightly off center to form a rudimentary crank. This has a short arm that connects to the bottom part of the saw frame. Note: Each link in the saw is press fitted with a skateboard bearing.
Above is the lower arm assembly with the lathe drive crank. As this was built from scratch with no drawings I had to have several attempts to get the off center bolt in the right place. I settled on a 5mm offset giving me about 25mm of saw stroke at the blade.
Above is the assembly fitted in the chuck.
Vertical alignment is key here, I made sure the saw can slide laterally on the lathe bed so the drive disc fits in the chuck without any sideways tension. If its not aligned vertically you will generate lateral shake in the saw.
Once aligned I tighten the base clamp as shown below.
Lower Arm Assembly
The lower arm is 17 inches long and 1 inch wide. The blade holder is fitted at one end, the crank arm attaches at bearing fitted about 1/3 of the way down and a pivot bearing is fitted about 3/4 of the way along. At the rear is the linkage to the upper arm and the blade tensioner.
General layout of the lower arm below
Note I’ve used two bearings side by side in most cases here. This kept things rigid. You could use one though.
Linkage and blade tensioner
This is a key part of the saw. The rear linkage transfers power from the lower to the upper arm. Both have to work in sync. You also need to ensure you have tension on your saw blade and this fulfills that role too.
The linkage has two links in it, all with double bearings, however you could do it with one linkage.
At the top is the blade tensioner. This took a while to get right. If I was to rebuild this it would have a bearing at the top too and I’d dispense with one below it.
Note: I’ve trimmed this shorter than it was originally. I moved the lathe and it’s new position was closer to the workshop wall, which meant the arm fouled against the wall.
Lower arm guides
In order to keep the lower arm in perfect vertical alignment I fitted two bearings on a support bracket on either side of the arm. These are the lower ones in the shot below. The upper ones are blade guides. If you are familiar with bandsaw blade guides, then you’ll see where I got the idea for these from!
You can also see the blade holder in detail here. It’s a hardware store bracket with a slot cut to hold the blade.
This is the same size as the lower arm and it’s mounted on double bearings at the rear and has the upper blade holder fitted on the front. In the shot below you can see I am using a spanner to adjust blade tension.
The cutting table is a thin piece of plywood with a hole in for the blade.
You can see more detail of that in the videos below.
In operation this is a quiet saw when compared to a commercial one.
Here is the saw in use :
I’m more than willing to share more details about this scroll saw if you need them. I just don’t have detailed plans or drawings for it.
If I do remake it the only things I would change are:
Make the slots in the blade holder narrower to stop the blade moving. It’s not a huge issue at the moment but it could be better.
I would also make the top arm slightly longer than the bottom. This is to ensure the blade is always leaning into the work on both the up and downward stroke.