Fibonacci gauges #2: rounding jig and a near disaster...


This is part 2 in a 6 part series: Fibonacci gauges

Fibonacci gauges
rounding jig and a near disaster…

Hi again Craftisan’s.

In the last part the measures, cuts and holes were made to the gauge arms, here we start by making a wee jig, that can make the ends round on the sander.

A piece of MDF, one gauge arm are put on the edge and with a drill bit of the size of the holes, a hole are made into the MDF, almost through.

We got a hole!!!

Now you can put the same drill bit into the gauge arm and it will be a swivel point.

On the table saw one arm is shortened a wee bit, so I don’t have to sand too much.

The MDF is put up to the sander, not touching it, just a hair away – or two hairs if you like, smiles.
You can do this trick at any sander, even a hand sander, that you fix in a base, or totally low-tech, sandpaper on a piece of wood.

Put the drill bit through the arm and into the MDF.

Turn on the sander and turn the gauge arm slowly half a circle.

We got a perfect round end.
(With a little burn…).

With this one made, mark where the ends should be cut on the table saw.

But let’s take a detour first…
I were not happy with the burn, so I decided to improve the circle jig.
Here making a runner on the table saw.

That fit into the miter slot on the sander.
On this picture, you can see how it was just attached with two clamps at this moment.

Super glue on the runner.

Under the MDF and hardener sprayed on.

Some more of this hardener.
(Think it has a different name…).

Then a few brad nails, just to be sure.

We got an updated jig.

Gauge arm in place, disc sander powered up.

And while turning the arm, also moving the jig sideways, like this there will be less burn, but more important the sandpaper will not get clogged up and warm.

Remember to clean it from time to time, these sticks are as important as the sandpaper it self.

Hmmmmm, I still got some nasty burn, I were probably too impatient.

But it was easy solved, just by pushing a little bit forward on the jig while doing a second turn, that moves it half a hair closer to the sandpaper.

That’s fine in my book, we have to remember we are making a tool.

Finally the extra hole at the end, for the hanging on the wall can be made, here marking it’s position.

And with a drill bit put through all three of them, they can be clamped up in the drill press vice.

Mark made with an awl.
This awl is my favourite, as it is a gift from an old woodworking friend.

Last holes drilled.

Ends trimmed.

Finally they can be rounded on the jig and the jig can be put aside for next time, something round is needed, or what ever we can make it useful for.

The drill bit I used was a 5 mm, this because the hardware going through the holes are 5 mm, if you choose a different hardware, you need a different hole size.
The reason we talk about this now, is that I will put it into the gauge hole and measure from that point, so I need half the width, as the length is from centre of hole to end of arm.

I’m sorry I did not take a full picture, so you have to imagine the gouge arm, with the drill bit inserted in the other end (on those with two holes in the second hole), the end of folding ruler against the side of the drill bit – then we can mark up the lengths, we have from the drawing in part one, with minimum chance of imprecision.
On the long legs, it was 34 cm, so we have to subtract half the dill bit size, here 0,25 cm.
34 cm – 0,25 cm = 33,75 cm as you see on the folding ruler.


For the short arm it’s 21 cm.
21 cm – 0,25 cm = 20,75 cm as you see on the folding ruler.


Measures taken from drill bit, not the back hole, hope you get it now, otherwise ask.

This was where I discovered that the mahogany had a soft area, where the wood seemed to be weak, so I tried gently to bend it, at this happened…
I did it on purpose, as I don’t want a tool that will break, so I decided to skip the mahogany all together, I should have been more clever in the first place, mahogany is not a tool wood – but we are learning by doing and taking chances.

Back to start…
Cutting a new set in Ash, as I want three sets, now that I have ordered the hardware.
I love Ash by the way, so that’s fine.

After having the new gauge arms made, sawn, drilled, rounded, drilled and so on.
It was time for a light sanding and then we call it a day here.

Next time we will start with trimming, then making the end points in brass and some jigs probably, we never know…

Hope it can be to some inspiration, or perhaps frustration if yours also break…

Best thoughts,


MaFe vintage architect and fanatical rhykenologist.

You are giving the inspiration here.

Main Street to the Mountains