Darkly Labs Community

Circular slide rule

Evening all


After a poor start due to PEBHK on my part I am making progress on this project. It is a gift for an engineer friend of mine and when finished will include a custom machined and engrave box.

First trials herewith.

This card BTW is 300GSM Colorline White from Eckersley’s the art suppliers. They have store all over Australia and mail order as well. I am very impressed by how the card takes the engraving particularly on something as fine as this.

Engraving was one pass, 1000mm/minute at 100% power on the orignal model Emblaser. Cutouts were 100mm/minute, this is tough card.

I will post updates as it progresses



Love your work DC

Thanks Daryl, I was actually inspired to make this based on your Fives calculator.

I love slide rules and have a couple of 1970’s German ones. Interestingly enough it seems that pilots still have to learn a variant of these to do navigation. Nice thing about a slide rule is the batteries last forever…


Can anyone point me at a source of 2mm or 3mm orange transparent plastic that the Emblaser will cut here in Melbourne ?



Glad you were inspired by my Circle of Fifths Calc.  Yes you are correct…the pilot calc is colloquially known as the Whizz Wheel.  Used to pass the cross country navigation test and then discarded forever.  I remember when calculators were introduced at school but we weren’t allowed to use them in exams.  Could never figure this out.  Pardon the pun!


I found some orange acrylic on good old Ebay.

The Whizz Wheel

Course 180, crosswind 075, indicated air speed 220, destination bearing 227, groundspeed …
Whoops spending too much time with my calculator gizmo and did a controlled descent into terrain.

Anyway I digress.
Do you have an eBay link you can share, I am getting on UK or US links for translucent orange.





Sent you an email link.  Could not find the original supplier but this one was cheaper.  It is orange (Not sure if that’s what you wanted) but they mare have other stock if you look in their store.

Thank for digging that up but I had a good score this morning from a mob called Plastics for Industry in Keysborough (VIC)

1600mm x 1220mm x 3mm Type 994


$88 including GST for the entire sheet, that works out to $45 per square meter which is a bargain as far as I am concerned

My 3w Emblaser wont cut it but it sure engraves well, see below
250mm / minute at 100%, single pass
Then dug out the shoe cleaning kit and rubbed Kiwi Black shoe polish into the engraving, left to dry for an hour and polished the surface.

The lines are much better defined than they look in this photo.

Next development will be to laser the base dial onto a light background then engrave a revered perspex dial so the engraving is underneath eliminating as much parallax as possible in reading the dial

Good work.