Thoughts on Signed Distance Functions for CAD
Fri 7 March 2025
I've got into signed
distance functions recently and am interested in their application
to CAD software. Read more
How to abort calculations in OpenCascade
Thu 27 February 2025
Hands up, how many times has this happened to you? There you are, minding your own business,
designing some sick new parts for your 3d-printed hoverbike, you go to make a PolarPattern of 3 or 4 sweet ridges just to really finish it off
and BOOM your hand slips and you accidentally ask for 3 million.
FreeCAD hangs for the rest of the week and you feel your will to live slipping away. If only you could cancel the task and change 3 million to a smaller number! Read more
I'm building a fixed-gantry CNC machine out of composite kitchen worktop material
Sun 21 April 2024
Composite kitchen worktop material is a good choice for a CNC machine because it is very heavy and very flat.
It is a bad choice because it is quite soft. But mainly it is a very good choice because I already had the material and
it is therefore free. Read more
FreeCAD vs SolveSpace
Tue 24 May 2022
I've been a happy FreeCAD user for about 5 years. Occasionally I
read comments on Hacker News from people who are raving about SolveSpace.
I have briefly looked at SolveSpace before and didn't really get it. It seemed so obviously inferior as not to
be worth looking at. I assumed that all the SolveSpace users were just not willing to put in the work to
understand FreeCAD, and they only thought SolveSpace was good because they didn't know how good FreeCAD is.
But it occurred to me that I was doing exactly the same thing to SolveSpace: I assumed it was worse than
FreeCAD mainly because I couldn't be bothered to put in the work to understand it.
So this evening I finally gave it a proper try and noted down my observations. Read more
Meshmill: open source 3D CAM
Tue 3 May 2022
For the last couple of weeks I've been working on Meshmill.
It's a new 3D CAM program for Linux. Read more
Bubble packing puzzle
Tue 23 November 2021
I designed a new puzzle this morning, it's a relatively simple packing puzzle where you have to fit
21 circle-ish pieces into a case. Read more
CNC toolpath generation from heightmaps
Sat 24 October 2020
I've been struggling with generating complex toolpaths in FreeCAD and thought that an easy approach would be to render a heightmap of the
part, and then generating a toolpath from that should be easy.
I understand that this is already a recognised technique, although I could not find an open source tool that
would do it for me. Most of the heightmap-related stuff I found on DuckDuckGo was to do with auto-levelling the bed.
And, anyway, it's a relatively simple idea and a fun challenge, so I did it myself. Read more
First steps into CNC machining
Mon 5 October 2020
I have bought a "6040" CNC router, and have been getting to grips with how to use it.
This journey started with converting the machine to Grbl because I'm not interested in running
proprietary software. Once Grbl was all working correctly, I clamped a small piece of plywood to the bed, fitted a 2mm end mill and made my first cuts, manually
"jogging" the tool position using the buttons in the UGS interface. Read more
Chassis Design with Finite Element Analysis in FreeCAD
Tue 7 January 2020
Finite Element Analysis is a way to calculate the stresses and strains on an
object in various load conditions. The object is modelled as a series of "finite elements" (in our case triangles), and then we specify the locations
of points that can't move (fixed points), and the locations, magnitudes, and directions of forces that are present. Read more
Towards a Better Pythagorean Cup
Fri 4 January 2019
There was an article on Hacker News the other day by David Richeson entitled
Make Your Own Pythagorean Cup.
A Pythagorean cup is a cup with a built-in siphon. Supposedly invented by Pythagoras, the cup functions just
like an ordinary cup as long as it is only filled to a certain level. If anyone gets greedy and tries to take
too much wine, the level rises above the top of the siphon, which causes the siphon to self-start, and the
greedy person is punished by having the entire contents of the cup dumped into their lap. Read more
I designed a trick chess piece with hidden compartments
Sun 4 February 2018
It's quite easy to model a traditional chess piece (apart from a knight) using CAD software. You basically just have to draw a sketch of the outline and revolve
it around its centre. I modelled, and 3d printed, a Queen that includes some hidden compartments for storing small bits of paper, e.g. containing passwords or Bitcoin
keys. Read more
I bought an extremely cheap 3d printer and it's great
Wed 25 January 2017
I had a look on eBay last week to see what sort of price 3d printers are going for
these days, and was surprised to find some on offer for £150. At that price it's
obviously not going to be very good, but should be fun anyway. Read more