CNC routed cat tower

Andrea asked me to make a cat tower as a gift for her niece.

I might have got a bit carried away.

Version one failed user acceptance testing. This is version two.

I wanted this with no screws at all, just wood that slotted together and locked itself in place. I also wanted it to be easy and obvious to assemble correctly and impossible to assemble wrong. That part turned out ok.


Packs down for easy transport.

The cut-outs were generated using the Ready reaction-diffusion simulator and the Grey-Scott algorithm.


Ready has some weird glitches that left me scratching my head for a while but I worked out a suitable tool-path. Start with the component in Fusion 360.

Screenshot that and turn it into a bitmap mask.

Import the mask into Ready and run the simulation and tweak the parameters until it looks ok.

Take a screenshot into Gimp and simplify.

Take that image into Inkscape and trace bitmap to get paths. Save those paths as an SGV.

Insert that SVG into a sketch in Fusion 360.

Extrude to cut the component.

And then repeat for different parts with different parameters.



Andrea finished the raw ply with linseed oil to avoid anything toxic and old carpet cut out and stapled on. It was cut in cat shapes, in case anyone hasn’t worked out the theme yet.

Smoofy approves.

Plywood gifts for Chur

Chur is a sound system/theme camp/workshop centre/temporary community/group of awesomely inspiring people.

Designs by Simon Crook, routing by the Vertigotech router in my basement.






Allegedly, Islamic artists deliberately introduce mistakes into their art, as only God is perfect. Well, I screwed this one up without such an intention. Spot the bit I forgot to cut out.

Router-made signs for KnowYourStuffNZ, Kakariki and Sanctuary

I’ve been making a heap of signs with the router.

Turns out my favourite technique is to mask off, cut the signage through the mask, and then spray the cut areas. This gives coloured inlaid lettering which is resistant to getting scratched when bouncing around in the back of the ute on the way to festivals.

The best guide to this technique that I’ve found comes from totrand on Youtube:

For a mask I’ve been using the self adhesive film from Bunnings. I’ve been using spray on shellac to help the mask stick to the ply and to stop paint from bleeding from the cut areas along the grain.

The tool for most of these was a 1/8 inch down cutter. I had got up to 700 metres with the first one with no visible wear before I rammed it into a clamp and snapped it off.

KnowYourStuffNZ can’t have a sign that says “test your drugs”, so I made a heap of alternatives.

They ended up all over the place.


And some art, in the style of Gordon Walters.

One for the Sanctuary, with lettering from Melissa Mepham. This one I did in melamine-coated chipboard. This gave great sharp edges that looked good in sunshine. I thought it might have problems with humidity from being outside. Turns out it cracked horribly. Oops. Won’t do that again.

And some for Kakariki Brewing Company at Beers at the Basin.

…and now I’ve a few more to do.

SciBlogs articles digging into the how and why of pill testing

With KnowYourStuffNZ, I’m right in the middle of the summer season of pill testing at festivals. We’ve been getting lots of press about the results, so now’s a good time for some more in depth articles. I wrote these two for SciBlogs.

First, the technology of testing. Summary: reagents are good, IR spectroscopy is great, and it’s all very much better than taking drugs that haven’t been tested.

Sciblogs – Recreational drugs and the technology of pill testing

Secondly, why does pill testing change people’s behaviour and lead to safer decisions? We don’t judge, our clients trust us, the testing service is a gift, our clients are involved in the testing, and the results are immediate. That’s why our clients listen to us.

Sciblogs – The psychology of pill testing

Enclosure for a Vertigotech M2 CNC router – attempt 2

Made from the shipping crate and bits I had lying around, the first enclosure for the router did a good job of keeping down the noise and dust from the router. It was, however, too small and didn’t allow the router to use the full range of movement possible before the router started banging against the inside of the cabinet.

The second attempt works much better – 18 mm white melamine from Cut to Size in Lyall Bay joined with aluminium L section from Ullrich in Petone. Size internally is 1564 wide, 864 deep, and 582 high.

Shared Fusion 360 design, if you need:



Cutting the window rebates was fun. The panel wouldn’t fit into the router, of course, so each end of the rebate on each side had to be cut with the panel sticking off the bed of the router. Four cuts, four setups, all to be lined up, and then the cut ends were joined by some careful work with a circular saw.

Turned out ok though, I just hope the glue I used to hold in the acrylic windows holds in the acrylic windows.


Overdoing it – drawers for the router bench

Routers need bits, not just cutting bits, but clamps, collets, spanners, t-bolts, feeler gauges, laptop, and other random crap. So I made some drawers for the crap, to fit under the router bench. This was a chance to explore relief carving, coz I’ve lots more of this to do.

Original image from Ashlyn’s dirty cup pour:

Relief carved drawer fronts:

The drawers are 1300 wide and the router will only do 1200, so the three long pieces were made up with lapped dovetail interlocking joints taken from Jochen Gross’ Fifty Digital Joints.

The other joints were simple finger tenons with dogbones for relief at the corners. I varied these enough so that all the pieces could only be assembled in the correct way. I tried a few blind mortises, but the outside of this piece is pretty hidden, so they weren’t really needed.

Tolerances. *humpf*

The goal was to have all of these pieces just push together. Testing finger joints on small pieces suggested that cutting each piece 0.2 mm undersize would do this. However, oops, small pieces are not large pieces, nor are they pieces made up of two bits of wood joined together. So yeah, there was lots of filing to make everything fit. I’d suggest 0.2 mm for small pieces, add an extra 0.1 mm for large pieces, an extra 0.1 mm for joined pieces, and an extra 0.1 mm where pieces are joining in three planes. Live and learn.

But got there in the end.

I was going to just glue these joints, but bottled it and put some screws in, just in case. It’s probably massively over-built.

I splashed out the NZ$ 200 on PhotoVCarve to turn images into toolpaths. Fusion 360 with the Image2Surface plugin will do this for free, but it’s really struggling – it can take over an hour to process. PhotoVCarve does it in seconds. Total carving time was about 13 hours, with 0.4 mm step-over and a 1/4 inch ball-nose carbide bit. The surface finish needed very mild touch-up with fine sand paper on the steepest relief, but overall, this is straight from the machine with nothing more than linseed-based priming oil.

Turned out all right in the end.

Vertigotech router – Controlling noise and dust

Routers are painfully noisy and throw dust everywhere. If I wanted that, I’d go to Burning Man (again). So:

Step 1 – Dust Shoe

Vertigo do a dust shoe to stop chips flying everywhere. They were kind enough to give this to me for free, as the magnets aren’t perfectly aligned, but it still grips well enough.

Step 2 – Dust Extraction

Dust now gets pulled into a Triton dust collector bucket by an old Dyson vacuum.

This does a reasonable job, although fitting the hose into the dust shoe requires some surgery – the shoe has to be split into two parts so the hose can feed through the hole and then be clamped in place. The shoe is acrylic, so this isn’t hard.

The hoses do pop off the connectors too easily, but it takes twenty-odd litres of dust and chips that are now not spread throughout the workshop.

Step 3 – A Cabinet

It’s still loud, so I used melamine from the shipping box and some random ply to build an enclosure. Long hinge and a wide opening, spaced double layer of acrylic for a window, big handle for the opening lid, and a port for the dust hose. There’s an air filter to let air in when the vacuum pulls it out, but given that the box isn’t that well sealed, I’m not sure this is really needed

Much quieter and the dust is under control.

Best investment was $40 on an LED strip inside the box, for excellent work lighting.

Step 4 – Spoil Board

And a thick ply board to protect the router bed from the inevitable over-cuts, with slots for clamp bolts and shallow marks for aligning stock.

Step 5 – Route ALL the things

Design from Nathan McIntyre.

How easy is it to copy a physical object? Very easy (in this special case).

The Old Government Buildings in Wellington is one of the largest wooden buildings in the world. I’ve walked past it on a regular basis for fifteen years but it wasn’t until this morning that I noticed the beautiful cast iron grills over the ventilation holes to the sub-floor. So I thought – I want that.

You can just see one of the grills, at the bottom right half-hidden by trees.

Copying the design took nothing more than a quick photo, then tweaking the image in Gimp, getting Inkscape to trace the outline and make a vector file, import that file into Fusion 360 and make a solid body, and then messing about for too long making tool paths. Total time from uploading the picture to starting the router was an hour and I could have done it in half that if I hadn’t been messing about.

Cutting this out took four hours, but I expect I could get that down to under two with more CAM experience (I’m still a real novice at that part of the process). Turned out not too shabby.

So how easy is it to wander along, see something you like, and copy it? Pretty trivial, provided that what you want is a 2D shape that can be cut on the machine you have in your workshop and you’re not concerned with making it the same size.

Regarding intellectual property here – NZ allows architectural works to be copyright, which includes the exclusive right to copy that work. This building was originally built for the NZ civil service, so it either falls under Crown copyright or the copyright of the architect William Clayton. However, NZ copyright is only fifty years and this is from 1876, so I think anyone can copy this now.

New workshop addition – CNC router

I bought a CNC router, a Vertigo Tech M2 from down in Westport. Lead screws, 1200×600 bed, and a frame of pretty chunky aluminium extrusion. I thought about building one, but I’d rather buy it, plug it in, have it work, and put my time into building things with it.

Design shared from Fusion 360: Router Test Box 2

What I’ve learnt so far:

  • Plywood rules the world.
  • Up-cut bits give a really fluffy top edge. Straight bits are better, but compression bits ordered. Getting perfect edges on cuts isn’t easy.
  • Making it quieter is needed if I’m going to run this at night in the suburbs, so cabinet being designed.
  • Dust and chips go everywhere, so dust shoe on its way to me and the cabinet will help.
  • Fusion 360’s integrated design (CAD) and manufacturing (CAM) is just plain awesome. Being able to draw something up, have it work out toolpaths, and then simulate the cutting used to be $100k-worth of software. Now it’s free.
  • CAM is at least as hard as CAD, if you want to do it right.
  • Cutting to just above the base board (onion skins) results in lots of time breaking out the uncut material and cleaning edges. A proper spoil board is needed so I can cut all the way through the ply to avoid this.
  • Fusion 360 is great for generic CAD/CAM, but isn’t the best for a router. Nesting and layout you have to do manually and it barely does tabs for part holding (only for 2D contour toolpaths). It’s not VCarve Pro, but it’s also not NZ$1000.
  • The machine will cut big chips with lots of noise or fine shavings with lots of dust. Finding a happy medium is going to take a bit of tweaking.
  • If you cut interlocking ply parts 0.2 mm undersize, then all the pieces will slide together and hold without glue. If you cut at 0.1 mm oversize, you have to hammer the parts together. If you cut at 0.3 mm undersize, it all wobbles.
  • There’s a heap of fancy joints you could do, but finger tenons are simple, easy to draw, easy to cut, self-aligning, can be hidden, and are strong enough with glue.
  • T-track bolts need to be just the right size or they twist and stick.
  • If you are drawing finger tenons, then you need to relieve the sharp internal corners. Casey Crogers’ dogbone plugin draws these automatically and makes this much faster.
  • And if you want to do Voronoi patterns, coz you have a cnc router and you can, then Hans Kellner’s Voronoi sketch generator does the job.

Please ignore the plunge marks:

Tweaking feeds and speeds and checking accuracy like an old-school metal machinist:

KnowYourStuffNZ goes public

We’re going public today with KnowYourStuffNZ and the drug checking work that Wendy has led at festivals this summer.

It’s a Wendy on TV:


NZ’s PM agrees that drug checking at festivals is a good idea – ‘People can see what they’re taking is dangerous’ – legal festival drug testing could be a good idea, says PM Bill English
TV1 – Ryan Boswell has an exclusive story about a new tool that tells drug users what is really in their pill or powder, then an interview with Associate Health Minister Peter Dunne – does the drug testing kit win his support?, and then the discussion The panel on the drug testing kit
NZ Herald & Otago Daily Times – Covert drug testing reveals many Kiwi festival-goers consuming dodgy drugs
Russell Brown at Public Address – Know Your Stuff: getting real about drug-checking
NewsHub – Third of recreational drugs aren’t what buyers think they are
Radio NZ – Festival drug testing results prompt calls for law change
Probably the best overall summary comes from Russell Brown at Matters of Substance – the NSZ Drug Foundation journal – Taking a reading of the pills


If you want to help… our PledgeMe for a new FT-IR spectrometer: More free drug checking at NZ festivals

And you’ll be seeing us at more festivals next summer and possibly before then as well.

A living roof after five years

In 2010/11, we planted out the first living roof on a home in Wellington. It’s been just fine.

The initial plants were a mix of succulents, seddums, and native ground cover. The roof has enough variation of sun, wind, and shade that some did well in areas, some in others, and nothing died out. Since then, koromiko has self-seeded and grown up, just as it does all over Wellington. It’s growing so well that we’re trying some other, lower-growing hebes.

A few other native trees have found their way up there on their own, like taupata . We were originally told that the soil depth of only 100 mm was too shallow for tussock, but last winter we planted carex secta, flagellifera, and comans green and that’s doing just fine. There’ll be more this winter, though not the secta as that’s too sharp to weed around.

Maintenance has been weeding and the only real problem plant has been oxalis. The birds ignored the roof for a few years, but have started to tear the soil up to get at ants. We’re just planting hebe and tussock as that’s too large for the birds to damage and they give more variety to the height of the planting. The koromiko needs pruning at knee height – the thin soil means if they get too big they will fall over. And the random lancewood will need to be transplanted off the roof, coz that can grow to fifteen metres tall.





And the firewood shed roof is going great, with the panekenake trying to take over, more carex, and the hen & chicken fern hanging on in the most shaded corner.






My reference run goes from home in Brooklyn, along the road to Kingston, into the Tawatawa reserve and down Wharangi to Carlucci Land, up the Tip Track, along Barking Emu and Car Parks to the wind turbine, down Sawmill and Aston Fitchett and past the war memorial. 15.6 kilometres and I don’t know the height change, coz my phone gets a tad confused and today started 400 metres below sea level, but come on – Tip Track. An “honest altitude change”, to quote the Kennett brothers.

October 2015 with no training – 2.45
November 2016 three months of training – 2.15
Today – 1.55 and made it up the Tip Track without having to walk/sob/vomit

Oh hey look, if you do something regularly, you get better at it.

New workbench

From wood left over from the house build, bolted to wall and floor, and flat and level.

Possibly making the top from three layers of 18 mm ply is overkill. Possibly not.

I made a thing, part 58: a 3D-printed double helix candle holder

A friend lives out in the Sounds, way out beyond where the electricity grid stops, so her lighting is solar and candles. So I made a candle holder as a birthday present.

I’d had something else made in the transparent ColorFabb filament and I liked how it looks with a light behind it, so thought I’d give that a go for a mock-up, before getting the final version printed in porcelain for heat resistance. Oliver Seiler did his usual job of a great print and it turns out that the plastic version is far enough from the flame that it doesn’t heat up at all, so the mock-up became the final thing.

And any excuse to improve my Fusion 360 skills. Turns out F360 isn’t great at drawing helices and what I thought would take five minutes to draw took five minutes to draw, after I’d spent two hours scratching me head and trying a bunch of approaches.

Anyway, here’s the design in Fusion 360 and the printable STL file will be up at Thingiverse tomorrow (new users at Thingiverse get a 24 hour probation period).

What I’d do differently next time:

    Making this smaller would make it cheaper, but then the plastic would be closer to the flame and will get hotter. How close is too close? Given the risk of the plastic creeping, melting, or burning, I’m happy with the size, but I am being fairly conservative.
    The filament is a little stringy, so this print needed a fair bit of manual finishing with all those holes. A less stringy material might work better, but then again, the ColorFabb is PETG and pretty heat resistant. So there’s a trade-off to be made, as ever.

Thoughts on Splore 

  • Everyone was delighted that we were there with Wendy’s project (second pic down).
  • I am amused that my snarky “Giant Scabies” sign is now a thing.
  • It’s a commercial festival, so all the friendly people wanting to start a conversation with you want to sell you something. I rapidly stopped seeing people as people and started seeing them as hindrances. Commerce, man, just say no.
  • Bars with really loud music. No alcohol outside the bars, with fences and security to enforce that. So, beer and shout till I lose my voice, or tea? Tea won.
  • It is a spectacular venue.
  • Except for the rain. Fuck that rain. Set up in rain, packed down in rain, and mostly rain between the two. Hence ankle deep mud everywhere.
  • 2017 Splore business idea – stall outside gate selling gumboots. Would make millions. Just need to go back in time to before the festival.
  • Better time machine idea – go back to before the festival, stay home by the fire instead.
  • Worked too hard, failed to party. Again. Equally failed to spent much time with lots of my friends there, but that’s cos we were all mostly there to work.
  • The ute got blocked in by bad parking, yuppie SUVs without 4wd, and soaked ground turning into bog. I wasn’t delighted. Kiwiburn has better parking organisation.
  • The stuck cars resulted in people just standing around, not self-organising, and waiting for the festival to fix it, where “festival” meant one sleep-deprived secuirty guy and four 4x4s to unstick vehicles for 10,000 people. We got out by ourselves, where “we” means several vehicles and the people with those vehicles. Literally all it took was  Wendy and myself just walking up to people and saying, hey, why don’t we try just pushing? Burners are better at seeing a problem and just fixing it.