News and Events

Keep up to date with Steve Nurse's designs and 3d printing.

Wednesday, 10 August 2022

A Few faves

 Hi

Recently I entered Design Fringe for the fourth or fifth time and went through the slightly complex process of entry, which included questions about my favourite designs and designers.  I didn't really think too hard and just put down a few of the first and most current things I'd thought of. So most of this post was mentioned in my Linden New Art Design Fringe Entry form, except for the pipe cutter, that is a ring-in, but I had discussed it with a colleague at work a few days ago.

PIPE CUTTER

About 15 years ago, I bought this in a market in Cabulture, Queensland, while on holiday and bought it back with me. Its lived in my shed ever since, and is the heaviest pipe cutter I have ever seen. Its from the 1960's / 1970's Australian Ford / Holden / Valiant school of engineering, ie strong, not much engineering, lots of weight. It works well but is possibly too heavy.

STICKY TAPE DISPENSER



This was found in a drawer in our house, and I have no idea where it originally came from, but its nice and simple, was made in Australia has nice symmetry and is different to every other tape dispenser I've seen.

BRIAN SADGROVE






Brian Sadgrove was a designer for Sun Books, and for a long time Sun Books' subjects and covers have appealed to me, especially covers by Brian Sadgrove. So I've bought a lot of Sun Books from op shops for not very much and will buy almost anything irrespective of quality. A few of Brian's covers from books I own are shown above. After handling these I ran away to some op shops and free book stalls to try to find more, without luck this time.

VI VUONG


 Vi has made many many bikes, and shares their designs on youtube. I've taken his design, the "Ilean trike" or simple leaning trike a bit further than he has. Vi has been a great inspiration.





Friday, 8 July 2022

Some models in context: skeleton octahedron etc.

 

 

 

Hi

A few weeks ago our friend Chris came over and introduced me to a type of cube, which I made a paper model of (fig 4 here ) After making a few different versions and variations of it, I realised some of the characteristics of the polyhedra that were being made:

* Models made from paper or flexible cane can represent the platonic solids. A basic version of these particular models have a ring around the outside of a face as the best representation of that face, like pictures at the bottom of the page here.

* These models have corners consisting of overlapping edge elements, and two canes or paper elements as edges.

* Because edges consist of 2 canes or strands joining each node, each node is "even", so by definition the network has 2 or no odd nodes, which is the condition for traversability. As well the network (no odd nodes) can make a Euler Circuit. Forming single circuits requires some twists in the edges, but more will follow on this later.

So there are node and edge variations of these polyhedra. This post concentrates on the node variations. 

I've made a few edge net models from laminated paper (ie figs 5, 8, 14 here ) , and I thought I recognized an unusual polyhedron - the great dodecahedron - in the icosahedron model I'd made. (see this post also, I have drawn a great dodecaheron in 3d so knew what one was). 

Then I saw another polyhedron that was new to me in what I'd already made, and I couldn't name it at the time. But on this page, fig 9 , and on this page, (figs 7 and 8 left) are versions of a skeletal octahedron, a polyhedron which in its pure, mathematical form has no volume. At that stage, I decided to map some of the work I've done, roughly as follows:

So the table goes through the platonic solids with rows corresponding to the number of edges meeting at nodes. Columns correspond to the turns that edge halves make as they go through the nodes. In the first column, edges join to form simple polygon faces. Intervening columns have overlap of faces. Lastly when the edges turn right around in the node, edges can merge. It should be possible to make all these forms in basket cane, and previous examples are figure 5 here (equivalent to figure 2 below), and figure 9 here, which is the skeletal octahedron.

3d printed great dodecahedron and skeletal octahedron


 

Made up models, top to bottom skeletal octahedron, great dodecahedron, tetrahedron.


Most of the rest of this post is the figures described in the table without too much wordage. Some of these have been posted before, but more or less as isolated things, and this is the first time I've placed them in context. This post is a "sketch", not an exhaustive "picture" so I hope you can work out what's going on.

Figure 1 shows an angle which corresponds to the angle in the table. Figure 3 shows 2 different node structures, the interlocking nodes can be put together 2 ways (see also figure 4) and the overlapping nodes 6 ways (or n!  / n factorial where n is the number of edges joining at the node). Figure 3 has a form that is slightly cheating, the tetrahedron is made up of sides defined by different-coloured edges, whereas the others show sides defined by same-coloured edges.

 

A version of this post with downloadable dwg and stl (3d printable) files is at https://www.thingiverse.com/thing:5427703 .

The octahedron and icosahedron sequences are nice!















Monday, 13 June 2022

Edge nets for polyhedra continued


 

1. Pattern from my first post on this subject. It shows a continuous loop, of a form that can make a tetrahedron like shape. There are 4 triangular nodes, and 3 edges with cane crossings, and 3 without.
   


2. I wanted to make the shape shown in 1. in 3d from cane but didn't think I could with the jigs I had previously. What was built along these lines previously was a 4 loop version of the same part, and I used 4 discrete jigs for that. This pic shows the revised jig, * The previous jig design was changed, so that there is now an 8mm central hole, * A central tetrahedral jig was designed and made, so that 8mm allthread rod fits into the 4 sockets. * 8mm allthread rod was added, so that the outer rods ends are at the corner points of a tetrahedron. * Lastly, the new black jigs were bolted securely in place. 

3. Then starting with some cane poking into thin air, the cane was pressed into the black jigs and clipped in place. I made 3 crossing edges and 3 that didn't cross.

4. I needed to lengthen the cane a bit, so added an "invisible" join from clear heat shrink, but besides that, the whole thing can be made in 1 loop with 1 start / end join. In this photo, the loop is ready for gluing so the jig can be removed, and it looks like

5. This!

6. Here it is again. The jig makes a nice stand for the cane loop, as the corner sits snugly in place without glueing or clamping.


Hi. More 3d printing and weaving! Regards Steve Nurse

Update June 15.

When I started looking at the cane weaving I had made, (5 and 6) I started wondering what sort of polyhedron I had made. The 4 loop version ( 19 to 22 here) was a cuboctahedron, what is the one loop version? As answer of sorts I made some diagrams this morning, some highly modified versions of pic 1 above with different colours representing triangles, rectangles and pentagons (topology, not the actual number of sides). They are shown on 7 and 8.

There are lots of different ways of changing the number of loops in the basic cuboctahedron, and I thought of a couple that would preserve symmetry and sketched them by hand, and as per 9a and b below. Plan to make these at some stage. Also make more diagrams as per 7 and 8. 

Regards

7.


8.


9.

Update 17/6/2022

10. is the same thing as 9a

11. is the same thing as 9b


12. I wanted to explain the type of pic I made in 7, 8. 10, 11, where the outside border of the paper "doesn't count as sides". I was trying for a flat part printed both sides. "A" is the start, the same as fig 7 above and fig 10 on this page. "B" starts to divide it up, inside the hexagon will go to one side of the paper, outside the hexagon will go on the other.

13. Here, "A" is starting to construct the shape that will go on side 1, "B" is the finished side 1 construction and "C" is side 2.

14. Finished result. Blue = topologically 3 sided, red = topologically 4 sided. Some extra tabs were added to make the final form,

15. Which is here

16. and here. I didn't have to fold it flat, I manged to tape edges together to make a 3d shape.

(Link to next post)

Tuesday, 24 May 2022

Braided Knitted Ball / Edge Nets for Polyhedra

 Hi

After making a paper tetrahedron (see my last post), I have kept on working on polyhedrons which follow Marleen Hartog's pattern for a braided knitted ball.  So I have made considerable progress, and have been able to work out along the way some of the theory and principles of what I've been doing. 

So from the last post, I had made a paper cube as per Marlene's instructions, and had made a cane version (figure 9), and also managed to make some paper tetrahedrons. The tetrahedrons had one paper loop per side, with the paper loop completely surrounding each face, and an over and under pattern at each corner. The corners end up being mostly flat, and the assembled versions mostly spherical.


Starting with the pattern criteria that an octahedron has 4 edges at each corner, I started drawing an octahedron net based on what I'd done with the tetrahedron. The octahedron is more complex than the tetrahedron, and I took a simpler approach to making it this time, just putting different colours on white paper instead of printing outlines on different coloured sheets of paper.

So I think I've made a few "edge nets" here. The geometry nets I've heard of consist of full faces joined at hinging edges and accurately reproduce polyhedra. The joins between faces are the edges, and these are either joined like hinges "inside the pattern", or are split edges "outside the pattern". Pairs of split edges combine and coincide when polyhedra are made from nets.

The edge nets I've made consist of edges made of 2 distinct areas / struts and "roundabout" or over / under / over intersections for corners. There is nothing at actual corner points as they are at the centre of the roundabouts. A result of the 2-struts-per-edge feature is that given the correct nodes, an edge net can be made fully traversable, or made from one piece of cane. They have "two or no odd nodes" , a mathematical concept which I somehow remember from school, or engineering at uni. A long time ago!

So now I've managed to make all 5 platonic solids in this form. It makes the edge nets more complex than necessary, but also more versatile and mathematically- , and generally- interesting.

The dodecahedron was tricky and the icosahedron looked even trickier, until I realised that the edge polygons nets fit in the conventional nets of their dual. That means a cube net can be used as the basis of an octahedron edge net, and vice versa. The "rule" I used is that a dodecahedron net can be used as the basis of an icosahedron edge net and vice versa.

That is probably enough for one blog post, I will add in the pictures now. Drawings were made from scratch in Draftsight, other materials are printing ink, paper sticky tape and lamination sleeves. I plan to make a few more cane structures next, starting with the tetrahedron.


 

1)  3 tetrahedrons

2) Tetrahedron edge net, makes the shape shown at the bottom of 1).










3) Conventional net for cube

4) Edge net for cube

5) Conventional and edge nets made into cubes


6) Octahedron edge net 1: colours surround each side, 8 loops

7) Octahedron edge net 2 with colours surrounding each half, 6 loops

8) Octahedrons

9) Conventional edge net for icosahedron made from the 3d printable construction kit available here. Playing with these helped me work out the icosahedron edge net.


10) Dodecahedron edge net

11) What it says!

12) Above pattern with icosahedron edge net overlaid

13) Icosahedron edge net



14) Dodecahedron, Icosahedron

15) Laminating after printing

16) Kerrie quite liked them, we gave her a few patterns to make


Update June 1, 2022

Over the last 2 days, I've made and started to use a new jig which holds basket cane in the right position to make a tetrahedron based on the patterns of figure 1 above. I managed to design and 3d print the jigs one night, (17) and use them to make a tetrahedron the next. 

The 2mm basket cane was soaked in water, then 1 ring was connected using heat shrink tube. The ring was then clipped into the bend jig (19) , and gradually more rings added. When all rings were in place and closed, I glued the rings together at the 3 crossing points of the nodes. When the glue was dry I removed the clips and jigs.

In the middle of last night I realised the photos of the finished shapes would look good on a white background without a flash, to show off the shadows, so got up and took a few photos in my pajamas, and they are shown below (20 - 22).  The end shape is like an inflated tetrahedron with chamfered edges (it is topologically a cuboctohedron )   More to follow.

17) 2d drawing printed out. 3d drawing and 3d printed jigs followed.


18) Jigs and clips

19) Jigs and clips in place while glue dries.

20) Et Voila! Much easier to see what's happening in 19!

21)

22)

(link to next post)