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Past Work - Block Wave 2

3D CAD model of glass op art sculpture by Peter Heywood

If you dig back through my "past work" on this website you'll find "Block Wave", a lot of painted wooden cubes stacked into a row of twisting columns. After I'd made it (some time in the 1970s!) I discovered that the arrangement also resulted in diagonal waves across the installation:

I've toyed with making a second version in glass or ceramics for quite a while, but I've now got the bit between my teeth on a glass version following an email exchange with Dail Behennah, an artist that's made a lot of 3D op art out of rods of willow, and who gave an interesting talk at Plymouth College of Art (PCA). See my blog about it.

Dail pointed out that if I threaded glass cubes onto rods, the different angles of the faces of the cubes would defract the image of the rod in different ways, so I'd not only get twisty columns and diagonal waves but I'd also get interesting stuff happening within the glass. I'm totally sold on the idea!

I then chatted to Lawrence West, glass technician at PCA, who pointed out that I could make the cubes by pouring molten glass into graphite moulds. There's a LOT of cubes! 180 in the design below; these are screenshots of a model I've generated using Rhino, a 3D CAD software package:

3D CAD Model of Glass Sculpture by Peter Heywood

Time to start my usual photo-journal:

			18th November. This is the result of making a test cube with a hole in it, formed by a graphite rod. Lots of lessons: A bubble formed when molten glass was poured into the graphite former. It's probably because the graphite rod was sticking up and the glass flowed around it, trapping some air that then expanded as it got hot. The cube was about 50mm versus the 70mm I have in mind - but we still think this problem could occur. The graphite rod was 12.7mm diameter and the hole it made was about 12mm. Would be too tight for a 12mm rod but okay for 10mm.
			The inside of the hole was clear/polished, which was nice. I also like the ripples on the outside surface of the cubes, formed by the hot glass touching the cold graphite mould.
			This is my first effort at designing a jig to make the cubes, with the goals of: Making it easier to cast a lot. Preventing air getting trapped in the glass by filling the mould and then pushing a graphite rod up into it. Flattening the top of the cube, to minimise the grinding I might have to do on that surface.
			The jig is almost complete. All that's left is cutting 5 lengths of 12mm rod and putting threads on them. The dye for doing this is lost in the post! I ended up making a wider platform than originally planned, because the 5mm plate we had was 200mm wide. I also ended up with the top plate sliding up and down 4 rods rather than 2. Other modifications: I've made the plunger (pictured on the right) from 5mm steel plate rather than graphite. I've done away with the graphite base of the cube. The glass is poured onto the steel plate. I've made a hinged contraption either side of the jig to prop up the top plate.
			6th January 2015: Completed jig. The plunger is out of view. Getting the whole thing to slide freely proved difficult. In retrospect, it might have been a good idea to have used a hydraulic ram to force the central rod up into the molten glass.
			7th January. First tests of making cubes weren't successful. In the first test, the glass cube was pushed out of the graphite mould as I lowered the top plate. In the second test, we tried to stop the glass cube being pushed out of the cube by pressing down on the plunger. We couldn't stop the glass rising above the top of the cube. In the third test, we lowered the bottom plate so the rod was projecting through the mould and then used the plunger to try and force the glass into the mould. The result is pictured. We couldn't get the plunger onto the rod because it cooled the glass. We decided a bigger hole was needed in the plunger. I've now increased it from 12.5mm to 16mm ready fir another test.
			21st January: Test with rod already in cube mould (top plate lowered) and with the rod wrapped in copper foil. Not enough glass for a full cube but the copper foil worked - the rod slid out easily. However, in the second trial of this method, the copper foil scrunched up and we ended up abandoning it. When it had cooled the cube had a crack in it. Love the ripples on the surface!
			21st January again. Same set up but this time we coated the rod with graphite. Removed the rod too soon and the hole collapsed. When it had cooled the cube had a big crack in it.
			27th January. I've now made a "plunger" that makes the hole in the cube from the top-down.
			28th January. This is the jig setup for casting cubes using the top-down plunger. We made about 5 today and 2 or 3 were probably successful - ie big step forward! Points to note: Heat the graphite mould on the furnace beforehand, and heat the corners some more, using a blow torch just before pouring the glass. Don't heat the plunger. The plunger needs to be cooled after each pour - so I need to make another 2. It doesn't need to be coated in graphite. Tapping the plunger with a hammer is necessary to break through the solidified glass beneath the hole. Move the plunger around so the glass can;t stick to it. Use it to pat the top of the cube, but do this gently Remove the graphite mould after 1 minute. Remove the plunger after 90 seconds Put the cube in the Lehr at 2 minutes. Make something to transport the cube to the Lehr.
			24th March. An update: None of the above cubes were successful. The fundamental problem is that the outside of the cube cools and cracks before the inside of the cube solidifies sufficiently to avoid the hole collapsing. See photo. I've let this project go to sleep for a couple of months while I work on other things, but I'm now trying a different approach - casting solid cubes and making the hole with water jet cutting. I've found a company in Plymouth that's prepared to try cutting a hole in a cube, with a view to giving me a quote for cutting 180 cubes if it works. So I've now cast 3 solid cubes and hope to get them to this company in the coming week.
			24 September. Water has passed under the proverbial bridge. The water jet company cracked the first cube I gave them but said that if it drilled more slowly the cube probably wouldn't crack. It gave me a quote of £4.06 +VAT per hole, so holes in 200 cubes would have cost about £1,000. Gulp. On the other hand, it could result in a stunning work of art, so I didn't give up. I asked them to demonstrate that they could drill a hole without cracking the cube, they said okay, and I went off to make one. But casting the cube proved really difficult. The surfaces cooled and cracked before the inside had solidified. When I took it out of the mould, the cube went slightly wedge shaped, the sides bulged, the top sank. At the same time, cracks appeared in the corners. I put the project to one side.

			In early July I went on an orienteering holiday in the Trentino area of northern Italy. While we were there we went around the Arte Sella sculpture park. It was amazing! One of the (huge) exhibits was several of these giant box-type hollow corkscrews. I realised that this was based on the same concept as "Block Wave" - each layer is twisted slightly - and that got my mind racing: Maybe I could make the glass version of Block Wave from strips of glass?
			When I got home, I played around with making similar structures using Rhino, a 3D CAD program. I discovered an additional attraction to the above idea: That the slats created interference patterns as the model was rocked backwards and forwards, as this screenshot demonstrates.
			I put a twist in later models that I generated in Rhino. Then I decided to try making an example out of scrap plywood, pictured. There were the beginnings of interference patterns. Just recently we've discovered that 2 of our double glazing units need replacing, so a plan is forming to re-use the glass from the old windows to create a slatted version of Block Wave. Free material! No expensive water jet cutting!
			26th September. Raining - so I've had a little play, using Rhino to try and visualise twisted columns made from 70 x 30 mm rectangles of 2-mm-thick glass.
			27th September: Yesterday I made a simple jig to enable me to place 2 panels of glass on top of 2 others at sort of 89.5 degrees - ie with a tiny twist. Today I tested it out on some scrap plywood, pictured.
			10th October. Got these out of the kiln today. They're stacks of float glass that have been tacked together. The glass had been knocking around the workshop for a while - think it might have been a spare pane for the shed. Anyhow, I cut it up into a lot of 3cm x 7cm panels to create these. I started off trying to twist each layer using the jig I used to make the plywood mock-up, but the fuser's glue didn't stick the glass together well enough. As a result, I abandoned trying to give the columns a twist. The exception is the one in the foreground, where I used superglue to stick the glass together. In all cases some evidence of the glue was evident after firing.

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