New tools and techniques

I’ve been working on a new ideal rebar bender for the 6mm rebar…will work for the 10 mm or 12mm too I’m sure. Requires welding but worth it I think. The bending grooves I cut using standard angle grinder. One model I made by welding a square of hard steel onto the flattened end of a piece of old electrical conduit pipe, the other is the cut off end of an old wrench. Handles formed by winding soft polypropylene cord around the pipe with plenty of pva glue. Frayed ends soaked in glue can be tucked under the windings.

Also see this cool way to crosscut chicken mesh to make nice stretchy strips for winding around curved railings or spirals such as this sculpture I’m building to house a spinning bronze ‘sun-wheel’ for a customer. I use strips a lot now. It’s quick to cut them if you just fold a length of chicken mesh lengthwise twice so it’s a quarter as wide, then tinsnip this long strip crosswise…strips about 150mm to 25mm wide. They stack well until use when you just grab the ends and pull. Strips cut like this are very stretchable. There are cut ends of mesh of course, but I’ve found if I wear leather rigger’s gloves (soft pigskin – quite cheap) they don’t hurt… also on the first plaster coat I now wear either rigger’s gloves or thick nitrile gloves safety equipment shops have these..or the local bigger hardware shop (Bunnings here in nz). The sharp ends of the mesh are buried in plaster at the first coat with a little care, or at least by the second coat. For longer rails or tubes of ferro – e.g. branches or garden arches – it is the only way to go I think. And being wound on in overlapping windings it doesn’t need much – or any – lacing wire to hold it in place, just at the final end of the winding. See one of the folded cut strips in the first picture. Note the tins nips screwed down for quick snipping.

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Ferrocement raised beds really are great!

I’ve just done another one at the Story Ark, out the front this time. About 7 metres long, one-sided as it is against the front of the Ark. Framework was minimalist, and one length of 13mm mesh chickenwire folded over it lengthwise, and laced with thin (.7 or somm) tie wire. As per the book fantastic ferrocement of course! Oh and the ends of the framework I stapled onto the wood of the Ark, and plastered right up to the wood. I will line the Ark side of the bed with black plastic to prevent the soil from rotting the wood.

It only took two mixer-loads to plaster it – about 40kg of cement (or two 25kg bags at most), and one coat (round-ended trowel finish) was sufficient. done in an afternoon (by yours truly alone). Then lightly sanded with about 60 grit and stained a couple of days later (can do it same day – it works apparently by chemical reaction with uncured plaster, at least not fully cured) with garden-store-standard iron sulphate, strong solution put on with a rag, two applications to make sure. Apart from keeping under cover for a few days to maximise plaster curing, that’s it!

I grubbed a shallow (maybe 50mm) trench for the framework to discourage the invasive kikuyu grass we have here courtesy of a mad council decades ago…

new raised bed in front of ark

 

This finish goes darker when wet, as you see in the photo. I suppose I used three quarters of a kilo of the iron sulphate – about NZ $5 depending on the garden store you go to.

The mega-fibre II I used to get for plaster isnt available here now, and I havent sourced the Sika fibre here yet, so I improvised: I chopped up some old polypropylene rope into about 30mm lengths, rubbed it a bit to loosen all the fibres, and added it to the mix. It was coarser than the other but plastered fine, and did the job of helping the thick coat not to sag.

I thoroughly recommend ferrocement for serious raised beds. It’s probably about as quick as wood for the same height, or at least if you count the lifetime cost of wood, which rots in proportion to your success in filling it with a fertile soil bursting with microorganisms! Of course, you can make a wooden one then line it with plastic, but why go there when there’s ferro, which will outlast all wooden outdoor structures…