Tidying up cables for the laser

26 Apr

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I’ve had the new laser cutter hooked up via various extension cables and plug boxes. Every time I turned the shed lights on, I had to listen to the sound of the laser’s exhaust fan and air pump, as it was too much trouble to hunt down the appropriate cables and unplug them when I wasn’t using the laser.

I decided to make it easier on myself by using a switched plug box – but then I needed to remember which switch turned on which device.

With a cad diagram sorted out, I grabbed a random chunk of white painted hardboard (I have no idea what it came off – probably some bit of demolished furniture). I covered the surface with masking tape.

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Next step – burn all the mounting holes. There was some metal shelving near the laser, with holes at 50mm spacing, so I made holes for attaching the board using those. Also holes for zip ties, and for the plug board (which I’d hot glued small feet to).

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Now, lightly engrave the text, along with some indicating lines. The sockets on the plug board weren’t evenly spaced, hence the odd angles.

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The result, fresh our of the laser.

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I peeled off the masking tape over the letters. It came off easily, but I should have been more careful to press the remaining tape back down. I’d wiped the board down with a damp rag before I applied the masking tape (it was very dusty) and the heat of the laser may have bubbled the remaining moisture.

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Now an application of black spray paint.

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After an hour, I peeled the remaining masking tape off. There’s a few blotches, especially near the bottom, but it’s certainly readable. The letters are about 50mm (2″) high.

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The final result. A bit rough, but quite satisfactory for a first try, and it should do the job.

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Straw and cardboard vegetable bed

21 Nov

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As a bit of an experiment, we knocked up a couple of beds for vegetables.


 

The outer frame is just four length of Oregon 100×25, joined at the corners with screws. I added 8x 45° braces in the corner as well. The result was fairly rigid. I did try nailing them together with my framing nailer but it didn’t work well. Here you can see Barbara watering the ground inside the frame, which is simply plonked on the ground.

S vegetable bed - 01 watering

We covered the ground with a couple of layers of cardboard from packing boxes.

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We marked out a grid of points (about 200mm spacing). Then I got out an electric drill and a 75mm (3″) holesaw and drilled 48 holes through the cardboard. The slowest part was digging the cardboard disks out of the holesaw.

S vegetable bed - 03 holes

I didn’t have any proper soaker hose, but this “sprinkler” hose was on special so we wound that between the rows. Once the straw goes on, it should still let us water under the mulch.

S vegetable bed - 04 hose

Then the planting! Here Barbara and Rachel are placing seedlings (cabbage, beans, etc) and putting pea straw around them. I dibbled a bit of dirt out of each hole with a grubber, and Alexandra recorded which seedlings went where. Ignore the messy wood pile in the background.

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Final result doesn’t look to bad. This represents about $5 of wood, $2 of screws, a $7 sprinkler hose, and about $20 of seedlings.

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If it works, we can easily replicate a bunch of these.

 

 

Seedling propagating bed – two week update

19 Apr

First – there are seedlings growing!

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And quite a lot of them. The first seedlings came up after about 7 days, and now there is at least one seedling growing in 215 of the 350 pots.

An automatic cutoff when the bed is flooded.

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This is a simple float switch. When the float (a section of pool noodle) is lifted by the water, the wire rotates around a bearing and presses the microswitch which cuts off power to the pump. There’s a “control panel” visible to the left. Pressing the square button powers up a relay which turns on the pump, but it also supplies power to the relay so it keeps running after you take your finger off the button. When float rises, it cuts power to the relay which switches off, and stays off until pressing the button starts the cycle again. There’s also an override switch, a fuse, and an LED to light up.

FISH!

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As the water flowed across the bed, then sat in the reservoir, it started forming algae. We started considering options to stop the buildup, then hit on the idea of advancing towards our eventual goal of aquaponics by adding a couple of fish to the system. We’ve always intended to have goldfish as part of the larger system we’re planning, but we had to do some furious research to see if it was workable.

The reservoir is renamed “the fish tank”

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A visit to a pet shop netted us two quite small fish, some fish-food, a thermometer, and an air pump. I modified an old sieve by cutting holes for outlet pipes and wires, then placed two water pumps (the original pump and a smaller one) inside the sieve. A collection of stones from the beach at Birdlings Flat and a couple of chunks of brick all serve to hold the sieve firmly against the bottom of the tank. I’m fairly confident that the fish won’t be able to get near the pump intakes. The air pump is outside the tank, with a hose leading to the bottom of the tank. We used it before the fish moved in to make sure the water was well oxygenated but haven’t kept it up as (a) it was really too loud and vigorous, and (b) it ran off 240V whereas everything else is running off 12V (solar) power. As an alternative, the second (small) water pump inside the sieve feeds out to a hose which splashes water back into the tank, adding oxygen in the process.

The algae has gone, the fish seem happy, and they have definitely grown.

Anti-cat barrier and air circulation fans.

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We strung some loose strands of bright 4mm rope on three sides to dissuade the cats from jumping up onto the seedlings. Seems to have worked so far.

We’re quite worried about “damping off”, the fungal disease(s) that like to destroy young seedlings. The seedling pots are quite moist and, while we haven’t had any problems so far, conditions are quite good for fungus to develop. Many sources recommend fans moving the air about to dry the top layer of soil, prevent stagnant moist air from sitting around, and also toughen up the young seedlings. I didn’t want to use a mains powered fan so I grabbed eight PC fans salvaged from various computers and hooked them up. They’re hooked up in pairs, with each pair joined in series so the fans, designed for 12V, only get half the voltage (6V) and turn over slowly and quietly. It took a surprising amount of time to hook them up but they seem to work very well. The biggest problem, and one that almost caught me out, is that each pair of fans should be of similar power. I was amazed how many different ratings there were in the my fan collection – each of the four pairs in use here is a quite different rating.

More controls

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Each step we take seems to require more controls, especially adding the fish. I really need to add some timers to the system, and perhaps a water level detector for the fish tank. Perhaps a moisture detector to tell how damp the soil is. Lots of options. I’ve started working up a system based on an Arduino microcontroller.

A prototype seedling propagating tray

3 Apr

A recent project has been building a “flood and drain” bed for raising seedlings. It’s all rather rough and experimental, but showing promise.

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Newspaper pots. Lots and lots (200 here, 350 when complete) of little biodegradable pots. Each group of 50 sits in a “seedling tray” which is has an open grid at the bottom.

The structure is built of 18mm MDF, with two layers of polythene sheet to make it waterproof. The polythene is trapped by a thin strip (18mm x 10mm) of mdf which is screwed down. That applies lots of even clamping pressure to the film so it doesn’t rip. Also visible is the hose that delivers water from the reservoir (currently a 50L “fish bin” just visible below the table).

S prototype seedling bed 003 - right
If the bed fills with water, there will be quite a bit of pressure trying to bend the walls outwards. I was going to put in cross braces, but ended up just using a strong method of fastening the walls. Vertical steel bolts (M6x65) come up through the base and into TAPPED holes in the walls. I recommend this technique for anyone who wants to really lock an mdf construction together. Note: the holes were drilled 5mm, then tapped with an ordinary M6 metal tap in a cordless drill. Very fast and very solid.

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This all sits on a chunk of material from an old office desk, which in turn rests on two homemade trestle legs (made from pallet wood). The tray is 2200mm x 600mm, and the walls are 100mm high. There are seven seed trays along the length, and an area at the extreme left which is where the drain is fitted.

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Inside the tray we routed some grooves along the base, hoping that the water would press the plastic down into the grooves and help to drain the bed smoothly. It didn’t. A simple work-around was to string some 4mm poly rope underneath the seed beds. This lifts them up enough that there is no water permanently pooled around the base.

S prototype seedling bed 006 - grooves

The seed trays don’t go all the way to the end. The last 200mm or so is routed down about 4mm deep to act as a drain, and has a “bulkhead fitting” installed to connect to a hosepipe. This was one of the points I was most worried about, as any leak here would get into the mdf and really damage it.

One of the things about polythene is that it’s really hard to glue to. Glue, or silicone caulking, won’t stick to it. I did some experiments with gluing a disk of plastic to the polythene which did work (light sanding, alcohol wipe, blowtorch at a distance to react free radicals with the surface layer) but in the end I decided to just trust the pressure fit of the rubber washer in the bulkhead fitting. So far (though it’s very early days) it’s been fine. If I build another one, I’ll epoxy a few inches of the mdf around the hole so it’s waterproof.

The bulkhead fitting is about 4mm high which prevents draining the last of the water away. Half a dozen pieces of ordinary string (held down by an old 12V battery which proved to work better as a heavy weight than as an electrical device) wicks the last of the water away perfectly. The plastic is dry at the end of the draining period.

S prototype seedling bed 007 - drain
DO NOT LOOK AT THE “TEMPORARY” WIRING!

Just in case a leak develops, the whole apparatus is sitting inside a rectangular ring of mdf, again with polythene inside to form a catch basin. The screwed down strips to hold down the plastic on the tray worked well – much better than simply stapling it as we did for the catch basin. Even when stapled through little bits of cardboard, the plastic rips free if you look at unkindly.

For safety, this is a solar powered setup, in this case with a hefty 12V battery intended for a lawn mower or similar ($100 from Super Cheap Auto). Just visible at the back (by the window) is a 1.8W 12V solar charger ($20 from The Warehouse).  I’ve actually got a proper solar panel and controller I can hook up if it needs it.

S prototype seedling bed 005 - wiring

The tray is a fraction longer than the support it rests on, leaving room for the bottom of the bulkhead fitting in the drain section. This leads into some perfectly ordinary domestic hosepipe. Partway down the hose is a tap fitting. This can restrict the speed with which the bed drains. The more it is closed down, the longer the ‘flood’ stage of watering lasts. Currently it takes a few minutes to fill the bed about 10mm deep with water, and about half an hour for that to completely drain away.

S prototype seedling bed 009 -  drain pipe and tap

Inside the reservoir is one of these, a 12V, 840L/hour, BRUSHLESS dc motor. The advantage of a brushless motor is that there are very few moving parts. Basically there’s some circuitry inside that turns DC into AC and uses that to spin the rotor. The supplier claims 30,000 hours operation, compared to some brushed dc motors (e.g. bilge pumps) that often fail after about 200 hours. There are lots of discussions about the problems of brushed dc motors on hydroponics websites. These were about $25 off Ebay.

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If you wondered about the little paper pots, these are made from newspaper strips with the gadget shown here. It’s just a slightly tapered former with a hollow at the bottom and a handle, plus a matching base. I turned these (on a metal lathe) from some branches cut from our eucalyptus trees. There’s various instructions for making them on the net, or you can buy one (e.g. from here). The plan is to plant the seedling complete with the paper pot which should save a lot of fuss.

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Hopefully I can put up an update in a few months to say whether all this worked. I have high hopes, but time will tell.

A (cheap) wood rack

9 Mar

I had a horrible mess in my wood storage area, so I made up this simple rack to tidy it up.

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This pattern of wood rack (with storage bins on one side and sloping sheet goods storage on the other) is well exampled on the net. In particular Steve Ramsey’s nicely documented build make a rolling lumber cart ,  various designs on LumberJocks, and this nice English/French site rangement-pour-panneaux-et-retailles. However, most of the examples I found used sheets of 3/4″ (20mm) plywood which is very expensive in New Zealand. Besides, a lot of my wood was scavenged and free, and I didn’t want to spend good money on storage for it, so this rack is made from some thin 9mm ply and a lot of scraps. Another difference is that this isn’t a mobile cart – castors won’t work well on a dirt floor.

The area was very messy. (The pink and blue cupboards used to belong to my twins when they were much younger).

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The first step was to make some temporary covered storage using some pallets, a tarp, some eye-screws, and a few bungee cords.

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I decided to make the storage bins 400mm x 400mm, which is wider than the capacity of my (small) tablesaw.  That meant clamping a temporary worksurface to the saw top to make the cuts.

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The only flat surface for assembly, anywhere near the shed, was the bed of my trailer. It worked quite well. The lines on the plywood mark some treated fence palings to raise it off the ground.

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Some free offcuts of mdf supplied spacers. I clamped four together to ensure each set of spacers were the same length.

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It turned out that four sheets was a trifle too much depth for this 200mm (8″) mitre saw, and I had to tidy up one corner on each batch.

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Once I had my spacers and the 400×400 squares of plywood, I assembled a set of bins. Rather a messy operation and a crude looking result.

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Now I could start assembling the structure in-situ.

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The shelves for the centre were, again, thin 9mm ply. That meant I couldn’t screw into the side of them so I cut small rails for them to sit on. One of my recent pickups was some 2.4m long strips of 20mm plywood, but only 20mm wide. These worked very well for rails. In the photo below, I am setting up to cut a 10 degree bevel on the edge of one of these 20×20 strips. It’s the sort of cut which isn’t really feasible without a tablesaw.

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I fastened the rails to the shelf before I attached them to the sides. This worked well.

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For the first (lowest) shelf, I was able to put some plastic buckets and some 4x2s down to support the shelf while I fixed it in place.

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Working my way up, I soon had the other shelves in place. (One of my daughters helped with this bit which made it easier as the two ends are 2.4m apart and the area was so messy that moving around wasn’t easy).

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Once I started filling the rack, I discovered quite a lot of nice bits of wood that I’d forgotten I had. The final result didn’t really pack quite as much in as I’d hoped, but it did make it far easier to see what I had. It also got rid of a major problem of wood lower down the pile developing a curve.

Large sheets are stored on one side, while thin but long strips, metal rods, etc go in the shelves.

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With planks, dowels, and narrower offcuts of mdf, going in the bins on the other side.

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A cheap and simple hutch for some power tools

19 Feb

I wanted to tidy up my power tools (drills, jigsaw, etc) as I’ve been leaving them scattered around the bench.This is only a temporary setup, as I’ll need something more enclosed when the wet weather comes in a few months (it’s high summer in New Zealand at present).

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Not an original idea, I swiped it from here and a number of others have done a similar setup – but probably not as cheaply.

I’d been thinking of making something up when I spotted a bunch of strips of mdf at the side of the road (put out for people to take, by a cabinet making business). This was four strips of the fifty or so I could have grabbed.

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Next I ‘rootled’ around in my (large) scrap mdf pile and found a suitable, if rough, chunk. The ends were broken and it tapered, but a few minutes with the tablesaw turned it into a couple of shelves.

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I set up the mitre saw on my homemade bench, and cut off a long strip to go at the back, and then a slew of short sections. The back and the first couple of short sections were glued on to one shelf to form the base.

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I wanted to be able to take the top off and replace it in the same place, so I drilled a 5mm hole through the the top and into the side walls, then tapped the base for M6x30 bolts  (similar to a 1/4″ x 1″ bolt). Mdf taps quite easily using an ordinary metal tap in a cordless drill.

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Now I could pile a bunch of tools onto the top and start sorting out placement and mountings. (In the background you can see that, yes, my workshop floor really is tarpaulin over dirt, then pallets, and free mdf!).

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Here’s what I ended up with (glue gun, soldering gun, hot air gun, jig saw, orbital sander, drill, drill).

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I had to get a bit inventive with mounting them. Various odd shaped bits of wood for the heavier tools, and bent pieces of wire for the heated tools (which are also, conveniently, much lighter). I found 1.6mm wire (16 guage) was just strong enough – it feels really flimsy but gets more solid when you screw the ends down. 2mm wire (about 12 guage) was much stronger.

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I glued the spacers into the bottom (here being weighted down by some convenient chunks of concrete paver), then bolted the top back on.

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The final result is not very pretty, but cheap and makes a good prototype.

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A very quick and dirty holder for some tools

16 Feb

Quick tool storage A

It’s sunday morning and I don’t feel like making too much noise (courtesy to my neighbours + alcohol on Saturday night!). I wanted to do something towards making the workshop better, but without using the tablesaw or mitre saw.

Quick tool storage B

I found some scraps of mdf that were roughly the right size, if somewhat rough, and chopped them to length with a handsaw.

Quick tool storage C

A quick grid of pencil lines. 50mm x 40mm. When I made the second set of lines I remembered to centre them on the wood. If anyone asks I’ll say it was intentional – to allow more space on one side. 🙂

Quick tool storage D

Off to the drill press and drill 28x 6mm holes.

Quick tool storage F

I drilled out some of the holes a bit bigger while I had the pieces separated. 25mm, 16mm, 12mm, and a couple out to 6.5mm to hold 1/4″ (6.25mm) shafts.

Quick tool storage G

Glue and staple three pieces of 50mm wide mdf strip. A bit damaged, and a bit curvy, but that won’t matter.

Quick tool storage H

And it should be harder to misplace the marker pens, drill press key, countersink, torch, etc. I also glued on a couple of small magnets to hold my favourite hex driver bits.  Since the holes were drilled on the drill press, they are nice and straight which means I can easily enlarge any holes I want with a hand-held drill.

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