Infrastructure

Infrastructure

A bit of tidying up and some infrastructure. First, scrap metal used to be in a slowly collapsing cardboard box. I replaced that with two wooden boxes made out of scrap:

These were quick to make and were made out of dinged wood anyway, so anything the scrap metal does to them is irrelevant. As well as being more sturdy than the cardboard version, they fill the space in the cupboard now:

so they can hold more bits and pieces.

The second thing I made was a tray to fit on the top of my drill press. I had used magnets to hold chuck keys and drill bits, but that was getting to be a bit messy and didn't work that well. I cut some scrap bamboo flooring to the same shape as the top of the drill press belt cover.

To stop the tray moving I 3D printed curved plastic edges that screwed to the flooring.

These stop the tray moving sideways and falling off the drill press. I put a piece of non-slip plastic on top of the drill press, this stops any sliding of the tray and should deaden any rattling when the drill is running.

On top of this I put a tray that will hold all the bits an pieces. It's plywood and more scrap,

and it totally screwed together.

How I will arrange what goes in the tray I haven't worked out yet, for now, the chuck keys are in a little area of their own:

I might put a drill index in there somewhere.

Water Level Monitor

Water Level Monitor

We've got a rainwater harvesting system that consists of a tank holding rainwater and a pump that supplies toilets and the washing machine. The system came with a mechanical water level meter which is fine, but it requires a trip to a cupboard and some hand pumping. The pumping creates high pressure air which runs in a pipe to the tank. The higher the water level in the tank, the higher the pressure. A pressure gauge in the meter shows the capacity in percentage capacity.

The reading is the height of water in the cylindrical tank. As the cross section of the tank is circular this doesn't quite represent the amount of water in the tank, but it's fairly close.

I started looking at an electrical version a few years ago. Using a pump instead of the mechanical hand operated piston was an obvious way to do this.You could then have a pressure sensor which gives you the same reading as the mechanical system.

The first problem was the pressure involved. The tank is about a meter and a half high and that leads to quite a pressure. The pump needs to generate at least this pressure and the pressure sensor needs to be able to read that pressure. I couldn't find either a pump or a pressure sensor that would work at the pressure I needed.

I left the project for a while, then I came across a cheap blood pressure monitor. This has a pump and a pressure sensor and performs a very similar task to the water level meter I wanted to create. The pressures involved looked promising as well. I dismantled the monitor and extracted the pressure sensor and pump. I reverse engineered the circuit for the sensor and recreated it on an arduino Uno format shield.

You can see the sensor below the IC, it attaches to plastic tubing.The pump drive is a power transistor driven with a PWM signal so I have speed control. If the pump is driven at full speed then it is a bit noisy. Running at a lower speed still gives a high enough air pressure and it's much much quieter.

The final system is mounted in the same cupboard next to the manual meter:

The electronics are in a 3D printed case,  the pump is on 3D printed brackets. The manual meter reads the air pressure when the pump is energised, so you can use it instead of the manual pumping system.

The manual pumping system (below the electronic system) still works exactly as it did before, so there's a backup in case the electronics fails.

The code is set up to energise the pump once an hour, it then stores up to 1000 samples which are offloaded to my laptop using a cron job. I can then graph the samples as needed.

There's a Global Shortage of Toilet Paper

There's a Global Shortage of Toilet Paper

But more importantly there appears to be a global shortage of PLA. I've been printing a fair few things recently and thought it'd be a good idea to stock upon PLA filament. Unfortunately I found that lots of suppliers were out of stock and the price had risen to about double what I last paid. I managed to buy some PLA at a higher price than my last purchase, so I have some in stock.
I had a look around and found that PETG was an odour free plastic (not biodegradable though) that seemed to be similar to PLA. More importantly it was available. I bought some as a sample.

My fisher 3D printer doesn't have a heated bed. This hasn't caused me any problems with PLA other than a slight warp on some larger prints. The bed has Buildtak (BuildTak?) on it which is a very nice surface. PETG seems to need a heated bed according to the internet. Anyway, the PETG arrived and I had a go at printing with it using my normal PLA settings and no heated bed (I've ordered some parts but they won't arrive for ages).

First, the robot that came with the printer:

He didn't print very well, in fact his foot half fell off, but it wasn't a total disaster. I then realised that the file was an STL that was on the SD card and it has a print temperature of 200C. I don't print PLA at that temperature, for some reason all my printers work best at 220C. PETG seems to have a slightly higher print temperature than PLA. I tried a couple of my smaller parts with PETG at my PLA temperature: 220C:

That's a dehydrator knob and a thicknesser latch thingy and both printed fine. No problems at all.

The layers look very similar to the PLA versions. The part does seem to have a little more flex in it compared to PLA.

My Panasonic lens fix was a success until I dropped it again, I then printed another part and fitted it, but it was a slightly different design and had a hole in it which caused too much flex for the contacts on the lens to reliably engage with the camera. It finally got to the pint where I couldn't use th elens, so I decided to fix the problem. I altered the model and printed a new part in PLA and an identical one in PETG. Of course, it's white not black as that was the PETG colour I bought:

The PETG part seems to be a bit more 'slippery' and this is useful on a lens mount, so the PETG part is better than the PLA one in this respect.

The PLA part doesn't seem to be quite as tidy as the PETG, but the difference in colour doesn't help the PLA.

The lens is now working with the PETG part, which is what I wanted. It looks like PETG is going to work for me in the same way I use PLA. Excellent.

Dehydrator Knobs

Dehydrator Knobs

To go with the new front panel, some knobs:

3D printed and then hand drilled to size so it fits nicely on the shafts. The printer didn't seem to be able to print the splines that were on the model. They stiil fit though as the hole was snug.

Dehydrator Update

Dehydrator Update

It was time for an update to a couple aspects of the dehydrator. Firstly, the trays I made to hold the stuff to be dried needed to be replaced. they were wooden and had warped really badly:

The replacement is a metal rod and 3D printed tray which hopefully won't warp. It also has a handle in the middle of the tray so lowering it into the dehydrator is going to be a lot easier.

Whatever is being dehydrated sits on a plastic mesh so that air flows easily through the trays:

The trays look a lot better than the wooden ones and I hope they will work a lot better as well.

The second update is an engraved front panel.

Which potentiometer controls what is now obvious, as is the function of the LED. This is engraved white on black plastic sheet. I need to make some nice knobs for the pots next...