Each week I attempt to crush and mill another local igneous rock for use as a glaze ingredient.This week I stopped off on the way to Mittagong Post Office to collect another stone, on the hill behind the post office.I passed it through the rock crushers that I have pains-takingly restored after the fire. Luckily, all these machines are made of very solid steel plate or cast iron, but more importantly, they were situated in the breezeway between the two buildings. Being largely out in the open with very little flammable material around them, just a polycarbonate roof over them. So they didn’t get too hot.They weren’t warped or melted. This meant that I was able to restore them, not just scrap them.New motors, bearings, seals, pullies and belts were required. The metal work was largely saved because I poured used engine oil all over them, straight after the fire and before it rained on them. With the assistance of my friends Warren Hogden and Len Smith, Along with my friend Dave and his crane truck, we were able to lift them out of the rubble and up to a safe place, out of the way of the demolition crew and then tarp them in their oily state. This was just enough protection to stop them from rusting and flaking really badly.
One very important aspect of my philosophy of self-reliance is never throwing anything out simply because it is no longer fashionable or is showing signs of wear. I keep working on my possessions, maintaining and repairing them, until they are really worn out, or past repair. In this regard, I have spent a lot of time patching and stitching my worn out work clothes and repairing some of my treasured pottery machines. Particularly the rock crushers. These things are as scarce as hen’s teeth and really worth working on. The Japanese have a word, ‘mortainai’ that means ‘making do’, I have written about it on this blog previously. It really sums up this repair and reuse philosophy.A year of part-time evenings has seen both my work jeans and the rock crushers back at work. These jeans are many years old and have patches over their patches, over their patches, especially on the knees.
My jeans mostly wear out at the knees and thighs, I have also had to reline the pockets, as the pockets are made from the lightest grade of cotton cloth that wears out in no time flat if you keep your car keys in there.
It’s just one more example of built in obsolescence. A product designed to fail. The retailers hope that i will just ditch the whole pair and buy another – in the latest fashion style! Well I won’t and don’t. I repair, re-use and re-cycle. I like to make them last me a decade. They start out as being for ‘best’ , going out etc. Then after a couple of years, they start to get a bit past their shiny best, they are worm in the pottery and for gardening. Finally after another 3 or 4 years, they are reduced to the welding workshop, rock crushing and angle grinding. This really takes it’s toll and they require more patches more often. In the past I have finally given up on them when I grew out of them and had to go up to another size. Then they became rags for painting and cleaning. These days I don’t get any bigger, so size isn’t the death knock that it used to be. Hence I a back log of three pairs of these patched jeans that just keep on being repaired and worn again and again.
But its not just the pockets, knees and thighs. They also wear out in the butt.
I think that ongoing hand stitched repairs like this are an important aspect of my creative expression. I exhibit my pots , but no one ever sees these creative endeavours. They are strictly utilitarian and for home use only, but this doesn’t meant that they are any less important. I kintsugi my pots and I patch my clothes. It’s the same thing.
After I had got the rock crushers going. I left it at that, as I wasn’t ready to crush any stones at that time. But the machines were ready.
At least I thought so. I didn’t have the time to test them all out with rocks. I didn’t even have any rocks at hand to try out. I was satisfied when the new motors were installed and the new drive belts were fitted in place, just to see the machines rotate successfully. That was all I got to do. Now is the testing time.
Straight off, there was one casualty. The smallest laboratory jaw crusher just doesn’t seem to work at all. I got it 2nd hand from a junk yard. I tested it, the motor ran, the shaft turned, it whirred and clanked, but now that I go to use it, nothing happens when I put rocks in. They just sit there bouncing around. Luckily, I only paid $250 for it. I’ll need to pull it to bits and find out why. But that will have to wait till later, much Later… I have other machines that do actually work and they are enough to get me started. What’s most important is that I can get some local stones powdered so that I can get a glaze firing full of test pieces done.
There were a few hiccups with the other machines before I got them all working. The big jaw crusher was found to be running back wards. I hadn’t noticed this when I first wired it up, as the degree of oscillation movement is very slight, but the first time I put stones in it, I noticed that it was very slow to engage with the rocks, it still crushed the chunks down to blue metal sized pieces, but very slowly. It was really only because I know this machine very well as I have rebuilt it previously over years and am familiar with it, such that I noticed its lack of performance. Luckily, it is a simple exercise to reverse polarity of a 3 phase motor. It works properly now.
The small jaw crusher, which I use as a 2nd stage crusher, takes the blue metal sized lumps and reduces them to grit.
This little machine is now painted industrial yellow, but was formerly dark blue and orange in the old pottery. Me painting my machines a different colour is a bit like a lady dyeing her hair. A change is as good as a holiday. It cheers me up to see all the brightly coloured machines. Like big kid’s toys!
I move the negative-pressure ventilation, dust extraction hose from machine to machine. I have found that the end of the tube is quite friendly and affectionate. If I get too close to the end of the bright orange ducting, it attaches itself to me with the pressure of the suction. It’s not too strong and easy to remove from my shirt, but it is very friendly and persists in wanting to get attached to me. It’s quite amusing. It keeps on seeking out my shirt every time I get close while I’m working. I keep brushing it off, it keeps wanting to nuzzle-up and attach itself to me. Maybe it’s my pottery-workshop-cabin-fevor, after all these months of lock-down. Janine says that I need to get out more! But it’s nice to be wanted! 🙂
The output of this machine is from 6mm down to dust. I bought the little, now-yellow, crusher direct from the manufacturer, ‘Van Gelder’ back in 1983. When we used to make things here in Australia back in those days. This company has now gone to the wall. It’s a shame, as it was established back in the 1800’s to support the late gold rush and the follow-on mining activities here. They were located in Silverwater in what used to be Sydney’s industrial manufacturing heartland.
The owner at the time said that they were just hanging on, all the workers were getting old and heading for retirement. He wasn’t sure how he was going to pay out all the retirement funds. He told me that he would probably sell the site and move out of the city to some where much cheaper. Before I left with my brand new crusher – which is still the most expensive piece of pottery equipment that I ever bought. He added my name and the serial number of my machine into his manufacturing log book. It was a quarto sized, beautiful old leather bound journal, that was showing a lot of wear around the edges. It contained a list of every machine that had ever been built by that company. I felt honoured to be on that historical list. It has occurred to me since then, whatever happened to that company’s records and in particular, to that journal?
In 2009, the cast iron static jaw broke in half, presumably from metal fatigue? I googled ‘Van Gelder’ and found them up in Gosford. We had an email exchange, but the new owner was completely disinterested in helping me out by selling a new jaw. In fact almost rude. Such a different experience from the old owner! So I decided that I’d make my own – only better than the original. Cast iron is brittle and not the best choice for a machine part that is under constant impact. I decided to make a new one myself. I tried casting one in bronze. I started out by making a wooden replica that was 17% larger. Making a plaster cast of that wooden piece, then casting a copy of that wooden one in wax, so that I could do a lost wax bronze casting.
The original is at the top. the larger wooden model is in the centre. The cast wax model is at the bottom.
I built a small foundry, and with the assistance of my good friend Warren, we cast a blank, which needed a lot of machining.
I decided to also make another jaw out of steel.
I made the steel jaw out of a series of 3/4” or 19mm. steel plates welded together to make up the 3” or 76mm thickness of the jaw. I was able to drill out the hole for the shaft in each plate before I welded the plates together and then ground them down to a smooth finish where it was necessary to fit the housing. This was quicker and easier for me to complete. This new jaw is still going strong. I had never attempted to weld 3/4” steel plate before. I was really chuffed that it worked. I decided to go with the steel jaw instead of the bronze jaw.
So it’s working again now beautifully. Producing a grit that is suitable to go into the disc mill.
The grit from this small Van Gelder crusher is then reduced further in the ‘Bico’ disc disintegrator mill, down to something close to a sand-like size. Interestingly, ‘Bico’ crushers are still available in the USA. I googled them, they are still in business and the identical machine is still for sale on their web site in a slightly newer version. I bought mine many years ago 3rd or 4th hand, no history and unmounted. It obviously hadn’t been used for a long time and was ceased, but I managed to get it moving again after a bit of work.
To get this disc mill working again, I also had to learn how to make, break and fit segmented leather drive belts, as the drive pulley is completely enclosed within the cast iron frame of the machine. I had to thread one open end of the broken belt through the frame and then rejoin the belt. I couldn’t find any way to extract the rivets easily from the segmented belt, so I just cut the head off two of the rivets and then replaced them with small bolts and washers. It seems to have been successful. It works! But I’m not too sure for how long?
I put ‘locktite’ on the threads, so I’m hoping that they won’t come loose during work.
This sandy stone grit then goes into the ball mill for 4 hours to be ground down to fine dust, ready to be made into glaze.
It’s quite a process and takes all day. And just like a time-saving kitchen appliance, it needs to be cleaned up after use. This cleaning and relocating of the ‘friendly’ dust extractor proboscis from machine to machine takes more time than the actual crushing.Such is modern convenience.
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