Shedworld

Workshop Shed is featured on ShedWorld, a new site by ShedMan John Davies, a writer and poet from Brighton. As part of National Shed week, ShedWorld is uncovering the diversity of activities (and relaxation) that people do in their sheds by asking them "What do you do in your shed?"



ShedMan has travelling the world finding out what people do in their sheds, and you'd be quite surprised with some of the thing he's discovered.

No Voltage

A local powercut launched a discussion about what would happen if I'd been machining something in the workshop whilst that happened. Well if it had been dark it might have been a little scary whilst all the equipment powered down but assuming I did not move into the path of the slowing equipment then I would be fine as long as I waited till it all stopped.

However, it could be a different matter when it all starts up again. If I did not unplug or switch, when the power came back on it would start up again. There is however something that can be done about this.



There is a clever little gadget called a no voltage release switch (NVR Switch) that turns off the switch when power is cut. I believe that many new tools contain one of these built in and it's possible that my pillar drill and bench grinder (offhand grinder) do have one already. I'm fairly sure that the lathe does not as it is older. Some NVR switches also come with a built in safety switch and some even allow additional switches to be wired in to multiple safety switches or a remote control facility. These are also known as "Undervoltage triggers" in some parts of the world.

So far, the following suppliers have been found that provide NVRs that can either be mounted on the wall or are in the form of an extention cable and hence could be used with the lathe. I've also seen NVRs on ebay that could be wired internally to some equipment.

• Axminster
• Poolewood
• Wealden Tool

I would be interested to know if there are others, particularly if it's possible to get a smaller (or perhaps just flatter) device that I could mount inside my mini lathe.

A related device is the safety interlock switch which is the thing that turns off the power when you open the case of your machinery, it stops you sticking your fingers into the spinning wheels of the drill's gearbox for example. It's might be a good idea for me to have one of these on the lathe too.

Tool storage and metal stocks storage

A few weeks back I was lucky enough to get hold of some wire mesh trays in the sale (a cuttlery holder from Tesco and a letter tray from WHSmiths). The cuttlrey tray has proven to a good container for storing my metal bars and rods (it could be a little longer) and the simple letter tray is great for storing some tools. The mesh is soft enough and fine enough to avoid damaging the metal but strong enough to hold a good quantity of tools or metal.

My problem is that now I want some more and no-one is doing them in the sale. My options are to wait till more are on sale, take a visit to Ikea (who appear to have similar items) or to get some mesh and make some of my own, being in a creative mood at the moment, this is probably what I will do.



On a related note, for long term storage of tools (or metal stocks) it's often recommended to wrap them in oiled brown paper. I discovered today that Chronos supply "Antirust" paper or to give it its propper name "Volatile Corrosion Inhibiting Paper". I'm not sure if this is significantly different from brown paper soaked in WD40 but it seems like a good investiment if you have some valuable items like chucks or cutters to store.

Clocks, robots and electric motors

An aspiration of many an model engineer is to make a clock. Roger Wood of Klockwerks has made hundreds of clocks in his livein workshop in an old munitions factory in downtown Toronto making a range of fabulous clocks. The clocks are made from found items (or scrap to us).

Gordon Bennett of Bennet Robot works also works with previously loved materials. His robots are all unique (complete with tags) and made from materials such as bakelite, metal and rubber.


David House of the Old Model Company prefers to keep things a little more conventional. His old electric motors are all exact replicas and show how the "pioneers of the time tried to mimic steam engine technology".

Building the flowerpot furnace

2020 Vision said: "Just wondering how you got the air into the flowerpot? Was it through the holes at the bottom or did you somehow cut a hole in the side? I would have thought the latter could weaken it."

Well the answer is yes, it probably did but this should not actually matter. The reason for this is two fold. The first is that the flower pot does not have to take a lot of weight, a small amount of charcoal and a full crucible are probably still a lot less than it's normal load of wet soil. The second reason is that the whole flowerpot is surrounded with mortar, at this point it's about 30mm thick.



When constructing, I followed the instructions from the Back Yard Metal Casting book on the flower pot furnace. I made a couple of changes. The first was that my outer "can" was in fact a fine wire metal waste paper basket. The second was to do with this hole. I could not work out how it was going to be drilled after the mortar was added so I drilled my first using a tile bit and cut one in the basket using some snips. This gave me a new problem of how to line up the two holes. I solved the problem by adding enough mortor in the bottom of the bin so that the flowerpot could be added, I then used some rolled up cardboard to span the two holds and packed the rest of the motor around then. After a few hours of drying, I removed the card and increase the size of the hole so that the air pipe would easily fit.

The hole in the bottom of the flowerpot is blocked up with mortar and a piece of angle iron with extra holes is laid across the pot so that it can spread the flow of air. A couple of blobs of fireclay give the crucible something to sit on. The air enters from the bottom of this photo.


My other change was not really intentional in that I added a new top to the furnace following the main construction so that it was level. Retrospectively, I'd have made more effort to ensure that this lip was part of the main pour. The top edge has now cracked off in just two melts. I'll give the furnace a good soaking (in water) before I try to put some new mortar on, as that should increase the bond.

Blobs to blocks 2

From my second cast, I produced the following two blobs. The left hand one was much better than previous attempts with a large section of straight sides and a better finish. I expect the right one would have been better if it was a deeper casting and had I not run out of metal for it.



These were hacksawed and filed into rough blocks ready for machining. A little like a famous meal with loaves and fishes, I keep ending up with enough offcuts to provide as starter material for the next melt. Obviously as I get better at preparing the molds this will reduce, as long as I'm melting some large blocks (such as the disk drive casings) then this should not be an issue.



Before I can continue with the larger block, I need to make up some suitable clamps or faceplate dogs so that I can attach them to a faceplate. This block is too large to be held in the chuck. The book Workholding in the Lathe (Workshop Practice Series) has given me some ideas on how to make these, I'm planning to make the faceplate dogs out of hexagonal steel rod with M5 clamping screws.

Model Engineer Exhibition tickets on sale next week

The Model Engineer reports that tickets for the Model Engineer Exhibition at Ascot in September will be on sale next week. Also see the website if you want to enter your model in the competition or run your engine on the track.

Special attraction this year will be the inclusion of 2.5km of track so that 5in guage steam trains can be run. This has been imported from Sinsheim in Germany with masses of straights and curves with turntables, traversers and passing loops

Other attractions will be

• Model Engineer Competition
• Clubs
• Displays
• Demonstrations
• Lectures
• Society of Model and Experimental Engineers Low Energy Challenge
• a range of suppliers of both machine tools and metal stocks