Design and construction - other


In this column

My workshop

A sheet metal workbench and machinery
A wood store
A chainsaw stand
Steam bending of wood
Safety in sheet metal work

My workshop

Above, part of my kitchen-workshop, not in the least elaborate. Most of my work is carried out with portable tools in the open air. On the workbench here there are three tools which do use mains power, from left to right, a router, with attachment, a drill press and a saw, manufactured by 'Evolution,' which can cut a range of materials, structural steel as well as wood. There are many more tools than the ones shown here. Some of them, including a chainsaw, an electric planer and a rotary sander are stored underneath the bench. Others are stored in tools cabinets in the workshop, or on one of the walls not shown here.

Above, a closer view of routing equipment

Above, another view of the workbench, showing some of the large area available for storage underneath the bench. As will be obvious, the workbench top was constructed using a wooden door (with a layer of plywood underneath. The four  recesses in the top of the workbench are useful for retaining a wide range of tools, fixings and other items, largely eliminating the risk of accidental falls  from the bench onto the floor.

A sheet metal workbench and machinery

Above, a view of part of the machine I designed and built for bending sheet metal and for making the cutting of sheet metal easier. It's also a workbench for general sheet metal work (to mention just one activity, joining sheet metal sections by riveting) and a supplementary bench for other work, such as general metalwork and woodwork.  It can be used for joining sheet metal sections by riveting, for example.  It's housed not in my workshop but in another room. The sheet metal is fed into the machine between the two perforated steel bars. I already owned a machine for bending sheet metal but the maximum width of the sheet metal which the machine can bend (by non-hydraulic power) is only 600 mm. This machine will bend sheet metal up to a width of 1300 mm by hydraulic power.

I made use of webbing straps (one of the two red straps visible here) rather than steel components when the forces are purely tensile, not compressive. I think this is a very useful design feature, which can be used in machines of many different kinds. Webbing straps can withstand considerable forces without breaking.

When the machine is used for cutting sheet metal, the sheet is placed on top of the two long and strong boards which form the upper surface and secured with clamps - there are two G-clamps which can be seen towards the left. To the right of the G-clamps is another clamp. Its main use is clamping  metal which is being drilled in the pillar drill of the workshop. On the far left is the equipment which does the cutting (Stakesy's throatless hand shear.) On the right is a bench swager and slip roller used amongst other things for strengthening sheet metal. On the nearer of the top boards is a router guide, useful for measurements of length.

To cut the sheet metal, the cutter is placed within the channel which separates the two boards, at one end of the channel. The channel is 12 cm wide and 10 cm deep. The cutting blade is at the correct height for cutting the sheet metal. In this position, the cutter can be moved forward. As it advances, the handle is operated to cut the metal with the blade. The cutter can be used without the machine, but it's much harder to obtain a straight cut - if a straight cut is the intention. The machine, and the separate cutter, can also be used for curved cuts. Again, the machine makes the process easier.

A wood store

Above, an outdoor project, in the backyard / back garden - a very simple structure for storing wood to be used in a multi-fuel stove. The wood store is in my small back garden. The wood store is constructed from off-cuts of railway sleepers, which support horizontals made from decking boards. The store still has to be finished with oil/varnish after it has dried out. The log sections here still have to be cut into smaller sections for seasoning.

A  chainsaw stand

Another outdoor project, a stand for supporting a chainsaw, used for sawing logs and branches, particularly repetitive sawing. A safer way of using a chainsaw for tasks like these. This chainsaw has now been replaced with a better model, a Grizzly chainsaw.

Steam bending of wood

Above, two views of the equipment I made for steam bending of wood. The wood to be bent is placed in the inner steel container, which is filled with steam from a steam generator. The container is well insulated with the foam, inside the larger steel container. Next to the steam bending equipment, the chainsaw stand.

Safety in sheet metal work

Above, reducing dangers in sheet metal work: unprotected and protected corners of sheet metal sections. Unprotected corners are very sharp corners, which can kill or injure.

Experienced sheet metal workers know about the hazards of sheet metal and take good care to avoid them. Even so, they may well be injured, perhaps when they're very tired and don't keep well away from the hazards, which include not just sharp corners but jagged edges of sheet metal.

The companies which sell sheet metal, in my experience, take absolutely no interest in matters of safety. They may assume that every customer is an experienced sheet metal but someone who has only recently become interested in working with this very interesting material is able to take away the sheet metal, with unprotected corners. Sheet metal comes in large sheets. Moving them calls for great care, but even with great care care, accidents can easily happen, when sheets have to be taken up stairs or moved round corners, for example.

In the lower part of the image here, the corners are made more or less harmless by the addition of plastic corner pieces. I use the plastic pieces which are sold to hold together loose printed sheets, easily obtainable from shops which sell stationery materials. It's just as easy to protect any jagged edges of sheet metal in the same way, although it will take more of these plastic pieces.

I'm glad that Dr Marcus Bowman points out the dangers in his book 'Sheet Metal Work.' It's one of the books on sheet metal work which I own. In the chapter 'Safety First,' he writes,

'Because the edge of a sheet is so thin, the pressure it exerts is very high. You might get a nasty bruise or even break a bone if you strike your hand with a hammer or a large flat piece of metal, but strike your hand with the edge of a sheet and the injuries are likely to be much more severe ...

'The edges left after a cutting operation usually have a fine, almost invisible burr which acts like a sharp razor saw ... Yes, the edges of sheet metal deserve the utmost respect. Whenever possible, avoid handling the edges of sheets, and atthe very least, wear good, heavy-duty, procetcive gloves of leather or Kevlar, and do not allow your hand to slide along an edge.'

He also writes well on the risks to hearing and sight, including this:

'Wear good eye protection made to proper industrial standards at all times.'

He gives many recommendations inthe section, 'Creating a safe environment' including this,

'Watch those sharp corners if you are moving sheets when others are present ...' but of course, there's a need to watch those sharp corners when others aren't present. It's much better to take great care but to have the sharp corners made blunt and more or less harmless by such a method as the one I've suggested.

In this column

A hydraulic apple press
A workbench- innovation is still possible

A hydraulic apple press

Some advantages of the PHD apple press, which is suitable
for a wide range of users. It's suitable for the owner of a small orchard, for a person with a few apple trees or a person who can obtain apples in quantity - but it's large enough for (very small-scale) commercial operation.

It's cheap to construct. The cost is less than 250 GBP.

It's easy to construct, if the cross-beams are made of timber rather than metal. Wooden cross-beams will have to be much thicker than the steel cross-beams used in my model, although thinner wooden beams can also be used - simply use more of them. More about drilling into metal later. The basic structure is very simple - paired hollow section steel horizontals, painted black here, and paired wooden horizontals at right angle to the metal ones. (Alternatively, the metal horizontals are replaced with thicker wooden ones.). There are four uprights, not, as in many designs, two. These consist of four threaded rods, without the need for a separate stand to support the structure. The pressing has nearly always been carried out at the orchard but here, it's  carried out in a room in my house - excusable, I think. The weather has been poor.

The arrangement for halving or quartering the apples and pulping the apple sections, prior to pressing the pulp:

The design makes for a convenient, efficient work-flow. Everything is near to hand. Apples can be taken from the container, cut into pieces on the nearby horizontal wooden support, thrown into the scratter (which is nearby) and ground into pulp, which falls into the tray, all without unnecessary movement. The only time that it's necessary to move from the spot is to operate the wheel of the scratter (if a helper isn't available.)

The wooden board can be placed on the horizontal members of the upper level, which form a flat surface, once two smaller wooden horizontals, provided with clips, have been put in position. The bin is supported by a metal bar (inside the larger hollow steel section) which can be extended. Later, it's returned to its original position. It gives extra structural strength to the larger steel section. On the lower level are some of the various items that will be used during pressing.

During the apple pressing process, it may be convenient to have a larger working surface available than the small wooden rectangle shown above. The large wooden tray can be taken from the lower level and placed on this higher level. Obviously, it may come in useful at other times, and for other purposes, throughout the year, in fact.

This photo shows some of the other components of the press, the hydraulic bottle jack and the pressing sunface. It also shows some optional additions to the structure. As well as the four main threaded rods, four smaller diameter threaded rods can be used, attached to two small metal sections. Two of these smaller rods are shown here, in front of the main rod. These are necessary if a higher capacity jack is used.

The press can be used on uneven ground as well as flat surfaces, if the position of the nuts is adjusted. This will often be useful in an orchard. If the press is placed on a hard surface, as here, castors can be fitted very quickly. The two sub-units at the ends of the top hollow section - they contain the four smaller diameter threaded rods - are removed by loosening four nuts. Here, the two units are shown against a door.

Four casters are screwed into the lower ends of the threaded rods and then the two sub-units are put back at the ends of the steel horizontal. One of the castor-pair at the end of one of the sub-units. One castor in each pair has a brake to stop movement when it's applied.

If castors aren't used, the press can be moved short distances by two reasonably strong people. The press can be dismantled easily, simply by loosening nuts or pulling away pieces with clips, and it can be re-erected very easily. None of the separate pieces are very heavy. The heaviest are the two hollow section horizontals. Each one weighs about 2.8 kg.

The main items to be bought or acquired, if the version with metal cross-beams is constructed. The prices given are the approximate ones I paid, except for 12+mm threaded rods (I used the ones I already had, which happened to be stainless steel - much more expensive than the price quoted below. The cheaper ones are completely suitable.

The most expensive item by far is the one given first:

4 sheets of HDPE sheet for the racks of the press (many people would use 5 or perhaps 6): 72 GBP. Plywood sheets can be substituted - much cheaper and perfectly usable, even if less easy to keep clean and less durable.
Threaded rods, 16mm diameter: 19 GBP for a pack of 5 (only 4 are used.)
Threaded rods, 12mm diameter (if the optional units shown in the photo above are attached to the ends of the upper metal cross-beams): 8 GBP.
Two lengths of hollow rectangular section structural steel: 15 GBP.
Bottle jack (I used an 8 tonne hydraulic jack, the minimum size recommended for a press of this size): 25 GBP.
Curtain net, to make the cloths which are filled with apple pulp in the former before pressing: 9 GBP.
Waterproof, food-safe cloth (manufactured by Pro-care), used for lining the tray, with an outlet to direct the apple juice to a storage container (other options, a stainless steel tray or varnishing the tray with a suitable product): 30 GBP.
Timber board, to construct the tray (a piece was left which can be used for the support for chopping boards when the apples are halved or quartered): 30 GBP.
Other wood, to construct the wooden horizontal members of the frame, the top plate and the form (I used ordinary softwood, spruce): estimated 15 GBP.

If castors are used, these will add to the cost. I paid 40 GBP for the four castors.

In addition, varnish was used for the wood and metal paint for the rectangular section. I used two convenient products, very easy to apply, Ronseal diamond hard Interior Varnish and Hammerite direct to rust metal paint. Costs not given here: only a small part of the contents of the containers had to be used.

It's easy to construct the version with these metal cross-beams, if  a bench press or larger press is available for drilling the holes. Ordinary portable drills can also be used, provided they have the necessary power and can take a 16 mm drill bit, and provided the person doing the drilling is cautious but confident - when the drill bit begins to break through the metal, there are large torque forces and the drill has to be held very firmly.

A workbench - innovation is still possible

More images of the workbench in the section my workshop.

No innovations are possible in workbench design and construction - everything that could have been thought of has already been thought of. That's a common opinion, but I don't share it. I'd claim that the PHD workbench does include innovations, even if the innovations aren't dramatic. Of course, I don't claim, of course, that an improved workbench necessarily leads to improved woodworking or metal working.

There's general agreement that a good workbench has to be solid and heavy, to provide a stable base for holding the wood or metal which is being worked. I don't dispute that. I think the same. The workbench I've designed is solid and heavy.

Manufacturers charge much more for very solid and heavy workbenches than  for very light and flimsy ones, but this one is cheap to construct. I used an old door for the top of the bench - it had been thrown out and put in a skip - together with a plywood sheet, but if a free-of-charge door can't be found, the cost of the workbench is still very low. For reasons I explain later, I put the door on top and the plywood sheet underneath. Anyone who wants to build a similar workbench and has a usable door is completely free to do it differently.

The door has an obvious flaw - there's a hole at one side where the lock was. The standard way of dealing with the hole is to use filler or to plug the hole with a circular section of wood, although it's  difficult to disguise holes of this size. The hole can be hidden very easily, for instance, by bolting a pillar drill in this area (a thick support is underneath the bench here.)

Workbenches which are solid and heavy are difficult to move. Shifting loads of this size is a job which should preferably be avoided. Changed circumstances may make it essential to move a  wonderful and very substantial workbench some distance. There are any number of reasons - a bad leak in the roof above the workbench, the purchase of a new piece of equipment which would be better off in the place where the workbench is now ...

This workbench is very easy to move, as I explain now. Workbench design doesn't have to be like tent design - the ideal backpacking tent is very spacious, very light, very strong - capable of withstanding gales - very cheap, very easy to erect and very easy to dismantle. In tent design, far more than workbench design, the problem of incompatible ends is a real one. In workbench design, it's much easier to achieve advantages without corresponding disadvantages.

We can move the workbench within the workshop or working area very easily, without taking it to bits. We can move the workbench longer distances by taking it to bits, something which is very easy. It's just as easy to assemble it.

How do we move such a heavy object within the workshop or working area? Answer, the bench has a jacking point. Place a heavy hydraulic jack or a small and light hydraulic bottle jack or a non-hydraulic vehicle jack under the jacking beam, at more or less the centre of the beam. I see advantages in equipping workbenches, like motor vehicles, with beams which are strong enough for the purpose. These beams are at the ends of the workbench, not the sides, of course.

When one end is in the air, attach blocks to the two legs - or supporting members - of the workbench at this end. The blocks are equipped with heavy-duty spindle castors. These castors have brakes, so that once the other end is raised, the castors don't move. Operate the jack so that this end is gently lowered and the castors take the weight of the workbench. Go to the opposite end and do the same. There's no need for the castors at this end to have brakes. Once this end has been gently lowered, the workbench is mobile.

Why is this workbench so easy to erect and dismantle? Primarily, because it doesn't rely upon mortice and tenon joints. The pieces which make up the workbench are either bolted together, with carriage (coach) bolts or, in some cases, where strength isn't a necessity, by means of screws, Unlike nails, of course, screws can easily be removed. The screws used in this workbench are substantial ones of M12 diameter, but are easy to insert and remove, with the aid of a club hammer.