Safety And Security

I tried to imagine all the things which could happen - fire, electric shock, minor and major injury, break-in and so on, deciding what I would need to do, and what I would need to do it with in order to deal with the situation. Then I thought of what I could have done to prevent it happening in the first place!

Some areas I covered were:

Fire - precautions, extinguishers, alarms

Electrical - cut-off switches, notices, correct fusing, first aid and immediate action training for shock

Medical - first aid training, medical kit, immediate action required in case of serious injury Security — locks and alarms

Dust - dust explosions in workshops are not unknown.

My wife was - willingly - included in all the training and planning, as she is most likely to be first on the scene if I am incapacitated. I took advice from relevant experts, added a bit of common sense, made my plans and installed the necessary equipment.

roofing felt with strong tape, available from builder's merchants, to vapour-seal and draught-proof it.

The floor was boarded over and racks made to store the wood. Sealing the wood store in this way means the dehumidifier can be used to keep the wood conditioned ready for use.

Again, I installed a small Ebac dehumidifier which is run for intermittent periods when the wood store is closed up for some time.

left: wv 2000 dust extractor with under-floor trunking. Planning at the moving-in stage allows for efficient installation

Dust and air

I was determined to do all I could to reduce workshop dust. The technical department at Axminster Power Tools designed a dust extraction system to meet my requirements, based around their WV 2000 vacuum dust extractor which I was able to mount downstairs in the garage.

This type of dust extractor filters the fine dust out as well as collecting the chips and shavings.

It was connected to the static machines upstairs by an under-floor ducting system, mainly comprising standard 4in rigid plastic soil pipe. The system can be reduced down to small diameter hose for use on sanders, routers and the like.

By using the extractor points and blast gates for the fixed machines, along with a small portable hose and nozzle, I can even vacuum the floor with it.

Below: Assembly area, incorporating the all-important HiFi

The Relax stove is designed for the job, with all accessories available, and produces a phenomenal heat output.

The suppliers at The Hot Spot gave me a great deal of useful advice concerning size of stove required and flue arrangements, siting and precautions.

Good housekeeping, care, and common-sense should be applied to the siting and use of such a stove, and, of course, fire precautions, extinguishers and alarms are essential.

The house and workshop alarm system includes a workshop heat detector and a DIY-type of ionising smoke alarm; this tends to be less affected by dust than the optical type. One alarm head is linked in the workshop and another in the house.

Triggering either sets off both to give warning of impending doom at that location. They are available at electrical suppliers, for about £10 per alarm head.

"If only someone would combine this air filter with a dehumidifier at a sensible price..."

Wood store

I converted the small loft over the workshop into a wood store by sealing the overlaps of the inside

above: a heating solution that not only Keeps the workshop warm, it keeps it tidy

BEtOW! Microclene air filter mops up ambient dust

All the various connections and fittings required to tailor-make a system are available from APTC, whose technical department are extremely helpful with design and advice.

The system works very well, providing a noticeable difference in environment.

The noise level from the WV 2000 extractor is quite high, so siting it out of the workshop is a great advantage. The downside is that in winter it will suck out my precious warmth, so I may duct the filtered warm air back into the workshop in due course.

I installed a Microclene air filter to complement the extractor by filtering, cleaning and recirculating the ambient air. Because of its noise, it is used specifically to clean the air of dust not extracted by the main system - by hand-sanding and routing for instance.

It accomplishes this effectively in about 20 minutes - if only someone would combine this air filter with a dehumidifier at a sensible price...

Local advertising

Now that I am in my new area I have to set up the local business again. That involves letting people know I am here and what I do - after I have fitted the new security locks!

I will employ my tried and tested methods of local press, local shop windows, exhibitions and glossy national mags.

One idea came through my letter box as I was writing this article - a Pits business card with a photo of my work on one side and message and address on the other. They are produced at less than half the price I paid for my last set of ordinary printed business cards, and they are currently offering a further discount.

I was very impressed with their excellent offers and they seem very accessible to the idea of offering discounts, so it is always worth asking their advice on the matter.

I put a lot of work into this new workshop, trying to learn from my experience in the last one. It won't be perfect I'm sure, but it will be better, and I'm happy that it is a lot healthier.

SUPPLIERS

Axminster Power Tools, tel 01297 33656 Microlene Air Filters, tel 02392 502999 The Hot Spot Stoves, tel 01889 562953 Ebac, tel 01388 602602 Pits Cards, tel 01934 603600

above: a heating solution that not only Keeps the workshop warm, it keeps it tidy

ABOVE right: Roof space timber store and conditioning room

BEtOW! Microclene air filter mops up ambient dust

ABOVE: End-grain, split and unpainted

Assessing and dealing with movement in wood, starting with drying

Coping with stress

LEFT! End-grain, split and nailed

WOOD IS not inert — it moves! This fact should be uppermost when designing or making anything in wood.

I do not intend to go into great technical detail concerning the physiological reasons for such movement, but rather to concentrate on the practical steps to take to avoid furniture-making disasters.

I am assuming that the timber purchased has been air- and kiln-dried, and that the finished piece is intended for use in a centrally heated house.

The movement I am addressing here is not that caused by bad making or unsuitable design, but by the inherent nature of the wood itself.

It's of two types — movement caused by the release of stresses in the fibres by machining and dimensioning, and that caused by changes in moisture content.

Air-drying

Timber in the round may contain half its weight in water, so the felled tree must first be cut into boards and left to dry out.

Once cut to thickness the boards are separated by sticks about 25mm (lin) thick which are stacked outside to dry.

The ends are painted or have a stick nailed to them to slow down the more rapid loss from the end-grain, so reducing splitting or checking.

During the drying the stresses released by cutting the fibres of

ABOVE: End-grain, split and unpainted wood, and those caused by the drying process itself, balance out. This takes about one year per inch thickness of the board.

The wood can then be said to be seasoned, air-dried and suitable for outside use. Very little general shrinkage takes place during air-drying.

Kiln-drying

The timber must now be dried further for inside use. It is placed in a sealed cabinet or kiln, and the humidity level artificially reduced to the required level. The wood loses more water until it is suitable for internal cabinet work.

The majority of the shrinkage occurs during this process.

I have given no figures, percentages of water by weight or relative humidity levels because these are difficult, expensive to measure and not constant.

Air-drying is to the average humidity level in that place at that time. Kiln-drying depends on the operator, and the level to which the wood is taken.

How long the wood has been out of the kiln, how it was stored before purchase, and how it is treated afterwards can also have a significant effect on the moisture content.

"Don't keep it in a damp garage with wet cars coming in and out, or even a dedicated timber store if it is not heated and damp-proofed"

Buying timber

A reputable timber merchant with whom a good relationship can be established is worth his weight in gold. Explain your requirements, ask when it was cut and how long it was air-dried, to what level it was kilned, and buy the best quality material you can afford.

Observe the storage conditions, feel the weight and touch the surface.

I long ago realised that the selection, felling, conversion, drying and storage of timber is a very highly skilled task, one that is best left to experts. What I want to do is make furniture well out of materials I can trust. It is important, however, to take responsibility for the material when it comes into the maker's care, to understand the principles and apply them, and to put the final touches to the process.

Storing timber

Once timber leaves the kiln it starts to adjust its moisture content to its surroundings, so it must be stored in conditions as close as possible to those in which it is to live as a piece of furniture.

Don't keep it in a damp garage with wet cars coming in and out, or even a dedicated timber store if it is not heated and damp-proofed.

Keep stocks of timber in the warmest, driest conditions possible — in my case the area between the beams in my insulated workshop roof.

If the storage temperature and moisture conditions are close to those of the end use, the timber can be stored and conditioned with sticks between the boards, allowing free air flow.

Make sure the sticks are lined

ABOVE! Quarter-sawn oak end-grain table top — right

ABOVE! End-grain, painted up directly over each other so that the weight is borne through the sticks and the boards are not deformed.

Sheets of newspaper can be placed between the boards instead to suck some of the moisture out.

If the storage conditions are not as dry as the end use conditions store the boards flat on top of each other, with no air gap, and cover with a waterproof sheet to minimise the moisture intake.

Moisture movement

The main movement takes place not in the length but across the grain. Movement per inch along the circumference of the growth ring is about twice that per inch between the growth rings.

From this understanding it should be apparent why quarter-

or radially-sawn wood is more stable than tangentially sawn, see diagrams.

The key to understanding moisture-related movement in wood is in being aware that the major amount of movement occurs when the moisture content is reduced from air-dried to a level suitable for interior furniture use and vice versa.

Wood will always move if its moisture content changes, and it will always try to equalise its moisture content to its surrounding environment, absorbing moisture from damp air and losing it to dry air.

As it absorbs moisture it will swell and as it loses moisture it will shrink — no matter how old the wood.

The level of moisture in the air

ABOVE! Quarter-sawn oak end-grain table top — right spacing right: Laburnum oysters showing growth ring circumference and

End Grain Desk Top

above: Drawer casings in stick with a weight on top

Distance between rings

  • gt; Growth ring circumference
  • k Growth rings above: Movement is twice as much per inch along circumference as between growth rings; more shrinkage on the long outside rings causes checks and cracks

above: Tangentially-sawn elm end-grain table top — wrong above: Drawer casings in stick with a weight on top

"The desk shrank, took up all its allowance and cracked along the top. My client said that when they entered the room they had to hang out of the windows to breathe!"

spacing

Distance between rings varies from summer to winter, warm summer air holding more water than that of cold winter. When this winter air is brought inside and centrally heated it can hold more water, which it takes out of its surroundings.

Drying effect

This is the drying effect which causes shrinkage in wood. The change of moisture content in the air — relative humidity — together with temperature and weather conditions, causes most solid wood furniture in a centrally heated environment to be in a constant state of movement from summer to winter.

It tends to swell in summer and shrink in winter, but fortunately wood reacts slowly to changes of humidity so the movement is gradual.

Moisture content change varies according to the variety of timber. I usually allow for about 3mm ('/sin) movement per 300mm (12in) of width of board across the grain direction in normal conditions, but adjustments must be made in the light of experience, and the end use conditions.

It follows, then, that establishing the likely conditions in which the piece will end up is important when judging the allowance for movement.

A desk I made recently in best quality, kiln-dried, quarter-sawn oak (Quercus robur) was left in a room unoccupied for some weeks in mid winter, with the radiators left inadvertently at full

  • gt; Growth ring circumference
  • k Growth rings chat with no thermostats!

The desk shrank, took up all its allowance and cracked a full 3mm ('/sin) along the top. My client said that when they entered the room they had to hang out of the windows to breathe!

Fortunately he accepted responsibility and a repair was made to everyone's satisfaction.

After six weeks near a radiator in Bowes Museum the drawers of the Apothecary's Chest in bun-elm (Ulmus procera), simply above: Movement is twice as much per inch along circumference as between growth rings; more shrinkage on the long outside rings causes checks and cracks right: Laburnum oysters showing growth ring circumference and above: Tangentially-sawn elm end-grain table top — wrong

Distance between rings

Distance along growth ring

Distance between rings

Distance along growth ring

Movement direction

Distance between rings

Movement direction

Distance between rings far left: Small amount of growth ring circumference included, movement fairly even and at right-angles to the faces, minimising distortion

LEFT' Little movement in the thickness of the board — between the growth rings — but a lot of movement along the circumference, causing the board not only to shrink but to distort or 'cup'

wouldn't open. I was puzzled until I discovered that the museum has humidifiers to protect all the artefacts that don't like central heating, and the wood had swollen, not shrunk as I had expected.

A few days in my warm, dry workshop with the drawers out to allow good air circulation, and some small adjustments, rectified the problem and it is now ready to live in a house again.

Secondary machining

Wood is constructed of fibres all pulling in slightly different directions but balancing each other out. When the wood is sawn or planed some of the fibres are cut, releasing the pull they were exerting, and allowing the remaining fibres to pull the wood into another shape.

The release of stresses is usually a relatively short-term effect in seasoned timber, and once complete should stabilise. If the wood is clamped in position, some of the stresses will be taken out by stretching the remaining fibres, thus minimising the distortion.

Properly seasoned, kiln-dried timber is stable on starting a job, but dimensioning it on the planer or saw cuts other fibres, releasing other tensions.

To minimise the resultant distortion, cut the pieces oversize and leave to settle overnight — or longer — on stickers, under a weight, in a warm dry place.

Finish to size and again store the pieces on stickers with a weight on the top until needed.

Workshop conditions

A warm dry workshop is a prerequisite to serious cabinetmaking.

Look at the basic construction — aesthetics count for nothing if it is damp, or can't be heated. H

ABOVE: Home-conditioning cabinet or kiln

HH'1* Dehumidifier

ABOVE: Home-conditioning cabinet or kiln

HOME-KILNING

A KILN OR conditioning cabinet for home use for small amounts of timber can be made easily. Its box construction uses a home dehumidifier to remove the water from the air and from wood stacked inside.

Make the box as air-tight as possible and line it with polythene to prevent fresh damp air entering, or moisture permeating the walls.

The dehumidifier should be set to the manufacturer's recommended level for domestic interiors, and the water it removes from the inside air piped to the outside.

The wood should be stacked as for air-drying, with plenty of room to allow the air to circulate.

The wood must be air-dried and seasoned first to allow as much water as possible to be removed, the machining stresses to stabilise and the distribution of water in the wood to even out.

This secondary drying process in the home-made kiln should be gentle, with plenty of time allowed.

Assume thoroughly air-dried wood has a water content of 20% by weight. Weigh a test piece and mark its weight on it. After about a month in the 'kiln', re-weigh the test piece; when it has lost about 8% of its original weight it is about ready.

I would recommend that the dehumidifier is not left on all the time, but is switched off every fourth day or so to allow the water in the wood to distribute itself evenly.

I use it very successfully for burr elm (Ulmus sp), which I find difficult to get commercially kiln-dried.

The cabinet can also be used to condition kiln-dried timber for a week or two as a precaution before making it up. Again, the timber is dimensioned slightly oversize and stacked on sticks in the cabinet for a few days.

The longer such timber has been out of the kiln, or in poor storage conditions, the more important this is.

below: Photo 2 Lid open, showing braces

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