WIRELESS

Wanganui Chronicle, Volume LXXXI, Issue 18973, 26 March 1924, Page 7

WIRELESS

By

The Grid

Practical Tips. Last week ‘ ‘The Grid” essayed to writes a few notes on the tools most needed by amateur wireless workers. This week he proposes to give a few tips on the use of these tools. He candidly admits that he is not a trained mechanic aud for this reason he prays the indulgence of those superior beings who daily practise the mechanic’s art. The following notes set out a few of the lessons “The Grid” has learnt from bitter experience with tools over a period which commenced when he first attempted to hammer a nail into a block of wood, and seriously damaged his thumb in the attempt. The homely hammer is a much maligned instrument in many w'ays —in fact it has almost become a stock source of humorous sketches, like mothers-in-law, newlyweds, etc. Enough of the hammer then; let us pass to more interesting tools. The saw is a tool which receives a great deal of abuse; most households possess a rip saw which has suffered such injury at the hands of various members of the family that it will scarcely cut butter. A wood saw is not primarily intended to cut through stray nails and screws in old timber, but unfortunately it is often tried for this purpose. No saw will cut well* unless it is reasonably sharp and properly set. The sharpening is done with a triangular file, the method being as follows: If one looks down the teeth of a saw it will be seen that the teeth bend alternately to the right and left. It will also be noticed on inspecting the teeth from the side, that the front slope is much steeper than the back slope. The reason for this is that the saw cuts only on the forward stroke; The teeth are therefore sharpened by filing away the back slope. But this is not simply filed at right angles to the blade of the saw; u careful inspection w r ill show that the tooth is shaped so that a fairly sharp point is formed. This is done by filing the back of the tooth at a slight angle, which is best understood by inspection of a new saw. When sharpening the saw it should be fixed firmly between two boards in a vise so that the teeth, project only enough to get at them easily. The boards may be shifted along as sharpening proceeds, so that the portion being sharpened is always firmly held. Go down one side first, sharpening the teeth sloping away, then turn the saw round and do the other teeth. The set of the saw is the distance which the teeth are bent over; it enables the saw tc travel smoothly as it works through. The set varies with the type of saw and size of teeth, and it is therefore difficult to give any directions on this point. The necessity fur re-setting will soon be apparent, as the saw will tend to stick when in use. When setting a saw two methods can be followed, the first being the best. A special tool, called a saw-set, can be bought or made, and it greatly simplifies the work. The saw-set is simply a piece of metal about one-eighth inch thick, with slots cut in it of varying width to suit the thickness of the saw blade. The saw is placed in the vise as for sharpening and the saw-set is placed over each tooth and pushed down so as to bend the tooth over slightly. The alternate teeth are done first, usually those bending towards the operator, and the saw is then turned round and the remaining teeth bent over. The amount of set should be as nearly as possible the same for each tooth. If a saw-set cannot be made or procured the work can be done by placing the saw on a board of soft wood, such as deal, and striking down the teeth with a punch. This method is not so accurate as the first, and it is liable to damage the teeth. The above remarks apply to tenon and lip saws equally, but do not answer for cross-cut saws, which are made to cut in both directions and are therefore sharpened and set somewhat differently. When using a saw do not endeavour to force it through the timber. Let the saw cut almost with its own weight and best results will be secured. Forcing only digs the teeth in and makes hard work of it. For cutting ebonite a tenon saw can be used; this work will blunt it rapidly owing to impurities in the material. Remember always that a saw well cared for is a pleasure to use, but one that is neglected is the very devil.

Turning now to the’ chisel, the following points deserve attention. There are two main types of chisel likely to be used by the amateur, these being respectively the hand chisel and the mortising chisel. The first is the common or garden type, which is used for general work. The handle of this type may be either plain or made of strong wood and fitted with a metal collar at the top. The plain type is entirely for hand use, the second type may be used with a maul for cutting slots and so forth. The mortising chisel has a much thicker blade than the above types, and is used for making deep slots and mortises. It is fitted with a strong handle so that a maul can be used. Chisels are sharpened by grinding on a grindstone to a rough edge and finishing on an oilstone. Care should be taken to see that the edge is kept square with the sides and that when grinding, or finishing on the stone, the chisel is held and kept at the proper angle. Water should always be used to moisten a grindstone, and oil an oilstone; if this is not done the temper of the steel will be spoilt by the heat generated. ' Do not use a chisel for removing tacks from the floor, it is apt to spoil the edge! Somehow the fair sex seem to think this is quite a legitimate use for chisels, but if care is taken to keep them out of sight this trouble will be avoided. Screwdrivers need little comment, as their use is fairly obvious. A strong tendency to use them for cold chisels should be combatted if possible. The steel in a screwdriver is usually not tempered very much, otherwise the edge would be liable to break and chip. An old filo can therefore be used for tracing up a screwdriver, although a grindstone or emery wheel is better. The edge of a screwdriver should be kept square but not made sharp. The blade should taper gradually and not suddenly just at the tip. Strictly speaking, each different size of slot should have its own screwdriver to fit exactly into it, but in practice one driver usually does duty for many sizes of slots. Several sizes of screwdrivers should bo kept if possible. The file is another much used too; it

unfortunately receives also a lot of abuse. Files are of many types and sizes; the types in common use are the flat file, the triangular file, the round file, the half round file and the square file. The first three types are most useful. There are varying degrees of coarseness of the teeth, which again classify the files into the following grades: Rough, bastard, secondcut, smooth and dead smooth. For wireless work the second-cut and smooth grades are most useful. Eight inch files will be found large enough for most purposes. The teeth of a file are very brittle and for this reason a filo should never be thrown down on to other metal tools. Each file should be fitted with a handle and be hung up after use. New files should be kept for copper and brass, while as the file gets worn it may in turn be used for cast iron find wrought iron and steel. Do not use a new file on hard steel as this will ruin it very quickly; similarly do not use it on lead as this will clog the teeth. When filing remember that the file is like a saw tnd cuts only on the forward stroke. The pressure should therefore be taken off as the file is drawn back. Properly used, a file will last a long time, but ten min- * utes' ill-use can easily ruin it. Another tool in common use (and abuse) is the twist drill. This tool will go through almost any material used by the amateur except cast steel, but different materials require different drilling speeds if the drill is to be kept in good order. As a general rule it might be said that the harder the material the slower the drill will cut and therefore the more care must be taken. When drilling elbonite it is advisable to work the drill fairly fast but with a light pressure; if the ebonite is thick the drill should be withdrawn every half inch or so to allow the shavings to get clear. If a heavy pressure is used on ebonite the drill will generate heat and soften the ebonite, thus causing the drill to run out of truth and also to stick. Experience alone will show how to use a drill on the various materials, but a safe rule is always to avoid undue pressure. It is quite easy to make the point of a drill so hot as to spoil the temper of the cutting edges. Care should be taken when drilling right through material that the pressure is taken off just before the drill breaks through. If this is not done the drill may jam and break, and even supposing this does not happen, it may tear out a piece of the material just as it comes through. Ebonite is very easily damaged in this way. The sharpening of a twist drill is a fine art and it is quite impossible to explain it in a short article. The best “The Grid” can suggest is that the amateur should get a new drill and thoroughly examine the cutting edges. He will then see what he has to aim at when he attempts to sharpen an old drill. Small drills can be sharpened on an oil stone, but large drills arc best done on emery wheels with a finishing touch on an oil stone. When sharpening a drill on an emery wffieel it is a good plan to have a can of water handy into which the drill can be dipped every few seconds. This will save both the temper of the drill and your own temper also.

“The Grid” finds that these notes have thken rather more space than he expected, and he must therefore postpone his intended comments on soldering, tapping and screwing, etc. He once more asks the indulgence of the trained mechinc, to whom the above notes will seem simple and self-evident. The untrained amateur usually ’finds great difficulty at first in using* the differt tools and it is “The Grid’s” desire to assist him if possible. D.X. Work. “The Grid” acknowledges with thanks the following report from Mr W. G. Cooper, of Rapanui:— “I am very pleased to report to you reception of telephony and music from a broadcasting station in Ohio, U.S.A. Unfortunately I was unable to get the call, but distinctly heard the announcer give the State, and also the time, 1.44 а. saying that he was now closing down. This was about 6.55 p.m. New Zealand time, thus a little calculation proves the authenticity of the reception. Also the same evening just previous to this I had been listening to K.G.0., Oakland, California. He was remarkably clear, his speech being even better than his music—which was an orchestra from one of the ’Frisco hotels. I was using 3 valves in each case—the first being H.F. (transformer coupling). On most evenings now from б. on it is possible to pick up as many as three or four carriers from U.S. stations, but it is only occasionally that one obtains really good reception. Spark is the worst interference, static being usually quieter at that hour than later in the evening. The Sydney stations 2FC and 2BL continue to come in well—the latter, Sydney Broadcasters, from the Daily Guardian Newspaper Office, Philip Street, Sydney, being easily the better. 2GR is worse on 1100 .metres. 2GR (Marks, Rose Bay, New South Wales) has also been heard testing quite a lot lately. He seems to be dead on lYß’s wave and they often jam each other. 2GR’s carrier has a bad chirp in it. There is a big improvement in the N.Z. stations during the last couple of months. IYA is now the best for modulation, and the fading which used to be so noticeable seems to be now almost non-existent.”

“The Grid” is always pleased to receive reports from amateurs in the district and hopes that more of them will take the trouble to record their results. In future years some written record of amateur wireless progress in this district will be of great interest, while at the present time the publication of results tends to stimulate other amateurs in the right direction. “The Grid” particularly desires reports of the apparatus used giving details of the size of coils, number of turns, etc. It is only by exchanging ideas and results that progress can be made, and amateurs who refuse to assist others in this way are deserving of little credit. General Notes. “The Grid” learns that a wellknown local amateur has been getting Yankee amateurs quite loudly on one valve during the last few evenings. Coils used; solenoids, four inches diameter, primary 15 turns, secondary 27 turns and reaction 40 turns. The local club-station continues to

put out good programmes. Reports from Timaru and Christchurch were received last week. It is a pity that the very noticeable echo ; caused by the plaster walls in the Y.M.C.A. cannot be overcome. This rather spoils instrumental and vocal items for local listeners, although the echo is apparently not so noticeable at a distance. “The Grid” is at present carrying out some experimental work with the bockaday circuit. He hopes to publish full details in the near future. He is using a C 299 valve, the filament being lit from a pocket torch battery. While not very sensitive, this valve is very handy for experimental work since it is so compact.