This piece first appeared in Practical Engineering 1940 Vol1 No20. The published article is therefore correct as of 1940. The writer shares the latest information related to Engineering at the time.
The outstanding feature of Rickert-Shafer tapping machines is that each machine is “designed for the job." These machines—for which the agents are Messrs. Dowding and Doll, Ltd., of 3. The Green, Wimbledon Common, London, S.W.19—are made with single or double spindles, horizontal or vertical turrets, and usually lin. or 2in. capacities, the various styles and sizes running into literally hundreds of different machines.
A typical example employs a revolving taper die head and can be used for cutting any tapered pipe thread within its range. On a particular job - 'malleable iron couplings for air brake hose’ - the production speed was 11 pieces per minute threaded lin. 11 1/2 pipe thread. This is much faster than could be achieved on a turret lathe.
The design of the majority of these Rickert-Shafer "D.F.J." machines is basically similar, and consists of an indexing turret containing holders into which the pieces to be threaded or tapped are inserted. With each index of this turret a piece is brought into the machining position—and the completed piece is ejected.
The die head or collapsible tap (as the case may be) for cutting the threads is mounted in a revolving spindle, which is automatically advanced to and withdrawn from the work in exact timing with the indexing of the turret. Any revolving self-opening die can be used, although the R-S die head is usually selected and ordinarily will give the best results because it has been developed especially to serve as an integral part of machines of this particular type.
The new B.E.N. No. 249 blow gun has already proved its value in machine shops, engineering works, aircraft factories and, indeed, in industries of every kind. Wherever dust, dirt, filings, cuttings and similar matter have to be removed from machinery, metal and other surfaces, this blow gun provides a speedy, safe and most thorough method of removal, is at once far more efficient and far safer than the use of rags, brushes or hand bellows.
Made of aluminium, the No. 249 blow gun weighs under 1lb., and is so shaped that it fits snugly in the palm of the hand. It is so designed that when not in use i. can be easily hung from a hook. Control is by a push-button throttle, conveniently situated, and a bronze nozzle and male screwed end hose connection of 1in. diameter are provided. Both nozzle and valve are renewable, and the former, which is available in several diameters, can be supplied in an insulating material for greater safety in electrical work.
The makers are B.E.N. Patents, Ltd., of High Wycombe, Bucks.
The Schori portable acetylene generator is a British-made high-pressure plant combining the efficiency of dissolved acetylene with the cheapness of self-generated gas. There are two different sizes on the market at the present time; one model is 34in. high, 12in. diameter, and weighs 77 lb., and the other one is 44in. high, 16in. diameter, and weighs 119 lb. The smaller plant takes a charge of 4i- lb. of 50-80 carbide, equal to 22i cu. ft. output, and the larger one 'll lb. charge, equal to 55 cu. ft. output. Both types are portable and can be used everywhere, indoors or outside, without any special installation of pipe fines, etc.
The generator offers to the user, in comparison with dissolved acetylene, a saving of about 70 per cent. The average price for dissolved acetylene is £6 10s. for 1,000 cu. ft.; the same amount can be produced by the Schori plant for £2, owing to the fact that the generator requires 2 cwt. of carbide at 20s. a cwt. to produce 1,000 cu. ft. of gas.
Although this saving is considerable, the quality of the work is in no way affected. The flame from the blowpipe connected with the generator does not show any fluctuation, and the gas is cool and clean, suitable for the most complicated and difficult job.
The reason for the quality of the gas is the fact that it has to pass the purifying and cooling water of the hydraulic valve before it can be drawn from the outlet. If the plant is not in use it stops generating automatically by water displacement, so that every ounce of the carbide charge can really be used and any waste of carbide or gas is avoided. No gas can escape, as the plant is hermetically closed, and the user will find the generator, even after a week, under the same pressure as he left it.
Low-pressure and high-pressure tools can be used, so that no other expenses are involved, apart from the outlay for the plant. Besides avoiding any waste, the oxygen consumption is 10 per cent, less with the Schori plant, which produces enough pressure to make additional oxygen unnecessary to draw the gas out of the blowpipe.