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dommekracht / jack

ALEX DEN OUDEN
EINDHOVEN - NEDERLAND

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Oude techniek en werktuigbouw,
industriŽle geschiedenis en archeologie
Historical engineering and technology,
industrial archaeology and history
© AdO 1998 ... 2004

     


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Can beeswax be used as dopping wax (arcanson) to hold small metal parts on a lathe?

It is a well-known practice in laboratory optics to use beeswax for affixing lenses to arbors for grinding. Would this method also be suitable in turning small metal parts on a lathe?

Well ... using beeswax for "dopping" in optics is only practical when large contact areas are available and then only for the lighter jobs like polishing. You see, pure beeswax gives a rather weak binding. For heavier (grinding) operations, more sturdy stuff is required. In these cases, the beeswax is "strengthened" (mixed with various substances to increase both adhesion and strength). Such mixtures are generally known as "dopping waxes". Various proprietary brands can be obtained. Similar waxes are also applied in grinding and polishing gem stones. They set quite hard and hold pretty well. Nevertheless, a finished part can easily be removed from the dop. A short and sharp tap (with a light wooden or hide mallet) should do the trick. If this won't work, the dop with attached part can first be refrigerated to make the wax brittle. It then easily releases its hold on the finished part.

O.K. So far for the optical use. Now for the real question. How about machining metal on a lathe? It would certainly be helpful if we could use some kind of wax to fix small parts of intricate shape to the lathe faceplate.

Yes. You may be sceptical, but it's been done. But in all honesty, the method is not really very usable. One slightly too heavy cut, and the part moves on the face plate; it even might drop off completely. The risk of failure is just too great, I'd say, to think of applying the method in practice.

So the proper answer should probably be: no, you can't use beeswax in metal turning, at least, not reliably.

Historical

As a consolation, a few notes on this stuff, mainly of historical interest, but fun to know.

Frenchmen call the stuff "arcanson". I found some recipes for and notes on it in an obscure handbook: "Recettes de l'Électricien"; E. Hospitalier; Ed. Masson, Paris; 1895. Hospitalier suggests a composition of about 2/3 "résine brune" (brown resin/rosin or Dammar) and 1/3 of "cire jaune" (yellow wax or beeswax). The resin was added to strengthen the beeswax. It was usual to prepare the mixture as and when needed. The recipe varied with the season. In summer, less wax was used; in winter more. By manipulation in this way, they obtained precisely the malleability necessary for good work. If the arcanson was mixed too soft, the work would slip during machining. If it was too stiff, it would not conform to the workpiece sufficiently and this might then just fall off.

To determine whether the arcanson was exactly of the right consistency, a few small lumps of it were melted over a small charcoal fire and then poured on a heavy flat iron plate (an anvil or similar) and quickly cooled to ambient temperature. The solidified material was then flexed between the fingers. If it snapped cleanly, more wax had to be added. If it just gave way, some more resin was required. Until finally: ".... if it doggedly tries to withstand, but in the end gracefully submits to, your efforts - this is precisely the correct composition".

To use arcanson on a lathe, again according to Hospitalier, it was best to provide the lathe faceplate with a suitably shaped arbour or holder (fitted to the product). Alternatively a large flat faceplate could be used. The latter could be of cast iron, but a wooden one was preferred (wallnut being the best). When using a wooden faceplate, first the turning tool was passed over it - very lightly - to dress it flat. A large lump of heated (softened) arcanson was then applied to the dressed faceplate and the piece was pressed into this firmly - in exactly the right position!

Machining could only be very light, not only due to the fragile adhesion, but also because otherwise the heat generated could soften the arcanson so that the work would slip.

Innovation

A recent innovation (in 1895) was the replacement of the resin with paraffin, which increased the holding power. This improved arcanson was known as "cire à luter" (sticking wax).


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