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Rivet Marking Tool

by

David Wootton

Having got to the stage of making and fitting the bodywork on my SWB supersport, I have been getting into some strange contortions trying to locate rivet positions to ensure they come in the centre of hidden flanges, leading to some complex measuring and marking out and much head scratching. Working at a friend who is a coachbuilder’s place recently, I watched him use a very simple tool, known as a back marker to mark the centre line of a row of rivets, spot on in the middle of a hidden flange, with no measuring, and all in a few seconds. These tools have never it seems been commercially available, but made up by the coachbuilder to suit the job in hand.

I resolved to make one at once, so have knocked one up this evening, and having just read David’s plea for articles for the next EPAG, photographed making it and made a couple of sketches. I haven’t given any dimensions, but to give an idea my block is ½” square (12.5mm) and the rods are 4.2mm dia silver steel (bought as a bargain job lot, this is the first I’ve used in fifteen years!) and the screws I used are 4BA, again they were knocking about. Nothing is critical, evidently a favourite to make the rods from was old heavy gauge spokes from wire wheels, already got a nice sharp bend on the end, and hard enough steel to mark on aluminium ok, really the size of any of it would depend on what sizes of materials you can find or scrounge, or as a last resort buy. Model Engineers suppliers or ebay are useful sources of small quantities.

Hopefully the pictures and drawings are pretty self explanatory, I heated the silver steel rod to bright red and bent it to just under 90 deg in the vice, reheated and forged the end to a flat point, then filed it to the shape in the pictures, it was then hardened by heating to cherry red and quenching in cold water. Then it was tempered to avoid being too brittle, by polishing so that colour change can be clearly seen, and heating with a gentle flame about ¾” from the tip, watching the colours run toward the tip, quenching as soon as the mid straw colour reaches the tip, it can then be cleaned up and honed with a fine oilstone, until it leaves a fine clear line when drawn sideways across a metal surface. However there’s probably no need to bother with all that as my friends friends gauge has mild steel rods unhardened, and he finds he has to sharpen them about every ten years with almost daily use on aluminium.

The holes for the rods are best drilled in a drilling machine if possible to ensure they are parallel. The reason for adding 1/16” to the centre distance of the rods is to allow to pass either side of the panel if measuring from an internal angle for instance., in practice there is a bit of spring to allow for thicker panels

The pictures show the method of use, can be from a panels edge as shown or from a flange or angle under the panel to show the position on top, or adding half the width of an angle will mark out a line for rivets or bolts, I’m sure if you make one you will find it useful, I’ve used mine already to mark the rivet positions on the outside of the rear upper body from the inside frame hoops, and the rear bulkhead rivets in the body sides.

Thinking that not everyone has small taps hanging around, there is a sketch of an alternative block, using nuts and bolts through clearance holes, closing up a sawcut to grip the rods, just don’t get carried away and saw right through! Hopefully this is clear enough to get the idea across, but I apologise in advance as drawing and writing are definitely not my thing. Happy rivetting.

Rivet tool
Rivet tool
Rivet tool
Rivet tool
Rivet tool
Rivet tool
Rivet tool
Rivet tool

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