OS 842 Muffler

[Engine Doctor]

Hi Andy . To make a head shim from Litho you dont really need a compass cutter. Use the cylinder to mark the litho plate and then cut with some small curved scissors. The internal hole can be  cut as follows . Make a sharp scribing tool from a piece of thick piano wire say 1/8 inch . Sharpen to a really fine point and harden then temper slightly. Now press the top of the cylinder down onto your piece of litho plate and scribe arond the inside a few times and also mark around the outside . Remove the cylinder and carefully bend the litho where you have scribed . It will usually snap quite easily. If it doesn't then finish with a new sharp scalpel . Now you have the hole cut, anneal the rest of the Litho plate and cut out the shim with your scissors . Should only take a few minutes .

[Andy J]

Will give that a go ED.

[Paul De Tourtoulon]

Start by cutting the inside with a sharp modelling knife over a strong plastic support then the outside afterwards with scissors, if you don't it will deform and be useless, don't bother with a compass knife they are only any good for cutting vinyl.

 

 Here's one I did earlier (like Fanny Cradock ),,,

Edited June 25, 2022 by Paul De Tourtoulon
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[Andy J]

Well by chance found I had a 1/2inch hole cutter for sheet aluminium which was a tadge just under the required dimension. Once cut using the cutter the hole was then increased in diameter using a brush as a taper mandrel with 400 grit sanding paper then the item inserted on the head protrusion and the cylinder liner used to mark the outer diameter. Not quite perfect but sure it will be good enough once annealed as there was some deformation of the litho sheet during the internal hole cutting process.