The simplest approach to this method is to used thin film double adhesive tape a
method that I have used a number of times, Photograph 14 showing one application
where a steam chest cover casting is being machined. Of course, the rear of the workpiece
must be reasonably flat so as to make good contact with the adhesive tape over much
of its surface and this was achieved by lapping the back on a sheet of abrasive paper,
about 100 grit. Providing the tool being used is sharp and only light cuts are taken
then the procedure should be problem free. Having machined the first side it can
then be reversed and the second side machined similarly. The photograph shows that
the part is additionally supported by strips being placed around the four sides.
However, these were added just to illustrate the principle as the part would have
been adequately held even without them.
There are two situations when the system being employed requires heat to be applied,
in one the heat is only needed to break the bond after machining has taken place
with the part having initially been assembled cold. Typically, bond the workpiece
to the faceplate using a two part resin adhesive and allow to cure. Using the tailstock
may make a good method of holding the part against the faceplate whilst the adhesive
With that done, machining can take place as required after which the part can be
separated from the faceplate by applying heat. Tubal Cain in his "Model Engineer's
Handbook" quotes a temperature of 120C to break the bond. I have seen both Locktite
and Super glues mentioned for this purpose, if the viewer wishes to adopt the method
I would recommend further reading on the subject and a few trial runs before applying
it to an important workpiece.
In the second method heat is required both to melt the adhesive so as to make the
bond and then to release the part after machining. Just using hot melt adhesives
as used in woodworking is not practical as it would rapidly cool as soon as it was
applied to either the faceplate or the workpiece and to overcome this both parts
have to be pre heated. With that done there would still be the problem of ensuring
that the adhesive coating was of an even thickness, if not, then this could have
a detrimental effect on the part being machined.
This problem can be easily overcome by using adhesive supplied in the form of a film
as used extensively in industry. However, this to my knowledge is only obtainable
in large quantities and is therefor a non starter. One material that is easier to
obtain in practical quantities is "Gluefilm" that is used in woodworking for applying
veneer to the base timber below.