The Box Bed 29
This is basically identical to the box bed on the 10V but longer and repeating the
machining method would seem the obvious choice. However, in my case, the casting
had a twist in it and if the top was clamped to the faceplate (or fixture) with an
internal clamp as was done for the 10V it would pull the casting into the faceplate
distorting it in the process. Then, after the base had been machined and the Box
Bed removed, it would return to its original shape and the surface just machined
would no longer be flat. Most likely, others castings will be OK.
To avoid this, I clamped it to the faceplate using simple low profile clamps as seen
in Photograph 74. The clamps have a single fixing and a grub screw either side of
this to grip the workpiece. The taper on the casting is such that the Box Bed is
bigger at its base and this was placed on the faceplate rather than the top of the
casting. By doing this any possibility of the casting breaking free was virtually
eliminated. Also, note the packing that is between the grub screws and the casting,
always use a softer material, aluminium or copper, when securing castings as the
softer material will conform to the rougher casting and improve the grip substantially.
With the top surface machined the casting can then be turned over and clamped directly
to the faceplate and the base machined, Photograph 75.
After doing the initial tidying up of the casting, stand the casting base down onto
the surface plate and using a surface gauge check the heights of the four surfaces
that support the crankshaft bearings, the aim is to get them the same height. File
those that are high and check again finally turning the casting over and checking
the four surfaces against the surface plate checking to see if it rocks, the four
should then be lapped as a group on a piece of course emery paper.
Now, mount it onto the faceplate using suitable packing and add a small angle plate
to secure the other end. This arrangement will be better understood by reference
to Photograph 76. If using a small lathe do rotate the machine by hand before starting
it to ensure that the casting clears the lathe's bed. With that done start up and
machine the casting's base. Having probably spent at least an hour deciding on the
method, locating suitable parts and then mounting them on the faceplate, machining
took no more than a couple of minutes, highlighting the fact that using the faceplate
is frequently more about set up than the actual machining.
As I stated at the beginning, almost all parts that make up the 10H, Photograph 73,
are identical to those in the 10V, with just a few being basically the same but
having different dimensions..
There is only one component that is markedly different, that is the Soleplate(11).
This replaces both the Soleplate (29) and the Standard (11) used on the 10V. However,
both the Soleplate and the Boxbed, being larger, stretched my Hobbymat to the limit,
there being just 1/32” clearance to the bed when the BoxBed was mounted on the faceplate
Unless the beginner has a very special reason for starting with the 10H my advice
would be to make the 10V, not because of size but because the Soleplate is definitely
more difficult to set up for machining if using just a lathe.