With so little experience to work on I needed to establish the basics before going
on to design a machine, and started by browsing the Internet for information. Having
found a few Photographs of industrial machines there was one that included a collection
of files, these though were quite large and appeared to have a round end rather than
the pointed tang , obviously making it easy to provide a secure mounting for them.
The files therefore seemed the next to investigate.
My very large industrial tool supply catalogue seemed the logical place, but none
were listed, with a similar result when searching the web. This, apart from just
one American company that had files specifically named as being for use on a filing
machine. Their dimensions though appeared to be no more than needle files, there
may though be an answer to that, more later.
I did subsequently find one other file manufacturer, again in America, who listed
filing machine files but no details were given as to their cost or where they could
be purchased. I anticipate that due to limited demand they would be quit expensive.
I also found a forum where the subject was being discussed and the approach being
taken by some was to modify standard files.
Most of the filling machines that I found illustrated the file supported solely on
its lower end, making it possible to thread the workpiece over it. This then enabling
it it to be easily removed for inspection as the work progressed. As I considered
this to be a very worthwhile feature I decided that the machine must make this possible.
Even so, this may limit the rate at which material can be removed as the file may
flex. Being able to be mounted on one, or at both, ends, therefore seemed an essential
feature to aim for.
It also occurred to me that using the tang as a single ended method it would be cutting
on the up stroke that contrary to normal practice, as, band saws and jig saws, etc.
all pull the work towards the worktable. It did though make me wonder if the files
mentioned earlier were in fact needle files but with their cut reversed. I decided
therefore that I would have to use standard files but to remove the tang and mount
them so that they cut on the down stroke, choosing 100mm long files for the purpose.
With what appeared would be a relatively crude method of mounting the file I was
concerned that the file face may not be parallel with the file's movement. Also the
sides if a parallel sided file. This would mean that the workpiece would have to
move backwards and forwards, albeit minutely, to keep in contact with the file at
each stroke, a situation that would be far from ideal. Some adjustment would therefore
have to be provided so that the file's face, and edges, were parallel with its movement.
Speed in terms of strokes per minute (SPM) would have to be decided and as I could
not find any data regarding this. I had therefore to come up with what I considered
to be a logical starting value. For this I chose 200 to 300 SPM being a little faster
than I would file manually. However, file linier speed would also depend on length
of stroke. I decided therefore that to provide the facility to change both SPM and
stroke length would be worthwhile, aiming at mean values of 250 SPM and 25mm stroke
length. I did though eventually find the design I had produced worked well at speeds
considerably in advance of this value, more about that later.