N_Cook Inscribed thus:

Baron wrote in message
...
N_Cook Inscribed thus:

Seem to have to do this a lot these days. I'm thinking of
converting one of these neat little pipe/tube cutters to roll on a
spline form.
http://image.bizrate.co.uk/resize?sq...5102&mid=82383 the
only pic I could find , a smaller version of these
http://www.choiceful.com/prod_image/66677_l.jpg by changing the
sliding-in cutting wheel to a toothed cog. Currently I do this
spline conversion by thin grind wheel and cutting splines freehand
, so rough and ready, does the job, but not very elegant and wary
of breaking the thin Dremmel type grind wheel. I cannot even find a
brass gear to fit in there for proof of concept, let alone a steel
cog. Anyone know where to look for a steel cog with about 1mm pitch
of teeth , between 10 and 24 mm diameter and between 3.5 and 5 mm
wide. I don't mind sawing and grinding out the slot that takes the
roller on one of these pipe cutters. Where would I find such brass
or steel cogs in some application that could be robbed out. Not
much of the shaft needs to be splined and remainder of shaft could
be undercut to clear knob and still engage well enough for finger
pressure. Or any other ideas ? I have a ball race that would fit in
there neatly , after widening the slot but would havre to grind
teeth to the outer ring of the race. I'm aware of engineering slit
saws and may even be able to justify the cost of one, but would
rather try a proof of concept first

There is one major problem to overcome ! For any given spline pitch
there are fixed diameters where the spline won't over ride ! You
basically want a fixed size forming tool for a particular diameter.
In which case there are companies that manufacture gears and I'm
quite sure that for the right fee they would supply a steel gear that
could be case hardened to do what you want.

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Best Reagrds:
Baron.


Yes as in knurling, the pattern repeats for only one diameter and a
certain degree of intrusion.

Actually it would be any diameter where the distance could be divided
exactly by the pitch.

Aiming here for 16 around a nominal 6mm
spindle. Proof the concept works. Robbed the steel gripper wheel from
a butterfly can opener, sharpened the points a bit and opened out the
central hole. Mounted in the pipe cutter and produced a neat ring of
indents. These were about 2mm apart and 7 equally spaced around, when
cutter advanced far enough in.

Good test ! The aluminium must be fairly soft then.

So a cog with 1mm spacing should work
even easier as long as not too wide. Actual splined shafts have a 1mm
spacing and 16 around. If nothing else a thin approx 1mm tooth spacing
cog from a clockwork clock mechanism would make an excellent way of
marking pot shafts before making axial cuts with a grind wheel.

I noticed you mentioned a Dremmel tool earlier.

OK so you know the pitch, you know the length of spline ! That
information should be enough for you to find a steel gear with the
right tooth profile and pitch.

There must be dozens on the net ! Google should help with those.

There is an engineering company just down the road from me and they tell
me that they no longer cut their own gears but buy them in because its
cheaper. They did ask me if I wanted any of their old cutters, but
alas I don't have any means to use them.

I do have a tool & cutter grinder with a dividing head that will do 10
degree steps but I don't have any abrasive wheels small enough for that
kind of profile otherwise I might have a go at making a wheel myself.

--
Best Reagrds:
Baron.