N_Cook wrote:
Baron wrote in message
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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 Regards:
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.
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Best Regards:
Baron.
It looks as though the pitch between crests of the gear wheel would
have to be about 0.8mm for it all to work. I may make up some sort of
dividing head, for light inaccurate work, as not the first time I
could have used one.
The dividing head is a small 3" chuck with what looks like a 35 tooth
gear at the back. A spring loaded peg just drops into the gap between
teeth. There is a large knurled nut at the back which is tightened to
stop any movement due to vibration. I use it mostly for sharpening
drills and end mills.
--
Best Regards:
Baron.