Cutters must be mounted carefully to run true with no dirt on the arbor or grit to put it out of flat.
It must be very rigid as any movement can cause chipping or even breakage.
Cutters must be kept sharp, inspect with a x2 (or x12 if below module 0.5 ) eye glass, as soon as a bright line is seen on the tooth tip it needs sharpening.
Fine tooth cutters cannot be resharpened.
We can supply borazon wheels for grinding the cutters if needed, these are used with paraffin as a coolant.
To improve rigidity of the pinion or wheel being cut, lock slides which are not in use on the machine that is used for cutting.
Make sure there is no end or side shake in the machine headstock.
Do not try to cut a pinion without supporting it at both ends, sometimes it is an advantage to put a V support opposite the cutter, resting onto the pinion blank.
Wheels need backing pieces to support the blank wheel. The diameter of these needs to be as near to the root of the tooth as practical.
If holding a pinion in a collet make sure that it does not slide into the collet when taking a cut.
If cutting pinions it is very necessary to use a continuous flow of cutting oil, this cools and washes the chips from the cutter teeth. Use a good quality cutting oil as a coolant not a water based soluble oil.
Recommended cutting speeds using H.S.S. cutters are-:
To get the best results for cutting wheels, speeds up to 1800 r.p.m. or faster can be used.
The best type of brass for cutting wheels is half hard engraving brass CZ 120.
Steel used for pinions -: For small pinions KEA 108 use to be ideal but is no longer made.
The nearest steel we have come across for longcase pinions is a type of carbon steel
which nearly matches the analysis of old pinions.( this can also be used for small
pinions )This is available from us see Steel and Brass page.
Climb milling (Where the cutter is revolving in a direction in which it could climb onto the work if it was not locked down.) is not recommended for cutting clock wheels and pinions.
If a flywheel can be mounted on the cutter spindle it will make a difference to the rigidity of the cutter.
If a new pinion is running with an old wheel or vice versa check the module of the old gear to make sure that it's module is similar to the one being used, otherwise it may not gear correctly. If it does not gear correctly it may mean you have calculated the wrong number of teeth or leaves for the new gear. With old gears some deviation from the correct calculation is some times necessary.