Toolpost grinding with PD 230/E and PD 400 lathes

When you want to reduce a shaft diameter within very close tolerances, toolpost grinding is often the best way. Your Proxxon lathe now has an available holder 24098 which holds the 28481 and 28485 grinders parallel to the lathe long axis. With this sturdy holder mounted in the toolpost and a suitable grinding wheel mounted in the 28481 or 28485, you can perform amazingly accurate and well-finished cylindrical grinding.

Because the grinder is fitted to the toolpost, it can be fed perfectly parallel to the lathe long axis. You can also reduce the working diameter progressively, allowing the grinding wheel to do its work gently and without strain.

Here we show a small stepper-motor gripped by its back-shaft in the optional collet adapter. For the PD 230/E this is item number 24042 which covers the range 2mm - 10mm. For the PD 400 it's item number 24419, covering the range 2mm - 14mm.

This stepper-motor has a 3mm original shaft size, so we are using the 3mm collet to hold the motor's back-shaft, while grinding the front-shaft to 2mm, ready to mount a precision 80DP stainless steel gear.

We found the stainless steel motor shaft responded well to the silicon carbide grinding wheels 28304. Ten grinding wheels and a precision arbor, screw and soft washer are included as 28304. Rotating the headstock at just 80 rpm and setting the grinder to 10 000 rpm, the process is very smooth and purposeful.

What about grinding dust and the precision lathe ways? We carefully placed a sheet of corrugated cardboard over the ways during the whole process. It collected the dust and was simply junked afterwards and the ways wiped with a tissue before re-oiling.. We don't recommend the use of a cloth to cover the ways, because it can catch on the rotating spindle and you may be tempted to re-use it, full of grit. Don't use compressed air to "clean up" - you will send grit everywhere!

The long nose grinder in the toolpost grinding attachment on the PD 400 lathe.
Grinding the stepper motor gear with a silicon carbide grinding wheel.
Deep grooving or parting-off with thin corundum grinding discs is possible too.
A close-up photo of a 0.7mm width groove, produced with a deep grooving disc.