Rear parting

The main thing, Derek is to get lots of practice, read one of the books on turning and gradually the turning will become second nature. Always remember to use the safe practices and never become complacent, having a healthy respect for the machinery is the best policy.

So first option is to do away with the holder, you will probably have to stone or grind the bottom of the tool flat as they are usually slightly angled otherwise the srews will try and tilt the tool, a small packer on top can also help.

The alternative is to use a holder like this one from Chronos that positions the 5mm high blade central to the 6mm part that is held in the toolpost rather than above it like the one you currently have. Not actually tried one of these but should think it will fit the Cowells.

If using tee slots for the rear toolpost, I would definitely make use of two for stiffness. After all, stiffness and the inverted tool are the main advantages over compound mounting.

You actually have a good way forward because the toolpost is low. Get a plate say 1/4 in thick and big enough to go under the toolpost and out across the second T-slot like the one in Phil's version. Bolt this to the underside of your toolpost with 4 csk screws. You could even consider making these small brass screws so they can failsafe.

My, admittedly large, rear toolpost is secured by one long T nut tapped M8 at each end, to minimise stresses, by spreading the load.

After some 15 years, no problems have arisen.

Howard