What is a toroidal pick-off?
This was a recent project to create a toroidal (doughnut) shape to surround a pelletron-chain in a high voltage machine with an applied potential. The cut-away section is to allow the chain to come out without damaging the part if it were to break while running.
It was proposed that the part could be made by machining a face plate with four holes equal spaced. Use these holes to mark a 25mm plate of aluminium for drilling & tapping. Mount the 25mm plate off the face plate for turning in a lathe. The outside diameter would be turned to 108.4mm and bored to 54.8mm. A template could then be used as a guide for machining the front circular profile. The part would then be unscrewed, flipped and the back profile created. After the toroid was shaped a flat would be milled on the bottom and two mounting holes drilled & tapped. A section would be cut out and the ends would be hand shaped and the entire part sanded to a smooth finish.
That’s a lot of work for one part and would tie up a lot of man power so it was decided that the part would be 3D-printed in aluminium.
The printed part may seem expensive but compared to the labour for manual fabricating the part it is quite comparable. Other benefits are;
- A more accurate part (~0.1mm or better).
- More intricate part detail.
- A hollow part.
- Manpower can be allocated to other jobs.
- Choice of exotic materials such as stainless steel, titanium or inconel (an aluminium alloy will be used in this instance).