Excellent idea and just goes to prove we never have it 100% right. Always room to improve.
The idea of dots on the plate to guide it came up in the past. I mulled it over and for some crazy reason dropped it in favour of keeping the design simple.
But I think center lines are something to put back to the top of the modification list.
Next time I have the injection mold in bits I will add them. Doesnt have to be much bigger than a standard witness mark.
Also for me its "metal off" so as an engineering procedure its fairly straight forward to do. My problem always starts when we need to go "metal on" which means drilling out plugs etc. Expensive and not so elegant.
I'll add cross-hairs (centre lines) as soon as we need to do any mods.
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With regard to the guide Richard, I have found it beneficial to run the drill through the guide hole prior to it's first use as it has less drag on the guide when you first start, therefore helps to keep it in place
When we first looked at the drill cores we found slight tolerances approx of 0.05mm. In the first prototype some cores rattled and others were a tight fit. So we modified the ports into a "V" shape.
In the finished model for example the 40mm hole is 40.05mm at the top and and 39.95mm at the base.
When you first put a core into the cone it nicks out a fraction of a mm of plastic in the first second of drilling to form a perfect fit for that particular core.
All ports now have a bevel or chamfer on the edge. A second benefit is the bevel makes it much easier to guide the drill cores into place.
