Originally Posted by Richard P
One suggestion: If you make the holding points a triangle cut into the surface rather than a semi-circle the brushes don't roll around and move so much.
I know you're an expert painter, and I'm a kinda sorta beginner at that - although I've come a long way. Your Rembrandt series was engrossing.
But as far as designing tools, fixtures, and such - I've been retired now for 3 years but I used to do that professionally, and for almost 40 years. I designed tooling from toys to military jets and submarines. Not to pound my chest or beep my horn - or anything - but - I do know what I'm talking about for once.
So let me explain why triangular points would be a really bad idea, although they would indeed stop the brushes from rolling laterally (side to side).
First of all let's consider if there really are any ill effects of lateral roll.
I don't see any - as long as the brushes can't touch because they are confined to their respective semicircular slots, which they are. And they don't roll around in there anyway unless you disturb them.
But even if there were a big advantage to absolutely minimizing lateral roll, the triangles would still be bad because:
- circular features are the easiest to locate and size accurately
- circular features are the easiest to manufacture
- circular features introduce the minimum stress on the material both when created and subsequently
- triangular points introduce the maximum stress on the material when created and subsequently, causing the material to crack and fail either immediately or over time.
Actually, triangular holes - or any angular holes - introduce infinite stress at the corners, and are guaranteed to fail at some point, unless you put a good radius there, and now we're back to semicircular holes again, except with much more effort.
So stay with circular features whenever possible. Triangular solids are strong engineering materials but as holes they are disasters waiting to happen.
So, sorry if this went on longer than anyone expected but I used to write engineering reports on very high tech equipment - and I kind of miss it a little, actually - so thanks Richard R for the opportunity to exercise some rusty old chops.