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Understanding 'simple' splines - help!
Hello everyone.
Unfortunately, I am an 'instinctive' inventor. As such I fully realise just how much I do not know. That said, invariably 'things' work and are reliable.
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This image is of an 'adapter'. Through its centre runs a stainless shaft of that profile. Another metal object slides over (around) the adapter so the 'adapter' becomes the linking mechanism between the two metals.
For reasons of cheapness and adaptability, the 'adapter' has to be plastic. Unfortunately though I'm finding with my fine detail 3D prints that the adapters blow out far too early i.e. they do not allow enough torque to be applied before failing.
After some uneducated analysis, I've concluded that the design of the inner shaft with its 6 (much tougher) splines is probably causing too high a point load (apologies for my terminology) on the plastic adapter so causing it to shatter. It further occurs to me that as the 'shear'? strength of the internal stainless is soo much higher that of the plastic the area of plastic it pushes against should be correspondingly higher!
I'd like to understand what's happening so I can redesign and get more torque transferred between the two metals.
Sorry for being thick! I can confirm that advancing age doesn't always guarantee increasing wisdom