chrisb wrote: ↑
Tue Mar 06, 2018 4:43 pm
Abdullah, you have freed us from wrong usage of the tangent+coincidence constraint, but I'm afraid we will get more like this problem https://forum.freecadweb.org/viewtopic. ... 07#p218558
where the block constraint yields a solved sketch which pretends to be sensible.
But I will rather have a good tool with problems on wrong usage than a bad tool leading to bad results even on proper usage.
I have destroyed a fair amount of screws and forks using a fork as screwdriver and I have destroyed a fair amount of screwdrivers using them as chisels.
It has been interesting to see how the block constraint was being used in this case. It will have to be transmitted that blocking per se is not a meaningful way of constraining. It does not actually enforce a geometric relation. It just freezes the thing in place and you can not have enough precision to exactly locate things in place and block them.
What I was expecting is that people will (mostly wrongly) use it to remove those remaining DoF that are impossible to find. And I say wrongly because if you do not know when the DoF is missing is mostly a bad idea to use the block constraint to get away with a "fully constrained sketch". It is what triplus once said is an obsession to have "fully constrained sketches" for the sake of having them so. The DoF finder, when merged, will help a lot to avoid this (mis)use case.
I still think that the main use of the Block constraint is for "artistic work", when you do not care about a geometric definition, but you are happy about how it appears. Of course you do need at least coincidences so that things are closed.
Anyway, I still get mad when I need an screwdriver and the one I find is the one I used as a chisel...