rolling constraint in sketch ?

nicolas_7

Hi all,

In my great noobism, I'm looking for a "rack and pinion constraint" or something of the effect, like having an equal length constraint between an arc and a straight line in sketch. Does anyone knows how to do that? that would be a powerful enabler for cycloids, trochoid, and all things in "oid" you wouldn't want on your annual blood checkup. UI wise, I guess the simplest would be to allow an equal constraint between an arc and a line (and then good luck, because people will want equal arc length between arcs, and they'll get equal radius, but it's not my problem, really).

Narayan_K

@ nicolas_7, Equal constrains can be added between two line or two curves(only for similar entities).
So you can do some work around to get that,

nicolas_7

I'm sorry I'm not sure I understand your example, it looks like you bound the radius of the arc to a line length, but I want to bind the arc length (the angle in radian times the radius) to a line length. What I want is like having a line length equal (or proportional) to an angle.

Nico.

Narayan_K

Sorry for the confusion.Presently Onshape don't have that capability in "Equal" constrain.
Once Onshape introduce equation capability in dimension then your requirement can be achieved.

viru

@niolas_7, Currently this facility is not available in Onshape sketch. This facility will provide value addition to sketch like "animate constraint" in CATIA.The animate constraint tool allows user to visualize the effect one constraint  has on the entire profile. This is a very helpful tool to user.

I hope in near future Onshape will provide this facility in sketch.

andrew_troup

I can think of workarounds using current functionality but they would be clunky and inexact.