Setting equal curve lengths

Malcolm_Cummings

Hello. I'd like to set the curve length of an arc equal to a straight line in a sketch, but can't seem to do it with the equality constraint. Is there a simple way to apply this relationship so that it updates automatically as one of the curves is modified? Thanks.

philip_thomas

https://cad.onshape.com/documents/b0e724a6a8b27808b343baa4/w/56dfdbbd0b4d8213284f7ca8/e/143d71743b20a72232a0eda1

bruce_williams

@philip_thomas

Effective but esoteric.  Is that why you have the 'visit Onshape' tab so we can get an explanation? 

philip_thomas

Lol - fair enough!
The challenge is that 'length' and 'arc length' are two different things. 
If i said, make this line and this arc 'equal' - what am i setting to be equal? The length? The Radius?
This solution uses a custom feature that allows me to measure something and assign the measured value to a variable. Once a variable exists, i can use it in any other sketch or feature (but not the same one).
By sharing the document, the user now has access to the custom feature

bruce_williams

Excellent - glad you splained.  Passing on the Custom Feature is good and I had not even thought of the ambiguity.

Jaimeeow

how did you make the custom feature from scratch? i'm so confused. there's two part studios? and the second part studio is just referencing the first part studio???

S1mon

This is an old thread. You can create a variable on the fly in a sketch and use it to dimension both the linear and arc lengths. You can start typing '#' for a dimension and you can create a new variable. Once you do that, enter that as the dimension for the other entity. Here's a very simple part studio with the sketch.

Note: you still can't dimension the length of a spline, conic or path in sketcher, just individual arcs and lines. See this improvement ticket.