Way to unwind rope from one spool to another?

chris_8

I'm pretty sure the answer is no, but I figured it was worth asking. People do some amazing things with Onshape
https://cad.onshape.com/documents/2f2a6c16d9881cf261c18e37/w/c1dfbcd3147fff60c372b2a5/e/796ba4fe86e35b4a01e01bbc

mahir

Ah, I see now. You have more than one layer of winding on each spool. One layer is easy - just make #helix2_height = #spool_height - #helix1_height. Two or more layers of spool would require some conditional logic to handle the "overflow" height from one layer to the next. I think it's doable, but not straightforward. The variable relations would look something like this. I'm sure there's a cleaner way, but since variables are still features that get processes sequentially, this should work. If I have time I'll test the implementation.

#helix2_total_height = #total_height - #helix1_total_height
#helix2_layer1_height = #helix2_total_height/#spool_height > 1 ? #spool_height : #helix2_total_height
#helix2_layer2_height = (#helix2_total_height - #helix2_layer1_height)/#spool_height > 1 ? #spool_height : #helix2_total_height - #helix2_layer1_height
#helix2_layer2_height = #helix2_layer2_height < 0in ? 0in : #helix2_layer2_height 

mahir

FS can definitely help do this and a lot of other useful things, but in this case I was just using conditional logic with variables. That alone doesn't require FS - just an understanding of variable expressions. In this case I was just using an alternate version of an IF statement (X?A:B translates to If X is true do A, if not then do .

mahir

I can't think of a way to do this as a smooth animation within OS, but I'm pretty sure you can link the height of helix2 to the height of helix 1 using in-context references. This would give you a similar effect as winding/unwinding both spools, but only when you updated the context. You could then create an animation by grabbing individual frames and stitching them together with a gif editor, but I don't think a live OS animation is possible. You can only animate mates/relations, not part rebuilds. If you model everything in one part studio it would be a little easier, but it still wouldn't animate smoothly. I'll take a look at it.

mahir

Ah, I see now. You have more than one layer of winding on each spool. One layer is easy - just make #helix2_height = #spool_height - #helix1_height. Two or more layers of spool would require some conditional logic to handle the "overflow" height from one layer to the next. I think it's doable, but not straightforward. The variable relations would look something like this. I'm sure there's a cleaner way, but since variables are still features that get processes sequentially, this should work. If I have time I'll test the implementation.

#helix2_total_height = #total_height - #helix1_total_height
#helix2_layer1_height = #helix2_total_height/#spool_height > 1 ? #spool_height : #helix2_total_height
#helix2_layer2_height = (#helix2_total_height - #helix2_layer1_height)/#spool_height > 1 ? #spool_height : #helix2_total_height - #helix2_layer1_height
#helix2_layer2_height = #helix2_layer2_height < 0in ? 0in : #helix2_layer2_height 

chris_8

Wow, thanks for looking into this @mahir .   I've skirted away from FS coding so far because I never feel like I have time to learn it.  But now it seems I should start reading.   I appreciate your input!

Chris

mahir

FS can definitely help do this and a lot of other useful things, but in this case I was just using conditional logic with variables. That alone doesn't require FS - just an understanding of variable expressions. In this case I was just using an alternate version of an IF statement (X?A:B translates to If X is true do A, if not then do .

chris_8

Ah, ok,  I'm familiar with variables in general, but haven't used if/then statements yet.   When I finally finish my current pile of work I'll try it out