Can you create a linear part pattern with the distance between entities growing or shrinking?

mspiccione

For example, I'm trying to pattern the frets/fret spacing on a guitar and each fret is 1/(2^(1/12))  (about 0.94387) smaller than the next starting at the top of the neck and the first fret is about 1.431 away. the second is 1.3506 away from the first. I tried using variables that built on each other like #fretspace = #fretspace*.94387 with the spacing but when setting the distance as a function in the linear pattern(feature), it sets the variable to number so it doesn't change with each iteration. thanks for the help 

eric_pesty

I think you are close, but you need the "seed item" for the pattern to use the #fretspace variable and also you need "apply per instance" checked in the pattern (I'm assuming you already know you have to include the "#fretspace=#fretspace*.94387" variable in the patterned features list).
I think what you need to do is create the first fret, then create the second one as a transform using "#fretspace" for the spacing, and then you can pattern that.
It looks like you also need a "counter" to multiply the spacing as it's always applied as an offset from the initial source part so it's a bit tricky to get what you want...

Maybe something like this: https://cad.onshape.com/documents/46a326b4a97bd99579866e64/w/98aff52f023b0b23139beb54/e/b0ee1add00fe2cfd11116696?renderMode=0&rightPanel=variableTablePanel&uiState=635c37154412af2de05532db

EvanReese

Something like what @eric_pesty recommends sounds right. I recall that @john_mcclary and @GregBrown both have some really nice guitar models. If they're willing to share, you could see how they did it.

john_mcclary

https://cad.onshape.com/documents/ca34f5c0e24fa48dae92b90b/w/7bfc84a9d2ab86c27af4c158/e/46dbc99443bb484fc7c464eb

john_mcclary

https://cad.onshape.com/documents/c903a1c146bd1014a01f9f76/w/b34f7e1ac2957f331d5c5603/e/02a42d2a78edcd83605b37d4

Here is one with a logorithim pattern 

GregBrown

I wrote a custom feature to automate this exact use case. I wanted to make it configurable too (Fender VS Gibson VS PRS etc…) I’ll dig it up and see if it is a good enough shape to share…

edit: here it is --->  https://cad.onshape.com/documents/4033d77aa314484c4e6cef03/v/30b45e4448b3a51bb8bab034/e/6b86baf93f53be5ddf00a926
It is not intended as any other than a proof of concept. I put this together ages ago and would write it completely differently next time around. But it was a fun experiment. 

SethF

Always a fun problem. Here's a related forum post from a year ago. https://forum.onshape.com/discussion/comment/75659#Comment_75659