Expressions - Returning a number when using a length

leecasey

Hi I'm having a bit of trouble generating an integer for a pattern number from an expression which is using an length (mm). 

floor((#length/2)/60)

I'm assuming the issue is incompatible types but not sure how to solve it. Is there any way to cast #length as an int? 

S1mon

You can divide by 1 mm to get rid of the units, but I'm a little unclear how you're trying to use this calculation.

I didn't test this, but something like this should work:
floor((#length/2)/60)/(1 mm)

If you ever change the units of the document it's going to break, and I can't quickly think of a way to make this so that it will just get rid of the units in a universal way.

_anton

Simon is correct. FWIW, though, I'd flip the logic around: make a variable like #number_of_instances, then make a #length variable computed from that. That makes it easy to update things and saves you from having to floor() anything.

S1mon

You might also want to look at Linear Pattern Plus. It might solve your needs without needing to write any expressions.

https://forum.onshape.com/discussion/18076/new-feature-linear-pattern-plus/p1

leecasey

Unfortunately that didn't work. Here's a better explanation of what I'm trying to achieve. I need to pattern some holes on this rail, the pattern must be central to the rail, hence why I'm dividing the length by 2. So I just want to generate the number of holes in the pattern from the length in mm. 

leecasey

Thank you, the above didnt work but a little change of parenthesis did the job! 

floor(#length/2/60/(1mm)) 

NeilCooke

You also don’t need the “1” - just “mm” will do. 

EvanReese

This is exactly the kind of situation I wrote Linear Pattern Plus for (as Simon mentioned). in your case, is the 60 the hole spacing? if so, you could also just make it 60mm and that'd do it. length/length = number

leecasey

Thanks everyone. 👍 will certainly check out LPP, Evan. 🙂