Dimensions don't add up?

3B 36 inch base sink cab ver 2.skp (480.0 KB)
I keep running into this problem where dimensions don’t add up in my models I’m and hoping someone can help me figure out what is going on.

I’m working with Make 2017 and have been switching back and forth between laptop and desktop. I’ve mostly kept the units at 1/16" and think I’ve been careful drawing/moving objects using typed in measurements. I’ve attached an image as an example where you can see the measurement across the 2 cabinet doors should be 35 1/4 (17 3/8 + 1/2 + 17 3/8) but shows up as 35 3 3/16?


How about uploading the SKP file so we can see what you’ve got?

Uploaded now thanks .

I’m not seeing any issues, front on 36 wide, made of 2 by 1 and a half and one by 33.
Your image doesn’t show and your model has no dimensions.

Looks like rounding errors to me. Your model isn’t as precisely drawn as it could be.How did you go about making this cabinet? Did you start with a 24 inch wide cabinet and scale it or something?

All your sizes are showing as approximate. When you see the tilde (~) in front of a dimension, it has been rounded up or down to that value according to your Units setttings. Turn up the precision to see more accurate sizes and you’ll see where the errors creep in.

To six decimal places of an inch, you have 35.508876", two doors 17.485073" wide and a gap in between of 0.538731". When you add these up, you get 35.508877 which is accurate to a millionth of an inch. No one can make a door that precise, but if you leave the precision at 1/16" and you see approximate sizes like ~ 35 1/2" don’t expect them to add up.

We didn’t watch you draw it, are you sure you typed all the sizes carefully?

I initially uploaded the wrong version of the model - here’s the correct one.

But I think you’ve identified my problem. Thanks for all the replies.

3B 36 inch base sink cab ver 2.skp (461.0 KB)

Yep. Same sort of problem.

How did you go about creating the model to wind up with these dimensions?

I started from scratch in most cases though I did share some components between models. I did not rescale. Mostly, I would draw a rectangle and then use the push/pool tool and the dimension box to pull it to size, make a component and move on to the next object. I’m now thinking I have to pay more attention to the tilde like how it shows up with the tape measure tool but not with the dimension tool - I think.

Working at higher precision will help and making sure you enter precise dimensions when dimensions need to be enter will go a long way to improving precision.

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