Dimensions of components add up to total dimension yet a gap exists


#1

I’m designing a cabinet and there is a discrepancy in the image versus the dimensions. The overall width of the cabinet measures 48" which is a combination of two upright elements and a cross piece. The widths of each component added together equals the width of the overall project yet a 1/16" gap exists where two components meet. I have no idea what the problem is and how to fix it. I appreciate any help.

Stuart


#2

All is clear the problem is…can you attach the model so we can see what is happening.
Drag and drop to the message box or use the upload button, seventh icon from the left when you are replying.


#3

You probably have your precision set too low. For instance, if it’s set to eighths, it will round dimensions to the nearest eighth of an inch, very definitely introducing discrepancies in sixteenths and finer. Discrepancies finer than the precision limit should be denoted by a tilde (~) preceding the shown dimension. Set precision at Model Info > Units. Keep in mind that this is a display setting only and does not affect the underlying geometry.

-Gully


#4

I suspect that @Gully_Foyle has the explanation of what you are seeing, but that @Box states the path needed for us to help you correct the underlying problem with the model. You need to alter the dimension of some part(s), typing exact sizes or paying close attention to inferences, but without seeing the model we can’t know which parts are involved.


#5

China cabinet 10:27.skp (183.0 KB)


#6

It is indeed a precision issue. change Precision to 1/64 in. You’ll see the problem. That post shows as 1-43/64 in. wide.


#7

Actually, all the parts show strange dimensions. For example the long rail is 44 39/64". Did you intend to have them such peculiar sizes, or did this result from imprecise modeling?


#8

You americans! I’m sure it’s accurate in cubits.


#9

Perhaps, but SU only allows setting cubits precision to the nearest hand!


#10

Let me say first that I’m self taught and as a teacher I’m happy I don’t have annual testing to determine my job!

Having said that, I was not my intention to have such peculiar sizes. I originally had my precision set at the default 1/16 and just changed it to 1/32 before showing the model. I assume this is a combination of the precision setting on the software as well as the precision limits I have on a the Measure Master Pro calculator app on my phone. When designing a project such as this and I know I want 3 doors I would start with the overall width of the cabinet. Then deduct the width of the structural elements of the cabinet, i.e. 1 11/16 for each frame member. Then I’d have my open space to split up. Subtract the total of all the door stiles, the gap between the doors and frames as well as any intermediate structural members. That remaining space would then be divided by the number of doors. The calculator app has I believe a precision default of 1/16 and I experience rounding, obviously at times when I don’t realize it. (You can complicate things further when you factor in that at times I use a hand held Measurer Master calculator that has possibly even less precision.)

So it seems my inexperience is the culprit, that and too many calculators?


#11

Another thing you should realize is that the display precision setting in the units affects exactly that and only that: the format of measurements displayed. It does not change or control the actual size of anything or the precision you get when you draw (you can set a snap to length, but it is pretty easy to dodge it by accident). That’s why we could up the display precision to see the strange sizes in your model. You get accurate sizes by typing in values or using inferences to snap to existing correctly-sized parts. SketchUp will accept fractional inputs such as 44 33/64, so you don’t have to type long decimal equivalents.


#12

You might also help yourself by using the inference system to make divisions for you.
That way you get equal lengths without having to use a calculator.


#13

First, if you can adapt your workflow to use decimal inches, you’ll find they’re much easier to work with than common fractions, and you can set reasonable and consistent precision limits.

As a rule, construct your geometry using a finer precision than needed, say, bump it out an extra decimal place (or go to 32nds rather than 16ths). You can twiddle with it after the fact and dimensions will conform to the currently set (new) precision.

-Gully


#14

Wow, thanks all for your suggestions. Just the terminology used illustrates I have a long way to go to understanding this software! I really need to devote more time to tutorials etc.


#15

Check your private messages Stuart.


#16

FYI if you have the snap to set to fraction it will snap to that but, the measurement input will override that so make sure you use the measurement box?