Google is your friend: https://youtu.be/KsM7u2d6JI0?si=3lRcZnRYbS36s7vt
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I see what you guys are saying. My drawing is more complex. I was using pushpull tool to elongate and to reduce one of dimension of the cube to a size.
Seems like you guys are reluctant to improvements
Seems to me that you are reluctant to learning how SketchUp works…
We are just trying to help you…
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That is quite possible. I am still not sure scale can apply for a fixed dimension. Even if I learn it. I am likely to forget it if I am an occasional user.
I am using push/pull tool and have several cubes and shapes and groups in it. It is very cumbersome to zoom in and make exact modification. Yes I can subtract numbers but that is not very convenient.
If I mark a measured dimension even that dam thing doesn’t update as I make the change so I can see how much to change.
There may be some ways around it but I don’t see an straight forward way.
I’m lost wasn’t it a single cube ? now it’s several cubes ?
could you share an example of file you’re working on maybe ?
yep. I’m actually typing this on a typewriter, can’t trust these electrical thinking machines. 
here. I take my cube, use the scale tool, press shift to stop scaling uniformly and click to validate any size.
from there, type the 3 desired dimensions and don’t forget the units. I remind you, the order is red / green / blue. here I asked for 2m;3m;5m and voila.
Personally I would probably just go pushpull. I’m good at maths.
I and many others here design large scale complex assemblies with many thousands of parts in SketchUp. It is fast and convenient and precise, it works great. It may not work like you were expecting it to work, but give it a try, learn how it does work and you may learn to love it too, or not. Nobody here is resistant to improvement, we just don’t think what you are suggesting is an improvement. Push/Pull is a great tool, but by no means the only or even the best tool for adjusting existing geometry, often the move tool or the scale tool is the right tool for the job.
Check out the Campus for step by step learning of what the tools do.
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Why? Some of the most skilled people here on the forum told you how it works.
Don’t you believe them?
Dimensions do update as you change something. You must be doing something wrong on your end if it doesn’t update.
But it’s a bad way to use a dimension for this purpose as it is not accurate because of display precision…
Dimension do not drive geometry. They (their values) are associated to the geometry and thus update while changing the geometry.
However when you manually change (re-type) the dimension’s value, then the association to the geometry is broken.
This can be restored by replacing the value by <>
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Well it seems like you guys are not interested in improving?
For a technical drawing it is essential that we be able to see the new size of the part as we move a surface or pull or push a surface or a side or a point. I do understand there is a way to do it by using guides. However, that is least desirable way.
Why do you need to see a changing number when moving something?
eyeballing it is the wrong way to do it…
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Wouldn’t adding a dimension line do just that? If positioned correctly, associated with the proper geometry it would follow the changes.
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See this SU file.
Changing dimension.skp (217.1 KB)
Thank you so much for this example. It works great in the simplified way. Now make that cube into a group. Try the same thing and it blurs out the dimension. Makes it unusable!!!
Try and let me know, Thanks
Also note when the drawing gets a little more complex the dimension number doesn’t change until you focus out of it.
I respectfully disagree. I design and fabricate large scale kinetic machines which are modeled in SketchUp. I output .DWG toolpaths directly from the SketchUp model which I send for fabrication in waterjet, CNC Plasma or other CNC tools with precision a precision of .001". It only very rarely that I ever use dimensions within SketchUp (I do all dimensioning for construction documents in Layout) and NEVER can I see any reason to be “watching” a dimension change while transforming geometry. SketchUp is capable of transforming geometry precisely and quickly using the native tools. I may seem like we are resistant to your suggestion, but I have been doing this a long time and I assure you the tools work very well, it seems like perhaps you are resistant to learning how the tools in SketchUp work to help you quickly meet your goals and for your modeling skills to progress.
Scale certainly can accept precise absolute dimensions, it is specifically designed to do so. You can change one, two, or all three dimension of an object quickly with one click. Choose the scale tool, click once on the desired scale handle then immediately type in the target dimension or series of dimensions you want, (as has been shown in the thread above). The scale tool is often the correct tool for changing the size of objects in SketchUp.
I only occasionally use guides, they are sometimes useful but for the most part anything can be sized or moved around precisely by inference or by simply typing in the desired dimensions, no guides necessary.
Again, I would rarely need to see the dimensions of an object in the model, I would make it the right size to start and build up the accompanying assembly around it, and if it required a change in size I would type in the target size ensuring precision. However, if you want to see the dimensions you certainly can as @jean_lemire_1 has suggested. If your dimensions are greyed out when you open the group for editing then you have not included the dimensions inside the group, put them there and they will not grey out while editing the group. It does work, although it’s not necessary to see the numbers to be accurate, just type in 2m.
Complexity has nothing to do with it, if the dimensions are attached outside of the current editing context they will not update until you exit the editing context, until the focus is on the context that contains the dimension. Put the dimension inside the group if you must see if update in real time.
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Here you go.
Click in sequence on the scenes tabs of this SU file.
Changing dimension with groups.skp (158.5 KB)
Thank you Jean in taking time to explain me all this, It makes sense!
I still think typing an exact dimension has a value. I do construction drawings and I can use it a lot.
Also, grouping something (in a greater philosophy) should only be a way to create an object which shouldn’t be bounding measurements.
With SketchUp, you enter precise dimensions in the Dimension Window as you create objects.
The Dimension Tool is there to allow you to show the dimensions that you want to appear with your sketch.
If you need really good looking construction drawings, you can use Layout that comes with SketchUp Pro.
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Dimensions attached to geometry in a lower context (from the outside of a (nested) object) do update realtime (either with ‘P/P’ or with ‘Scale’ or with ‘Move’) when applying these tools in the lower context(s)
Dimension must be in the same context of the geometry or attached to it from a higher context.
Dimensions can’t be associated in any way to geometry in a higher context for being able to update.
@endlessfix, I assume you made a typo here, you know all this don’t you?
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Hmmm, that’s not what I see. Dimensions that exist in a higher context than the geometry they are attached to do remain attached to their anchor points when changes are made within a lower context, however the dimension number does not update in realtime. The dimensions value remains frozen at it’s previous value until the focus returns to the context that contains the dimension, then the value is updated. In the second part of this gif you see one dimension (red) inside the component and another (black) outside the component?
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