Precision scaling in SU

Can anyone tell me if there is a method for precise scaling in SU?

I often have to import a drawing in a format that does not bring it into SU at true size. But I often know at least one dimension. What I do at present is to get SU to measure the element with the known dimension, calculate the ratio of known to actual, and using the scale tool and the ratio adjust the drawing to suit. At smaller scales, that works well, but for a building that is, say, 20m long, it only tends to be accurate to the nearest cm. I need it accurate to the nearest mm.

I know you can resize a line to a precise dimension but I need to apply that precision to a whole drawing.

Have a look here and see if it helps.

It does, thanks. Not so much the rescaling of the box but the instructions on how to use the Tape tool to rescale a complete model based on one known dimension. That is what I was after.

I would like to revisit this as I may be missing something.

Using the Tape tool to resize the entire model is a great feature but doesn’t seem to work when you just want to resize a component, say.

Here’s a typical problem: you import a component (a window, say) and you want to fit it into an existing opening. If you use the Scale tool, you would have to use one of the corner handles to scale everything equally. But you cannot then click on a relevant point to scale to. You can only approximate to it visually. Or can you?

Open the component for editing and then use the Tape Measure tool.

As I showed in the other thread, you can scale a component to exact dimensions by typing the unit.
You can put in 1,2 or 3 axis dimensions.
You with a window component you can scale it to fit the hole and the thickness of the wall.
You can even mix up the units, 50mm,1.2m,6’6" will resize to exactly that.

Box, thanks but that’s not what I am after. To do what you suggest, I would first have to know, or find out, the relevant dimension. I was hoping there was a way of using the scale tool handles, say, to lock onto a given point. That would be a lot faster.

If you are working on an existing building, especially an old one, chances are that nearly all the windows and doors will be a different size. I am looking for quick way to take a basic window or door component and then scaling it quickly for each aperture.

DaveR has suggested opening the component for editing. I haven’t tried that but even that would be more long-winded than I wanted.

Grab the middle handle on the corner and drag to the corner of the opening. It will snap to that point.

1 Like

Ah, I think I see the problem. I was trying to do it with a 2D object which has no central handles.

I do often use 2D components in 3D drawings (to show door swings on plan, for example), so it is a shame if it doesn’t work with them.

What @Box is showing should work for 2D items, as well, though you may want to use the top, bottom, left, and right handles, rather than the corners:

Or use the Shift+ corner to do exactly as he did:

If you do that, you stretch in one dimension only. I want to scale the whole component equally based on changing one dimension to suit an existing length in the drawing.

Sorry… I hit the Reply button a little to quick and had to add the second part as an edit. If you press Shift, then grab a corner, you can drag the corner wherever you want.

Or as @DaveR said, open for edit and use the tape measure.
There are many many ways.

I attach a simple drawing showing the kind of thing I often have to do.

The wall has two openings of different sizes. I have created a 2D Group showing the door frame and door swing. I have copied it to the second opening. Now I want to leave the left hand frame where it is, aligned with the wall as it is, but scale the whole thing up so that the right hand frame locks onto the reveal of the opening. If I try doing that, I cannot get the handle to lock onto any specific point. I am not sure that anything that has been suggested so far addresses this, or at least not without a lot of manipulation for each instance.Example.skp (209.3 KB)

I find that if I hold down the Shift key whilst pulling a central handle in Scaling, the group does maintain a consistent shape and you can select a given point. That solves the precise scaling issue. Unfortunately, as it scales it around its centroid, it does not keep its position, so you then have to move the group after scaling it.

It’s an improvement but not quite as simple as I hoped.

I don’t understand why it’s “too long-winded” to open it for editing and use the Tape Measure tool. it works very simply and quickly for me.

Try it in this version of your model.Example.skp (209.3 KB)

A door swing is actually a rather bad example as the faces representing the frame should remain a constant size - it is a job for a dynamic component.


True, @Anssi, but Simon was asking about scaling to fit.

Bad example? It’s just something I have to do often and need to be able to do simply and quickly repetitively.

I could try using a DC (and I do see their theoretical advantages) but I have found them more trouble than they are worth. Fine for a manufacturer perhaps, but not for an architect.

DaveR may have the answer with the Tape Measure tool but I am not being able to replicate his ease of use yet. More effort required perhaps.

DaveR I cannot quite see what you are doing here. The SU help file page about using Tape Measure to scale things suggest you have to know a final distance or proportion. What I am after is something a lot more intuitive than that. I don’t want to have to interrogate to find distances for each instance.

What I hope you are indicating is that you can use the tool to define a dimension to be altered (width of component, say), and then use the same tool to define the new width (ie. opening width). If you choose the two widths along the same notional line, the component will be enlarged/reduced keeping the defined line constant. Or put another way, the first point you click both to define the datum distance and the revised distance will be the point around which the scaling occurs.

As things stand, I have not found a way to achieve this either with the Scale tool or the Tape Measure. But I am very ready to listen to anyone who tells me there is a way.