For some reason, this model consistently fails to scale using the tape measure method of scaling.

I select all, measure with the tape from central origin to apex (centre point of the red pentagon above the origin) and click on the apex.

I then type the size I want this to end up as - `20'`

.

The model moves a little, but the dimension that should become 20’ is unchanged.

Does it work for you?

If so, what am I doing wrong?

I am able to scale it using the scale tool and uniform scaling, but because it isn’t symmetrical about the origin, I can’t usefully scale it to a particular and exact 20’ with the scale tool.

I originally scaled it down from a 20’ radius by a scale factor to OO gauge scale (1:76.2 or 4mm to the foot, scale factor 4/304.8 = 0.01312335958) and foolishly started to work on it at that scale, and using Scale Definition to reset all the components to their new size, but instead of the radius coming down to 80mm , it ended up as 90.4mm and I didn’t notice immediately. I copied the scale factor from a Google Chrome calculation of 4/304.8, so I didn’t think I could have used the wrong scale factor through a typo.

Fails to scale.skp (213.1 KB)

I can fix it by first scaling down by 80/90.4, then scaling up by 76.2 and slightly to my surprise that does give me an exact value of 20’ for the radius, but I’m curious why the tape measure method doesn’t work.