I model for fun in SU Make17, live in the UK and am familiar with Imperial measurements having grown up with them at school, however since 1974, I have used the Metric system. I model in Sketchup in metric which requires less maths to complete a task - no this IS NOT another debate on which is the better system!! It is a request to those who model in Imperial to help me with an issue I’ve run into.
On the Happenings category, there is a live stream scheduled for this Friday to model an interesting grasshopper steam engine and the person who requested this kindly posted the 2D plans. The plans are Imperial and there are some extremely small components and miniscule radius holes which I can’t model as Sketcup tells me that, either the radius is too small or the number of segments is too large for the given angle and radius. The result of this is I can’t accurately model these small parts and need to be able to scale them up.
I am aware of this limitation so when I come across this in my normal metric modelling I just change the modelling units from mm to cm, a scale factor of 10 or mm to metres, a scale factor of 1000. This results in it being easy to do as the numeric input is the same and I don’t have the issue I get with Imperial. Here is my issue using Imperial.
I have tried scaling up but the maths required to do it is not the easiest. For example, ⅞” scaled by 10 in SU gives 8¾“ and scaled by 100 gives 87½”. I tried all the various feet and inches combinations, architectural etc but could not get the numeric input the same as I can in metric. Is there a workaround?
(I was going to reach out to @DaveR because of the number of these types of models he has drawn but I think I’ve bothered him enough over the years).
When I model small things like these little engines with the dimensions given in fractional inches, I still model in meters as I do with models for 3D printing. I know most of the decimal equivalents for the common fractions and can convert in my head on the fly but SketchUp will accept input in fractions. So instead of typing 1.875 i is possible to type 1 7/8 and get the same thing.
So the plan for this engine calls for the flywheel to be 2.5 in. dia. but I modeled it as 2.5 meters in diamter. Fancy 2 Engine
I appreciate that Dave and I’ve got my conversion equivalents. Being lazy, What I want to be able to do is type the numbers on the plan. I can’t do the same in Imperial as a 29/64" scaled x 10 = 4+17/32" which is a pain as I’d like to type the numbers on the plan that automatically scale up.
It looks like I’m going to have to use the longer way round, but I suppose I’ll get used to it.
I think you’re missing my point. I don’t do any scaling at all. No need for any scaling factors while modeling. I change the units to meters and enter the dimensions as they are shown in the plan. The only reason I might scale a model created that way would be if I was going to 3D print it. And in that case I would scale the model up by a factor of 25.4. If I exported the .stl file of the components in the little steam engine in my previous post as it is, the flywheel would print at 2.5mm dia. when it should be 63.5mm.
That’s exactly what I wrote in my previous post. The units are set to meters but I type the numbers as shown in the plan.
If you want the model to be actual size when you are finished, scale the entire thing down in one step and scale the component definitions afterward.
oh yeah, that’s the sort of things I know, that I know I know, but at the same time, I’ve never had to use it so I completely forget about it every time
I have this little voice in my head saying “inches are the only thing SketchUp displays as fractions, so that must be what it will assume if you input fractions, regardless of units”. I scale to meters for imperial just seldom enough that it misleads me every time!
