Virtual Designs in Sketchup #4: File Size (WATCH OUT!)

  • Advertise with us
Blog entry by rance posted 06-05-2011 08:44 PM 5565 reads 1 time favorited 7 comments Add to Favorites Watch
« Part 3: Rolling Tool Cart Part 4 of Virtual Designs in Sketchup series Part 5: Rolling Wood Storage Rack »

So many times I see a great SU drawing, but the author totally ignored the idea of file size economy. What am I talking about here? If you plan on sharing your file with someone else, it might be beneficial to both parties to stay cognizant of the size of the file you are creating.

Even though I am getting to the point in SU where it no longer impeeds my progress, I still watch SU tutorials from time to time. Just a few months ago, I came across one that went into a some detail about file size consideration. Unfortunately, for the life of me I cannot recall where I saw it and did not save the link. If you know of that(or another) tutorial that talks about file bloat, I would appreciate you sharing that link so I could review it for myself and pass it on to others.

When building objects, I make every separate piece of wood, a component. Why not a group? Well, when you copy a Group, you are copying each and every line and face that makes up that object. When you copy a component, you are essentially only copying a link to the definition of the object rather than a full copy of that object. The definition is stored in your SU file only once and each copy of that Component points back to the definition to understand how it is built. That ‘pointer’ takes up a whole lot smaller space than the actual definition does.

Another aspect of SU that often contributes to file bloat is curves. Curves are really only a series of straight lines. The default for drawing circles is to make them up with a series of 24 straight lines. You have the option to change that though. When you select the Circle tool, look at the lower right corner of your SU window. See the 24? You can just type 12 and press the Enter key. You have now changed the definition of a circle to only take up 12 line segments rather than the default of 24. Yes, you loose a little bit of resolution and ‘realism’, but how ‘real’ does a hidden hole really need to be in a drawing? Not often in most cases. Take the case below where we draw a caster. The one on the left takes 77kb to draw, whereas the one on the right reduces that to only 33kb:

Once you zoom out to see the whole project, you’ll likely not even notice the resolution difference. To compound that, imagine a Sphere. By default, it is made up of many faces. 288 to be exact. By changing your default circle to just half(12), you reduce the number of faces to a mere 72:

I’m not suggesting that you ALWAYS reduce the resolution, but you can certainly reduce it when it is not needed. After all, the purpose for most of us woodworkers in using SU is to 1) get an idea of an object’s shape and dimensional ratios before we go cutting up possibly expensive lumber, and 2) to have the drawing tell US what the exact dimension of a piece is that we’ve designed.

And as mentioned earlier, using Components rather than Groups, you can further reduce your file sizes. I hope this is helpful to some of you.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

7 comments so far

View ptweedy's profile


75 posts in 4642 days

#1 posted 06-05-2011 09:03 PM

excellent blog on su. why dont we have a on going thread on su. The length was just right. thank you,,,, phil [email protected]

View Brad_Nailor's profile


2545 posts in 5206 days

#2 posted 06-06-2011 02:13 PM

I like to use groups and components more for the ability to control interaction between geometry, to keep parts separate, ease of drawing and manipulating elements…but I guess the file size reduction is a nice benefit. This is similar to blocks in the AutoCAD world. Also with components (and blocks) you can get global updates….you make a change to the component and all like components reflect that change.


View rance's profile


4279 posts in 4409 days

#3 posted 06-06-2011 11:33 PM

Thank you Phil. DaveR used to post on here with a lot of SU stuff but he’s concentrating his efforts elsewhere. When folks ask SU questions, there are still several folks here to answer. Do you have any particular areas of SU that you’d like to see discussed?

I agree David. Like parts on a machine that all move together should be ‘stuck’ together so they move as a cohesive unit. I’m trying to learn to use BobCad for my CNC work. I realize SU has some scripts that can export but BobCad(or TurboCad) seems to be a better fit for that kind of work. But for woodworking(and for free), SU does a pretty good job.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View EvilNuff's profile


60 posts in 3876 days

#4 posted 06-07-2011 05:47 AM

Those are some good tips but I find myself asking…are they really needed? Even a pretty detailed sketchup model doesnt get over a few meg and really even if a file ran 100meg that’s not significant these days. To me its just easier to make the components the way I want them as opposed to worrying about the size.

View smitty22's profile


714 posts in 4195 days

#5 posted 06-18-2011 04:30 AM

Thanks for the tips! I will confirm that a SU model can get bloated pretty fast as the project grows. As an example, and although it’s way out of the realm of woodworking, I’ve modeled an entire 30 acre 25, 50, 100, and 200-yard shooting range with lot’s of construction details and groups, file size was above 24MB, but with some judicious use of these tips and and the ‘purge unused’ function under the model info window, reduced it to under 5MB.

-- Smitty

View rance's profile


4279 posts in 4409 days

#6 posted 06-25-2011 08:52 PM

Evil, Yes, computers have grown to meet some of the older challenges. Storage is only one reason to keep the file size down. As files grow in size, it also affects the speed at which you can orbit an object or move parts around. Folks with bleeding-edge computers may not notice these affects but I’m guessing that the woodworking community rarely has that fast of a computer.

Smitty, I’ll have to look into ‘purge unused’. There are still so many things in SU that I have yet to explore. One thing I’ve found is if I open a model, select everything(Ctrl-A), and copy it to the clipboard. Then create a brand new file(File/New), and paste in place’ the contents of the clipboard and save this new model. The extraneous stuff is eliminated. This may in fact have the same effect as ‘purge unused’. Hey, we’re BOTH learning here. Thanks for sharing.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View Tootles's profile


808 posts in 3750 days

#7 posted 08-04-2011 02:47 PM


Thanks for this blog. A few days ago I was trying to solve a problem using the intersection of two circles where the standard 24 segments per circle was simply not accurate enough. If I’d known then how to increase the number of segments, I would have been able to get a much better result.

-- I may have lost my marbles, but I still have my love of woodworking

Have your say...

You must be signed in to post the comments.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics