How to select a circle's quadrant with precision / scaling a caster wheel

SketchUp Pro
1

A couple questions about scaling a wheel with precision:

1)I imported a caster from the 3D WH, but I need it to be exactly 3" in height.

When I select the lowest insection of the polygon forming the circle, it the leader line defaults to a location ABOVE what looks like the desired quadrant point (pictured).
Is this just my display playing tricks on me or have I actually selected the tangent I think I’m selecting?

  1. What’s a good practice to scale these types of object (those made of multiple shapes and contain circles)?

Thanks!

Caster
Caster709×579 24.8 KB
Scaling%20reference%20point

2

Go View and turn on hidden geometry so you can select a specific vertex.

1 Like
3

Simple scaling something like that may not actually result in the correct result. In order to keep the round parts round, you must scale equally in all three directions. This will make the wheel thicker, increase the diameter of the axle and maybe most critically change the size of the mounting plate or stem which could inaccurately impact the design of the project. Maybe it won’t matter in your project but my inclination would be to either redraw the wheel from scratch or even draw the entire caster from scratch with the right dimensions.

Do you want the wheel diameter to be 3 inches or the mounting height to be 3 inches? Mounting height of 3 inches makes for a pretty small wheel.

4

As @box alludes to, you are probably falling victim to thinking that the model is 2D when it is actually 3D with a torus shape to the wheel. You likely selected a point that is slightly around the curve, not on the ultimate perimeter. Turning on view->hidden geometry and orbiting a bit should reveal this situation.

Regarding scaling, one thing to beware is that it will scale all parts of the selection proportionally, which might not be what you want for the hub and bearing above the wheel.

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5

If you know only one specific dimension, grab the corresponding green handle and hold Shift for keeping the other dimensions in proportion.
So:

  • Select object
  • Select Scale Tool
  • Click on the right handle, move the mouse in a direction
  • Hold Shift, then Click and let go of the mouse
  • Type desired length. including units! (otherwise it uses scale factor) eg. 3" hit Enter

This way, you scale the bounding box of the object.

scale
scale3376×1736 3 MB

3 Likes
6

Thanks for the response.
I am trying to create a 3" tall caster (including wheel) …
They are going under a cabinet of specific height, so I need to get the height correct…
My usual method is to draw a line of the desired length, and then using the scale tool, snap the imported model to that reference line… That method fails me in this case however, since I can’t seem to snap to a tangent point on the wheel…

Thanks again.

7

Aha thank you!

1 Like
8

It might be worth looking at the casters that are available in the height you need. I looked at 3 or 4 different sources and didn’t find any caster in the style you show at least with that style of tire.