Sketchup 2018 measurements are incorrect

I am building a single-seat airplane using Sketchup. The airframe will be cut from 2500mm x 1220mm plywood sheets, so I drew a 2500 x 1220 rectangle in which to place my parts. So far, so good.

However, when I imported the DXF file into a CAM program which had its work surface set to 2500 x 1220, the dimensions of the Sketchup file were wrong. The drawing was in fact about 10% (exactly 10.32%) oversize.

I opened the DXF in QCAD, measured the 2500mm side of the rectangle, and it measured 2758mm.

Fortunately, I could scale the DXF to the required size (using QCAD),. But this is a nightmare - I have scores of drawings which now have to be scaled.

Has anyone else come across this?

Duncan

The most common reason for this sort of discrepancy is that the scene created in SketchUp for the LO viewport doesn’t have the camera set to Parallel Projection and a standard view selected. Did you do that in your Sketchup model?

Out of curiosity, where do you get 2500 x 1220mm ply?

In the UK, and I thought, most of the world, it’s 2440 x 1220mm, or 8ft x 4ft in ‘old money.’

Would this discrepancy matter in your ability to fit parts onto a slightly smaller sheet?

John, there are some types of plywood that are available in 12’ long panels.

Thanks, Dave. I’ve seen hardboard in the past at 10’ x 4’ but never ply bigger than 8’ x 4’ in the UK, at least not from ordinary timber or builders merchants.

I’ve never seen in the US either, in the few similar stores I’ve been in there. Good to know you can get it bigger.

2500mm still seems an odd dimension, if the OP is trying to use the last few tens of mm of it, so I thought it worth raising a possible warning flag.

Hi,
I get my aircraft plywood from Boatcraft Marine, on the Gold Coast (Australia). For some reason they sell the 1.5mm and 3mm ply in 2500 lengths. 1.5mm Mourikis Gaboon Ply 2500x1220

And yes, I need all of that length to squeeze my fuselage panels in.

I didn’t set the camera to Parallel projection. Let me try that…

Duncan

Good to know that the US and UK aren’t the only places governing the size of materials in other countries!

Thanks for the information.

It was for that reason I thought to ask the question. Glad you can get it the full size you need.

Perfect! Thank you. You’ve just saved me from having to buy QCAD to scale my drawings and also saved me a HEAP of re-work.

:smiley:

So does that mean setting the Camera to Parallel Projection and the standard view took care of it?

That was my guess. A long time ago, in a galaxy far far away, I had a model in parallel projection, slightly tapped my mouse with orbit selected and saved the scene. All the dims were off. Took me a bit.

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OK - new issue: I’m using SketchUCam, which is extremely convenient. However, I can’t seem to get the pocketing tool to work. In the video tutorial it show the user selecting a face, selecting the pocket tool, and then applying the tool to the face. When I do this, all I get is a thin red outline round my rectangular object.

Where are the zig-zag lines?, and I don’t understand how to set the stepover percent.

Duncan