I know the topic of aligning off-axis geometry has been discussed on this form, and I did get some help from this post and this video . But I still had trouble applying those methods to the spindle group in the attached file. I wanted this group to be aligned with the global x,y,z axes.
off-axis.skp (303.2 KB)
After trying many things, I finally came up with the method in this screen recording, but it seems more complicated than it needs to be.
Any advice?
What you describe seems to be the same thing that I have done, but getting “the bottom face centered on the origin” was not so easy for me (since they are not circles) and that’s why I had to draw those lines.
Maybe there’s just not an easier way to do it than I’ve already done.
My goal was to extract its profile so that I could change the spindle geometry; make a new version.
| DaveR SketchUp Sage
August 9 |
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Rotate the spindle in two steps. First around the red and then around the green. I moved the spindle so the bottom face is centered on the origin to give an easy to locate position for the Rotate tool and I locked the Rotate tool’s alignment first with the right arrow key for red and then the left arrow key for green.
What is your ultimate goal with this?
As @DaveR has said in another thread, “practice, practice, practice.” Remember that Dave has been using and teaching SketchUp for decades. We can’t expect to be as proficient in just a few years as he is. Things get better by following his instructions and advice and lots of practice.
Yes, I see what you’ve done now. Thanks again for the help.
@DaveR After thinking more about it, your method relies on:
So we both do (1) & (2), but you get to the end result quicker by seeing that there were “vertices aligned on axis” – I didn’t see that.
This is not the only time I’ve come across this problem and I was looking for a general way to do it. Focusing on that central spindle axis was the best I could come up with. Without that line of symmetry, I might have been completely lost.
I notice that you used one point which touched the bounding box and could have used the other. I wonder if this might hold to answer to doing it generally?
I have been playing around with this but all of my methods leave the spindle slightly off vertical.
Have a look at your own solution in Plan View with your camera set to Parallel Projection to see what I mean.
@DaveR Nice tip on offsetting the rotation & using inferencing. I have to ask though, why not just change the Axes of the group / component?
Yes - there is definitely something not quite right with that spindle. I think it should look perfectly round after exploding it and aligning the view to a cut face.
@kevin58 I looked at it more carefully and see that I made mistakes drawing the lines to find the center of each end in the original file that I posted. Nice catch!
I’m attaching a new file here which includes the previous one (labeled “wrong”) and a new one at the origin which I worked on more carefully.
But this sharp observation by @kevin58 makes me wonder all the more about the correct way to do this? To me, finding the center of those oval spindle ends is not simple, and perhaps my method of drawing intersecting lines between opposite vertices is not valid. I was so uncertain about this that at one point I removed the last portions of geometry at top and bottom so that I could work with the circular cross sections beneath them.
So, once again, I’m left with my question of how to put off-axis geometry “on-axis” in a way that will work generally?
By the way, this spindle drawing is not mine – I found it on SketchUp Warehouse, called Traditional Wood Dining Chair - Detailed – says it was drawn by “SketchUp” – my goal in using it was to have a starting point for making my own spindle profile.
off-axis2.skp (389.6 KB)
Hi Tony
I think the original spindle is drawn asymmetrical in some way in which case it will be impossible to align it vertically because their isn’t a true vertical centreline. If you put the camera in parallel projection and look in plan view you can see your second attempt is still not quite perfect.
I think once you have a truly symmetrical spindle there are a number of ways to align it. My own way without thinking about it too much would be to take a copy - paste in place, hide the original and explode the copy then create circular faces at the top and bottom and draw a line between the centres. Then delete everything but the line, unhide the original, select the original and the line and rotate the line along the green then the red axis to be vertical. I know that sounds complicated but it isn’t and eventually you would refine the method anyway.
Or maybe even something as simple as this if the spindle was sufficiently accurate and the diameters being sampled were exactly the same (which they are not).
Best of luck 
@DaveR I appreciate the advantages of working with components and how to make geometry that is properly aligned in the first place. But neither of these is what I was asking about.
My question focuses solely on how to align pre-existing off-axis geometry found on SketchUp Warehouse – a wonderful resource where we are able to make full use of other users’ hard work (in this case, by “SketchUp”).
The first step to doing that, in some cases, is to properly align off-axis geometry. Although this particular example may be difficult, I have run into many other cases where I had trouble doing this. It is for that reason that I’m looking for a general method and trying to understand the principles involved.
I appreciate all the help that has been posted so far, but I’m coming the conclusion that there may not be an easier way than I originally proposed.
I think you already have the correct principle:
But once again - the component in your example does not have a true centreline
@mihai.s Thank you for your video. I like the idea of using the axis tool to help solve this problem.
To me, the method of @mihai.s is the simplest solution to the problem I presented in the original question. For completeness, I’m including a video of how I applied it, as well as the .skp file.
The steps are:
The key to this method seems to be the “reset” command in step (4). I don’t understand exactly what that does, but the result is that the move tool rotation handles can then easily align the object to the global axes.
Another point: @kevin58 believed the spindle itself was not symmetrical, I tried to check that by drawing 10 circles over the key edges that define the spindle. They all overlapped perfectly as far as I could see. So I conclude that original spindle is symmetrical (again, it was not made by me, but by “SketchUp” in the Warehouse).
I’m not sure how well this method will apply with other off-axis objects, but at least I’ve learned a thing or two. Thanks to all for the help.
off-axis3.skp (281.8 KB)
