Something has gone awry, I don't know what or how


#1

I’m trying to accurately record and draw the dimensions of my drill press ledge.

Everything looked fine until I checked the dimensions across the drawing and two were not equal.

I have tried adding a circle to the centre to check it out and placing it in the centre seems to actually make it slightly offset. It goes over some lines and doesn’t touch others.

Can anyone see exactly where the problem is and let me know how it can be fixed?

Drill Press Table.skp (561.8 KB)

It’s clearer in the original with dimensions.

Drill Press Table Dimensions.skp (537.9 KB)


#2

Just an observation: The circle you have drawn has either a number of segments that is not divisible by 4 or it has been drawn off-axis. SketchUp circles are represented by regular polygons drawn within the radius specified, so it is the vertices that represent the real radius.


#3


#4

I think the place to start is the outside dimensions of the table. Do you really want them to be as they are?

And then, as Anssi mentioned, you should be drawing circles on axis and with segment counts that are divisible 4. I prefer divisible by 12 because that makes the circle easily divisible by 2,3, and 4


#5

Most importantly is that offsetting arcs and circles will produce unwanted results, because the offset is not derived from the ‘center’ of the arc/circle but from the midpoints of the edges that represent the arc/circle


#6

Thank you all for your replies. You have all given me useful feedback.

I did not realise that using offset could cause problems and neither did I realise that dividing circles and arcs so that they appear smoother could also have negative implications.

If I want to duplicate a shape without having to draw it repeatedly and also ensuring that the positioning is exact, how should I do it?

When I created the outermost shape originally, it was a square and I typed in the dimensions so I don’t understand why they are now different.

This project has brought a lot of issues to my attention and I need to understand these and how to avoid them whilst also working effectively/accurately before I can carry on.


#7

It’s not the dividing, it’s the number of divisions you choose and the orientation when you drag out the radius.

None of you model is difficult to draw without using Offset. And Offset might not be a problem for the model. It’s really only likely to be an issue with offsetting circles and arcs because offsetting is relative to edges while circle and arc radii are measured to vertices.

The precision you are using is fairly coarse for the size of the model. What size do you really want?

I guessed at your dimensions by rounding.

I used Offset from the outer perimeter of the table and just drew two different circles in the center.


#8

Thanks for your reply Dave.

The outside of the base is 245mm, not sure how it ended up larger. I thought I was offsetting inwards, perhaps I ended up offsetting outwards and the first true dimension was the second in. The dimensions are correct for the squares, rectangles and circles otherwise.

So in theory when I used offset on the squares, that should be fine.

Out of interest, how would you draw this quickly yourself without using offset for the shapes when the dimensions of the curves for the corners of the squares are specific and relative without losing the correct radius?

Although it doesn’t look like much, it took me a long time to get the right dimensions for the curves and to create the shapes.

I really hate how unsmooth circles and arcs look in SketchUp by default within the modelling side of things.

Thanks for all your help, I hope that you can impart this knowledge on me.


#9

First of all, how are you planning to use the drawing once you’ve made it? Are those radii inside the corners really all that critical? If they are, offset the edges before rounding, identify the centers of the arcs and use the Arc tool to draw them. You only need to model one quarter of this thing, anyway.

In many cases the default 12 and 24 sides for arcs and circles work out just fine. You have the option to increase the number of sides when it is needed.

I used 24 segments for the arcs and ended up with 96 for the circles in the center. I think that’s more than adequate for this.


#10

Wow, that’s a great tutorial. Thanks.

This is an interesting way to work.

I wasn’t sure how you drew the arcs the right distance from the middle/edge. How did you do that?

I couldn’t see how you duplicated the two parts when rotating for the third time, creating two quarters instead of one. Also, I couldn’t see how you set 24 segments for arcs and 96 segments for the circles as you went through.

How did you do those things please?

The accuracy is important for making a template that fits perfectly.


#11

The Arc tool takes a radius input and then a swept angle. I typed the radius for the central arcs and then used inferencing to sweep the arcs from edge to edge. In the case of the corner arcs, it was all inferencing no typing required.

It’s a radial array created with the Rotate tool. Invoke the copy function of the Rotate tool by hitting Ctrl. Thenrotate the first copy 90°, hit Enter, type x3 to make a total of three additional copies.

Immediately after activating the Arc tool and before setting the center point, type 24 and hit Enter. It’s the same for the 2-Point Arc, Pie, and Circle tools. If I’d draw the centeral circles with the Circle tool, I’d have set them to 96 sides but I got that by default by copying the 24-sided arc to make the circle. (24 x 4 = 96).

How are you making the template from the model?


#12

Thanks again for your useful information.

Going back to basics, when you created the squares, how did you specify how far from the edge that they should be (like using offset)?

In relation to how it will be templated, I am not sure yet. I am looking into my options.


#13

I used Offset. I only select the two outer edges before running it, though.


#14

Thanks, I am slowly going through your information to see the process through.

What did you calculate the dimensions to be to set the guidelines for the arcs and how do I increase the number of decimal places in the measurements?


#15

I don’t remember what I used for the outside radius on the corners. I didn’t keep the file after I made the screenshots. I rounded the radius I measured off of your model and made it something reasonable. The crossing guidelines then indicate the centers of the arcs as well.

In Window>Model Info>Units, set the Units and Precision as needed. I would model with Precision set as fine as available for the selected units but I wouldn’t create dimensioned drawings with the precision set to more places beyond the decimal than you can actually measure. I showed 6 places to prove that the model is drawn with precision and accuracy. 6 places can be a good thing for troubleshooting but it isn’t appropriate for a plan or even your pattern or template. A human hair is around 0.06mm in dia. and for a project of this sort that’s more than precision than you need.


#16

Thank you for that information Dave.

Going through your GIFs, I have noticed that you can be using a particular tool and then drag so that you can move somewhere else and immediately after dragging you revert back to the tool you were using pre-drag, how do you do this please?

This could save a ton of time!


#17

This is one of the fundamentals of Sketchup.
Hold down the Scroll wheel for Orbit, add shift to that to Pan and roll the wheel to zoom in and out.
All these actions can be done while using a tool, so with the pencil tool click and release to start drawing a line, then press down on the scroll wheel and orbit around to find where you want to end it, click and release to finish.


#18

Thank you Box, that’s really helpful.

Is there a way to change the default sides for arcs, pie and circles so that I don’t have to keep setting it and don’t forget to change it?


#19

Not from session to session, the default will always return to 12 and 24 each time you restart, but will retain what you have set within a session until you change it.


#20

I have been rechecking the measurements and going through your instructions. I’m currently stuck on this part:

It’s a radial array created with the Rotate tool. Invoke the copy function of the Rotate tool by hitting Ctrl. Thenrotate the first copy 90°, hit Enter, type x3 to make a total of three additional copies.

When I do this, at the point I hit enter nothing happens. If I follow this with x3 nothing happens. What am I doing wrong?