How to deal with "jerkiness" or undesired "snapping" as though there were an inference

[JanSteinman]

I quite often am frustrated when moving things, and they get “jerky” for lack of a better term.

It’s as though the thing I’m moving knows where I want it to go, and diabolically goes anyplace but!

Here is an example. I’m building different reciprocal roofs with 20 logs. I have two 20 segment bonding rings (inner and outer) that I want to be tangent with the logs.

I somehow managed that, and had even managed to rotate the ring so the flats on the ring aligned with the logs. However I did it, it “snapped” to the logs perfectly!

But I made adjustments to the centre diameter to get a lower pitch on the roof. Now, I’m trying to Scale the bonding ring to the new hole size. Here’s where I begin (top view):

At this point, I selected the bonding ring (a Component) and chose “Scale”. I hit Option to make it scale about the centre.

When I move the mouse, I can easily make the ring smaller. But when I try to make it bigger, it refuses to go past the original size, until it suddenly “jerks” to a much larger size!

I tried to establish an inference, by touching a log, but it did not react like an inference; it just ignored the log. I tried editing the ring component, selecting all within the component, with the same result — it jerks way over where I wanted to resize it to!

So this is now the closest I can get to making the bonding ring tangent to the log circle. (This is editing the ring component, which you can easily see buried within the logs, )

I’m sure this is a cockpit problem. It’s annoying that I managed to make it work before!

Any thoughts about what I’m doing wrong?

[bmike]

@JanSteinman

Any thoughts about what I’m doing wrong?

Scaling from a corner on a circular shape isn’t really the right way to get your geometry to be the right size - on a circle your geometry is no where near the corner that you are scaling from - you are essentially trying to scale the bounding box of your shape to work with existing geometry.

Start a new drawing and practice scaling circles until you see the logic of how it works, then you might see that you’ll need to draw some guidelines where your corner reference needs to be so you can reference it correctly…

But I wouldn’t even waste my time:

If it were my project I wouldn’t bother with scale at all. Draw a circle on the ground, reference where you need the face to be by locking onto the ground plane. Offset that circle to the real world thickness of the ring you need to build, push pull that shape to the height of the beam you will make, make a component and move it up into position.

[JanSteinman]

Thanks for your help!

First off, these are not circles. They are 20-sided polygons.

Reciprocal roofs are single-point-of-failure without a bond ring. These are 2x12 boards with the ends mitred off-square by 8.5°.

I started out with what I think you are saying. I made a 20-sided polygon on the R-G plane, offset it by 1.5", then extruded it to 11.5", then blue-moved it up into the ring, then rotated it until the flats aligned with the logs.

At that point, I had a 39° roof pitch for my desired 6’ centre opening. That was too steep for the planned living roof.

I re-calculated my spreadsheet, and a 10’ centre opening gave me a workable 24° pitch.

Then I got lazy. I knew the eventual site work would be different than the model, so I thought I could simply scale it to make it look good. That turned out to be frustrating!

But this sort of thing rears its head often. The roof column supports in this view were similarly frustrating to position. They’d dance and jerk around endlessly while trying to move them, refusing to go where I wanted them! No scaling involved! Just positioning and extruding the ends.

Orbiting my point of view and zooming in and out would sometimes make it easier to position them, but it seemed to take waaay too long to accomplish what I thought should be a fairly simple task!

So I’m interested in how you would have precisely positioned these column supports? (Reducing the roof pitch should make it easier, no?)

[mihai.s]

@JanSteinman

First off, these are not circles. They are 20-sided polygons.

Offset the ‘polygon’, as Mike indicated.

Just an idea (02)

Use simple shapes, with as few segments as possible, and then add the desired details if necessary.

Use Tags for all objects and when working on the roof, it will be easier if you turn off the furniture tag, just like the others, except for the rafters.

[JanSteinman]

Thanks! I will study that! I’m still playing with different openings and pitches, so that looks helpful!

How did you lift that roof like that? I see you’re starting with flat rectangles, then extruding into boards, but are you using push/pull on just the centre somehow?

It’s taking me a lot longer to “play with” different configurations.

I’ve determined I need 8" logs for loading, but I can see your approach providing a lot of “what if” information before modelling with cylinders.

[mihai.s]

You can create it according to your needs or desires.

A tutorial that can help you somewhat if you are using a rafter component, which you make a circular array of.

Reciprocal Roof Frame in Sketchup 6 sided.avi

[mihai.s]

Start with just an edge or a rectangle, then add the details you want (only if you really need them).

[bmike]

@JanSteinman

So I’m interested in how you would have precisely positioned these column supports?

I would have lots of geometry to use as guides. It looks like you have a centerline on your log rafters, you could have a simple surface for the centerline of the ellipse of the plan that is tall enough to intersect the rafters and then generate intersections of the center of the log down to the wall using the ellipse surface.

I modeled this in SKP and detailed it for permit drawings. And it was built:

Think about what geometry you can use or generate to align / move / etc.