How to fully constrain circles from rotating in sketch

[skarol112]

Hello, 

I keep trying to "restrain" these circles, but only the ones that begin at the origin appear black or fully constrained. I'm out of options as to how to do it or what caused the first two ones to be constrained properly. What I have tried so far:

- Setting dimensions between points (they're now deleted).

- Setting the dimension between the circle's center point and the line as 0 (didn't work) - initially, that line was part of a different sketch where there were only dimensions between different points, but I remade it for the 2nd sketch to see whether it would work. The line goes straight through all the points, along the left view axis.

I can see the possible issue because I can rotate these circles through RMB>Move/Copy. What I don't get, though, is why the black ones can be rotated as well?

This is to satisfy my thirst for knowledge, however. Ideally, I'd like to know how to prevent that rotation, so that (hopefully) the circles become black.

In case my approach is vastly ineffective, this is what I'm trying to model:

I'm not 100% certain of the measurements, so I decided on the extruding circles approach instead of creating "pipes" around a line, because I feel it'll be much easier to tweak if my 3D print comes out wrong.

If you need anything more from me to help me solve this issue, I'll be happy to provide. I'm quite burnt out already, spent 3 hours on various constraints trying to get it to work, but to no avail.

Regards

[davebYYPCU]

Use Revolve.

You will have lots of grief using 3d sketch for this model, including rotating sketches.

I would expect 5 sketches, one each on an offset plane.

Might help....

[HughesTooling]

Revolve is probably the best option but you could also draw all the circles on one plane then set the start offset to the end of the previous extrude.

[HughesTooling]

Just a note on creating a sketch for a revolve. If you use the centreline line type for the revolve centre you can dimension using diameters.

[laughingcreek]

agree with the others. revolve is the way to go here.  moving sketch entities off plane (creating a 3d sketch) is only for certain circumstances.  this isn't one of those circumstances.

attached is a model demonstrating some of the things discussed in this thread.

[TheCADWhisperer]

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@skarol112 wrote:
…this is what I'm trying to model:

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@skarol112 

3hrs?

Ask questions early and often.

I would do it in Fusion the same way I would do out on the shop floor lathe - Revolve.

[skarol112]

Thank You all, did it according to your instructions using Revolve, and it turned out to be relatively easy indeed. I'm really grateful for pulling me out of the hole I dug for myself there. I also wanted to use the centreline, but it didn't work out well for me. Here's where I am currently at:

There are still two things that need to be done:

1. Turning that cylinder into an actual gear. @laughingcreek, how did you do that? I was planning on using a plugin for that:

But I'd like to hear Your opinions as to how to tackle it, so I don't get stuck for hours again.

2. The original part has a smooth descent from the first cylinder to the second (the gear):

(Hopefully, it's visible in the picture) The smoothening starts about 2mm in and gradually narrows the hole till it looks like in the first picture. Mine is steep because I just used an extruded cut. How do I go around modeling that? In this case, I have no idea how to do that.

[laughingcreek]

for the gear, a plug-in might not be a bad idea.  what i did was just for effect.  more effort would be needed to make a proper gear.  basicly  you need to work out the geometry of a tooth, sweep it up the cylinder, and then pattern it.  

for the bevel at the end of the gear, that's just a revolve-cut.

[laughingcreek]

p.s when ever someone supplies you with a model, it's a good idea to step thru the time line, exam the inputs to each feature, etc.  you can pick up a lot that way.