Can't Push / Pull Certain Wall


#1

First post, hope I’m doing it right.

First off, here’s a recording of what I’m trying to do: https://www.gfycat.com/GeneralAmpleFerret

You can see that I’m able to push and pull the right side of the little extrusion, but the left side doesn’t move. I created the extrusion by using those lines you see coming from the center to pull it out, so I have no idea how the left/right side got treated differently. Please help!

Thanks, Pillar


#2

It looks like it’s due to the face that the face you’re trying to push can’t go because of the shape at the bottom of the sector. How about uploading the SKP file instead? That’ll give us more information and make it easier to help you.


#3

That makes sense haha
GearSKP.skp (193.1 KB)


#4

My mistake. It’s actually the outer end where the problem lies. The face is longer than the space you’re tying to extrude it into. Are you trying to make all the vanes narrower?

Also, what is it you intend to do with this when you have it drawn? Are you hoping to 3D print it?


#5

Yeah, exactly. The heat from my 3d printer makes everything about a bit wider so I wanna make it narrower to account for that (so I’d be pushing the walls closer together, not pulling them apart)


#6

In this case I think you would do best to redraw the thing from scratch with the narrower teeth. You won’t be able to just push those faces in because of the trapezoidal shape of the tooth. Your model’s got other issues that will prevent it from being printable, too.


#7

Uh oh, what are the other problems? That’s a shame, but if that’s the only way then alright.


#8

There are a bunch of internal faces and stray edges. You could fix it but you’d probably spend more time trying to do that than it would take to redraw it. As it’s draw it would make a pretty rough gear, too.

How wide do you want the teeth to be? Are those edges that meet at the center supposed to be there? What do they do?


#9

I used the edges to extrude the teeth of the gear, just left them there for now in case I need them later. I need the gear to be about .3 mm shorter on each side.


#10

That means the teeth are 0.6mm narrower than you have them drawn? Is that at the wider outside end or the narrow inside end?


#11

Ideally, yes.


#12

And 24 teeth?


#13

Yep, although that doesn’t matter as much.


#14

Alright. Hang on.


#15

Oh wow, thanks so much! The only really important thing is that the out parts are .6 mm thicker than the in parts, if that makes sense. Thanks again :smiley:


#16

**But when the item cools down and depending on its cofefficient of thermal exanpsion it will shrink some too. There are several Sagas ( Box comes to mind) that post often related to printing of gears or maybe it would be better to use a print technology the is not FDM to avoid the issue. It will be a cost benefit trade off assuming you are limited to FDM.? Also you will have to export your model as STL to print and and it is my concern it may not be the correct choice => check with Box.
You have not indicated the ultimate application of your gear, after opening you model I am surprised it is not a spur gear. I was expecting an involute profile so it would help to know your design intention: " Form follows function" .


#17

OK. Here’s how I went about drawing it between interruptions. I drew just a single tooth and recess in a sector.


Since there are 24 teeth, they are 15° apart. I divided the 15° into 5 which makes the tooth about the right width. The tooth is 2/5 and the space 3/5.

Then I used Rotate/Copy to make 23 additional copies about the center.

And finally, I deleted the coplanar edges to remove any internal faces and softened the edges on the inside and outside surfaces. Finally I made it a component which is a solid and should be printable. If the teeth aren’t quite the right size, you can do the same process and divide the sector into a different number of sections.


GearSKP.skp (181.0 KB)

Now you do it.


#18

A fast way to combine the many solids into one ist the “Outer Shell” option of the Solid Tools (this one is available in MAKE too)…


#19

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