Lattice2 more restrictive in 0.17? (globoid worm drive attempt)

[glabifrons]

I'm trying to replicate the example of how to rotate on sweep (to make a globoid worm drive) posted by DeepSOIC a couple years ago, and am running into a problem.
https://forum.freecadweb.org/viewtopic. ... 06#p111075

I got as far as the point where I'm attempting to create an array of the half involute gear along the varying angled and rotated arrows (airplanes) and I get the below error:

SelectionError: You can't use population tools on shapes in partdesign body. Use Lattice PartDesign Pattern instead. Or deactivate active body to use populate tools on shapes.

That was from using the tool shown in the tree of the model attached to the above post, so apparently that's no longer a valid method.

"Lattice PartDesign Pattern" gives a different error:

Error: 'NoneType' object has no attribuge 'isDerivedFrom'

I'm not sure what to make of that or how to fix it.

Ideas?

Code: Select all

OS: Ubuntu 16.04.5 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13528 (Git)
Build type: None
Branch: releases/FreeCAD-0-17
Hash: 5c3f7bf8ec51e2c7187789f7edba71a7aa82a88b
Python version: 2.7.12
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedStates (en_US)

[TheMarkster]

Can you attach your file? By the looks of it he was using Part, not Part Design. Did you try deactivating the active body?

[glabifrons]

If I deactivate the active body, I cannot select the part to array it.
I used Part Design workbench for the InvoluteGear and the Sketch as I don't see either in the Part workbench. I made two attempts, in the second I used a pad where he used a pocket because it won't let you make a pocket without something to cut the pocket out of (I'm not sure how to get the BoundBox to have thickness). I ended up deleting the unused BoundBox from that one.
In my first one, I was somehow able to pad the BoundBox (after fighting with it for a while, not sure how I finally managed to do it) and pocketed it with a sketch the same way the person who uploaded the example did, but found the method I used in the second to be easier to cut the InvoluteGear, which is the piece that needs to be arrayed. Both attempts resulted in the same error when trying to array the split gear. The reason I decided to start from scratch a second time was to see if I could reproduce the pad and to see if I could figure out what I was doing wrong to cause the error. I have both files still so can upload both.
I did use Part workbench for the Common in both cases (just as he did).

I don't see a way to upload a file. Is it blocked because I'm new here?

Thanks.

[TheMarkster]

I don't see a way to upload a file. Is it blocked because I'm new here?

Thanks.

Look below where you type in your reply, below the submit button there are 2 tabs: Options and Attachments, the latter being the one you want. Open it and click Add files button. But it has to be less than 1MB or the forum software won't accept it. Sometimes you can delete some parts of the file that are not critical to the issue you are having in order to get under the size restriction. (You might want to save a backup before deleting stuff though.)

[glabifrons]

Thanks I totally missed that.
I've attached both attempts.

[DeepSOIC]

Yes you must use Part workflow for this task. PartDesign is quite restrictive, unfortunately.

[DeepSOIC]

There are also other changes, particularly fusing shells is no longer working the way it used to. I'll try to recreate the thing.

[DeepSOIC]

Good news is, the old file required only a minor tweak, and became parametric. I have changed the last step: it is now Part Slice + Compound Filter.
https://drive.google.com/file/d/1JexdLK ... sp=sharing
Bad news is, the worm is quite obviously unusable. If you look at it, and imagine a gear inserted into it, you'll see the gear cannot be disengaged, it should be stuck together forever. Likely, there are other (minor) imperfections in the shape.

[glabifrons]

Actually, this works nicely! Thanks!

I added a spreadsheet to automatically calculate the spread and angle of the PolarArray based on the specified number of teeth (so you don't have to edit each field each time you make a change), dimensioned the sketch, changed the radius to 8.5, the modulus to 0.5 and the number of teeth to 50, and I think it'll mesh well with a gear without going past perpendicular to the axis and still have ~6 teeth engaged

I'm going to try and recreate it to make sure I have a good grip on the tools used. Thanks again for fixing it!
Next, I'll have to try and figure out how to make the double-enveloping worm gear to match it