Helix-parameters from spreadsheet

[MarianAldenhoevel]

Hi,

(I am a complete beginner in working with FreeCAD, I have some experience using Rhino)

Q: Is there a variant of the Helix that can pull parameters from a spreadsheet?

Background:

I am designing a model of a vibratory bowl feeder. I want to ultimately 3D-print it and try to get it working. Similar in intent to this project:

https://bytechlab.com/2018/07/smd-parts ... prototype/

I have made some progress using a Part/Helix, a ShapeBinder to get that into Part Design and then an additive pipe using an L-shaped profile:

feeder.png (38.21 KiB) Viewed 582 times

Now I do not know any of the final dimensions like pitch and angle of the track. These are the variables in the experimentation. So I am trying to make this a proper parametric design. That is why I would like the thing to use a spreadsheet.

Any pointers are appreciated, also some for further reading.

Thanks for reading and Regards,
Marian

OS: Windows 10 (10.0)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.22960 (Git)
Build type: Release
Branch: master
Hash: c5a4b01d2e4218bcc0eb6650337650a6c65ef0e4
Python version: 3.8.6
Qt version: 5.12.5
Coin version: 4.0.0
OCC version: 7.4.0
Locale: German/Germany (de_DE)

[chrisb]

As soon as you have created the helix, the property fields are expression aware.

[jmaustpc]

Another point to consider is that if you make a sweep from one profile to another then the path could potentially be a flat 2d curve or spiral etc. because the offset from that path will start at the first profile and end at the offset of the last profile. So if the first profile is at the same height as the sketch then the whatever vertical-to-the-2d-curved-path offset defined for the second profile will be the top of a 3d helix.

May or may not help is this specific case.

Another thing to what for is that it could be possible that FreeCAD might complain that you object in the image is a self intersecting solid, check with Part WB... part Menu... Check Geometry...".

[jmaustpc]

Q: Is there a variant of the Helix that can pull parameters from a spreadsheet?

the simple answer to that is yes, I have added the Expressions into the properties of the helix for you in this file.

Wendelförderer1.FCStd

(225.57 KiB) Downloaded 10 times

Note that after the additive pipe I have been experimenting so other aspects of this file are messed up.

Note2, I ran the check geometry at the additive pipe stage and it is not valid due to the solid being self intersecting.

[MarianAldenhoevel]

Hi,

As soon as you have created the helix, the property fields are expression aware.

Thank you for your answer, this is clearly a case of confused noob. The property list shows the expression icon, the double-click-dialog does not:

dialog.png (13.71 KiB) Viewed 544 times

data.png (16.38 KiB) Viewed 544 times

Now that I know where to look it works as expected.

FreeCAD might complain that your object in the image is a self intersecting solid

It has not complained to me yet, but I am aware of the issue. I expect to fix that by appropriately constraining the L-profile-sketch based on the dimensions from the spreadsheet. If I take into account the helix-pitch and -angle I hope to avoid the self-intersection.

Thanks for pointing that out.

Regards,
Marian

[chrisb]

It is a known issue that some of the Part dialogs are not fully expression aware yet.

[MarianAldenhoevel]

Hi,

I have redrawn the thing. I based the helix on dimensions the from spreadsheet, that works perfectly. Thanks chrisb. I have also redone the track profile to avoid self-intersections. Thanks jmustpc.

The result is looking good visually and check geometry does not flag any problems.

feeder.png (54.17 KiB) Viewed 523 times

Unfortunately it is not as alive and dimension-aware as I'd like it to be.

If I change the bowl height (B5 in the spreadsheet, alias bowl_height) the helix does adapt, but that change does not propagate to the rest of the model that is based on that helix.

Instead I get an error-icon on the ShapeBinder. The message is "Index out of bound".

Find attached my model just before I change the bowl_height.

What am I doing wrong?

Regards, Marian

[jmaustpc]

One other tip I forgot to mention, don't give things labels with spaces in them like you did for your spreadsheet, (better to use an underscore), because if you do then you can not read that label from an expression. In your case I used "Spreadsheet" which was the "Name" as distinct from the "label" originally on first creation label is the same as the name, but name can never be edited where as label can.

[chrisb]

You should have used the whole helix in the ShapeBinder, not only some edges.

[MarianAldenhoevel]

You should have used the whole helix in the ShapeBinder, not only some edges.

Thanks! That did it.

I did add all edges, but that apparently is not the same as adding the object itself. I have also renamed everything and avoided spaces.

I have attached the new model for reference if someone else revisits this thread in the future.

Regards, Marian