Spring mechanical part

[abdullah]

Hi!

I continue with my "direct-extruder" exercise:

extruder_progress.png (61.44 KiB) Viewed 4720 times

I need a spring for the tensioner (space between those washers):

extruder_tensioner.png (29.44 KiB) Viewed 4720 times

I have searched the forum and discovered a spring macro. However, this seems to be "just" one helix, not a physical spring that I could just drop into the design.

How do you add springs to your projects?

I have tried to find in FreeCADParts and Bolts without success (I get lost among references, so maybe there is one and I failed to find it)

Thanks in advance,
abdullah

[ulrich1a]

Springs suffer like screws from the poor quality of the OCCT-helix-function. Additional there is the question what is the length of the spring for the model. A spring has no fixed length. So a macro would need to know the compressed length of a "standard"-spring in the special situation. Just some thoughts.

In general a spring can be modeled with a part-helix. A circle is than swept along the helix with the parameters checked: make solid and Frenet. The first and last turn may have a different pitch in a real spring. The ends have to be cut. And here starts the fun, as in a lot of cases this fails. I have not tried myself, but read it in the forum.

Ulrich

[mario52]

hi
try this macro Macro_FCSpring_Helix_Variable you make the profile of the spring and sweep and cut

Spring00.png (112.84 KiB) Viewed 4617 times

mario

[ektus]

If you are looking for springs, go to some vendor, browse the catalogue and download models.


Main page of producer Gutekunst (no login required):
https://www.federnshop.com/en/
There's an online catalogue available where you can enter geometry/size, range of movement and force and select the matching stock part, from which you get direct links to the product in the CAD downloads page:
http://cad.federnshop.com/default.aspx?cul=en-US



Regards
Ektus.

[abdullah]

Thanks to you both!!!

That macro is very cool.

I went to the catalogue. I did manage to select a "compression spring", but I did not find the "range of movement" or diameter. I am not a mechanical engineer. I "just" wanted a spring for a M4 bolt with two M4 washers (I know this sounds "stupid" to a mechanical engineer). It is a good link to have it handy though...

EDIT: I managed to make the catalogue "work" by going to the calculations first and then from there to the catalog. This is very cool. Thanks!!

[abdullah]

Much better now!!

Extruder_w_spring.png (46.11 KiB) Viewed 4551 times

[ektus]

EDIT: I managed to make the catalogue "work" by going to the calculations first and then from there to the catalog. This is very cool. Thanks!!

You're welcome.

To select a spring by mechanical dimension, select wire diameter d (e.g. 1mm), outer diameter De (your screw diameter (4mm) + 2 times wire diameter + gap, e.g. 7mm) and uncompressed length L0. Then apply "search" and you will get a selection of stock products that match those parameters within the tolerances shown to the right of the search values, see screenshot. You may use any other combination of available dimensions, though, by changing the variables to the left of the input fields.

Gutekunst_Katalog.png (147.61 KiB) Viewed 4515 times

Regards
Ektus.

[triplus]

@ektus

Thanks for sharing the resource for springs.

P.S. As for modeling springs in FreeCAD as already mentioned it can be done manually or macros are available and there are issues involved like performance hit. Maybe in the future similar approach could be taken as with Fasteners WB. Users inserts spring in "simplified form". Maybe just as helix or helix with less turns. But there would be a property that could be changed to "make solid" if needed.