Updated: Thread for screw tutorial

A place to share learning material: written tutorials, videos, etc.
Forum rules
Be nice to others! Respect the FreeCAD code of conduct!
vocx
Veteran
Posts: 5197
Joined: Thu Oct 18, 2018 9:18 pm

Updated: Thread for screw tutorial

Post by vocx »

I updated the Thread for Screw Tutorial in the wiki for v0.19.

This tutorial was originally made with v0.14, and I think it assumed use of the Part Workbench only.

I added more information about the process using the PartDesign Workbench, and better images.

I did not touch significantly the methods 4 and 5 because the instructions they contain are a bit hard to follow in my opinion. So I would have to investigate exactly what they mean, and then re-write them.

I add in this post the files that I used to generate the models and the images. I will reference this post in the wiki as well.
T13_Threads_01_fake_threads.FCStd
(90.72 KiB) Downloaded 281 times
T13_Threads_02_real_helical_threads_small.FCStd
(840.79 KiB) Downloaded 279 times
T13_Threads_03_real_helical_threads_Part.FCStd
(151.85 KiB) Downloaded 258 times
T13_Threads_04_flat_images.FCStd
(59.6 KiB) Downloaded 234 times
Always add the important information to your posts if you need help. Also see Tutorials and Video tutorials.
To support the documentation effort, and code development, your donation is appreciated: liberapay.com/FreeCAD.
chrisb
Veteran
Posts: 53930
Joined: Tue Mar 17, 2015 9:14 am

Re: Updated: Thread for screw tutorial

Post by chrisb »

vocx wrote: Sat Mar 28, 2020 7:48 pm T13_Threads_02_real_helical_threads_small.FCStd
We often recommend to minimize the number of dimensional constraints, so I propose this sketch for the section:
Snip macro screenshot-a2eb76.png
Snip macro screenshot-a2eb76.png (7.69 KiB) Viewed 6693 times
It has the additional advantage that it shows directly the important angle of 60° and omitting the obsolete construction line.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
User avatar
jruiz
Posts: 479
Joined: Tue Oct 28, 2014 1:07 pm
Contact:

Re: Updated: Thread for screw tutorial

Post by jruiz »

I think that in Thread for Screw Tutorial, the
Method 3. Sweeping a vertical profile
should be complemented explaining how to cut the thread so that no abrupt ends appears.
Furthermore, instead of using Part WB for creating the inner cylinder, Part Design WB should be used.
I have uploaded many FreeCAD video tutorials to my YouTube channel
chrisb
Veteran
Posts: 53930
Joined: Tue Mar 17, 2015 9:14 am

Re: Updated: Thread for screw tutorial

Post by chrisb »

jruiz wrote: Sat Apr 04, 2020 1:31 pm I think that in Thread for Screw Tutorial, the
Method 3. Sweeping a vertical profile
should be complemented explaining how to cut the thread so that no abrupt ends appears.
+1

Furthermore, instead of using Part WB for creating the inner cylinder, Part Design WB should be used.
There is nothing said how threads have to be made using PartDesign. So either it has to be explained in full detail or only the principles should be shown; thats how it is now.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
User avatar
jruiz
Posts: 479
Joined: Tue Oct 28, 2014 1:07 pm
Contact:

Re: Updated: Thread for screw tutorial

Post by jruiz »

chrisb wrote: Sat Mar 28, 2020 9:23 pm
vocx wrote: Sat Mar 28, 2020 7:48 pm T13_Threads_02_real_helical_threads_small.FCStd
We often recommend to minimize the number of dimensional constraints, so I propose this sketch for the section:
Snip macro screenshot-a2eb76.png
It has the additional advantage that it shows directly the important angle of 60° and omitting the obsolete construction line.
Don't know how about, but sometimes I get unwanted behavior from FreeCAD when using previous profile.
For example, the profile shown in threadProfile.png has worked fine for me.
In the image, the arrows point the difference between the two profiles.
Attachments
threadProfile.png
threadProfile.png (24.45 KiB) Viewed 6569 times
Last edited by jruiz on Sat Apr 04, 2020 2:18 pm, edited 2 times in total.
I have uploaded many FreeCAD video tutorials to my YouTube channel
User avatar
jruiz
Posts: 479
Joined: Tue Oct 28, 2014 1:07 pm
Contact:

Re: Updated: Thread for screw tutorial

Post by jruiz »

chrisb wrote: Sat Apr 04, 2020 1:49 pm There is nothing said how threads have to be made using PartDesign. So either it has to be explained in full detail or only the principles should be shown; thats how it is now.
A simple way I found for cuting the ends of the thread is using a groove:
Attachments
1.png
1.png (210.95 KiB) Viewed 6571 times
2.png
2.png (263.42 KiB) Viewed 6571 times
3.png
3.png (253.74 KiB) Viewed 6574 times
I have uploaded many FreeCAD video tutorials to my YouTube channel
User avatar
jruiz
Posts: 479
Joined: Tue Oct 28, 2014 1:07 pm
Contact:

(Errors when submiting)

Post by jruiz »

.
I have uploaded many FreeCAD video tutorials to my YouTube channel
User avatar
jruiz
Posts: 479
Joined: Tue Oct 28, 2014 1:07 pm
Contact:

Re: Updated: Thread for screw tutorial

Post by jruiz »

Another way of cutting up the thread I like best:
Attachments
Captura de pantalla de 2020-04-04 10-21-11.png
Captura de pantalla de 2020-04-04 10-21-11.png (194.76 KiB) Viewed 6566 times
Captura de pantalla de 2020-04-04 10-21-21.png
Captura de pantalla de 2020-04-04 10-21-21.png (220.62 KiB) Viewed 6566 times
Captura de pantalla de 2020-04-04 10-21-32.png
Captura de pantalla de 2020-04-04 10-21-32.png (385.43 KiB) Viewed 6566 times
I have uploaded many FreeCAD video tutorials to my YouTube channel
chrisb
Veteran
Posts: 53930
Joined: Tue Mar 17, 2015 9:14 am

Re: Updated: Thread for screw tutorial

Post by chrisb »

I guess that real life bolts have neither of these, they rather have a 45° chamfer.

It may also be worth a discussion whether in PartDesign additive or subtractive sweeps are better. Most sweeps I see in PartDesign use subtractive. Together with the chamfer that seems to be easier than the additive variant.

Another topic is the inner runout in a partially threaded bolt like the Fasteners ISO4014 bolts.
Attachments
Snip macro screenshot-72a167.png
Snip macro screenshot-72a167.png (19.6 KiB) Viewed 6540 times
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
User avatar
jruiz
Posts: 479
Joined: Tue Oct 28, 2014 1:07 pm
Contact:

Re: Updated: Thread for screw tutorial

Post by jruiz »

chrisb wrote: Sat Apr 04, 2020 4:42 pm I guess that real life bolts have neither of these, they rather have a 45° chamfer.
Ok.
Attachments
1-4.png
1-4.png (517.76 KiB) Viewed 6522 times
5-8.png
5-8.png (461.95 KiB) Viewed 6522 times
I have uploaded many FreeCAD video tutorials to my YouTube channel
Post Reply