Screw Maker

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triplus
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Re: Screw Maker

Post by triplus »

ulrich1a wrote:Thanks!
You're welcome.
Most nuts have a chamfer between 30° to 45° at the inner thread. This chamfer cuts some material from the first/last turn.
You may test this and create a nut without thread. Then create a screw tap of approriate size and length and make the inner thread yourself. (The screw tap is the last item in the list of screws standards.) If everything is allright, it should create the same geometry as the nut created with real thread from the macro.

Ulrich
Yes this procedure creates the same result. I am guessing procedure used in manufacturing real nuts is slightly different and "simple chamfer" isn't used. If you compare real nut (if possible big size to observe fist/last thread) to the Screw Maker 3D model there is slight difference in the first/last thread. Anyway this is just observation as trying to create the same result would probably complicate things too much.
ulrich1a
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Re: Screw Maker

Post by ulrich1a »

triplus wrote:Anyway this is just observation as trying to create the same result would probably complicate things too much.
Yes, I made the chamfer as big as allowed due to the standards. This was to avoid a more complicated procedure to create the geometry. I tried a lot of ways to generate the thread at the screws, in order to get a valid shape. So I did not spend that much time on nuts. Anyway a real form from production is in the most cases not identical to the ideal geometry shown in a technical drawing. My goal was to get a geometry that is valid according to the standards.
Differences between real life and ideal model will happen. I created the thread with nominal dimensions. If someone wants to build screws and nuts with a 3D-printer there could be an option needed to introduce tolerances as well.


Ulrich
triplus
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Re: Screw Maker

Post by triplus »

ulrich1a wrote:Yes, I made the chamfer as big as allowed due to the standards. This was to avoid a more complicated procedure to create the geometry.
Yes that makes sense.
My goal was to get a geometry that is valid according to the standards.
This is the part i was referring to. I do believe (i could be wrong) first and last thread on the nut are not valid geometry according to the standards.

For example:
Thread.png
Thread.png (51.56 KiB) Viewed 3751 times
The thread (green) is "colliding" with chamfer (yellow). If nut like that would be made would it "work"? There probably shouldn't be any chamfer above it in that place (empty pocket). The thread itself would need to "get closer" (looking from top down) to the nut in that last 30 to 40 degrees of turn.

I am not saying this should be done as it would probably be hard to do. I am just mentioning it to be discussed.
Differences between real life and ideal model will happen. I created the thread with nominal dimensions. If someone wants to build screws and nuts with a 3D-printer there could be an option needed to introduce tolerances as well.
I think this is geometry not tolerance related difference.
triplus
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Re: Screw Maker

Post by triplus »

I took image here:

Image

Observe the last segment of the last turn. How it "blends in" with nut.
ulrich1a
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Re: Screw Maker

Post by ulrich1a »

triplus wrote:The thread (green) is "colliding" with chamfer (yellow). If nut like that would be made would it "work"?
As there is no nut-material where the bolt is, this works without problems. I had a look at a real nut here at home and it looks like the model. It only has a steeper chamfer in the tapped hole. So I see no problems here.
ulrich1a wrote:Differences between real life and ideal model will happen. I created the thread with nominal dimensions. If someone wants to build screws and nuts with a 3D-printer there could be an option needed to introduce tolerances as well.
This is a different topic, and may be an future option if anybody wants to make screws or screwholes with a 3D-printer. There could be a need for a clearance gap between inner and outer thread.

Ulrich
triplus
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Re: Screw Maker

Post by triplus »

ulrich1a wrote:
triplus wrote:As there is no nut-material where the bolt is, this works without problems. I had a look at a real nut here at home and it looks like the model. It only has a steeper chamfer in the tapped hole. So I see no problems here.
Yes probably you are correct. As for looking at a real nut if you ever get a chance look at bigger one. As the bigger the nut the easier it is to observe the first/last thread. There is small difference in my opinion between 3D model and real nut but if 3D model would be printed there is a good chance it would "work".
hpb
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Re: Screw Maker

Post by hpb »

Your Screw Maker macro is great, I like it very much.

For my actual project with really lots of screws, washers, some nuts and would it be nice to have also T-Nut with spring ball, without guidance I-Type slot 5 for M3 and M4. I use actual the profile 20 I-Type slot 5.

I know there are a lot more of profiles, t-nuts etc. Maybe we could see something in this direction in a future release?

Thanks hpb
Attachments
T-Nut.tiff
T-Nut.tiff (44.88 KiB) Viewed 3548 times
Kauli
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Joined: Wed Feb 17, 2016 8:20 am

Re: Screw Maker

Post by Kauli »

Hi Ulrich1a,

Thanks for the wonderful Job you and all the others are doing for the whole community !!!
I love unsing FreeCad.

I have a question.

Is it possible to add Din 912 and Din 6912 ?
often needed in model construction ..........
Or is there any way i can add these or other Screwtypes into the code by myself ?

Can you give me some Tipps ?
Thank you in advance for your answer
Kauli
ulrich1a
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Re: Screw Maker

Post by ulrich1a »

Kauli wrote:Is it possible to add Din 912 and Din 6912 ?
I would not add Din 912, because this standard is not in use any more, please use screws ISO 4762 instead. Those screws are included.

I may add Din 6912 some time. At moment I have a different personal project. So it will take time.

Din 6912 may not so difficult, as it is very similar to ISO 4762. It would be needed, to add this bore to the head and to create a table for the data.
Due to performance reasons, I have chosen a relative complicated approach to model the screws.
The modelling involves creating bodies and extract shell elements, which are cut with other elements in order to get the hull of the screw.
The hull-pieces are then collected together and gives finally the solid.

As an alternative Din 7984 would be much easier to add.

Ulrich
Kauli
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Joined: Wed Feb 17, 2016 8:20 am

Re: Screw Maker

Post by Kauli »

Yes Ulrich,

you are right
The normal ISO 4762 is included.
Sorry for confusing....
And the Din 7984 is more usable than the 6912.

I have some experience in programming (Pascal, Basic, Turbo Pascal, Visual Basic, Assembler) for some privarte Projects in the past.
But i dont think that i can analyze your code and add the right lines into your existing ScrewMaker code.
My thoughts are .........
Maybe there are some Datafields have to be updated with the DIN7984 Norm-Datas and some variables
to increase to raech the new Bolt number Datas when the code is collecting data for the calculation of the object.
The Code for the Body calculation of the ISO 4762 can copyed and has to use the new Datafields (Lower Screw Head).

Maybe i will make some Trials........

THX
Kauli
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