# Internal screw threads and knurling
**URL:** https://discourse.shapr3d.com/t/internal-screw-threads-and-knurling/2383
**Category:** Modeling Questions
**Created:** [May 15, 2018, 4:52pm UTC](https://discourse.shapr3d.com/t/internal-screw-threads-and-knurling/2383 "2018-05-15T16:52:14Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@tadream](https://discourse.shapr3d.com/u/tadream)
#### Post date: [May 15, 2018, 4:52pm UTC](https://discourse.shapr3d.com/t/internal-screw-threads-and-knurling/2383/1 "2018-05-15T16:52:14Z")
How do i create an internal thread. I wish to draw an hexagon shaped nut such as would be screwed onto the end of a bolt.
Thank you for help, i am still in my trial period and i need to find a way to do this. I can create an external thread its the internal one holding me back.
I also need to find a way to put knurling on a cylindrical surface, can this be done?
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### Author:  [@Istvan](https://discourse.shapr3d.com/u/Istvan)
#### Post date: [May 15, 2018, 5:37pm UTC](https://discourse.shapr3d.com/t/internal-screw-threads-and-knurling/2383/2 "2018-05-15T17:37:25Z")
You just have to use the subtract tool, and subtract the male part from the female part.
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### Author:  [@tommyn](https://discourse.shapr3d.com/u/tommyn)
#### Post date: [May 15, 2018, 5:50pm UTC](https://discourse.shapr3d.com/t/internal-screw-threads-and-knurling/2383/3 "2018-05-15T17:50:08Z")
If you are going to make these parts, you will need to scale up the nut or scale down the bolt by a bit so they will easily fit together.
Your knurling question is interesting. I would approach it by doing an external thread like the bolt with a shallow pitch and then do the thread in the opposite direction and see the result. Trial and correction should work for this.
Best,
Tommy
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### Author:  [@tadream](https://discourse.shapr3d.com/u/tadream)
#### Post date: [May 15, 2018, 5:59pm UTC](https://discourse.shapr3d.com/t/internal-screw-threads-and-knurling/2383/4 "2018-05-15T17:59:39Z")
I’m not sure yet how to do that, is there a YouTube tutorial.
Any thoughts on knurling?
Thank you for your help, I am having great fun getting to grips with the features.
Mike
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### Author:  [@Istvan](https://discourse.shapr3d.com/u/Istvan)
#### Post date: [May 15, 2018, 6:50pm UTC](https://discourse.shapr3d.com/t/internal-screw-threads-and-knurling/2383/5 "2018-05-15T18:50:51Z")
Here is the documentation of the subtract tool:
[https://support.shapr3d.com/hc/en-us/articles/115001414994-Subtract?mobile\_site=true](https://support.shapr3d.com/hc/en-us/articles/115001414994-Subtract?mobile_site=true)
The knurling I would create by creating one piece of it, then I would use the tranform tool and copy it.
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### Author:  [@tommyn](https://discourse.shapr3d.com/u/tommyn)
#### Post date: [May 15, 2018, 8:03pm UTC](https://discourse.shapr3d.com/t/internal-screw-threads-and-knurling/2383/6 "2018-05-15T20:03:08Z")
You can find YouTube videos on knurling using a lathe. I remember seeing some…
Often, thinking in a machining sense (metal removal) helps, but then thinking in an additive sense (3D Printing) is also a complementary paradigm.
Good luck,
Tommy
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### Author:  [@tadream](https://discourse.shapr3d.com/u/tadream)
#### Post date: [May 15, 2018, 8:08pm UTC](https://discourse.shapr3d.com/t/internal-screw-threads-and-knurling/2383/7 "2018-05-15T20:08:50Z")
Thanks for your help, I have fitted a bit to a bolt , I will try the knurling and let you know
Mike
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### Author:  [@Chayanne](https://discourse.shapr3d.com/u/Chayanne)
#### Post date: [May 21, 2018, 3:56am UTC](https://discourse.shapr3d.com/t/internal-screw-threads-and-knurling/2383/8 "2018-05-21T03:56:04Z")