slpitch
by Tim C. Lueth, SG-Lib Toolbox: SolidGeometry 5.6 - Kinematics and Frames
Introduced first in SolidGeometry 5.4, Creation date: 2024-08-04, Last change: 2025-09-15
returns the required fit dimension for steep screw thread
Description
The DIN13 thread is designed for a clearance fit during screw movement. For this reason, the screw nut must have a shrink of slfit('c') ("clearance fit") so that a printed screw can be moved in the screw nut. In the case of a steep thread, however, the unexpected pitch causes jamming. This function calculates the necessary clearance for a steep thread. The normal pitch angle for DIN13 is 28.5 degrees and the necessary clearance is 0.24. For steep threads, the fit must be increased.
slpitch is required if the original thread geometry is maintained; Type "B" or Type "C"
See Also: SGDIN13
, PLthreadDIN
Example Illustration
Syntax
slp=slpitch([D,p])
Input Parameter
D: | | Diameter in mm |
p: | | pitch; default is pitch of DIN13 |
Output Parameter
slp: | | required distance for steep screw threads |
Examples
SGDIN13(-16,40,8,PLcircle(24/2),slpitch(16,8),'Type','B') % NUT for Steep thread type B
SGDIN13(+16,40,8,PLwrench(6+slfit('c'),6),0,'Type','B') % SCREW for Steep thread type B
Copyright 2024-2025 Tim C. Lueth. All rights reserved. The code is the property of Tim C. Lueth and may not be redistributed or modified without explicit written permission. This software may be used free of charge for academic research and teaching purposes only. Commercial use, redistribution, modification, or reverse engineering is strictly prohibited. Access to source code is restricted and granted only under specific agreements. For licensing inquiries or commercial use, please contact: Tim C. Lueth
Algorithm (Workflow)
The function slpitch calculates the required fit dimension for steep screw threads, specifically for the DIN13 thread standard. The function is designed to address the issue of jamming that occurs with steep threads due to unexpected pitch angles.
Input Parameters
- D: Diameter in mm. This is the primary input parameter that defines the size of the thread.
- p: Pitch of the thread. If not provided, the default pitch of DIN13 is used.
Output
- slp: The required distance for steep screw threads to ensure proper clearance and avoid jamming.
Algorithm Steps
- Retrieve the diameter
D from the input parameters using getfuncparams function. If not provided, a default value of 6 is used.
- Call
PLthreadDIN with D to get the default pitch p and a parameter kd.
- Retrieve the pitch
p from the input parameters using getfuncparams. If not provided, use the pitch obtained from PLthreadDIN.
- Calculate
ak as the absolute difference between kd and D, divided by 2.
- Calculate the pitch angle
pw using the formula atan(p/ak/3)/pi*180.
- Compute the required fit dimension
slp using the formula sin(pw/180*pi)/2.
Example Usage
The function can be used in conjunction with other functions like SGDIN13 to design nuts and screws for steep thread types. For example:
SGDIN13(-16,40,8,PLcircle(24/2),slpitch(16,8),'Type','B') - This creates a nut for a steep thread of type B.SGDIN13(+16,40,8,PLwrench(6+slfit('c'),6),0,'Type','B') - This creates a screw for a steep thread of type B.
Algorithm explaination created using ChatGPT on 2025-08-19 08:13. (Please note: No guarantee for the correctness of this explanation)
Last html export of this page out of FM database by TL: 2025-09-21