nut_knob

What:

A parametric model of a knob for tool free adjustment of nuts and hex head bolts.
Based on the tutorial: 
(29) FreeCAD 0 .17 Tutorial : . Design a Knob using Part Design - YouTube
https://www.youtube.com/watch?v=rgstQi9jpGc

More info on this below.

Status: Printed, seem to work well, lets see in a year.

  Working pretty well, in process of adding some additional mounting options.  
  Have printed and used about 5 of these so far, pretty happy with them.

	Standard Disclaimer:
		If you have more than a casual interest in this project you should contact me 
		( no_spam_please_666 at comcast.net )and see if the repository is actually in good shape.  
		I may well have improved software and or documentation.  
		I will try to answer all questions and perhaps even clean up what already exists.	

Documentation:

Some documentation for the Model Tree:

ss spread sheet with some important and and modifiable dimensions

b_knob body for the knob, without fillets -- body all done in part design

s_master_dims		sketch with some drawing with dimensions used as external geometry for other sketches
					these are all ( probably ) based on the spreadsheet ss

p_base_cyl pad: a cylinder we "cut" the knob from s_outter_radius sketch for above

dp_knob_upper_face datum plane: I think i attach sketches to it for the flutes

p_bolt_shaft pocket: for the bolts shaft

p_flutes pocket: first pocket for the flutes to make the circular cross section parts

p_straighten_flutes pocket: second pocket for the flutes to straighten them out

PollarPatern takes the straighten flutes ( one arm only ) and propagates them around the knob

p_bottom_relief pocket: gives relief so arms of knob do not touch

p_final_parametric_model pocket: this is as far as I could go with parametric model, I cannot get fillets to work on this sucker

s_hex_insert		sketch: insert for nut or hex hear

Fillet fillet of refined part below, this is not parametric but is the basis for a mesh and stl export grass_collect_v1 (part workbench) refinement of p_final_parametric_model it appears to be some sort of copy without links to p_final... so is not parametric but I can ( part workbench ) fillet it

Fillet001 same as Fillet but with different dimensions, see info below for different dimensions ..... more fillets

Info on fillets ( names in the refined parts )

for 1/4 nut nut one_quarter_v1

shaft radius             3.15  printed too tight   try 3.25
nut_point_radius         6.30  printed too tight   try  6.4
nut_depth                5.00  may be just enough  try 5.0
knob_outer_radius		21.00
knob_inner_radius		10.00

one_quarter_v2

shaft radius             3.25  easy to thread in, seems same as above,   
nut_point_radius         6.4   still too tight, say another .2 for next
nut_depth                5.00  may be just enough  try 5.0  adjusted knob height, so ss does not match this
knob_outer_radius		21.00
knob_inner_radius		10.00	
knob height of 15 + 5 may be more than needed, try 10

one_quarter_v3 this seems to work

shaft radius             3.35   still pretty tight 
nut_point_radius         6.6    
nut_depth                5.00   add a mm or two
knob_outer_radius		21.00
knob_inner_radius		10.00	
knob_height at flutes   10 mm  

printed
     30% on c clone printer top side down 

grass collector lowest bolt hold one grass_collect_v1

shaft radius             3.85  printed too tight   try 4.00
nut_point_radius         7.2   printed too tight   try 7.5
nut_depth                5.00  add 1 mm 
knob_outer_radius		21.00
knob_inner_radius		10.00

grass_collect_v2

shaft radius              4.00
nut_point_radius         7.5
nut_depth                6.00   
knob_outer_radius		21.00
knob_inner_radius		10.00
knob_height at flutes   10 mm  

------------------ knob tutorial --------------------

(29) FreeCAD 0 .17 Tutorial : . Design a Knob using Part Design - YouTube https://www.youtube.com/watch?v=rgstQi9jpGc

I originally followed the tutorial, except that I skipped the material saving cutout in each flute.

Then I added a spreadsheet to control some of the dimensions of the design.

I also did some renames of sketches..... to make it easier to understand the model.

The spreadsheet seemed to interfere with the chamfers of the object. I was never able to get these to work again. I came up with a sort of work around:

Use the part workbench to refine the un-chamfered model. This creates a new object in the model which does not seem to be parametric with the model: It does not update when you update the base features from which it was created. But using the part workbench you can in one step chamfer all the edges.

So the work-flow to make a new knob with different dimensions is:

• Check to make sure there is not already a refined part with the desired dimensions. If there is just mesh and export stl.
• If not: Change the spreadsheet to the desired dimensions.
• Refine the model, create a new refined part.
• Chamfer the refined part.
• Mesh and export the stl.

...... to do .........

would be nice to have a table of dimensions of different fasteners to use in customizing the model.

find a better way to chamfer the model.

...... about ( my version of )freeCad .......

OS: Windows 10 Word size of OS: 64-bit Word size of FreeCAD: 64-bit Version: 0.18.15959 (Git) Build type: Release Branch: master Hash: 397418078a6f61e8c39cedfe1160adc2abd73510 Python version: 2.7.14 Qt version: 4.8.7 Coin version: 4.0.0a OCC version: 7.2.0 Locale: English/UnitedStates (en_US)