Round object holder (print in place)

UPDATE 31/08/2023:

Added a “half continuous” version with some sizes suited for ESP tonfas.
This version has some extra walls connected to the inner part around the hinges, as those turned out to be a weak spot. Now the wall is continuous and much more stable and the holder is even less prone to breaking - use these versions for the best results

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I enjoyed the original clip mechanism design, but it wasn't quite perfect for my use.
After successfully improving it once, i decided to bring it even further.

Short version:
IT CAN NOW FRICTION HOLD OBJECTS WITHOUT TAPE!
your stick, your flashlight, your broom all will hold firmly in place but remain accessible!
 

First changes and improvements:

• Moved the object farther from the wall
• Stiffened up the mechanism
• Added funnel “hands”
• Added an extra hole in the tape option
• Lowered total height
• Added more parameters to the f3d file

Further changes in this update:

• Improving grip by offsetting center and adding clamping forces
• Top and bottom cover layers
• Further construction strengthening
• Tightened the gap on the sides and in the front to have more surface area grip
• Done a lot of tests to find optimal balance
• Added even more parameters to the f3d and fixed a few errors i made previously
• Added a pattern option
   

I tested a 24mm size which fits perfectly a convoy S2+ flashlight or my escrima sticks (which are uneven in range from about 23,5 to 24,5mm) 
Other sizes have not yet been tested.

Details for these updates are below.
 

HOW TO PRINT:

When slicing, pay extra attention to the bottom layers of the hinges and make sure enough overlay is present. 
Another weak spot to mind is the hinge connection, where a lot of force can be applied. I suggest using several perimeters. A single wall here will not last for long as the holder needs to flex.

TIPS:

• As with the original, feel free to edit the fusion 360 f3d file to adapt it to your needs.
   
• I suggest using a woodblock (2x4 or similar) underneath to make it stand out even farther from the wall if used for martial arts and you want to hit it comfortably without damaging your wall
• For better looks and less dust, hang it with the flat side up
• My printer can handle pretty tight tolerances and this print doesn't stick at all. Experience may vary

• When editing the d_broom parameter, it can happen that by changing it by a large value the change fails!
  If this happens, go back a step and then proceed to slowly change the parameter by not more than 5mm at a time until you reach your desired size
  • I have not yet tested any other sizes than 24mm but i have made sure the changes work
• Set your size to exactly the dimensions of your object, everything has been set up in a way you dont need to worry about tolerances
   
• You can use small zip ties to add anti slid material and make the hold more tolerant to size deviations and stronger. Although the current update does not need it, it can be helpful with oddly shaped objects.
  • If you decide to use any anti-slid material, only put it on the outer half, that way it grips much better.
     
• Sometimes, especially the hinges printed in the air, tiny surface deviations cause the stick to not fit perfectly snug and hang in the air a little bit, not using the entire surface area of the holder and thus losing grip. A few seconds of sanding solves this issue. If your object is perfectly round it should fit without gaps.
  

NEXT STEPS:

How about you add a model of hands to the front to make it look like its trying to catch the tool? i think it would be funny.

If i wanted to improve this mode any further i would have to redraw it from scratch and print in the open state (that would allow for more options in the front without crossing itself)
I think i am at a point of diminishing returns now as already these changes have been barely visible (but improved its functionality a lot)

I ran out of material testing what the different values of parameters cause and i managed to find a decent enough compromise, i will now concentrate on adapting it to more different tools such as long staff or a tonfa.



 

I did some testing… maybe a bit too much

 

DETAILS about the changes:

Moved it farther from the wall

•  I have moved the stick position farther from the wall so there is more space for your fingers when you grab it and you don't hit the stick on the wall every time you use the holder.
• I still find its better to attach it to something like a woodblock to stand even further away from the wall, especially for hitting it comfortably without hitting the wall

Stiffened up the mechanism

• I added a bottom layer and triangle support to the hinge holding extrusion
  • This prevents the back from bending during use (which easily unstuck tape on the original)
  • This makes the entire mechanism crisper and firmer and slightly improved grip

Added funnel “hands”

• Helps guide the stick
• Can be used to attach zip ties for some anti skid material
• You could possibly design a locking mechanism on them and lock the object in place

Added an extra hole in the tape option

• I found that the vertical support could be also used with screws for a better stability.
  • This matters more for short versions of the holder, if the holder is tall enough, it can handle quite a lot without needing this support

Lowered total height

• This was mostly done to save print time and filament for my testing but it turned out to be strong enough even this way
• You can change the total height by changing these parameters:
  • h_hinge_middle
  • h_hinge_topbottom
  • cover

Improving grip by offsetting center and adding clamping forces

This was one of the main changes of this version. Although the difference in looks it makes is maybe a single mm, the resulting way it functions is changed dramatically.
 

When testing the original and even my first changed version i felt that no matter what dimension i set, it never was strong enough to friction hold a smooth stick. Then i finally found out why:

• The entire holder is designed in a closed state, which is one of two resting states. The other one being when its fully open
  • In these two resting states the holder exhibits no pressure and moves loosely due to tolerances in the hinges and similar aspects
• The original holder had a perfectly round hole designed in the closed resting state
  • This meant that although the grip was theoretically the best, since there was no force holding the stick, it just falls through
  • The obvious solution was to set slightly smaller dimensions but in the pressured state, where there is enough force to hold the stick, it has little area and therefore grip to hold it and it ends up being weak as well

The changes i made try to solve this issue by offsetting the circle in a way, that it is perfectly round in the strongest area of the holder

Two approaches, two parameters:
1) tilting the circle halves makes the perfect center move
 

• Parameter: Offset_angle
  • Defines in degrees what tilt it should do from the original position
    • Set this too low and you have the same problem as the original
    • Set this too high and the mechanism will not close or be very loose
    • i have tested values between 0,25 and 2 and ended with a compromise at 1

2) Adjusting the grip of the spring

• With a perfect definition in the original you can easily fit the stick into the opening and it will match however, as pressure is applied the flexible material opens and the surface area is lowered again
• Solution is to slightly close the gap in the resting state, so that the pressure opens the flexible mechanism into the perfect position
• Be aware that the pressure needed to open these sides is borrowed from the native pressure the holder itself creates when closing. a good balance is needed
• Parameter: Offset_spring_fit
  • Defines in degrees the tilt of the front half of the grip
  • I have tested values between 0 and 10
    • 0 is very loose but closes firmly, 10 has amazing grip but it will open very easily or not close at all
    • I found great values are between 4 and 7 and chose 5.5 for my compromise

These two parameters do effect each other. Either of them set too far can cause the mechanism to stop working and prevent you from closing it.

Using these two parameters you are able to adjust the grip strength vs how easy it is to place the stick in or take it out.

As a side effect not only did this change improve the ability to friction hold objects, it also made it easier to take them out and place them in, lowering the force on the tape/screws the holder can be attached with!
 

Top and bottom cover layers

• Further testing showed me some weak spots of the flexible construction
  • Hinges only held on one half
  • Sharp corners around the hinges made the slices put sharp edges there, which made it break easily
  • While it could be argued that its the slicers fault that it only put a very thin connection there, i wanted to prevent it from happening. (print tips above are shown with the fixed version already)
• Fillets around hinges
  • Large fillets around the hinge areas not only make it thicker but also force the slicer to connect the perimeters in a tougher path
• Top and bottom cover layers
  • In order to connect the hinges from two sides and make them stronger, i have added a new layer to the model
    • This had the side effect of making the entire mechanism stronger and making it more difficult to insert or take out objects, basically returning the side effect of the offset parameters to the original yet still keeping all the advantages.
    • I believe further adjustments could be made to make it easier but i am happy enough with the current compromise
  • 
     

Further construction strengthening

• I have enlarged the outer triangle supports yet again and also applied a curve on the inside to stabilize it further

Added a pattern option

• If for whatever reason, you need it much stronger, i have added the ability to stack hinges
  • I believe this will make it even tougher to insert and take out objects and have not tested a stacked version yet
• Change the parameter “Pattern” to the number of stacked copies you want to make
  • All other parameters like hinge height and size are still applied
• I plan on using this feature in the near future in order to hang a large heavy pole on the wall
• 
   

More parameters in the f3d file

• Hinge tolerances for top and bottom are now separate from circle tolerances (fixed)
• Added sizes for tape extrusion (not tested)

If you were crazy enough to read all this, thank you. Hopefully it was interesting to you.

If you just scrolled down to find the conclusion: I assure you this print works and is fun, give it a shot!