Parametric Caged Ball Bearing by rohingosling

Last crawled date: 3 years ago

Parametric Caged Ball Bearing
This is a customizable parametric ball bearing, that is designed to be printed in a single step.
Note:
It is extremely challenging to free up the components of this bearing after printing. However, once the components are free, it works great. See the linked video, to get a feel for how various configurations of the bearing perform.
Video:https://youtu.be/iAHtHwBg-FU
Hint
When your hands are bleeding, because you have stabbed your fingers multiple times with the utility knife, and you have friction burns on both hands, ...you are halfway to freeing up the bearing. Maybe the real hint here is that you should wear gloves.
Parameter Overview
All linear, axial and orthogonal dimensions are measured in millimeters. Angles are measured in degrees. And ratios are normalized to the range, [0.0 .. 1.0].
Model Options

Resolution
Resolution specifies the tessellation factor of the model. The higher the tessellation factor, the more polygons make up the model. And in turn, the smoother the model. For moving parts like a ball bearing, the smoother the model, the better. So a fairly high resolution of 64 or greater should be selected. I used a resolution of 128 for all the bearings I have printed with this model.


Enable Inner Ring
Include the inner ring if yes. Else, omit the inner ring from the model. This is mostly used for debugging, visual analysis and testing.


Enable Outer Ring
Include the outer ring if yes. Else, omit the outer ring from the model. This is mostly used for debugging, visual analysis and testing.


Enable Cage
Include the bearing cage if yes. Else, omit the bearing cage. Due to the friction induced by the cage, most 3D printable ball bearings may spin more freely without a cage. However, even though a cage introduces more friction, load forces are distributed more evenly to the bearing raceway with a cage, leading to an overall better performing bearing. High volume space filling cages like the one in this design, also serve as a spherical support guide for the balls during printing, which improves the spherical quality of each ball.


Enable Balls
Include the bal array if yes. Else, omit the balls. This is used for debugging, visual analysis and testing.


Enable Inner Ring Chamfer
Enable a chamfer on the inner ring if yes. Else, ignore inner ring chamfer parameters.


Enable Outer Ring Chamfer
Enable a chamfer on the outer ring if yes. Else, outer inner ring chamfer parameters.


Enable Inner Ring Knurling
Enable knurling cuts on the inner ring if yes. Else, ignore inner ring knurling parameters.


Enable Outer Ring Knurling
Enable knurling cuts on the outer ring if yes. Else, ignore outer ring knurling parameters.


Enable Bottom Cage Access Ports
Enable access ports on the side of the cage, that is facing the build plate during printing. Presuming that the bearings are oriented flat on the build plate, then we can call this the bottom face of the cage. Access ports serve a dual purpose. 1.To gain access to the support material used to for the balls, if support material is used. 2. To gain access to the balls themselves after printing, so that they can be manipulated in order to free them from the cage and the rings.


Enable Top Cage Access Ports
Enable access ports on the side of the cage, that is facing away from the build plate during printing. Presuming that the bearings are oriented flat on the build plate, then we can call this the top face of the cage. It is a good idea to include access ports on both sides of the cage, to maximize access to the balls for post printing manipulation, as well as to ensure balanced rolling in the cage, once the balls have been freed.



Ring and Cage Parameters:

Bore
This is the inner diameter of the inner ring. It is a good idea to make this value slightly larger than the diameter of whatever shaft is intended to pass through the inner ring, by about 0.1mm to 0.5mm. Presuming, that the target shaft diameter can't be adjusted itself. If need be, the Model Options above may be used to print only the inner ring as a test part, that may then be be fitted to the target shaft, in order to iteratively evaluate physical assembly characteristics, without having to print the entire bearing assembly each time.


Outer Diameter
This is the outer diameter of the outer ring. It is a good idea to make this value slightly smaller than the diameter of whatever bracket assembly the bearing is intended to fit into, by about 0.1mm to 0.5mm. Presuming, that the target assembly dimensions can't be adjusted themselves. If need be, the Model Options above may be used to print only the outer ring as a test part, that may then be be fitted to the target assembly, in order to iteratively evaluate physical assembly characteristics, without having to print the entire bearing assembly each time.


Shoulder Height
This is the raised boundary edge of the bearing raceway. In general, lower values are prefered. The minimum shoulder height required to give the balls a secure raceway to roll along, should suffice. For bearings whose outer diameters are less than 60mm, a 1mm to 1.5mm shoulder height is usually enough.


Radial Gauge
This is the thickness of the rings, as measured from the deepest point of the ring raceway, to the inner or outer diameter of the inner and outer rings respectively.


Axial Gauge
This is the thickness of the ring and cage walls.


Cage Access Port Diameter
This is the diameter of the cage access ports. In general, the larger the better, especially if support material is going to be used to support the balls above the build plate during printing.



Mechanical Properties:

Ball Count
The number of balls.


Ball Ring Clearance
The clearance between each ball and the rings. The radius of the balls is reduced by this clearance amount. In general, fairly low clearance values should be used between the balls and the rings, in order to promote grip between the balls and the ring raceways. For most applications, clearance in the range of 0.1mm to 0.3mm, works well for clearance between the balls and the rings.


Ball Cage Clearance
The clearance between each ball, and its cage cavity surface. The radius of the cage cavity surfaces, are increased from the radius of each ball, by this clearance value. Larger clearance values are suitable for the clearance between the balls and the cage, in order to reduce friction. It is a good idea to set the clearance between the balls and the cage, to a larger clearance value, than the clearance between the balls and the rings, in order to promote frictional contact between the balls and the rings, rather than unnecessary contact between than balls and the cage. In general, a value of two to three times the clearance between the balls and the rings, works well for the clearance between the balls and the cage. Most of the bearings that I print using this model, are configured with a ball to ring clearance of 0.1mm, and a ball to cage clearance of 0.3mm, using a 0.3mm nozzle, and a print resolution of x=0.3mm, y=0.3mm, and z=0.15mm.



Feature Parameters:

Inner Chamfer Size
The radial size of the inner ring chamfer.


Outer Chamfer Size
The radial size of the outer ring chamfer.


Inner Knurling Count
The number of equally spaced knurling cuts made into the inner ring.


Inner Knurling Depth
The depth of the inner knurling cuts.


Inner Knurling Cut Ratio
The proportion of the knurling arc, that is cut into the ring. The higher the ratio, the more material is cut from the ring.


Outer Knurling Count
The number of equally spaced knurling cuts made into the outer ring.


Outer Knurling Depth
The depth of the outer knurling cuts.


Outer Knurling Cut Ratio
The proportion of the knurling arc, that is cut into the ring. The higher the ratio, the more material is cut from the ring.



Color Settings:
Color settings are used for debugging and analysis.

Enable Multiple Colors
Render each class of component in using different colors if yes. Else, render all components in the model using one color.


Default Color
The color to use if "Enable Multiple Colors" is set to No. If "Enable Multiple Colors" is set to Yes, then "Default Color" is ignored.


Inner Ring Color
The color to render the inner ring, when "Enable Multiple Colors" is set to Yes.


Outer Ring Color
The color to render the outer ring, when "Enable Multiple Colors" is set to Yes.


Ball Color
The color to render the ball array, when "Enable Multiple Colors" is set to Yes.

Cage Color
The color to render the bearing cage, when "Enable Multiple Colors" is set to Yes.