Stainless steel control knob a design that looks seemingly simple but was fairly complex
This stainless steel control knob design was produced to solve a problem, modernize and improve the look of the machine it was mounted on.
What is the stainless steel control knob design and why did we design it?
To solve an issue with a control panel where the high-precision valves on the machine were updated to new ones. The problem was new valves had increased in size behind the panel.
So it was awkward to position with the rigid stainless steel tubing being used.
Not only did the original knob have one fixed position. But also it was pointing in the wrong direction.
Subsequently, the new high-precision valves need to turn by 90 degrees to fit in the space behind the control panel.
Pictured above is the original control panel and control knob on the left.
The middle picture shows the original off-the-shelf knob position, note the stainless steel stop (marked in green) built into the valve which stops the knob rotating.
Finally, the picture on the right is how the control knob needed to be positioned but is currently held in position by hand for reference.
Positioning the control knob was made difficult as it had a set stop built into the high-precision valve and in the knob itself. This can be seen in the pictures above.
The off-the-shelf plastic knob from Parker had a die-cast insert in it that had the stop feature built in as well as two flats for the shaft of the high-precision valve to fit in the knob.
Making use of the die-cast insert on the stainless steel control knob design
In an effort to minimize the potential machining issues due to the small cutters required and the depth of the recess also to help simplify the design. The decision was made to reuse the die-cast boss that had the built-in stop and features required.
The die-cast insert was carefully removed from the off-the-shelf plastic Parker knob.
We had enough information to start formulating the 3D cad design
Measurements were taken from the original insert and the high-precision valve, then the new design was roughed out based on these dimensions. We also had some input from the client regarding the required size.
The design evolved over a few versions and then we came up with the final version.
Care was required to locate a hole for a locking screw that had to be at a precise axial position as well as three grooves machined in for precision location on the insert and to stop any unwanted twist.
The final design and finished part
The new stainless steel control knob design is finished. You can see in the images above a laser-etched flow direction on the top face and the fitted insert with the new position of the built-in stop.
The insert was a press fit but to retain its precision location 3 pins were fitted to locate it accurately and to stop the knob from twisting/rotating off-axis.
The new knob design helped to lift the overall look of the machine it was fitted to with its new sleek design and finish.
A seemingly simple but detailed design by Adrian Walker.
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A seemingly simple but fairly complex problem
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