Switch Lever Used on HP Equipment

Posted Monday, August 23, 2021
Updated Friday, August 19, 2022

I’m working on bringing an HP 8007B pulse generator back to life. One of the things I needed to fix is the snapped off paddle to the output attenuator. The switches on this and other HP products from this era, uses a custom scheme where the switch is integral to the PC assembly and the switch contacts are on the PC board. A plastic assembly that contains a slider with switch fingers, spring for detents, and a switch paddle fits between two plastic rails or guides. The guides for the slider is riveted to the board. This page provides the details on creating and 3D printing a replacement paddle. Tam Hana and Wilko Bulte were instrumental in helping make this a successful repair. Wilco provided a sample paddle from which I was able to make accurate measurements needed to create a 3D model suitable for printing. Tam provided help and guidance on using OpenSCAD to create the model. I also used Tam’s very excellent book "Technical Modeling with OpenSCAD" as a resource.

The printer used, a Creality Ender 3, was not very exotic or high end so I was skeptical that it would have a high enough resolution to print such a small part. It turns out the Creality printer was able to make a part that was more than suitable. Here is some of the details about printing the 3D part:

The finished printed part did require a small ammount of re-work using small files and an X-Acto knife. When the first layer is printed the notch for the spring tended to close up slightly. Cleaning the notch with the knife and files fixed the problem. On the completion of the repair the newly created part works perfectly and can barely be distinguished from an original lever.

Photo of bracket

Photo of Switch Lever

Blender Image

Rendered in Open SCAD

Open SCAD image

Photo compared to Meshlab Render

Dimensioned Drawing

Dimensioned Drawing

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3D rendering of STL File Using JSC3d

						
							

//
//Switch lever used on HP equipment.
//

/* 
Changes from hp_lever-2.2.scad to hp_lever-2.4.scad
    Increased size of notched cube by .6mm in x (50 to 56)
    Translated notched cube -.4mm in x (33 to 29)
    Translated notch cylinder -.3mm in x (57,5 to 54.5)
    Translated notch cube -.3mm in x (50 to 47)
    Decreased size of main body cube by .3mm (50 to 47)
    Increased size of spring notch by .05mm (7 to 7.5, 3 cubes)
    Changed SVG lever_06.svg to lever_07.svg (improved curve)
*/

// Set Viewport
$vpr = [55, 0, 323];
$vpt = [10, 4, -2.5];
$vpd = 70;

//Scale by 1/10
scale([.1,.1,.1]){
//Merge geormetries
    union(){
//Import and extrude SVG geometry for lever
        translate([82, -25, 15]){
            linear_extrude(height = 30, center = true, scale=1) {    
                import(file = "lever_07.svg", center = false, dpi = 96);
            }
        }
 //Notched cube
        difference(){
            translate([29, -25, 0]){
                cube([56,50,70]);
            }
            rotate([90,0,0]){
                translate([54.5, 35, -26]){
                    cylinder(52,7.5,7.5, $fn=100);
                }
            }
            translate([47, -26, -1]){
                cube([15,52,35]);
            }
        }
 
///////////////-Subtracted Geometries-///////////////
        
//Main body and spring holder
        difference(){
            translate([0, -95, 0]){
                cube([47,190,30]);
            }
            translate([11, -96, -1]){
                cube([7.5,36,32]);
            }
            translate([11, 61, -1]){
                cube([7.5,36,32]);
            }
            translate([11, -95, -.1]){
                cube([7.5,190,15 ]);
            }
            translate([-3, -23, -1]){
                cube([8.5,46,32]);
            }
//End Notchs
            translate([-.5,80,-1]){
                cylinder(r1=5, r2=5, h=32, center=false, $fn=100);
            }
            translate([0,-80,-1]){
                cylinder(r1=5, r2=5, h=32, center=false, $fn=100);
            } 
        }
 /////////////-End Subtracted Geometries-/////////////
        
//Mounting tabs
             translate([-13, (35.5+11.85), 9.75]){
                cube([26.5,23.7,19.5], center=true);
            }
             translate([-13, -1*(35.5+11.85), 9.75]){
                cube([26.5,23.7,19.5], center=true);
            }
//Center Support
            translate([9, -4.5, 0]){
                cube([26,9,30]);
            }   
    }
}
						
					

Open SCAD Code

						
							
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!-- Created with Inkscape (http://www.inkscape.org/) -->
<svg
   width="210mm"
   height="297mm"
   viewBox="0 0 210 297"
   version="1.1"
   id="svg12"
   inkscape:version="1.1 (c4e8f9e, 2021-05-24)"
   sodipodi:docname="lever_05.svg"
   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
   xmlns="http://www.w3.org/2000/svg"
   xmlns:svg="http://www.w3.org/2000/svg">
  <sodipodi:namedview
     id="namedview14"
     pagecolor="#ffffff"
     bordercolor="#666666"
     borderopacity="1.0"
     inkscape:pageshadow="2"
     inkscape:pageopacity="0.0"
     inkscape:pagecheckerboard="0"
     inkscape:document-units="mm"
     showgrid="false"
     showguides="false"
     inkscape:zoom="3.3602084"
     inkscape:cx="170.07874"
     inkscape:cy="1075.8261"
     inkscape:window-width="1312"
     inkscape:window-height="936"
     inkscape:window-x="62"
     inkscape:window-y="29"
     inkscape:window-maximized="0"
     inkscape:current-layer="layer1" />
  <defs
     id="defs9" />
  <g
     inkscape:label="Layer 1"
     inkscape:groupmode="layer"
     id="layer1">
    <path
       fill="#f8da2d"
       d="M 25.00236,297.04 H 0 v -50 h 25.00236
       c 0,0 11.685749,4.95901 32.498645,9.97199
       20.812893,5.01298 32.498993,5.02816 32.498993,5.02816
       v 20.00077 c 0,0 -12.15564,0.43744 -32.498993,5.0278
       C 37.157649,291.65907 25.00236,297.04 25.00236,297.04 Z"
       id="path73"
       style="stroke-width:0.352773" />
  </g>
</svg>							
					
					

Inkscape SVG XML

Dimensioned Drawing

Freshly Printed Part

Dimensioned Drawing

Lever Installed on Board

Dimensioned Drawing

Repaired Amplitude Control

Dimensioned Drawing

Working HP 8007B

Download STL

Download SVG File

Download SCAD File

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