C64 Mini – Keyboard – More CAD…

Extrude out

Extrude that sketch the length of the F Key – 13.8mm on the Mini. A bit longer on the real 50% scale one!

Construct a “New plane at an angle” – chosing the bottom right part of the extruded key. Make the angle the same angle as the keyboard is from Horizontal – (8 degrees here, so the new plane is at an angle of 82 degrees)

On That new Plane – create a new sketch and ‘project’ the Key to it. Draw up the angles on the sketch and then extrude all the way down

Extend the projection sketch up a little to ensure you cut everything. Measure the two angles, or like I did, just measure the top length, the bottom length and divide by two, then add a tiny bit one side as they’re slightly lop-sided
Don’t just extrude the projection – add a bit more to the top to cut everything

Extrude a cut with extra at the top

Now, Start the grind – Create a sketch on every surface by projecting the extrusion. Measure 1/2 way along, create a line and a circle. Then a 3 point Arc.

The midpoint line is needed later for the surface modelling. The Circle is ‘easier’ to place than a single line – this is used to set the depth of the concave bowl in the top of the keys – I’m starting with 0.4mm so am using a circle of diameter 0.8mm. The centre of the 3 point Arc goes Tangent with the circle!

Back of the Key
Left Hand Side Sketch
Back and Left Showing
All Sides done

Now, to create the tops of the keys. Create a new sketch on each key, you can just Project the top of the extrusion, ensure to lock the projection to the source.

Now Create a rectangle on each key. Create a Fillet – I’m using 2mm here. Remove the two vertical constraints on the rectangle. Make the two verticals co-linear with the sides. I’ve added an offset to the oval shape also as I think this is needed later in surface modelling

The White verticals show where I’ve removed the constraints and then made those lines co-linear

The Tops of the keys aren’t perfectly square due to the slopes on the sides . Hopefully now all this is constrained enough to allow the parameterisation to work

Trying Out parameters. In theory, changing one of these will change the entire keyboard once it’s done

Next, Create a sketch on the bottom of the keys and add a 1mm fillet to the corners. I just create a rectangle over the top of the projection, then fillet that.

Create a new offset plane half way through the keys. Create a new sketch for the keys (just project each) and the curve. We should be almost setup for the surface modelling now

New Sketch being created in the middle of the keys

Hide All of the Bodies and the un-needed sketches, just showing all the sketches for each key surface. Switch over to the surface modelling mode

Surface modelling ready! There’s probably an easier way to do t his but I couldn’t figure one out

Create a whole bunch of lofts to get the nice smooth corners! one by one, every key….

At This point, realise you haven’t added the Bulgey bits to the front of the keys….Go back to Solid mode, unhide the extrusions, add the bulging bits then come back here

With the New curves, Create a loft using the bulge as the centreline

After lofting all 4 corners on all 4 keys, and all four sides to all four corners, you should end up with………..

Stitch all those seams together

Now, to make things easier – and what I should have done from the start. Create a plane in the midpoint of the original extrusion with the ‘concave’ dip. Do that for both axis and….you don’t have to put a sketch on every face! – Just top, bottom and one of the sides.

Once you create the midpoint plane, you can ‘intersect’ the body, draw the curved surface, then you can patch using both curves to create the bowl.


Now with the Centre plains with three points.

Go back to the original sketches and make sure they all have a ‘lock’ symbol on them, then play with the parameters….here are some 50mm wide F keys!

and some 2mm Fillets for waay too curvy

Author: bleughbleugh

Early Fourties, Wife, two kids in primary school. Both of us work full time...3 years now Back in Blighty after a decade away...It's a new country for everyone! Still finding time to tinker!

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