At the end I got tired of all these variants on a theme and decided to stay with one and the same type in all places as it would be more unified. Since I do not have a ball turning accessory I choose another shape for my handles, a shape that is very easy to do on my machines with only basic equipment.
After some thinking and sketching I found that it is the overall proportions that is the dimensioning factor, the size of the arm being one of the more important. The end knob should then relate to the arms thickness proportionally to result in a well balanced result. Some testing produced the following "model"
x
Alla mått i mm.
A = Arm diameter, B = Knob length (= 4x arm diam.),
C = Knob diameter (= 2x arm diam.), and D = arm diam -2 mm (except for 3 and 4 mm arms when it is only 1 mm). The following table shows the results for several dimensions. The knob angle is normally 6 degrees, but if a slimmer variant is desired 5 degrees will work well.
|
A |
B (4xA) |
C (2xA) |
D |
|
3 |
12 |
6 |
3 |
|
4 |
16(15) |
8 |
3 |
|
5 |
20 |
10 |
3 |
|
6 |
24(25) |
12 |
4 |
|
7 |
28(30) |
14 |
5 |
|
8 |
32(30) |
16 |
6 |
|
9 |
36(35) |
18 |
7 |
|
10 |
40 |
20 |
8 |
The two parts, the arm and the knob, together makes up the handle which means it is easy to adjust existing handles nad levers to this new shape. Only very short handles/levers needs to be made as one piece, something that simplifies the whole job. The following shows an overview of the various sizes of handles.
A few pictures of examples of new or part new handles on my machines.
Handles on the QCTP, arm 6 mm.
Tailstock lock lever, arm 8 mm.
As can be seen, this kind of shape fits basically everywhere there is a need for an end shape on a lever or a handle.
