How much arc would I gain (approx) ?

[Vipersan]

Your ingenuity knows no bounds...

Thanks CJ ...it's more like ..
I just hate to be beaten.
lol

 

[Huevos]

VS, I'm confused. B > C = 13cm - 67cm = 54cm stroke. but 24" stroke would be 61cm. Which if you add it together gives 74cm. In your case though that would be impossible because the combine lengths of the other two sides adds up to 72.2cm so you could never exceed that.

Also green triangle is meaningless because what you are opening is B > C. But there is another triangle and that is B > C > D, i.e. there is going to be a slight difference between the the B > C distance and the D > C distance and that relationship is not going to be 100% linear, but for the purpose of the calculation I'm going to ignore that small difference.

Anyway, for the following:

• $side1 = 13.0; # min actuator distance joint to joint.
• $side2 = 38.7; # polar axis to joint 1.
• $side3 = 34.0; # polar axis to joint 2.

I get this:

• 1cm = 1.71º
• 2cm = 1.7º
• 3cm = 1.69º
• 4cm = 1.69º
• 5cm = 1.68º
• 6cm = 1.69º
• 7cm = 1.69º
• 8cm = 1.68º
• 9cm = 1.69º
• 10cm = 1.7º
• 11cm = 1.7º
• 12cm = 1.71º
• 13cm = 1.71º
• 14cm = 1.72º
• 15cm = 1.73º
• 16cm = 1.73º
• 17cm = 1.75º
• 18cm = 1.76º
• 19cm = 1.77º
• 20cm = 1.78º
• 21cm = 1.79º
• 22cm = 1.81º
• 23cm = 1.82º
• 24cm = 1.84º
• 25cm = 1.85º
• 26cm = 1.88º
• 27cm = 1.89º
• 28cm = 1.91º
• 29cm = 1.93º
• 30cm = 1.95º
• 31cm = 1.98º
• 32cm = 2.01º
• 33cm = 2.03º
• 34cm = 2.06º
• 35cm = 2.09º
• 36cm = 2.13º
• 37cm = 2.16º
• 38cm = 2.2º
• 39cm = 2.25º
• 40cm = 2.28º
• 41cm = 2.34º
• 42cm = 2.39º
• 43cm = 2.45º
• 44cm = 2.51º
• 45cm = 2.59º
• 46cm = 2.66º
• 47cm = 2.76º
• 48cm = 2.85º
• 49cm = 2.96º
• 50cm = 3.1º
• 51cm = 3.24º
• 52cm = 3.43º
• 53cm = 3.65º
• 54cm = 3.91º
• 55cm = 4.26º
• 56cm = 4.72º
• 57cm = 5.4º
• 58cm = 6.52º
• 59cm = 8.93º
• Total arc = 144.81º

It stops at 59cm because after that the variable length would be greater than the to fixed lengths added together and that is impossible for a triangle.

 

[Vipersan]

Thanks Huevos ..
I'll check those lengths again tomorrow ..Ignoring the additional point D
I could well have written something down wrong..
Cheers
VS

 

[Huevos]

Thanks Huevos ..
I'll check those lengths again tomorrow ..Ignoring the additional point D
I could well have written something down wrong..
Cheers
VS

Could be how the limit switches are set.

 

[Vipersan]

Indeed it could be Huevos ..
As I said earlier ..I have adjusted the Eastern limit switch ..
..(the Western being fixed)..
To gain a bit more arc ..thus the extension will push a bit further than the factory setting...

Ok ..back to replacement actuator magnetic disc..
It's now tided up .
More circular ..and the right diameter.
Achieved by using a stand drill as a vertical lathe..
Here are some pics of it complete and fitted .
No magnetic hot spots as yet ..but since the original had 6 ..I'm going for 8 ..only because I don't want too many magnetic spots ..this may confuse the reed.
..and cos dividing the disc equally by 8 is relatively straightforward.
rgds
VS

 

[Vipersan]

@Huevos ..
Just re-measured centre bolt to centre bolt
The two fixed sides of the triangle are 38.8cm and 34 cm

The 3 variable sides are max 67.2 mid 46.0 min 11.8cm
cheers
VS

 

[Vipersan]

Ok ..the basic principles of construction of the rotating magnate ..are good.
I'm pleased with the result.
It transpired I needed 4 x 2mm by 1mm magnets stacked per 'hotspot' in order to activate the reed..
and this works well enough..
BUT ..I may have another problem.
Closer testing of the enclosed reed switch shows that it activates at either end ? ..not in the middle as expected.
So ..it could be that there are in fact 2 reeds internally within the casing of what apears to be a single switch ..
Possibly in parallel ..and activated ..not centrally ..but by 2 magnets simultaneously activated at a fixed distance between 2 magnetic hotspots...thus maintaining the count and behaving as one switch....
A sort of count failsafe.
If this IS the case ..my replacement will not work as the spacing is different ..having increased the hotspots by 2 ..ie closer together.
All that effort for nowt if this is the case.
cest la vie.

 

[Vipersan]

Single step movement of the actuator was not possible using the original reed ...as I suspected..
A reed is not neccessarily a reed ..in the strict sense ..
So borrowed one of an old motor which was centre activated ..ie only one internal switch ..
placed the disc upside down and positioned the reed above the disc in such a way as to facilitate it's activation when a magnet was directly under the reed centre ..
Now single step was possible ..and would count as it should.
So yes it would be possible ..but would require re-engineering the reeds position ...and replacement of type..
here is a photo of the crude lash up..

Also it is worth pointing out that each neodymium magnet is positioned alternate poles ..
ie N - S - N - S - N - S - N - S
I did this so that the reed would not become permanently magnetised in a specific way ...as the disc passed under it.

 

[Huevos]

@Huevos ..
Just re-measured centre bolt to centre bolt
The two fixed sides of the triangle are 38.8cm and 34 cm

The 3 variable sides are max 67.2 mid 46.0 min 11.8cm
cheers
VS

Forgot about this.

1cm = 1.73º
2cm = 1.72º
3cm = 1.7º
4cm = 1.7º
5cm = 1.69º
6cm = 1.69º
7cm = 1.68º
8cm = 1.69º
9cm = 1.68º
10cm = 1.69º
11cm = 1.7º
12cm = 1.7º
13cm = 1.7º
14cm = 1.71º
15cm = 1.72º
16cm = 1.72º
17cm = 1.73º
18cm = 1.75º
19cm = 1.75º
20cm = 1.76º
21cm = 1.78º
22cm = 1.79º
23cm = 1.8º
24cm = 1.82º
25cm = 1.83º
26cm = 1.85º
27cm = 1.86º
28cm = 1.89º
29cm = 1.9º
30cm = 1.93º
31cm = 1.94º
32cm = 1.97º
33cm = 2º
34cm = 2.02º
35cm = 2.05º
36cm = 2.08º
37cm = 2.12º
38cm = 2.15º
39cm = 2.19º
40cm = 2.22º
41cm = 2.28º
42cm = 2.32º
43cm = 2.37º
44cm = 2.43º
45cm = 2.49º
46cm = 2.56º
47cm = 2.64º
48cm = 2.72º
49cm = 2.82º
50cm = 2.93º
51cm = 3.05º
52cm = 3.2º
53cm = 3.37º
54cm = 3.57º
55cm = 3.82º
56cm = 4.14º
57cm = 4.57º
58cm = 5.16º
59cm = 6.11º
60cm = 7.92º
Total arc = 143.87

 

[Vipersan]

Cheers Huevos ..
Very happy with the arc coverage ..even though there is such rapid acceleration at the Eastern end ..where I pinched a bit more extension.
I'll swap over the positioners at some point and hope for a little more accuracy and control.
The old Vbox is counting in twos ..and it shouldn't be ..
This never happened with the original jack ..only since the QARL was fitted.
Possible overshoot or registering that 'theoretical' second reed switch as a pulse ..thus doubling the count ..though..it is uniform so shouldn't cause problems returning accurately to a stored position.
rgds
VS