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Mathematically, the torque due to the mirror is proportional to the sine of the angle of the tube away from vertical.

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Hows this for ugly? It is a 42" f/4.

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I would have to agree, that is very ugly indeed.

now if you had a dragon [for heavan] or a tiger [for earth] burnt into the wood somewhere it would add the coolness back.

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There are some wonderful ideas here. Markus, your travel scope at the top of page 6 is magnificent!

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Thanks a lot, Dick.

Danny, at 0° you will have the least torque moment.
Let´s have a look to a bearing and a mass (kg) which is fixed to the bearing with a stiff rod. Now, the gravitation will accelerating the mass by 9.81 m/s^2. This mean, that a wight force will pressure to the bearing in N ((kg*m)/s^2). If the force vector is going vertical through the bearing, your mass will hanging vertical, and the torque moment in the bearing is 0 (like the sin0°=0). Now we will deflect the mass (i.e. the scope) for some degree. There is now a distance (measures in m) between the wight force vector and the mass. This distance is your lever arm (standing rectangular on the wight force vector). Because of this lever arm, you get a torque moment ((kg*m^2)/s^2 or Nm) in your bearing. This will increase, when the deflection angle will increase, because the distance between the wight force vector and the mass (your lever arm) will increase, too. The torque moment will have the maximum at 90° (like sin90°=1), because if the angel further increase or decrease, your lever arm will always decrease, and there fore the torque moment will always decrease, too.

Now let´s look to the other side:

You have a counter mass hanging vertical and produce a wight force on the bearing (N). If you deflect the telescope, the mass will move along the wight force vector, so the wight force would always be the same. Even if you give a lever arm to that counter mass, the resulting negative torque moment at the bearing will be always the same, too. Now you can adjust the counter mass to equal one torque moment at the bearing, which is equal to one deflection angel of the telescope. If you deflect the telescope over that angel, it will sink back and in the other direction, the counter mass will rise up the scope to the point of torque moment equation.

I hope, you can understand, what I would say...


@Tom: Wow! That´s a huge scope! If you will make a more beautiful telescope for you, I will dispose the old one for you in the "garbage can" in my backyard...

cs
Markus

Edited by etalon (02/05/13 12:07 PM)

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You have a counter mass hanging vertical and produce a wight force on the bearing (N). If you deflect the telescope, the mass will move along the wight force vector, so the wight force would always be the same. Even if you give a lever arm to that counter mass, the resulting negative torque moment at the bearing will be always the same, too. Now you can adjust the counter mass to equal one torque moment at the bearing, which is equal to one deflection angel of the telescope. If you deflect the telescope over that angel, it will sink back and in the other direction, the counter mass will rise up the scope to the point of torque moment equation.

I hope, you can understand, what I would say...

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I understand all that but don't you think there would be capacity because of the radius of the bearing to minimize the differences in the angled vector force of the mirror and on the opposite side, the counter weight that has no changing angled vector, if you could understand my english?

one reason why I asked this is in a dob I rehab'd it wasn't balance very well. so when it got too close to zenith it tilted back, when it got below 30* it would nose dive. like the forces weren't linear and formed a curve base on what direction I was from 45*. I since have balanced it better and made bigger bearings.

just starting to rehab it.

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Since the talk has turned to ugly scopes, I feel i can post a pic of ours in the basement where it was built. Do we win anything?

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double the pleasure, double the fun.

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