Engineers tip for Big Eyepice Balance & Gearbox Wear problem.

[Pliadian]

Hi All,

You may know this already, as my point is simple.

But this is a point from an Astronomer and an Electrical Engineer with 25 years of experience on stepper motors, DC braking and gearboxes.

I recently bought a large SCT and want a 'huge' eyepiece to compliment it. However, there are worries about the load on a scopes motors and gears foremost, with these eyepieces making the scope  back heavy.

From an engineers view, I can say that when a DC stepper motor & gearbox finishes moving. IE: Locked onto an object to view.

The motor & gears are locked by DC braking. (as long as there is power - the motor holds itself as a DC magnet under no gear loading).

So I recommend leaving your heavy eyepiece off the scope until it has finished panning. Maybe use a lesser size, light eyepiece  for panning.

This WILL result on no extra gear loading on any scope over time, especially if your scope has 'Plastic' gears.

I have worked on 6 axis robots for years and the Stepper motor / Encoder & Gearing are all the same principle.

Years of wisdom taught me, if it's not broken, don't fix it. But as soon as you overload it. It IS a matter of time.

Basically, keep the weight down and balanced when you pan and your gears will never wear out. Balance = Less Force.

Clear Skies,

Scott x.

[laser_jock99]

Does this apply to worm drives?

[Pliadian]

Any drive that has it's load increased, if the load is not balanced.

So, yes. Not a missive difference in load, but it does add up over time.

The worm is more suseptable, than a gear to gear arrangement.

As the worm has more contact per rev than the gear. (which does a full circle before it touches the worm twice, the worm touches the gear several times)

It's all about load and wear points.

Then minimalising it.

Scott.

[laser_jock99]

Technically my mount is overloaded (70kg on an EQ6) though I'm careful to be always well balanced. The steppers have a good 12V/7A supply so I'm not overly worried about straining the steppers per se. My biggest concern for damage is sudden stoppages at high slew rates. There is a lot of inertia when the scope is moving- if that comes to a sudden halt then the load on the worm & wheel must be enormous. So I never cancel any GOTO's mid slew and always let the mount slow down as per program. If a big slew is involved I always watch the trailing cables- that has been a cause of sudden stoppage in the past.

[Pliadian]

Honestly - I am new myself to goto's but I always set min slew rate for alignment and comfort.

This stops any jolts I find. Also better for wandering.

All I could say is lighten the load when you pan. Then drop your eyepiece in after.

I don't want to sound al 'warning, warning'. Just from my tech view a good 12v plenty of A hrs battery, is better than an 18v with less A (Amps).

Because all the scopes electronics will get hot changing voltage down to 5v and regulators etc develop problems over time. This leads to motors, hotspots (weak joint with too many A) and main board fuses blowing.

A good steady battery with 12v instead of 18v with plenty of Amp Hrs.

This and minimizing jolts means they will never damage.

[Pliadian]

Honestly - I am new myself to goto's but I always set min slew rate for alignment and comfort.

This stops any jolts I find. Also better for wandering.

All I could say is lighten the load when you pan. Then drop your eyepiece in after.

I don't want to sound al 'warning, warning'. Just from my tech view a good 12v plenty of A hrs battery, is better than an 18v with less A (Amps).

Because all the scopes electronics will get hot changing voltage down to 5v and regulators etc develop problems over time. This leads to motors, hotspots (weak joint with too many A) and main board fuses blowing.

A good steady battery with 12v instead of 18v with plenty of Amp Hrs.

This and minimizing jolts means they will never damage.

In 25 years as a Professional Electrical Engineer - 9 out of 10 times, failure is mechanical. Fact!

Never overload mech or elec = runs forever.

[Pliadian]

Technically my mount is overloaded (70kg on an EQ6) though I'm careful to be always well balanced. The steppers have a good 12V/7A supply so I'm not overly worried about straining the steppers per se. My biggest concern for damage is sudden stoppages at high slew rates. There is a lot of inertia when the scope is moving- if that comes to a sudden halt then the load on the worm & wheel must be enormous. So I never cancel any GOTO's mid slew and always let the mount slow down as per program. If a big slew is involved I always watch the trailing cables- that has been a cause of sudden stoppage in the past.

Reading further - Yes. 70kg is fine because your balanced. Its when your slew and hear the gears working at a certain arc. Stop that and weight doesn't matter. Balance does.

Cheers, nice point,

Scott.