Author Topic: Balancing an LX90  (Read 439 times)

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Balancing an LX90
« on: Aug 20, 2020, 15:43:50 »
Having cleared some space in our garage I am bringing my LX90 back from furlough (about 12 years worth).

A few years ago I managed to acquire an equatorial wedge at a reduced price from Amazon but I am only getting to use it now. This has led me to discover, in the course of daylight practice sessions, that the LX90 (and I suspect most if not all fork mounted telescopes) is inherently unbalanced because of the declination drive train in one fork.

I have a sliding weight on a dovetail rail which attaches to tube but that was not curing the problem. I then noticed that in addition to the central mounting points there were fixing points each side of the central line. By fixing the dovetail rail angled away from the drive/clutch side I have found that the tube seems capable of decent balance.

My question is: Is there a BIG NO NO in doing this? Am I likely to damage anything?

I hope to be able to do some planetary imaging as well as small items such as planetary nebulae (I have an ambition to image M1). The fork design will preclude the use of a cooled camera and filter wheel so I will be relying on a ZWO ASI 224 OSC.


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Re: Balancing an LX90
« Reply #1 on: Aug 20, 2020, 16:22:57 »

I had an LX90 back in 2002 (!) so working from memory here but I guess you are referring to the mounting/fixing points on the OTA?  If so, offsetting your weight away from the clutch arm should work but keep the weights close to the axis of rotation for DEC so not to cause undue strain on the motor (DEC+/- balance).  You will not need much slewing in DEC when imaging (ideally none) but since the gears inside the LX90 are mostly plastic, you want to keep them running as freely as possible.


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Re: Balancing an LX90
« Reply #2 on: Aug 20, 2020, 20:12:31 »
Back in the day I had a sliding weight on a rail that Mac sold me for my Lx90 8". I seem to remember it had a 2d capability, up and down and side to side. I had a standard wedge and a mega wedge, both flexed. I tried all sorts to the mount in a usable configuration, even strapped a weight to the other DEC fork (nearly worked). I ditched the forks eventually as they were no good for imaging, they now support an old LX10 in an observatory somewhere in the Middle East! The scope was then mounted on an HEQ5 (that had been Roberts - these things get around :) ). Problem solved. Ish. That mount has had new bearings all round, belt drive, an upgraded (old Meade) tripod etc. I guess what I'm saying is these things are never completely satisfactory and bodging them is half the fun!

We're all guinea pigs in the laboratory of life. Better a fluffy guinea pig than a lab rat!
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