Quote:
Originally Posted by g__day
Suggestion, get a 4" * 2" block of wood about a foot long and drill two holes about 5mm - 10mm deep with the largest drill you have (I used a 1" wide drill). Separate these holes by about 2/3 of the width of your cross bar )for me using Losmandy D rails (4" wide) that meant centre of cavities I drilled was 3" apart).
Now in each hole put the largest glass marble you can find (I used ones that were 1" diameter). This leaves you with a block of wood with two marbles of equal height (check this with a spirit level).
Use these two marbles as a perfect surface to determine the balance point of each component of your side by side set up individually - and mark these positions on your individual OTAs dovetails with a pencil. When you do this make sure you attach all the gear that will be on your OTAs - dew shields, cameras, focusers - even allow for cables if you can. So what we are attempting to do is find the balance point of each individual OTA.
Now place each OTA and all its gear in its desired dovetail of your side by side dovetail holder. Centre each OTA on the point of suspension you marked previously. Now with the fully loaded side-by-side set up - balance this on the marbles and mark the exact balance point. This is the spot you want to be centred over the top of your mount.
The two marble approach gives you a very effective and cheap means of finding the exact balance point of your gear and makes it very easy to balance the whole rig before you place it on your mount.
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Sorry but this seems like an awful lot of work just to check the balance point
Option 2 get a knitting needle or similar and sit it on your kitchen bench.
Next sit your fully rigged scope on top of the needle so you can roll the dovetail forward and backward on the needle until it rocks over the CofG.
Mark the centre balance point as above, no drilling no marbles and nothing for it to fall off except a knitting needle.
