fork mount at SG latitude

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rlow
Posts: 2400
Joined: Fri Oct 31, 2003 7:36 pm
Location: Jurong

Post by rlow »

I built a eq. wedge and tripod for my c8 a decade ago. Wedge was built-up from several 1" thick plywood, very solid. took me more than a month to complete.

Generally, unless you also design for oversized forks, the fork mount on eq. wedge is not so stable, it's the vibration due to the "tuning fork" effect, that's the issue. It may work better at higher lattitude, but not such a great idea at one degree North. I still prefer GEMs and dob mounts.
rlow
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timatworksg
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Joined: Mon Feb 01, 2010 9:42 pm
Location: Pasir Ris

Post by timatworksg »

Ah...thanks for that rlow! So in nutshell, the wedge base has to counter the Fork length while at the same time the stress and vibrations from a design that wasn't made to suit 1 degree or 90degrees sideways. Did I get that right?...lol! Besides the fear I have is sticking a moving and shifting weight sideways like that with gravity wanting to pull it down, creates many stress areas that may give way. Then again we have tracking issues.

I like the Dob Mount design....simple and always effective!
My wife never complained about how much time, effort & money I spent on my Astronomy hobby!................suddenly I met her!!!
kochu
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Joined: Tue Sep 30, 2003 9:51 pm
Favourite scope: Sharpstar-107PH Triplet.
Location: Jurong West

Post by kochu »

timatworksg wrote:................ Now Im lost with the Dobson hole!! whooosh!
@Kochu
Have you tested your DIY wedge and noticed any stress factors?? Curios as what may work with a Meade system may not work with others...in terms of stress points on a fork mount sideways??



Hi Tim,
I did give some thought to the stress aspects on the centre bolts. To relieve it I made two reinforcements.
The first is to clamp the fixed base of mount with a pair of heavy duty 6 inch c-clamp so that the centre bolt do nothing more than act as a locating bolt.
The second is to make the moving part of the base of the mount to rest on 4 small ball bearings , to relieve the bending load on the mount's base bearing while it rotates.
Kochu/14-2-11
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