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Old 06-11-2019, 08:00 PM
gts055 (Mark)
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Location: Mornington Peninsula Victoria Australia
Posts: 295
Thomas Gaunt equatorial mount and pier finds another home.

This piece of history has been through many hands in the last few years and now has yet another home and some further enhancements through the work of a brilliant machinist friend. A new counterweight bar has been machined from bar stock to accept rough cast counterweights from an Australian "Samson" mount courtesy of Matt T. The bar has been bored and threaded so that it screws onto the existing thread on the end of the declination shaft.
The beautiful ra gear was hidden from view so consideration was given to a different clutch setup. A new simple and very effective right ascension clutch assembly has been machined from bar and clutch discs out of delrin. The ra gear was trued and faced on both sides for the clutch discs to engage on. The ra gear sits on a central hub which is threaded internally to screw onto the existing thread on the end of the ra shaft. This hub is shaped like a "top hat". After screwing the hub onto the ra shaft, a clutch plate is slid onto the hub, then the ra gear, then another clutch plate then a circular "nut" is screwed onto an outside threaded section of the hub to give the required friction/slip. The whole hub/clutch assembly is then screwed up or down the ra shaft for correct meshing with the ra worm gear. A bolt screws into the end of the hub to contact the ra shaft thus locking the hub/clutch assembly to the ra shaft. Works a treat.
The mount was originally built by Gaunt to carry a 3" to 4 1/2" refractor. I happened to have an old english made 3" Broadhurst and Clarkson from the early 1900's that was originally retailed in Melbourne by a firm "Sewards". Nice to have this collection of parts all originating in Melbourne Mark
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Click for full-size image (IMG_3694 counterweight shaft.jpg)
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Click for full-size image (IMG_3698 ra gear end.jpg)
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Click for full-size image (IMG_3700 ra gear and clutch side view.jpg)
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Click for full-size image (IMG_3701 mount and telescope ra end.jpg)
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Click for full-size image (IMG_3703 mount and telescope dec end.jpg)
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Old 07-11-2019, 09:20 AM
Rainmaker (Matt)
Strictly Visual......

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Join Date: Jun 2019
Location: Canberra
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Fantastic work, Mark.
I have some eyepieces to suit your scope ( depending on the thread...)

I spoke to one of Thomas Gaunt’s descendants, Marion Miller, and supplied a picture for her book “Gaunt’s Time.... “
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Old 07-11-2019, 10:40 AM
gts055 (Mark)
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Hii Matt, I am really delighted to have this mount and pier. Its through the work of many enthusiasts that the mount has come to life again. Lars Hanson in saving its bones, yourself for the complete dismantling, sand blasting, careful brass cleaning, shellac and painting then reassembly. Zane H for the magnificent ra gear and worm, Fahim for the Losmandy/Celestron drive and Matt T for the construction of the tangent arm, azimuth adjuster and ra worm gear with steppers controlled using a Losmandy/Celestron 492 digital drive. Love the way my engineering friend redid the clutch so the ra gear is now completely exposed. I dont think the electric drives detract from the mount as even most of the great old large observatory refractors have lost their clock drives for more modern electric systems. The old telescope eyepieces have a whitworth thread, apparently thats what was decided upon by the Royal Astronomical Society in England 1847. Nice reference here on page 152
http://www.brayebrookobservatory.org...REFRACTORS.pdf
The 3" refractor is a heavy lump at 12 pounds of brass.
Mark
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Old 07-11-2019, 02:13 PM
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MattT (Matthew)
Reflecting on Refracting

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Join Date: Jul 2011
Location: Melbourne, Australia
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Hi Mark,

You are an artisan. Your RA clutch is simple and perfect, very much in keeping with the original.

May you get many years enjoyment looking at and using this beauty.
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