Re:Martin Mobberly and his 19.3″ (49cm) f/4.5 mons

Forums General Discussion Martin Mobberly and his 19.3″ (49cm) f/4.5 monster Re:Martin Mobberly and his 19.3″ (49cm) f/4.5 mons


Posted by Martin Mobberley at 21:11 on 2010 Feb 21

Hello David,You say you are surprised (about the tracking), but think of the timescales involved. Every manufacturer learns from its mistakes and the AE mounts from their earliest days (the late 1960s and 70s) are completely different to those from the 1980sonwards. My 14" was on a modified C type head and the wormhousing was very poorly designed. Like all telescopes of thatera guiding with a separate guidescope was required. But the1992 built 19.3 inch with its 18 inch wormwheel was a totally different design with the worm position adjustable and held ina solid ball race. After 25 years in business it would have been amazing if Rob Hysom’s design had not changed…. In addition the 19.3 inch was a much larger instrument than the usual AE amateur telescope, although they made quite a few massive telescopes like the 16-inch Cross Axis at Armagh and Hatfield Polytechnic and the 24 inch at Keele.Both my 14 and 19.3 inch instruments had very good axis clamps. Richard’s C type AE mount is virtually identicalto the one I gave to Mark Stuckey. As you say, the opticswere by Jim. It is not a pure AE but then neither wasmy 19.3 inch….the focuser and setting circles were made by another company. After Jim moved from Luton to Cambridge the era of pure AE telescopes ended….indeed before the late 1970s AE was more than just Jim and his brother. There were other characters (Goddard, Shuttlewood and the Astrotech drive people) involved. Incidentally, in 1987 I went on a trip to an observatory in Somerset where there was an 18 inch f/6 Newtonian (Charterhouse) made by Fullerscopes. An impressive beast, with, as you say, a worm held in a substantial block.Nick James drove me to see it and use it. However, on the subject of having any design ‘sense’ it was hysterically badly designed. The worm appeared to be made from hardened steel, but the aluminium wheel was as soft as butter. Every time the worm rotated another tooth on the wheel was shaved off and ended up as swarf in the worm housing…..half the teeth had disappeared after a few years of use. So, yes, the early AE worm designs were poor, but the big Fullerscopes worm and wheel designs were catastrophic. By contrast the AE wheels of the ’80s were phosphor bronze!!! I guess there is probably a single tooth left on that wheel now….if the telescope exists at all! It’s difficult to find any manufacturer whose mounts have no shortfalls, with the exception of Software Bisque and Astrophysics.Martin