Alan64

I used only one of the thin-plastic washers, and for the RA-setting-circle; and in addition to a thicker, white nylon washer for the red-fibre, and here... ...and merely to keep the setting-circle from backing out of its cavity towards the RA-gear. That thin-plastic washer was one of only two of the original parts that I retained. The rest were replaced; the refuse... ...and with bronze, sintered(powdered) and solid(additions). For the DEC lock-nut, the thin-plastic washer was cast aside, the red-fibre washer replaced with two of bronze compressed together with a vise, and with the inner diameter wallowed out a bit... All of the sintered-bronze within this project was sanded smooth and polished with #0000 steel-wool and machine oil... The Phillips-head screws of the lock-nut were also replaced, and with those of hex-sockets. The lone red-fibre washer on up was also replaced... The paint within the clamp-ring, and round the clamping-stud, was removed. A 0.20mm-thick shim of phosphor-bronze was added, and for a snug, yet not tight, fitting of the two components... I also did not want the clamping-screw to dig into the stud; better against the bronze instead, so I think. Further up, and lastly, a 0.20mm-thick phosphor-bronze washer was fashioned and added above the clamp-ring, and where the ring contacts the rest of its slow-motion assembly and the mounting-saddle...

I simply cannot abide by painted bearing surfaces... Look at how the paint stained that red-fibre washer, and the others as well. The factory couldn't even wait for the paint to dry. You've got to get this stuff out in a hurry, you know; pathetic. Saturating the painted surfaces with 100% acetone, then scrubbing with steel wool, makes for a much safer alternative for gel-like paint-stripper. Everything for the hyper-tuning was acquired locally, save for these, which arrived from California soon after ordering: needle-thrust bearings... ...28mm O.D. x 15mm I.D. x 2mm thick... The RA and DEC shafts are 12mm in diameter; hence, a bit of slop... ...which was corrected with rods of brass formed into rings... Not every last bit of slop was eliminated, but most, and good enough if not ideal as I didn't want any binding.

And now, for the hyper-tuning portion of the show; I won't say that I love one, but I am quite partial to an EQ-2, hence my driving desire to make the mount the best it can ever be... The Bronze Age... The Bronze Age is looked down upon, in relation to the Iron Age. Once many everyday items were made of iron, steel, and stainless-steel, bronze took a back seat; but not in my household... Those red-fibre and thin-plastic washers had no place within my mount. Bronze is known to outlast the equipment, the machinery, into which it is placed.

Basic tuning continued, and this time with the DEC-axis... You first remove the lock-nut, which, again, also hosts the bar for the counterweight... You can easily see the red-fibre and thin-plastic washers there, and the parts removed in that order. But what's that at the top of the image? Why, it's a shallow well, or depression, like something or other is supposed to fit there, but there's nothing there. The RA-axis has one, too... Hmm, the included washers simply cover those depressions. Oh well, I have no idea for what they might be; as I do have quite a few blond hairs on me head, still. After the lock-nut is removed, you simply pull the upper assembly up and out of the lower body... ...and there you see the lone red-fibre washer, and with no others. The uppermost portion consists of the DEC slow-motion assembly, and the mounting-plate for the telescope. You do not need to disassemble the slow-motion assembly. You can simply clean off and away what factory-grease is accessible, then re-grease. The DEC spindle, the shaft, should be cleaned as thoroughly as possible, in particular, and re-greased. To make cleaning and re-greasing easier, the assembly can be taken apart quite easily. You simply unscrew the spring-loaded tensioner, remove the black clamp-ring, and for easy access to all of the components... Now, you don't have to take it apart, if you don't want. I did, and it was rather enlightening in either the discovery or rediscovery as to how it functions. Alas, however, there's no continuous, perpetual rotation possible with the slow-motion control; only with those of the EQ-3 and larger, I'm afraid.

Now for the basic tuning; the RA-axis... Let's see what it looks like upon pulling it apart. The lock-nut must be removed first... Now to see what lies inside... There's the RA-axis gear in all its glory, along with the setting-circle, and the basic red-fibre and thin-plastic washers. The typical factory grease was found within, and of two types: a very-thick, whitish, glue-like substance, which served only to stiffen the fitting of the setting-circle within its cavity... The other type was this yellowish, oil-like grease, which was the predominant lubrication throughout the mount-head... All of the parts and surfaces were cleaned with what is used for outdoor grilling(steaks and what-not), which is a kerosene-type liquid. It's called charcoal-lighter fluid here in the States, and it cuts through that factory-grease almost instantly. Said cleaning-agent is rather evil-smelling, so use only with adequate ventilation. After cleaning, all the parts and areas that required it were lubricated with Super Lube, a "Teflon" or PTFE-based lubricant, then the axis was reassembled. But before reassembling the axis, there was room for immediate improvement, and of the setting-circle's fitting. The fitting of the circle was not tight by any means, which is why that glue-like "grease" was applied; in effect gluing the circle in place, yet whilst allowing it to rotate, however it did its job most poorly. Instead, I added the thicknesses of aluminum-foil tape(0.10mm), double-sided tape(0.07mm) on top of that, and PTFE(0.50mm) to the outside of the circle's flange... ...and for a dry and tighter fit within its cavity; no more rattling around loosely and unevenly. I used strips of said materials, and combined were 0.678mm thick, and no wider than 13mm. If these materials are unavailable, then quite possibly only a strip of self-adhesive felt may serve. The cavity, of course, must be cleaned and degreased, and kept that way, as you don't want to muck up the felt, or the PTFE, therefore be careful not to apply new grease where contact occurs... ...like when re-greasing the shaft seen jutting upwards there. Incidentally, the new lubricant needs to be applied only to the shaft and the very bottom of the cavity where the gear's flange makes contact with that bearing surface.

Thanks. As far as I know, there may be only two companies in China that manufacture these clones: Synta, and Ningbo Sunny(who owns Meade now). However, it could be that only Synta makes them for all the brandings. In any event, the factories are just down the industrial road from one another over there.

Shop classes, at school; they've seemingly gone the way of the Dodo, here in the U.S. at least. They were phased out at about the time I had entered high school, and with computers looming above the horizon; shame, that. The three main portions of the EQ-2 mount-head that may or may not require servicing... For those who do not wish to take their EQ-2 apart, there are nonetheless three elementary points of adjustments that should be checked, adjusted if necessary, and in the hopes of freeing up these mounts, for smoother operation, particularly when using a motor-drive in order to prevent damage to same due to binding... 1. The lock-nut of the RA-axis, located at the rear, or "butt"; it should not be too tight, nor too loose, just right rather... I could not fit a socket-wrench within that cavity, so I used needle-nosed pliers. As the nut is screwed in and out it remains in position once released; good thing that. 2. The DEC lock-nut is held in position by three set-screws round about. Simply loosen the screws and rotate the nut; and again, into a position that's neither too loose, nor too tight... The DEC lock-nut also hosts the bar for the counterweight... 3. The lock-nut and the adjustable-bearing for the RA worm-assembly... The lock-nut is removed, the bearing screwed in and out, not too tight, nor too loose, and then the lock-nut is reinstalled to hold and lock the bearing in that position. You should then be able to twist the worm-shaft with your fingers, freely, smoothly, and with no binding whatsoever. If the worm does not mesh with the RA-gear just behind it, square and true, then these two bolts are used to adjust that... It is the worm and the gear of the RA-axis that allows for tracking objects across the sky, day and night. When the worm is motorised, it takes 24 hours for it to turn the gear, the RA-axis, once round.

I once had a Japanese-made EQ-2... I ended up passing it on to a relative, and after I had acquired a Vixen GPD or GP-DX(EQ-5). I haven't had either one since 2003-05; the former given away, and the latter destroyed in a fire. In any event, the EQ-2 and EQ-5 are my only favourites among the series. Here in the U.S., it is almost impossible to acquire an EQ-2 as a separate purchase, however they are readily available within kits, the most economical of these being the one I chose... https://www.bhphotovideo.com/c/product/1061422-REG/meade_216004_polaris_114mm_german_equatorial.html?ap=y&gclid=CjwKCAjw2MTbBRASEiwAdYIpsdkrTeKGLoav4d7BipwU59Q5vvs09DfieIfZJlRKqKyFDr3DncRd_xoCn0YQAvD_BwE&smp=y This kit, and many others come bundled with an EQ-2 mount, and are acquired by more than a few first starting out, worldwide. They are Chinese clones of what was once, and all that that entails. To wit, they do not necessarily arrive in working order; for example... I could not rotate the declination-axis, and the setting-circle's pointer wasn't helping in being seemingly welded to the circle. Others, no doubt, have received less-than-stellar examples of these mounts as well, again, worldwide. It's quite a pretty thing, yes, but pretty is as pretty does, and this one wasn't quite so pretty once I began to take it apart... Of the current EQ series, the EQ-2 is the quintessential grab-and-go equatorial, in so far as an equatorial might be, and is capable of supporting a wide range of smaller telescopes that do not necessarily cause bouts and fits of aperture-fever. Indeed, quite a few acquire one of these mounts after having fiddled and puttered round with those larger.

For those who wish for their maps and charts to match what they're seeing through an ocular, at night, then yes, a penta-prism seems to be the new ideal... https://www.amazon.co.uk/Orion-52055-1-25-Pentaprism-Diagonal/dp/B07C85Z8V4 I saw that one, the only one I believe on the market at present, and just the other day... https://www.youtube.com/watch?v=mJEl6Rba_VU Would that the presenter had had a wee screwdriver handy, then to take out the prism and exhibit it. It's likely made by either GSO, or Synta; the former I'd wager. The port, where an ocular would be inserted, its stop looks to be narrowed, and similar to that of this 90° GSO Amici that I have... ...with its Amici-line visible, and as the camera revealed. The line wasn't visible to the eye at the time. The clear aperture of my GSO is 20mm; that of the penta-prism: 29mm, and most generous for an erect-image diagonal. Still, the presenter didn't tilt it quite far enough to see its full aperture, there where an ocular would be inserted, and either unwittingly or intentionally as the case may have been. It may be narrower on that end. Perhaps they'll drop the price a bit in future...

Thank you. There is that, at least. Yes, the aluminum-foil tape turned out to be the ideal thickness to make the focusser tight enough to allow the battening down of the screws without it slipping out of alignment. I had tried two strips of it: far too tight; and then one of the double-sided tape with the one foil: still too tight. I had it right the first time, I found. I then ripped the last layers off; and applied a single foil, again. The decorative, scored, bronze tabs, and flat-washers, help in retaining the alignment afterwards. This was the result of my first attempt at collimating the focusser... ...much improved, but I've removed everything since, and in preparation to flock the tube. How gracious it is indeed that the current manufacturers have allowed an f/13 achromat to slip out of their factories. However would that it were an f/15 or f/18 instead. Incidentally, my brother has a C90. I've used it more than he has, at night instead, but very little at that. The Maksutov simulates this 70mm f/13 achromat; but the achromat is lighter, albeit longer, with minimal false-colour, and most importantly, unobstructed; hence my drive in the correction of this one, and with no holds barred.

I decided that what I had done to the objective-cell, I would also perform upon the focusser, and in making it collimatable as well...

The TS "Photon" is Teleskop Service's house-brand. I would venture to guess that the manufacturer of its mirrors is Guan Sheng Optical in China, aka GSO. I say this because the vendor High Point here in the U.S. carries a house-branded 150mm f/5 Newtonian, and manufactured by GSO. Mind you, I'm not stating that it is indeed, but only that it's quite probable. GSO manufactures the very popular Apertura AD8(formerly Zhumell Z8), a "Dobsonian" which is also marketed here in the U.S. The vendor Agena Astro of California sells all sizes and focal-ratios of GSO primary-mirrors and optical-flats. In addition, a U.S. manufacturer of premium "Dobsonians" sports within its base-model offering: GSO mirrors. Give TS a call and ask.

Hi Gerry, A 70mm secondary is not that bad for that sized aperture... The secondary for my 150mm f/5 is 47mm, and I don't even have a 2" focusser. The reason that one may seem too large is because it has a 2" focusser, and so to illuminate 2" oculars. The Bresser linked to previously, its secondary is 74mm in diameter. If you like the specs overall of the TS, give it a go.

For this fix, six strips of PTFE were used. Before I cut the strips to size, I treated one side of the long strip with a flame from a mini butane torch, passing the flame over it, back and forth, for a few seconds, and in the hopes of increasing the surface tension for the adhesive, in this case the double-sided tape. I tried the 0.020"-thick PTFE out first, and with scraps of that inserted loosely between the drawtube and its supports... But I could only insert those for two of them, not all three. So then I knew the PTFE would need to be thinner. In went the 0.015"-thick next. Success... The three supports on the interior required just three strips of 0.015"-thick PTFE, and the double-sided tape, as did the two of the outside supports and marked with green arrows... The outside support at the top, the oddball, required a strip of the 0.020"-thick PTFE, the double-sided tape, and two strips of the aluminum tape, stacked. It required that in order to bring its level up to the level of one of the interior strips just behind it... I placed the strip in between the molded runners, and above them in the process, thereby eliminating same. Now, the drawtube racks in and out, smoothly, straight-and-true, and with no slop whatsoever(as there was before the fix)... Afterwards, I checked the collimation; not bad, I think... But yes, it could be better, of course.

On the side, I thought that the interior of the focusser's housing was a bit too reflective, so I blackened and dulled it with a rattle-can of ultra-flat black paint, whilst carefully masking off the surfaces of the supports and the channel for the drawtube's rack. I used the blue painter's tape for that. You also want to ensure that no paint lands on the outside areas of the focusser, the supports, and in general... I also went ahead and spritzed the inside of the drawtube, as well as blackening the bevelled end of the drawtube which points towards the doublet-lens at the front of the telescope... The tip of the rack was blackened, too, there at the bottom of the image. *NOTE: In addition, you want to clean out and away all of Synta's original "glue, and what they try to pass off as lubrication, on the rack of the drawtube, between the teeth even, the gear of the pinion-shaft, and everywhere else, throughout. During this project, I replaced the "glue" with Super Lube , for example, a Teflon-based lubricant.

On the flip-side of a five-pence coin...<flip>...we have Synta's wonky, plastic focussers equipped on the refractors, too; gads. The Celestron "AstroMaster" 70 EQ, a 70mm f/13 achromat, and seen here perched upon my AT Voyager I alt-azimuth... ...and brimming full of promise and devil-may-care; more of the latter I expect. It all started when I had wanted an EQ-1 mount, and for my vintage 50mm f/12 achromat. I could have gotten the bog-standard EQ-1, in black and silver, but the mount's interfacing with a telescope is not up to current standards, but doable if one is so inclined. Standing out from that was Synta's zooted-up version, the Celestron "DeLuxe" EQ-1, which comes equipped with a Vixen-type mounting interface; and about time, too. But the deluxe version is not sold separately. If you want one, as I did apparently, you must include one of Synta's Celestron telescopes along with it. I didn't want one of Synta's Jones-Bird simulations, as I have enough work to do, so I chose said refractor instead. Much simpler, no? No, not actually... The refractor's focusser... This is not your typical plastic focusser for an imported refractor; the focusser's housing... It looks like a spaceship, and one of those 3D printings to boot. What will it take, I wonder, and for a smooth, slop-free, straight-and-true racking motion. The interior... There's another one of those pitiful, plastic, self-adhesive glides, and the only one within the entire focusser. Note the three drawtube supports. On the outside, we have these three supports, in addition... The top outside support is unique, in that it has molded runners... Next, the fix...

Said experiment resulted in no difference between using the epoxy or double-sided tape for the adhesive. Again, when the PTFE was pulled parallel to the substrate, it wouldn't budge. But when pulled straight upwards. it peeled right off. I am now looking into the possibility of increasing the surface tension of the PTFE, by passing a flame over it, and from what I had read online. In that case, scoring the surface of the PTFE might not be done, unless I scored the PTFE before the flame treatment.

I am now conducting an experiment with the PTFE and 2-part epoxy, the resin and hardener. I've found that the PTFE can be very easily scored on one side, cross-hatching it, and with an X-acto knife. I also scored a piece of plywood as the substrate. Epoxy readily grabs a hold of common plastic and wood, so I chose wood for this experiment; plastic, wood, no matter... I applied a thin layer of epoxy to both surfaces, then pressed them together. I have now set the experiment aside to cure, for at least a day. I placed a short metal rule on top of the PTFE, and a small screwdriver as the only weight to hold it down... You want to save the remainder of the epoxy, and to better discern when that between the PTFE and its substrate is cured... We shall see...

Thank you again. Yes, you always want a grease-and-oil free surface where any adhesives are concerned, paints too, and you definitely don't want to omit that in this project. For other applications, as I understand it, the surface of PTFE must be etched with a chemical compound, involving an acid I think, and then the ability to use a permanent adhesive, or a glue of sorts, presents itself. I had experimented with the PTFE and the double-sided tape a year ago or so. I could lift the PTFE straight up off the tape after applying it, with no effort, but when I pulled the PTFE parallel to the tape, it simply wouldn't budge, and I pulled with considerable force; an amazing and delightful discovery that was. For that reason, with the drawtube in place pressing tightly against the PTFE, the PTFE should never slip out, and for ever how long the tape's adhesive lasts. No matter then, just remove the old tape, clean said surfaces again, and replace the tape. Incidentally, the double-sided tape's adhesive is rather tenacious, the Scotch-brand in any event, as is that of the aluminum tape that I used. I only used the aluminum tape for its slight thickness in addition to those of the other two components. I'm thinking that there would be some cases where you would not need that extra slight thickness; this and other projects involving trial-and-error, you know.

Thank you. I do hope that this post not only helps, but also encourages others to fix theirs similarly.

I've had Synta's base-model 150mm f/5 Newtonian, an Orion-branded "StarBlast 6", since the fall of 2012. I didn't start using it much until a couple of years later. Since that time I've enjoyed it quite a bit, and eventually flocked and blackened the interior of the optical-tube. The particle-board mount that came with it had been long since abandoned, up in the attic now where it will remain until it rots, my preferring instead a tripod-type alt-azimuth for the Newtonian. There was only one thing left to do: enable the focusser's drawtube to rack in and out, smoothly, straight and true, and for an exacting collimation and the best images the parabola might produce. Until yesterday, whilst somewhat satisfactory, I did not have a focusser quite up to par. The problem all along was with these, and what I call "coffee-cake tray-liners", or for packaged cinnamon rolls, albeit of plastic instead of paper, and for the drawtube to glide against... I could actually see the wonky path the drawtube took as it was racked in and out. The rest of the telescope is somewhat first-rate, particularly the primary-mirror cell and the secondary's spider-assembly. The parabola of the primary isn't bad either, not at all, with my having witnessed snap-to focussing at high-power on at least one occasion, with slightly above-average oculars, and with a 3x barlow integrated to boot. During my initial attempts to fix the focusser, I ended up spoiling the original plastic drawtube. Then a year ago I was able to get a replacement, but only by being the original purchaser. A real stickler for that they are, Orion in California... I gave the inside of the replacement a fresh spritzing from my rattle-can of ultra-flat black, then I prepped the outside for more... ...but in satin-black. I didn't want a chromed end jutting into the light-path. That step is optional, of course, but the next is not, I daresay... PTFE, or Teflon®, sheets, and of varying thicknesses... For this step, I chose the 0.020" or 0.508mm thick sheet. The materials used: said PTFE in three 3/4" or 19.05mm wide strips, double-sided transparent tape 1/2" or 12.7mm wide, and aluminum-foil tape(perhaps 0.0025" or 0.0635mm thick, and the strips cut to the same width as the PTFE)... First, the interior of the focusser's housing was degreased with 91% rubbing-alcohol. I then applied the three strips of aluminum tape in a triad around the drawtube's cavity, then the double-sided tape, then the three strips of PTFE... Both the aluminum tape and PTFE should be degreased as well, after handling with the fingers, and before and after applying the double-sided tape, respectively. The drawtube now racks in and out smoothly, straight and true, and with no discernible slop...at long last. Incidentally, the PTFE will lift right up off the double-sided tape, easily, but pulling on it parallel to the tape exhibits the opposite effect: it will not budge in the slightest. The visual-back of my own is not 1.25", but 1.255" or so. I lined the inside with a strip of the aluminum tape, and now it's quite close to the ideal, and a snug fit for my eyepieces and other accessories... I stopped just short of extending the tape past the two holes for the locking screws, then pressed and burnished the tape down. This fix is for all imported plastic focussers of overseas manufacture, whether for a Newtonian or refractor. Would that, one day, it would not need to be so.

Yes, a 12mm Plossl is not bad, not bad at all. You may not want to go with anything shorter that a 10mm however, like an 8mm, 6mm or even a 4mm, as the eye-relief will be tighter and where you'd almost have to touch your eyeball to the field-lens of the eyepiece in order to see the full field-of-view.

That one may just screw onto the visual-back, and without having to get this, and as I had mentioned before... https://www.telescopehouse.com/accessories/meade-lx/meade-sct-thread-to-2-adapter.html You would need that adaptor, however, if you got a standard push-fit 2" diagonal. It's best to build up an eventual set of eyepieces, one or two at a time. The quality of a barlow is just as important as that of an eyepiece. Don't get the cheapest ones that you can scrounge up, but you don't have to break the Bank of England, either.

Were you able to determine that you can in fact connect a 2" diagonal to the telescope? You will need a specialised adaptor to connect one, if one is not already fitted... https://www.telescopehouse.com/accessories/meade-lx/meade-sct-thread-to-2-adapter.html The goal of upgrading to the 2" format is in realising the lowest powers with the telescope. For example, you can insert this 2" 56mm ocular for one of the lowest powers with your telescope... https://www.harrisontelescopes.co.uk/acatalog/Meade_Series_4000_56mm_Super_Plossl_Eyepiece_2_.html (36x) That's why owners of Schmidt-Cassegrains outfit them with a 2" visual-back, for the lowest powers. At the moderate-to-high powers, the 1.25" format is generally preferred. An 8mm ocular will give a power of 250x... http://www.365astronomy.com/8mm-the-planetary-uwa-eyepiece-58-degrees-1.25.html You can back off the power a bit with a 9mm... http://www.365astronomy.com/9mm-the-planetary-uwa-eyepiece-58-degrees-1.25.html (222x) ...if the atmospheric seeing will not permit 250x. Or, you can go with a 12mm... http://www.365astronomy.com/12mm-BST-Explorer-ED-Eyepiece.html (167x) The Moon and planets show considerable detail at 167x. You might wonder as to why Schmidts are not equipped with 2" visual-backs there at the factory, when they're new. The reason is simple... The hole in the center of a 200mm Schmidt's primary mirror, and through which the light from the object passes, is not 2" in diameter. It's more like 1.5", and ample for the 1.25" format. The inside of a Schmidt-Cassegrain... But given that extra 0.25" of the hole's diameter, 2" eyepieces can be used to make use of that extra bit, and for the lowest powers and the widest views that 2" oculars can provide with the design. You won't get the full view of a 2", like you would with a Newtonian or refractor, but you will get more than what a 1.25" 32mm or 40mm ocular can provide, and even lower powers in addition. It's a compromise, and simply to make a Schmidt more versatile. As a Schmidt comes from the factory, it is primarily configured for the moderate-to-high powers, and with the 1.25" format. I think that many users simply stick with the 1.25" format, aside from the more adventurous.

For the record, when observing at night, it makes no difference if the images are backward or upside-down, therefore always use a star-diagonal at night. Now, you can use an Amici at night, but the view may be narrower, in addition to seeing what is known as an "Amici line" when viewing brighter objects...