Rusted

I'm thinking any wear on the worm tips is probably self repairing. It will bed in before the wheel teeth ever wear out. This morning I drilled more holes, well spaced apart, in the motor housing bases. Then I sandwiched tiny O-rings [over the fixing bolts] between the motor housings and their support plates. I had instant Fullerscopes MkIV adjustability without the tears. The motors ran remarkably quietly too. These new fangled "wheels" I've just invented are great!

Not quite what I had in mind, M'lud. I was looking at "torsion" bushes. Not squashed tap washers. You are quite right, of course, Sir. I was seriously overthinking the problem. The rubber bushes have no need to be individually restrained. The worm/motor housing can be restrained externally.

I have a new idea! The linear movement required to maintain mesh between a worm and its wheel is really rather small. So why not use rubber bushes expanded into metal tubes as "hinges?" Just like a car engine mounting or skateboard truck. Massive restraint against lateral movement but with just enough compliance to achieve their intended purpose. No need for bonding the rubber to the metal like the heavy duty, commercial vehicle devices. Using cones, or cupped washers, on both sides of the rubber bushes will stiffen them while providing easy adjustability. External, screwed stops might still prove useful. Now tell me I have just reinvented the wheel.

The Beacon Hill wheels have 287 "teeth". That is most definitely on the coarse side of things so tooth breakage is highly unlikely. The thickness of the "teeth" is considerable in comparison with higher tooth counts. I am seeing brightness on the crests of the DEC worm "thread." Suggesting that it is bottoming in its wheel. Ironically, the DEC worm and wheel set were vastly better quality than the RA. The latter was very rough and the worm distinctly eccentric. The roughness of the wheel machining and cyclic changes in "graunching" with worm rotation were readily audible during slews. Hence the attempt at lapping the worm with the wheel. Based on a couple of hours work it would have taken many hundreds of hours to achieve much change using metal polish. Most of the wear would have gone into the brass worm. The wheel having far more circumference and active surface area than the worm. The next stage will be adding external restraint for the entire motor assembly. As the worm acts on a tangent, to the wormwheel, any longitudinal movement must be strongly resisted. If there is any movement it will be exhibited directly as backlash. The most obvious ploy would be adding angle profile to the large, 10mm thick motor support plate. These angle profiles will be provided with adjustable stops. Ideally these stops should be placed close to the ends of the worm. Where maximum longitudinal force is applied. I have collected several [scrap] aluminium box and angle sections which have been looking for a useful purpose. The largest box section is 100mmx200mmx6mm thickness or 4"x8"x 1/4"! So I can produce any L-profile I am likely to need. I may even be able to contain the entire motor/worm assemblies with a compete box section for greatest stiffness.

Thanks for the continuing feedback. I've been in the workshop adding angle profile, mutual reinforcement to the RA motor and worm housing. Still experimental but I'm making progress: Even added a crude, push-off screw adjuster. I'll be back.

Enjoy! You'll soon find out if you can focus inwards enough to get a sharp image.

Thanks Huw. It must be an age thing but I'd completely forgotten about your thread. Some really good ideas in there. Looking again at your mount and mods I realise that my worm mountings are seriously "undernourished." I also realise that my guiding technique is using top gear [of 3] on the AWR paddle just to overcome the backlash. I'd have to wait for [literally] minutes for the lower guiding speeds to have any visible effect. It's time to get serious about worm containment, hinging and support! Thanks for all the feedback chaps.

Thanks again Peter. How many Chinese mountings would I need to buy to get enough "gloop" for a pair of wormwheels? It might still be cheaper than one supplier who wanted 825 Euros for a tin of 'Kilopoise! I could start a market for scavenged "gloop" from belt drive modifiers and upgraders. I'll have see what is available over here. A lorry repair workshop who might have something useful. Just aim for the stickiest stuff they have? I'll take a teaspoon and a jam jar and throw myself on their mercy. I'm afraid eccentricity is strictly in the eye of the beholder if you buy a commercial pair of the "finest available" wormwheels in the UK.

Thanks Andrew. I wish! BUT, I'd need welding goggles if I had that much 'bling' in a solar observatory. The telescope making gods are against direct purchase from the USA. Freight + import taxes, customs clearance and 25% VAT could easily make the US retail price look [almost] cheap.

No, the complete opposite. You need more inward travel because the wedge eats up your focal length.

Thanks Peter. No, I haven't tried using screw stops. I keep adjusting what I have but it is never the same twice and never for very long. I'm using white grease as a worm lubricant. I have no idea if this is low friction or whether there is something better out there. Lower friction would allow greater spring pressure. When the worm is deep into the wheel the friction surface area must rise accordingly. Worms, in theory, aren't supposed to be in full contact with their wheel. So an adjustable stop would make good sense. I tried lapping the worms against the wheels, when new, but all it did was reduce the graunching sound.

Thanks Alan. I've tried the constantly climbing eastern bias to no great effect. When you are trying to capture solar close-ups with over 3m of focal length you need full and instant control in all four directions. The slightest backlash and you have lag and then overshoot. The length and moment of the refractors seriously exacerbates the problem. Any mounting can carry a huge weight quite effortlessly but they just can't control it.

Thanks Dave. But wouldn't doubling the spring be the equivalent of one stronger spring? I have tried a variety of springs but despite the 287:1 advantage and the huge radius the motors don't like strong springs.

Hi, How do you eliminate backlash in your drives when routinely using several meters of equivalent focal length? I have enough eccentricity in my 11" and 8" worms and wheels to cause tight and loose spots with rigid worm housings. But I want the exact opposite. Stiff against unwanted motion but perfectly free to turn. I have tried pivoting the worm housings with various tension springs. You'd think it was the perfect answer, but it isn't. Not so far. With the moment of my long refractors there is still far too much backlash. Add too much spring tension and it just stalls the big, 210 stepper motors. Push-off screws would surely just short circuit the springs? With all the experience out there I badly need a fast track fix. Other than burning well over £10k on a commercial mounting. 😱 Thanks for your time.

I have both the 2" Lacerta and the 1.25" Lunt. I have grown to totally dislike the Lacerta for its Brewster Angle for visual use. Though it has worked fine with my ZWO cameras in my 7" f12 refractor. The 1.25" Lunt is a very recent purchase and used in my 90mm f11 Vixen achromat. I much prefer the Lunt to Baader foil and have the 1.25" Continuum filter permanently fitted. There just seems to be an extra degree of crispness to the image over [admittedly ageing] foil. The wedges use up focal length if that is an issue. Or even a benefit? Wedges are compact and easily stored compared with fragile foil. I tended to use rather bulky food containers for my home made foil filters. Only you can decide if the considerable cost of a wedge is acceptable to you. Do not expect a <cough> night and day improvement in image quality. It feels nicely "traditional" to use a wedge after all this time. More "serious solar observer," if you like. It was something I could never afford when I used eyepiece projection decades ago. Baader foil was truly magical when I first tried it years ago now. I used it for afocal "snapping" several transits and eclipses with handheld, compact, digital cameras.

Congratulations Nigella! A very worthy SC POD. I found that specialisation was a fast track route to improving my own solar images. And, abject poverty if I tried to compete at the highest level. Though you certainly don't need to spend a fortune if you take the self-build, modification and secondhand route. Nor will you ever be sneered at for doing so. Results, in the form of new and better images, or new ideas, are what count. The advantage of SC is its incredible knowledge base and ready willingness to share every detail. The feeling is a cooperative desire for constant improvement via capture, processing and equipment choice. Ideas are tried and exchanged for modification and trying new ways of using unlikely combinations of tools. Such an environment provides a solid base for specialist equipment manufacturers to invest in R&D and production. Knowing that their highly specialised wares will find a ready, if relatively small, market. Where their equipment, or software, will be pushed beyond their wildest hopes by those best able to do so. Producing images which might easily be mistaken for professional results. This is the unique advantage of pushing the envelope by such a varied band of clever, inventive and dedicated individuals. There is now a move towards using larger apertures, like SCTs, to produce quite incredible surface detail. Nobody is poached from the more generalised forums. Nobody is hooded and dragged away screaming for their mums! When you discover that your own results are steadily improving, you will still find a ready audience here, for your latest images. Probably leading to investment in more specialised equipment, or accessories, by the familiar, forum members. You can start solar imaging with any "normal" astro refractor. Just by adding well proven and SAFE filters or accessories. You dip your toes and are excited by your results? Then what? It is your choice in how far you want to climb the path to producing stunning images like Nigella's.

It is possible that these smaller FF focusers are only intended to be rotated and then locked in place with the screws provided. Both my 2.5" and 3.5" FF focusers rotate freely and securely but without any play. They are cleverly designed to do so. I can clearly see a location groove in the images the OP provided. If this is just a matter of three screws having worked loose in the post, or were never tightened properly, then no "repair" is needed. It just needs to be re-assembled correctly. Though I would certainly email FF and Lunt for their expert advice. And, as a formal notification of the problems the OP has experienced. One even wonders whether customs have "fiddled with it" en-route?

To repeat the earlier warnings on electricity: You have live mains terminals on your "naked" PSU. Which is specifically designed to be fully encased for user and public safety. It is fitted in a dark and damp environment. You put your hand out when the lights suddenly go out and .... 🎇 You become just another, sad statistic. After a few days somebody comes to see what the awful smell is. They touch your live, dead body... and .... 🎇 They become just another sad statistic. Then somebody else comes to see what the awful smell is and they touch both your live, dead bodies... 🎇 Can you see where this is going? 🔌

Thanks. I like the "industrial" look. It avoids having to obtain and maintain a very high quality finish. Commercial instruments must be pretty to seem like they offer real value for money. Cosmetic perfection means high wastage or highly skilled workers. I do not have that need. Function before appearance every time. My main tubes are secondhand, galvanized steel, extractor ducting from a furniture factory. The lack of the usual spiral seam avoids dust collection potentially leading to a fire. They are incredibly stiff but thin. About 0.3mm from memory. Making them easy to drill but they offer no material thickness to take a screw thread. So it's a lot of arm stretching to reach nuts inside the tube! Which means baffles won't slide! Provided I align the single, longitudinal seam with the tube ring hinges these tubes are fine. They are certainly no heavier than any other normal tube material and cost me only small change. I was surprised to discover how little variation there was in main tube weight with material choice. CF is not lighter unless it is made as a foam sandwich with light weight in mind. Seamless aluminium would need to be much thicker for the same stiffness. Rolled and seamed aluminium not stiff enough without serious reinforcement. PVC ducting is a heavy and rather flexible material. Particularly as it warms. PVC drainpipe is worse on both counts. The lightest refractor tube I ever made was thin, aircraft birch ply. 5" f/15. Which was wrapped and laminated around, thin structural, plywood baffles. That was decades ago and I used Cascamite glue and cut down, inner tube, "rubber bands." Today I would use epoxy and ratchet straps. This was the 5" on an experimental, plywood equatorial. Far too much friction despite the PTFE and Formica.

Thanks. I always use Cropped. Expand seemed to do weird things.

From the OP's images I had assumed these were simple locking screws. Unfortunately they have reversed the focuser in their images. One can just see the white main tube beneath the focuser. Now I think these screws are to retain the focuser as it rotates. They project into the groove in the base of the focuser. It may be these which came undone in the post. Allowing separation of the components. The image you have just posted is a private replacement for a worn helical. It is not quite the same as images of the DS50 online.

Let me repeat that I found Starlight to be very responsive in their communications. So I would wait until FF has answered a first enquiry email just to get things moving ASAP. Lunt, or their dealer is, of course, legally responsible for repairs or replacement. Though this sounds as if it would be a rather slow process. While our OP is obviously keen to use their nice new telescope.

Sorry Nigella, but I was specifically advised NOT to dismantle my first FF by Starlight. There is a procedure for getting the friction just right. Starlight will be happy to advise by email.

The tiny screws are there to lock the focuser securely in place after it has been screwed into its main tube adapter. If you didn't have these screws tightened gently, the focuser would unscrew if you rotated it anticlockwise. FF focusers are designed to rotate smoothly in either direction. All FF focusers have dedicated main tube adapters to allow this rotation by design. Starlight Instruments use highly skilled staff to set up the degree of friction on the drawtube. As Peter says, contact Lunt for further advice. Or, email Starlight Instruments for specific advice. They are very customer friendly in my own experience.

Thanks for your interest. It was a desperate attempt to make a very long scope light and manageable. The beam was made up of heavy channel sections [alu.] holding builder's straight edges. Unfortunately the design was almost completely unusable on an equatorial mounting. The mass of the full thickness, 10" f/8 mirror was seriously offset from the twinned beam. So it applied heavy torque to the beam when not physically "upright." i.e. Not pointing to the Pole as in the posed picture. The mirror cell twisted visibly on the beam as soon as it was leaned to either side. It was awful to handle because the mirror cell always wanted to be hanging downwards. So I had to give up despite my best efforts to stiffen the design with extra brackets. I have tried several new tube designs but each lacked stiffness. Or were far too bulky and too heavy. I had no interest in mounting it as an altazimuth. The image shows some rough mock-ups of potential new tubes for scale. I have a steel duct 30cm [12"] in diameter x 6'6" [2m] long but the bulk and weight makes it too unwieldy. Yet ironically it weighs much the same as all the other materials I tried. Over 20lbs for the bare tube. I laminated the cardboard tube from thinner and shorter concrete piling forms. It was heavy and hopelessly flexible. Another dead end. The completed OTA has to fit up between the rafters of my shed as it stands on its mirror cell. It was just too much of a struggle to make it worth the effort. Ideally such a long OTA needs to be housed in a dome or roll-off. So it never needs carrying in and out by a [fit] septuagenarian.