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Fo_Cuss

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About Fo_Cuss

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    Home engineering, understanding the relevant fundamentals - otherwise, pretty much everything.
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    Aude FR
  1. I understand. However, at a fundamental level, the best prospects have been achieved. I would certainly modify my baffle assembly method, for a second attempt ... but that's normal when prototyping. The most important aspect is that the scope epitomises 'the black abyss of nothingness'. Consequently, I am of high hopes that, whatever colours are presented to the lens ... these will have the best chance of being recorded. Hahaha ... probably too much blue (I'm led to believe). Anyway, we will all see, soon enough. For a project of this scale; there is no point in hiding failure, or negative outcomes. Let's hope that there are none ... though, even 'post snagging' it would not be unusual for that hope to be forlorn
  2. Yes, it is a good image of the moon Expectations for my scope performance are very high. It is now 90 f/1000, flocked, baffled, and damped at each interface. Initial confirmation testing, produced very encouraging results - remarkable focus capability, with images now in full colour. However, we will see what we will see...
  3. The scope (generic refractor 60 f/700), at that time was in fairly original format, with a few minor improvements and Omni Plossl's ... but still not at all ideal (with a poorly ground crown). I'm fairly sure that Venus was out of focus - ie. operator error. It was our first stargazing attempt, and with such a wobbly scope ... gaining focus was problematic. The moon ... it was classed by the astronomer sites as being 'unviewable', due to its proximity to the horizon (on that date and time). We had a crack at it, because it was there in plain site. Venus (if that's what it was) was even lower than the sun. Focussing, as stated, was not at all easy, but I remember that this was the best that we could get for the moon. We were happy with that, as it makes a nice enough image, even though it is lacking detail. (Hahaha ... Gimp to the rescue) At that point in time, there was no dew. We were in the twighlight zone, waiting for darkness to arrive, and for the first stars to appear. My son took a stint on the scope, and it was he that announced that he had achieved focus on Polaris ... and that it was the best that he could get. All the stars were showing diffraction rings or Airy Patterns (though we didn't know that terminology at the time). It was around this time (shortly after) that the dew hit. A remarkable drenching, on a scale that I have no recollection of experiencing before, when camping out. My best guess, is that it was not condensation that caused the Airy Pattern ... particularly now, after reading up on the subject. Overall ... this was effectively a trial run ... experiencing the madness of working in the dark, and struggling to know exactly what one is looking at (other than Polaris and the moon) We learnt a lot, in terms of actual observing, rather than talking about observing. Anyway, my scope is nearly completed - this subject will be revisited in hopefully better conditions, and certainly with ourselves benefitting from this first experience.
  4. From this consensus, it is likely to be the case that most of the gains to be had, are closest to the eyepiece. For my scope, I have gone for all out elimination of stray light, to the extent of creating a cone of flocked baffles down the tube. It is currently in an unfinished state, but I have had a scope at terrestrial objects, and found that the images are now highly colourful (as compared to being previously dull and washed out). I have found that all flocking material does reflect some light, particularly at very fine angles (skimming across the surface). Consequently, by flocking the whole tube, there will be reduced possibility for this reflected light. Further; I would examine your eyepieces. Behind the field stop ring, there may be a shiny cylinder that could prove problematic. A blacked, thin piece of card, appropriately cut to the cylinder size, can fit behind the field stop ring. This should solve that problem ... and you can't get any closer to the eyepiece than that
  5. You may be right. Sadly ... I was quoting the Wiki opening paragraph, which annoyingly takes a different view to your own. https://en.wikipedia.org/wiki/Airy_disk Let us not forget that Wiki has a long and proud history of being incorrect Either way, delving a little deeper is never a bad idea. 1. R Nave - I would suggest starting here, because the subject is explained in an extremely simple manner, referring to a diagram: He doesn't specifically state 'best focus', but rather : "that is the best that can be done with that size aperture" ... (best focus?) http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/cirapp2.html 2. Edmund Optics has their take on subject. Personally, I would have liked a couple more sentences (or tighter punctuation) ... but a re-read brings clarity https://www.edmundoptics.com/knowledge-center/application-notes/imaging/limitations-on-resolution-and-contrast-the-airy-disk/ 3. Molecular Expressions goes to town on the long, unpunctuated sentences. Here is their opener: "The three-dimensional diffraction pattern formed by a circular aperture near the focal point in a well-corrected microscope is symmetrically periodic along the axis of the microscope as well as radially around the axis." In legal documents, punctuation is frowned upon, as it can be used to elicit specific meaning from a sentence https://micro.magnet.fsu.edu/primer/java/imageformation/airydiskbasics/index.html
  6. If you can't get hold of recommended flocking material... In the meantime, you can get experimental Acquire card, or rigid plastic sheet, that will self roll to the interior of the scope. If initially, it doesn't perfectly self-roll ... you can train it, by rolling the material into a slightly smaller diameter. In this way, when it springs out, it will grip to the tube. Once you have cracked this setup phase, you can experiment by apply different materials to the transport material. Find a light to point your tube at, and look down the other end. See which materials are best at absorbing the light. When materials are scarce, you need to be innovative
  7. Ahaaa! The mystery of the rings of light, around stars, has been solved Here is Polaris (the earlier image after denoising): I was reading a paper by Roger Ceragioli, discussing how he observed Sirius B with a 145 mm refractor. In it, he described using an aperture mask, as recommended by double-star observers such as W.R. Dawes. "It alters the diffraction pattern of stars from the normal bull's-eye pattern to one in which a bright star shows the Airy disk, but with the diffraction rings mostly suppressed." Boom! Further research indicates that the diffraction rings (Airy Pattern), result from the telescope being perfectly focussed (with the Airy Disk in the centre). That was such good news. Not only because we gained confirmation of ideal focus, but it eliminated the confusion over whether this ring pattern was due to condensation dew. For those who are interested; here is the aforementioned paper: https://www.rasc.ca/sirius-b-observing-challenge-results
  8. Baffle Assembly & Testing Preparation We can cast our minds back to January, when the final roll of the Baffle Transport Mechanism was completed. The BTM had been put on the back-burner, in the hope that the lighter gauge inox sheet would offer an easy 'self roll' option. It didn't! All the effort would have had to be reproduced. Surely easier, the second time around, but even still.... The task was enormous, and the challenge hadn't changed. In fact, it was worse, because the first attempt was begun under blissfully ignorant conditions (perfect when setting out on a project). No! We have the hand rolled tube. It fits. ... and it's as good as it needs to be (so let's crack on) First task was to implement a method to retrieve the BTM from the original tube. For this I chose an extended nut, to be bonded to the BTM. First abrading both the nut and the BTM surface, before epoxying the nut in place With the BTM in position ... the joined rolling pin assembly, was inserted, in order to support the BTM while it was being drilled for the scope mounts, and lock shaft. After the usual abrasion, the scope mount nuts, and lock shaft nut, were bonded in place. The lock shaft nut was thinned, to minimise blocking of light. My advice would be to not bother with the scope mount nuts. The epoxy bonding to inox, is so poor that it is far better to modify some large self tapping screws, that will bite into both the tube and the BTM. Focal length testing I wanted to place a baffle on the 'moving' focus tube. Consequently, I needed to assemble the scope with what I had, and make a few test observations of the wind turbines. The weather wasn't great, but the results were very encouraging ... I couldn't quite read the text on the side of the turbine fairings; though it was close. The tests indicated that, with Mirror and Barlow, the focus tube had only 10mm remaining movement. Mirror alone = 25mm Barlow alone = 90mm Direct = 100mm There were some minor changes between the 12mm and 4mm eyepieces, but '10mm available movement remaining', was the max. Baffle dimension calculation From these tests, I could measure the focus tube penetration into the OTA ... and from this; calculate the baffle internal diameter. ... this based upon the available lens diameter of 90mm (from 93mm), and the focal length of the lens being 1000mm. Using this knowledge, I programmed a spreadsheet, that would enable me to generate the intersection of the cone of photons, at the desired intervals for the baffles. Underlying maths Lr/FL (90/2)/1000 = 0.045mm cone radius change per mm from the lens I was measuring from the eyepiece side of the BTM (not installed in the scope). Therefore, the scope and BTM were assembled, to gain the measuring datum edge. Baffle 1 is the baffle attached to the end of the focus tube. Baffles 2,3,4,5 are carried by the BTM. Baffle 6 is the baffle attached to the 100mm scope tube, joined in the inox adapter. Two spare calculation lines were for experimental purposes. The 'Actual Baffle Diameter' is manually entered, based upon the calculated photon cone. This to allow for a margin of error. Creating the baffles I used stock card, of a thickness that enabled laser printing. I had it, so I used it. The better route would be to buy the thickest card available. I used a glue stick, to assemble 3 layers of the formed card. The better route would be to use epoxy resin, and more layers (or much thicker card). The baffles were sprayed 3 coats of black, and 3 coats of lacquer. For experimental purposes, the baffles were oven dried. I expected some warping, and was not disappointed. The warping is inconsequential to the task ... but I would recommend using a hair drier. The baffles were offered up: The flocking was cut to size, with the backing best removed by inserting a Stanley knife blade. With the baffles flocked, and the BTM spray-blacked ... they were epoxied into the BTM at their appropriate positions. The BTM assembly was then inserted in the scope, for initial testing. This being achieved with imaging that was 'normal exposure' 'over exposure' 'extreme over exposure'. The principal being, that if photons are passing the baffles, they will be revealed by over exposing the images. Note: Stray photons were expected around the baffles, but of interest was the reflection off the internal baffle edges. These edges were then filled with Black 3.0 ... the success of which, can be judged at the end of this post. The 'end tube' baffle was cut from 4 layers. Each layer was soaked on both sides, 3 times, with lacquer. The card could absorb no more lacquer. On the 4th occasion of lacquering, the cards were assembled (bonded with lacquer). After touch drying, the baffle was wrapped in wax paper, and placed under a heavy weight (overnight) ... and subsequently flocked, and bonded to the 100mm tube. BTM Flocking Nightmare! Absolute nightmare! If I had fabricated, more robust baffles, with more card, and epoxy resin ... it would have been far simpler. But I didn't. Therefore the bonded baffles could not hold the 'spring' of the rolled BTM. This meant that I was having to constrain the 'BTM spring' with tape ... which restricted access when flocking each compartment. I knew exactly this past error ... but I was not about to stop and repeat the very long process of fabricating the baffles, and bonding them etc. They were in the BTM. I had to somehow flock the damned compartments AND cover the open length of the tube (it makes me cringe, as I remember this task). Thank goodness I had developed the 'wet application' method. I removed the backing on each side of the central strip. That strip would remain with paper, to (hopefully) self support the radius, across the open section of the BTM. Each section was wetted, as were the glue sides of the flocking. I think that the felt would likely have been easier to work with ... but they went in Final testing of the baffles The OTA was assembled, and image tested using the aforementioned exposure test: Normal Exposure Image Test Zero stray photons. Over Exposure Image Test Zero stray photons. Extreme Over Exposure Image Test Zero stray photons. VICTORY!!! The few hours that it has taken to write up this post, is nothing compared to the weeks of effort that it took to achieve this success. You might think it madness (I wouldn't argue) ... but our needs include daytime imaging, when stray light will be severely problematic. As mentioned previously ... flocking and baffling to this extent, may have little impact upon celestial observation. I'll leave that judgement to the more experienced astronomers.... However, the detailing that I've provided, should enable similar success for a small proportion of the effort that I expended. Primarily; avoid rolling the tube. Get a tube, with a slot, that has no 'spring' ... and then your work will fly. For the section flocking ... flock each section with a single piece, and flock the entire length of a 0.1mm sheet, to be inserted in the gap, over the stronger epoxied baffles. Hahaha! Learn from my prototype. That's what prototypes are for I'll leave you, staring into the black abyss of nothingness (nice!)
  9. Flocking like a pro ... before getting baffled Stray light absorption I tried Black 3.0 on the inside of the scope tube. The problem is that it doesn't perform that well with 'low angle' glancing light. Rather than being absorbed, the photons merely bounce off the surface. It is excellent for small difficult areas (so it is definitely worth having, and using). However, for the tube section; material flocking will absorb a greater proportion of the photons. Having said that; the 'bouncing bomb effect' still persists... Hence, for those who are wanting to create a scope to the level of a scientific instrument, there is a need for baffles (to stop the light dead in its tracks). We are going down the 'hyper-scope' route ... vibration free, and the 'black abyss of nothingness' Consequently, the die is cast, for us. ... but from reading the many pages of SGL, I reckon that for most users; a straightforward flocking of the scope, will be sufficient. Below, is my take, on this task.... Flocking Material I went with the material recommended by johninderby. Veloursfolie made in Holland, and retailed by https://www.firstlightoptics.com/misc/black-velour-telescope-flocking-material.html fozzybear recommended felt: https://www.feutrine-express.fr/product/Feutrine-metre-adhesive-Noir-0148#content I had to choose one, so I took pot luck, and went with the first recommendation. Points to consider when purchasing flocking (lessons learned) Photon absorption efficacy Lint stability Sticky backed Thickness How it is rolled The veloursfolie achieves the first three objectives. Fozzybear would not have recommended the felt, if it lacked efficacy and stability (and it's sticky backed) Therefore, the key questions are 'thickness' and 'roll method'. Thickness If fozzybear is reading this, he might gently run a vernier over the felt. The felt is spec'd at 1mm thick. The veloursfolie is 0.5mm thick. For me, this small thickness was useful, because in certain areas, I was tight for space. However, my guess is that the extra thickness of the felt would pay dividends, in terms of supporting its own radius ... something that I would have benefited from (as will be outlined later) The felt will also provide superior insulation, and better moisture absorption. Therefore, if the budget runs to it ... both variants will be worth purchasing. Roll Method From a flocking perspective, the French win this hands down. The felt is rolled internally. The veloursfolie is rolled externally (the opposite of what is required). This means that the veloursfolie must be bought in advance, hung, heat treated, re-rolled, heat treated, and left in a sewage pipe (preferably without sewage) Here is what it looks like when it was simply re-rolled, and heat treated (hair drier) in a sewage pipe. Clearly, when the rolling is reversed, the material is larger than the paper backing, so it must ripple. Hence why I realised that it is probably better to let it first hang flat, using a hair drier to aid the movement of the bonding material. ... then roll it into a tube, and again blow hot air through it. By my estimation; this will reduce the rippling. Another (superior) method might be to use a warm iron (and some paper for glide and insulation), with the velour on a table. This would squeeze the velour across its backing ... then re-roll it in a tube, and use the hair drier. This re-working of the velour, will cause it to be bigger than the backing paper. Trim off the excess, or make sure that you measure to the velour not the paper. YouTube Flocking application First watch a few YouTube videos of people attempting to flock their scopes. They invariably recommend cutting the material into strips ... yet they still manage to plunge themselves into an impossible mess. The reason is because they attempt to apply the sticky material 'dry' Of course, the material is floppy, it touches the surface, it sticks, it's pulled off, it stretches. It's a nightmare. Don't do it this way! Flocking application - the pro method If the tube to be flocked, is too small to get your hand and arm in... Find a tube, smaller in diameter to the tube to be flocked (a rolling pin maybe) ... or a cut off length of broom handle ... or something that can reach at least half way down the tube (for access from both sides). ... something that might be needed to apply pressure to the flocking material. Take a spray bottle - say, one used for household surfaces. Fill it with water. Add a few drops of washing up liquid (not much). This will prevent surface tension in the water. IE. It will prevent globulation, and allow the water to 'wet' any surface. Test the solution on an offcut of the flocking material, to confirm that the glue becomes fully wet ... adjust the detergent accordingly. Measure the internal bore of the tube to be flocked, and subtract 2 x the thickness of the material ... to gain the correct internal circumference of the flocked tube. Mark off, and cut the entire section - circumference by length (a guillotine is ideal for this). Degrease the bore, and repeatedly mop it with the mild detergent solution. If it is a hot day, then cool the tube, or leave it soaking in a tub of water. The bore surface should be damp. IE. It should be wettable. If the water just glides off the surface, then wash it first with a strong soapy solution ... rinse, and apply your spray. Remove the paper backing off the material in stages, wetting it as you go (so that it doesn't stick to your fingers). If the water is gliding off the sticky glue ... gently rub the solution across the glue surface. Check the tube, to confirm dampness ... give it another spray & mop, if required. With the glue fully wetted, roll the material into a small diameter, and drop it in the tube. Lay the tube horizontal, with the material joint at the top. If needed ... manipulate the material edges, so that they lock together. Rotate the tube so that the material joint is at the bottom. Most of the water will be forced out by the material forming its circumference. Any bumps will contain water. Squeeze them out, using your hand, or your predetermined tool. Heat the tube internally and externally with a hair drier, until you are fed up with the task. Job done! ... and it's way quicker than the time it took to write this explanation. ... and you will have a perfectly flocked tube. ... and it is a stress free task (always appreciated). Here is what it should look like, after flocking: Very nice
  10. OTA Assembly Three pairs of clearance holes were drilled, equidistant around the 60mm - 100mm adapter. The surface around these holes was severely abraded, using a grinder and emery cloth. Six nuts were to be bonded over the holes, so each was also roughed up. Six screws were wrapped in cling-film, prior to the nuts being assembled over the cling-film. In pairs, two part epoxy was rubbed into the abraded surfaces of the adapter and nuts ... enabling the nuts to be bonded to the adapter. When each pair of nuts was sufficiently cured, the screws were extracted (leaving the cling-film in place, for later removal). Once all six nuts were fully cured, the scope was assembled for collimation testing. As can be seen from the image ... collimation was achieved. Here is the first image of the fully assembled scope with lens OTA Bonding I didn't think this through! Conical set screws had been purchased Six small location holes were drilled into the 60mm tube. The intention being to adjust the scope, as per the hex screw setup. What a stupid concept! Of course the conical screws locked into the holes, and full adjustment was impossible. I should have also acquired dome headed set crews, or set screws with a ball bearing at the tip. One location hole should have been drilled (to provide a pivot anchor) ... allowing the positioning set screws to float into their appropriate positions. Instead, I had to mess around (for ages) slotting the holes with a jewellers file, until the OTA achieved collimation. Note: The original steel baffle from the scope tube, was placed at the tube end, to prevent deformation of the tube circumference It wasn't great whilst doing it, but at least there was the benefit of six set screws penetrating the adapter. IE. it was well locked to the tube. For the bonding, I had a new tub of extra strong body filler called metal repair (Répare Métal by Sintofer). Very smooth paste, without fibre glass strands (armoured). If you intend to carry out a similar mod ... don't use armoured filler. It is very important to use a very smooth paste, as it must be rapidly squeezed into a tight gap. To carry out this task; the applicator edge was formed into an arc, to match the tube circumference. This was achieved using a sharp knife, by scraping the knife across the plastic. Sections of wood were clamped to the bench, and 20mm of packing was placed under the scope tube. The wood, running parallel with the tube, allowed the tube and adapter to be rotated, without it slipping all over the place. The packing ensured that this rotation did not stress the adapter. I then repeatedly practiced the action, in order to get my hands accustomed to the movements, and the turning of the scope. If you have ever used filler, you will know that the clock starts ticking, the moment that the hardener is mixed. ... it's highly stressful - particularly because the paste must penetrate sufficiently into the gap, around the entire circumference. This to prevent warping, as the filler sets. Without the practice trial runs, I doubt that I could have done it. As the final gap was being filled, the paste began to stiffen. I got the job done, with zero time to spare Once set; I checked the collimation ... and with huge relief, discovered it to be true (the relief IS palpable as I write this account). The gap from the 100mm side, was then filled. Apart from some cleaning off ... the job was done. The heart of the new OTA was permanently assembled
  11. Pan Handle Hahaha! What else do I call it? The scope pans and tilts, and ideally needs a handle for both operations. This one deals with the panning operation, so ... it's the 'pan handle' Sourcing the material One really needs a recycling centre that allows exchange. Bring something in, and take something out (for repurposing). This 'life balance' pays dividends (is it a game?) It has got to the stage, where I now expect my needs to be fulfilled. There was a beautiful 'big' piece of angle iron in the centre of the skip. It was there just to tempt me. I knowingly refused the option ... and as I moved to the other end of the skip, a lorry backed up and covered the angle iron (closing the option) ... however, I had made the right choice. At the other end of the skip were two lengths of machined stainless steel bar ... radius ends, with the most perfect chamfered slot (at the end) that you could ever hope to see. I could already envisage 'chamfered screw heads', locking the bar to the azimuth mount. Inox Bar It needed some work, to form it to purpose. Annoyingly, I didn't get a pic of it first. It had a right angled bend at the opposite end to the chamfered slot, but at that end, there were two holes for attaching a wooden handle. Applying heat to the bend, I straightened it out, to leave a kink (for strength). In order to position the handle for ergonomic use, the bar needed bending out (away from the scope) ... then bending in (further down the bar), to bring it to where the hand would fall (when operating the scope). These two bends were applied cold, in order to work harden the steel, and reduce flexing. The image below, gives you an idea of the steel, with straightened kink at bottom right ... and the two positioning bends that were made: This next image, provides a better 'top down view' of my chosen angles, and a better view of the kink: Next, you can see the chamfered slot 'to die for', and the visible reminder of the fact, that the steel was bent in a vice (a job for my peening machine, if I can get around to it) Here is the bar, fixed to the azimuth mount. I simply scribed the slot, centre punched, and drilled two clearance holes. Also note the first glimpse of the blacked and laquered azimuth mount (with the sultry pivot plates looking sooo nice): Here it is mounted: Making the wooden handle I knew that I had a piece of an old wooden handle. Perseverence paid off ... I unearthed it. Now it needed slotting ... but how? The little known fact amongst the general public, is that hacksaws are designed to hold multiple hacksaw blades ... typically 5 or 6 can be fitted at a push. I needed just 4 blades, to do the job: Sure, they are normally for slotting steel, but they will also slot wood: A perfect fit, requiring a 'tap in': The holes already present in the steel, were marked off on the wood, and then drilled. The freshly cut wood was stained, and the whole handle was given a stained wax treatment ... to end up looking magnificent: Yes, I know that I can tidy the edge, and maybe even fill the slot (though I doubt that I will). The plain fact is, that you can hear the old wood screaming out ... YES! ... A purpose in life AGAIN! ... and the steel saying "I'm with you there, mate" Hahaha! An engineer should have empathy with the materials that he uses
  12. Tilt Damping Washers & The (perfect) Spindle Bearing Tilt Damping Washers Easily and quickly made, once the leather has been staked out. A new blade in the Stanley knife, is best for tough hide. Then a hole punch to suit the clamp screws. The (perfect) Spindle Bearing This requires PTFE sheet - 0.4mm should be ideal, assuming the sloppy play in these bearings is universal. Determine the bearing circumference, and height. Cut the strip of PTFE short in circumference, by 2mm ... and short in height by 4mm. Wrap the PTFE inside the bearing tube (tripod head), centrally positioned, with the gap between two clamp screw holes. Using silicone spray, coat the azimuth mount spindle. With the leather damping washer fitted ... insert the spindle into the bearing tube. Simultaneously, press & rotate the components together (with force). You should see a gap between the leather washer face, and the bearing face. (if not, you will need a thicker sheet of PTFE) The objective, is to force the spindle home, compressing and stretching the PTFE. Initially, manually rotate & press repeatedly. ... you will make good progress. This is due the bearing being formed to the uneven surfaces ... necessary, to facilitate the next phase. Grab a copper & hide hammer. A No. 2 size will be ideal for the task ... not overly heavy, and therefore easy to control. Place the flat underside of the tripod head, onto the anvil of the vice. Using the hide face of the hammer, with minimal force, strike the base of the U bracket (azimuth mount). You will have to get a feel for the force that you use. Hit it too hard, and you won't be able to rotate the azimuth mount. Wedge the tripod head in the vice, and rotate the azimuth mount. ... repeat a couple of times, before separating the pieces. Examine the PTFE bearing (shell), in situ. In places, the circumference may be close to joining. Expect it to be uneven due to the uneven metal surfaces. Note the position of the PTFE shell. Before the next pressing, it should be refitted with the gap between the clamp screw holes (the same position each time). Clean off any metal residues. If the shell circumference has become joined, before the spindle is fully home ... with sharp scissors, snip a mm strip from the circumference. This will allow more expansion space. Clean the spindle, respray with silicone, and assemble for the next round of 'tap n turn' Continue in this manner, until the spindle & leather washer finds home. At close of play, the PTFE shell may be fully joined, though this is not critical, as the shell will not rotate in the tube. It may look something like this: When complete... In the lteral sense of the word; you will have created the perfect azimuth mount bearing The list of benefits is impressive: Rotational accuracy Exceptional stability (due to bearing interface height) Smooth 'friction rotation' Resonance flow barrier (zero metal contact) No 'lock movement' after locating the object to be viewed ... and in so doing; solved one of the major blights of telescope users the world over
  13. Horizontal Azimuth Damping Pan Gauge Two extra spindle clamps Horizontal Azimuth Damping Do you remember those old leather boots that you threw in the back of a cupboard? ... it's payback time Top right ... you can see where the leather was removed. This is strong hide leather, 2mm thick. While you are at it, remove the tongues ... they are 1mm thick. The leather appears to be in an unusable condition ... but this all changes, when washed and scrubbed in warm water. Stretch the leather pieces out on tenta-hooks (or cable clips ) Leave them a day, to dry out. Locate an appropriate flat drill bit, to cut the internal diameter of the damping washer. Cut so far, and finish with a very sharp knife ... and gain a spare leather washer, to be stored for future projects Cut off the piece, leaving more than sufficient width for the washer. Then thin (if required) using a bench mounted angle grinder. Fit the damping washer to the spindle, and grease. Press the azimuth mount into the tripod head, rotating the mount. Trim the corners, ensuring that the leather damping washer is projecting out, when assembled. This additional width will provide support for the washer, and prevent it from being squeezed apart, when in use. The leather damping washer provides the ideal material for resonance isolation between the scope and the tripod ... and excellent friction control for panning the scope Pan Gauge Buy a brass drawing compass off eBay (for a couple of euros). Install in your pedestal drill, a boring tool to match the outside diameter of the tripod head bearing. With three screws, attach the brass compass to an appropriate piece of wood - grinding off the screw points (if required). Mark off the drill centre (for the arbour), or use your best judgement. Adjust the drill speed to low ... and cut an arc into the brass compass. Offer up the piece to the tripod head ... and clean up, to fit. Then bond the gauge to the left, or right of the tripod head (when the tripod is set to the user position - typically with one leg forward). Buy an appropriate sized pipe clamp, which has a threaded attachment element The thickness, or band width, must be reduced equally (on either side of the attachment element), in order for it to fit the available space of the azimuth mount 'spindle shoulder'. Locate a bolt that will fit through the attachment element. Using a bench mounted angle grinder, and a bench grinding wheel... Undercut the hex head, converting it into a chamfered head ... that will fit in the pipe clamp, without interfering with the internal diameter. Flat the bolt threads, and drill a hole to match any stiff rod available (typically a cleaned up welding rod). Using a vice and hammer ... put a 90 degree bend in the rod. Assemble all pieces. Set the height of the rod ... and bond the rod to the bolt, as required (prior to cutting off any excess). Dissasemble, and degrease the compass. With rags to hand ... spray the visible compass surface black; and immediately wipe off the paint. A hair drier will speed initial drying, allowing a second coat to be applied almost immediately, before again, wiping off the paint. ... this to provide contrast for the gauge markings. Note : Out of chronological order.... Add two extra spindle clamp threads Before all the above ... mark and drill two equidistant tapping holes ... tapping the holes to suit the additional thumbscrews. Punch a similar sized diameter from a sheet of PTFE. These round pieces are to allow the spindle bearing to be clamped, without damage ... all as seen assembled in the above image (that shows the blacked brass compass). Nearly there, with the azimuth mount. Just the main spindle bearing, the tilt damping washers, and a lick of paint....
  14. The Azimuth Mount - Created Anew ! Someone is watching over me It must be the case, because I fell upon some beautifully soft, box section mild steel. Oh ... I needed it, as I was going to use angle iron (which is a different beast altogether). Just thinking about it, makes me thankful. I could cut it like butter with a hacksaw, or jig saw. Here it is being cut, after marking out : The plates cut, drilled, and formed : What's the formed curve for ? Hahaha! A moment of madness, when I thought " c'mon ... add some form over function " I accept that I am useless at pointless design. For me, the function provides the beauty (but anyway, I added a curve) How was the hole drilled ? This is an engineers technique worth knowing. The hole obviously had to be drilled in the exact position, to match the hole already drilled in the azimuth mount. The hole was scribed, and the drill hole was repositioned PRIOR TO FULL DIAMETER PENETRATION. A centre punch was used to impact a hole into the edge of the initial chamfer, to cause the drill bit 'to walk' in the direction of the centre mark. (If it's a long way out, you can impact a slot in the chamfer wall) In this way, the hole was positioned perfectly. Azimuth mount plates bonded : I allowed the plates to slightly ride on the epoxy bed. I could have adjusted the edge, but the shoulder provided additional bonding support, so it was left as is. Making Parallel : With the plates added, I needed to bring the faces parallel. Understand, that if attempting this mod; the area with the least metal will be cut the most. Therefore, the open end of the mount (to the right), had more metal removed. Hence it was blacked with a permenant marker. The dark band visible at around 9:30 O'clock was the high point. I got it parallel to within 0.2mm across the 45mm diameter... good enough, as more work was to be done. (and a very slight twist of the thumb screws would lock it parallel) Horizontal Pivot Plates Marked out & drilled These were made out of 1mm 304 inox. First marked out, and drilled using Rocol RTD cutting fluid : They were then cut with a jigsaw. Note how the plate was well clamped. Cutting with a jigsaw was a nightmare, as at 45mm diameter, the curve is too tight for the width of the saw blade. You need to arc past the tangent, then nibble a gap, to allow the blade to turn in. (or cut hexagonal, and trim later) Rocol RTD cutting fluid again used. Here is how they look, before and after initial trimming : Here they are, after final trimming, and 'hand ground' flat : ... and being bonded : Support screws were then ground : ... and bonded in place : Metal repair filler was then applied This was carried out in four phases, building the filler gradually : 3rd Filler Phase : 4th Filler Phase Note how the filler was piled higher than need be. This is necessary, to ensure that the final cutting can be accomplished. Here are two images of the completed azimuth mount reinforced pivot plates : Final Measurement This was always going to be of concern, due to shrinkage of both the bonding and the filler. ... and with baited breat, I measured. Phew! 0.2mm difference between the bottom and top of the plates. Ideal for full lock, when using the thumb screws, while offering excellent friction for controlled movement of the scope. Wow! What a journey that was. AND they look great ... hahaha ... form AND function
  15. A daft error - Misaligned lock shaft clamp So there I am, examining, and thinking about the azimuth mount (what a heap of....) I'm actually considering how best to reinforce the slanted 'U'. With the scope being extended, there will be an increased 'twisting' force, centered just above the lock-shaft clamp. The primary force will be along the scope clamp centre line ... but this will passed to the legs of the 'U' ... finding the weakest point, which is the horizontal centre line of the legs. Obviously, the rigidity of these legs must be increased ... but we have the pathetic screw length ... which leaves very little room for increasing the thickness of the leg. (this is really annoying) Consequently; I was looking at this in detail, and considering adding the 1mm sheet inox, to both sides ... and doing away with the washers. Nice idea! When I suddenly realise, that the lock shaft is 'sticking out' at a bizarre angle. How? How did I not see this earlier, when modding the clamp bracket? ( tunnel vision, I'll wager ) To get a visualisation of the error, I used my 'P' drill. It's shameful. My 'P' dill bit is around 45 years old ... very high quality Yet I've allowed rust to gather on it's surface. Embarrassing. It will be treated with phosphoric acid (and be born again) Realignment (sans milling machine) There's always the 'side of the drill bit' method. ... only the alignment is a long way out; beyond a bit of tickling. It had to be a grinding bit. Ahaa ... I had one. 8mm dome head, but wildly innacurately bonded to it's shaft. ... though easily dressed. With the cylinder perpendicular in the vice ... the 'clamped to' side was releaved of it's erroneous slant. What a load of messing around, to repair a production error that may even have been produced purposefully (to avoid the need for spacers at the scope tube end). Anyway ... it's done now
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