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wayne weedon

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Everything posted by wayne weedon

  1. Likewise with the Osborne 1 I had. Damn things are very collectable now. BUT I am sort of glad they are gone. They took up a lot of room even in the attic. When we last moved I had to make some tough decisons! I recall the two Xerox 820's I had with 8" SASI hardrives (I was a cp/m junkie for a while!). They took some lugging to the tip! Anyway back to the subject, I guess in a way our current and 1st telescope as purchased on evilbay could of easily been car boot stock a few years ago. Its a 1999 Orion Europa 150 f5, apparently according to Orion one of the very first ones. Wayne...
  2. The largest diameter that can fit I would try. I would recomend two really so you can get a little preload on them (both sides of base). Like I said earlier they are low tech and not aimed at astro applications at all. But a large precision thrust bearing is big money! The round ones go to about 12" diameter I think. What size is your base? What is the current bearing setup? Wayne...
  3. So did I! ...and just before, my 1st experience with computers was building a UK101 (6502 based) in 1979, and that was when my geek period started! I stopped being a hacker (used in the original positive meaning BTW) in about the mid 90's. I however can sometimes still be caught dabblling with the odd Microcontroller when the mood takes me. But I missed those days in a way. It was possible to do so much with so little and the hardware was so accessable. All the old stuff bar a couple machines with sentimental value are long gone, mostly to the local tip before that became a beurocratic nightmare! Wayne.....
  4. Around here (East Dorset)the Eastern Europeans seem to have taken over the Boot Sales. But I feel ebay has sometimes become the new boot sale, even though I trade on there I also use it for purchases and also disposing of more specialised personal items. I used to collect old 80's Computers and bootsales were the place to find them. They are no doubt more viable to sell via ebay now though. Wayne....
  5. A link for you Lazy Susan Bearing : Buy Lazy Susan Bearing at Axminster Power Tool Centre Wayne...
  6. You can buy large diameter "lazy Susan"/"dumb waiter" bearings from Axminster Power Tools. These are of a very commercial pressed steel quality though as they are intended for a very low tech application. But are certainly low enough friction. Wayne...
  7. Well there you go! It can work. Had to google Paramount ME to see what you had though. Nice design. Wayne....
  8. Hi Not sure what the JEM in that number refers to. But 2RS just means two rubber seals. 6008 is a stock bearing. Other common bearing designations are ZZ which means 2 x metal Shields, where Z means one. Why did you go for Ceramic bearings? Normally their use is for high speed applications like turbines and some machine spindles. If you want accuracy opt for the highest ABEC number you can afford. This additional designation covers aspects such as Radial Runout. Wayne....
  9. Some old "big" printers had some good drives in them! I broke up an big old A0 width pen plotter once just to dispose of it as scrap. It used Brushed DC Servo's with 1000 line encoders which kind of surprised me. Wayne....
  10. A link discussing direct drive. I would imagine he's running a position loop.
  11. Olly Antibacklash gears as you describe are off the shelf items, you can also get the same in worm wheels. Toothed belts of the short lengths we would be talking about are really not that stretchy believe me! But in my case I would propose still using the existing worm drive in my mount initially for my RA drive requirement. It's the easiest way to to get more reduction. You can't influence the input of a worm drive that much via knocks. Ah the desmo's! Love the ducati bevels, but I'm more a moto morini man at heart. Wayne....
  12. Tried googling " closed loop telescope control" One site was this one. Link 0.3 second of arc they claim. Wayne...
  13. No I'm not. I'm moving several hundred kilos's of cast iron at 10 metres/min and ending up within 10 microns of desired position when rapiding or moving much slower and holding tighter tolerances when cutting. Wayne... Edit : I should add of course we are not just using toothed belts but rather driving through very high quality Ball screws. BUT I think these systems have some merit over what appears to me coming in from the outside so to speak as very crude existing systems. It would be interesting to see what the larger class telescopes are using. I would imagine a fully closed loop system.
  14. I should dig out some old gear from an old project and give a servo and toothed belt a try just as a RA drive on our mount. I could fairly easily knock up a bit of microcontroller code to devise a basic RA drive. Anything further than that is beyond my capabilities I think. I need to do something as I bought a Celestron RA drive (Chinese manufacture) It broke within an hour and had to be fixed (Slipping Brass Gear) and once fixed found it just caused too much vibration for video use and also was just short on max speed. We have a NES Mount? and maybe is has a lower worm ratio than the Celestron mount the drive was designed for. Wayne....
  15. I have some experience with modern toothed belt drives as used in my cnc machinery. Very high accuracy stuff too. You can compensate for just about anything if the control loop is closed. From the short time I have owned a telescope and been reading on the subject it's been interesting to note that generally the vast majority of motorised mounts are totally open loop using steppers. Now a stepper motor whether you microstep or not can only accurately resolve to the nearest 1/2 step (generally 0.9 degrees on the motor shaft as most stepper motors are 200 step/rev) Any microsteps may or may not be linearly spaced between those 1/2 steps, all depends on the quality of the motor/drive combination. Servo motors on the other hand as used in all but one of my cnc machines generally make use of incremental or sometimes absolute encoders to track following error. My cnc lathe for example uses 5000 count quadrature encoders so thats 20,000 divisions of each motor rev. and thats on the other end of the belt not on the motor, so any pitch error in the belt/pulleys is compensated for. Belt stretch? Most quality belts are steel or kevlar reinforced it's a non issue even with the high comparative loads my machines deal with. Just my 2p's worth. Wayne....
  16. The trouble with your requirement, is tube is fairly specialised especially in Ally. My commercial suppliers list 4" 6082 (he30) tube from 16 swg right up to 1" wall inc 1/2" They would not hold it in stock though. If I was wanting something similar for a couple rings I'd be buying a few inches of 4" solid and turn it into rings. Wastful but probably cheaper for such a small quantity. Wayne...
  17. Socket Cap screws? I buy mine from a local supplier in Qty, BUT Screwfix have A2 Stainless and BZP at fairly reasonable prices. Wayne....
  18. My 6 year old daughter would like it. BUT I'd not go out of my way to let her see such a thing Besides for 10 quid less she got a "White" Orion 6" Reflector, albeit used. Guess the Orion is better! Even if they did use a nasty cheap and sloppy focuser! Wayne....
  19. That looks Whit more because of the radiused crest. I wonder what the various camera manufacturers are using in their bases. Wayne...
  20. You would need a shadowgraph (Profile projector) to check the angle properly. Thread gauges are too crude. It does not really matter. Most commercial threads have fairly low engagement anyway. I just looked at that Wiki page too. Hard to say for certain really. Wish I still had bucket loads of UNC bolts now to go try on cameras. Wayne..
  21. Hi. Threads unfortunately are a day to day thing for me with an precison engineering company to run. So here's my 2p's worth. 1/4 BSW and 1/4 UNC are both 20 threads per inch. Whit has 55° thread angle and UNC 60°. Thats the reason a Whit bolt in UNC hole seems loose. There are other subtle differences but for a camera mount they are fairly interchangable. The actual spec for camera mount threads I'm sure is UNC. Not all Whit/UNC thread sizes have equal pitch. 1/4 & 3/8 do though. UNC will be fairly easy to obtain as it's still prelavent in the USA. In these days of Metrification these "old" coarse thread styles are actually far superior to ISO Metric Coarse which sometimes isnt coarse enough for use in softer materials. Wayne....
  22. Dave Do you think Natural Acetal would be better? ie White colour. Not sure if I'll make anymore, at least for a while. Did however do something similar for T-Mount fittings over the weekend, as our modified camera was likely to suffer from a dirty CCD if I left it unprotected. Another guitar enthusiast too eh! I collect 80's Japanese Westones. John. I would imagine if the "Nagler" EP's can take a filter then the covers would of fitted. The dimensions were basically filter dimensions. Wayne...
  23. Tom The adapter shown in the last picture is a T-Mount adapter I machined from Delrin. It's Hot Glued to the body. It does have a spigot section that locates in the Cameras Lens opening snugly. I guess epoxy would work as well. I do like my hot glue gun though very handy tool and cheap. When I removed my lens it was all done from the front. Literally slowly removing parts using as little force as necessary. The CCD should be way back fairly safe as in my Nikon. The nikons CCD did have the auto focuser lens in front of it anyway. That was discarded too obviously. Most of the lens assembly on the nikon was molded plastic so easy to nibble away at. Wayne....
  24. Picture Basically the proximity sensor is a slot which a portion of the lens outer shell filled to block off the IR Led from the detector. On switch on the Nikon needs this slot blocked before pressing the power button, and immedatialy unblock as soon as the lens motor runs. On switch off it should be blocked before pressing the power button. If I had been able to get the thing apart properly I would of fitted a momentary switch to achieve the same effect. Wayne....
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