AWR LogoAWR DRIVES - FAQ's Hints and Tips


FREQUENTLY ASKED QUESTIONS
  1. I want to have a GOTO computer system but cannot afford it straight away.
    A The way to do this is start with our Microstepping NON-GOTO kit. The motors and microstepping drivebox are operated with the Simple Handset. As an example see the product lineup for the EQ5 GOTO KIT. The Intelligent Handset makes it GOTO at a later date and supplies fully remote operation.

    We can do it with SYSTEM 5 electroncs and STEP3 or STEP5 motors fitted, but only the motor assemblies are useful and we do not achieve the high slew rates as offered by the Microstepping product range.

  2. I have a Synchronous motor running off 110V 60Hz, can you drive it?
    A Yes our drive systems 1 or 3 can will do the job. Specify the motor voltage, power rating and frequency on the order form. We will provide the correct voltage output from the inverter. System 3 will give a stable frequency of exactly 60.1476Hz for photographic work. The whole system will run off 12V DC and so is portable for use anywhere in the world. These motors are still turning up on MEADE 2080's.

  3. How will I fit the motor assemblies onto my telescope?
    A Have a look at the drawings showing the physical dimensions of the motor assemblies. We do not make mounting brackets as there are very few telescopes exactly the same. Most of our customers are upgrading their old telescopes. The output shaft from the gearbox needs to be connected to the slow motion shaft of the telescope axis to be driven. We can provide an OLDHAM type coupling which allows some misalignment between shafts.

  4. I need 100Ncm torque to turn my RA axis as it is a very old, very big telescope.
    A We can tailor the torque output to match the telescope. By increasing the gearbox ratio we get more torque but the motor has to be worked faster to keep the final drive rate the same. This will limit the dynamic range available when adjust buttons are used on the handset. Alternatively we can specify a more powerful motor and hence get more torque. It is only in some instances will the torque available be limited by the gearbox. DISCUSSION and MEASUREMENT of TORQUE

  5. My drive system works in one orientation of the axis but when the telescope is moved about 100 degrees away the motor stalls.
    A This is a balance problem on the telescope. It may have altered since it was set up or some additional accessories have been added but the telescope was not re-balanced. To check this free off the drive and check by hand the force required to turn the telescope in both directions at the offending point.

  6. Can AWR repair other manufacturers electronics units?
    A Generally YES. We have repaired a few electronics handsets. A catastrophic failure is much easier to find than an intermittent one. We have also replaced more units by our own equipment, driving the original motors (stepper and synchronous types) and providing more features that the user requires. See repairs.

    DC motor drive chips used by MEADE in the 1990's went obsolete shortly after they were designed in. These components are subject to catastrophic failure. We do have an alternative chip which we have wired in.

    The modern single chip handset / drive control units are not easy to repair. If the main processor chip has gone we will not be able to get a replacement.

    Reversed power supplies: Some manufacturers do not count this as a typical User fault so they do not protect against it! Naughty!! We may be able to effect a repair, it is usually the Voltage Regulator and a capacitor that blow, but protect the rest of the circuits by doing so.

  7. My FULLERSCOPES Mk IV mounting has synchronous motors, is very heavy and yet I want it to move more under my control.
    A We can provide replacement stepper motors on the same type of gearbox that was originally fitted (STEP3 PRICE). This makes replacement with our system extremely easy. To drive such a system it is recommended to use our SYSTEM 5. This will provide adjustment controls of FINE (30%), MEDIUM (2x) and COARSE (about 20x sidereal).

  8. Which drive system and motors do you recommend to drive my VIXEN SUPERPOLARIS mount?
    A We would suggest our GOTO system KIT at 750. We can also drive Vixen's own STEPPER motors to achieve the maximum performance using our SYSTEM5/VIX product. We achieve higher performance from Vixen's motors than with the Vixen handset, driving up to 50x Sidereal rate with full mechanical load of 100Ncm.

    We cannot drive the VIXEN DC servo motors supplied with their SKYSENSOR 2000 (SS2K) but our GOTO kit achieves the same performance and features as the SS2K (but we don't have the planets).

  9. I want a driven camera platform.
    A Sorry we cannot supply this. We can't make it cheap enough. There is one available made by BEACON HILL TELESCOPES. It will suit camera with lens up to 100mm focal length and has a VFO, driven from 12V DC. It costs 108.00 GBP + VAT + Postage. Contact them directly.

  10. How does a friction drive compare in accuracy to a Worm Wheel set?
    A The main problem lies in the reduction of the final element. The reduction ratio of this pair is the ratio's of the radii of the two wheels. To keep the following accurate, the ratio cannot change by more than 0.1% - with a 10mm radius small wheel this means holding the radius to 0.01mm. This is a tall order especially in the presence of dust which can alter the radius locally. To get a reasonable reduction on this final pair the large wheel should be as large as possible, 0.5m radius would only give 50x reduction.

    There are several notable telescopes with friction drives that we have supplied motors and Intelligent GOTO systems for: the Nottingham Astro Soc 24 inch reflector, Hampshire Astro Group 16 inch Newtonian, Eamonn's 36 inch reflector. Ron Arbour has built many friction driven mounts. Consult his article in Sky & Telescope.

    In practise you get NO backlash. It is remarkable!


HINTS AND TIPS

  1. Keep the drive train regularly serviced.
    It is very easy for worm gears to become very tight or loose, either with end play or with a worn segment on the worm wheel. Old grease can become hard. The motor drive will probably cope but may cause excessive wear and ultimately stalling. One sign of things being amiss is that the backlash increases. Certain mounts (Vixen SP and GP) can be reset to realign the working components with a minimum of backlash.

  2. Avoid tripping over wires in the dark.
    Commonsense really but it is amazing the damage that can be done. AWR supply non-latching connectors to all motors so it is possible to pull the connector apart by tripping on the wire. A fixed lead will pull over the telescope or break a leg. Tidy the leads away cleanly against the mounting whenin use. Perhaps a component tray attached to the mounting would tidy up these items.

  3. Slow motion reduction ratio's.
    See the article Understanding Telescope Drives to see the effect the reduction ratio has on performance. We have GOTO KITS for the popular commercial mounts Of the commercial telescopes we have come across these are the more usual reductions:
         Super Polaris mount         144:1           (10 minutes per rev)
         GP / GP-DX mount            144:1
         EQ5 mount                   144:1
         HEQ5 mount                  135:1
         EQ6 mount                   180:1
         Fullerscopes        usually 359:1            (4 minutes per rev)
         Orion Optics(UK)            288:1            (5 minutes per rev)
         Beacon Hill Telescopes      287:1 and 360:1
         Intes Micro ALTER D6        200:1 (RA)
    

    In the UK slow motion worm wheel sets can be obtained from BEACONHILL TELESCOPES with sizes in the range 6 inches to 14 inches in diameter. Many of these have AWR GOTO systems fitted. AWR have provided systems to match worm reduction ratio's from 96:1 to 740:1 and the occasional tangent arm drive at 1500:1.
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