Jump to content

Narrowband

1parsec

Members
  • Posts

    681
  • Joined

  • Last visited

Everything posted by 1parsec

  1. The jam up may have moved the worm-wheel mesh and it might now be too tight causing the bad tracking & guiding effects you're now seeing. You need the smallest amount of backlash (free play )in the mesh. This explains the worm wheel adjustment procedure - https://www.astro-baby.com/EQ6 rebuild guide/EQ6 worm alignment.htm
  2. Hi, I would record a number of guiding runs in PHD2 of say 10 minutes each but with the actual guiding corrections turned off. The guide log will record the native tracking errors of the mount. Then load the guide log in to PecPrep to analyse and display where the guide errors originate.. Pecprep takes out 99% of the guess work on where best to do your fettling.
  3. Ali, The small clearance between the bore and bearing will allow the bearing outer race to turn. However when you fit the shaft and taper bearing at the other end and add a little bit of preload with the round nut, it will almost certainly hold the outer race in place with out slipping. Or a tiny bit of shim as mentioned by Skipper. I wouldn't use Loctite in this case as it will make disassembly much more difficult in the future.
  4. The belts & pulleys replace factory fitted gears. Therefore the number of teeth of the pulleys has to match the original gearing to maintain the correct drive ratio of 9:47 So the design constraint is pretty much fixed at those number of teeth or the tracking rates would be wrong. The belts are polyurethane and reinforced with steel tension members so wear is not an issue if the belts are tensioned correctly ie not over tensioned.
  5. Could be the worm wheel gearing is tight from taking a bump while in storage. Does the mount sound nice and smooth when slewing a various rates with the hand set ? If not, check and adjust the mesh so it has a fraction clearance so the motor does not bind. Also check the clutches are tight and don't easily allow the axis to slip.
  6. I'd guess it is backlash in the Dec axis worm wheel. When you image away from the zenith you probably have a small imbalance that keeps the contact on one side of the gearing. At the zenith the mount is more likely to 'wander between the gap in the gears causing the trailing because the scope is vertical. First thing to check / adjust is the Dec backlash. A search for' backlash adjustment' should show a lot of links on how to do it. ATB Dave.
  7. Rowan have never recommended that belt converted mounts should be perfectly balanced. Not sure where this has arisen from. Set a minimal RA East heavy imbalance to ensure the worm & worm gear clearance is working on the same side at all times. The wobble in RA is a common issue (backlash in the worm gearing) but it may not be the reason for the guiding problems. Thanks, Dave.
  8. Another way to 'fix' a damaged thread is to use a thread file. https://www.ebay.co.uk/itm/Sykes-Pickavant-Metric-Thread-Restorer-File-01560200/174655192797?epid=1310959088&hash=item28aa42bedd:g:ipwAAOSwYcJgOUTz I've used these on various jobs to good effect when a die isn't available.
  9. If you take the cover off the side of the mount you'll be able to to see the motor 9 tooth pinion gear. The end of the motor shaft can be seen and measured for the extractor size.
  10. Hi, It looks like the noise is in sync with each complete revolution of the belt. This could point to the belt tension being too tight. Loosen the tension a fraction and see if that help.
  11. I'd buff it with a Scotchbrite pad and wipe over with an oiled cloth. Most stainless steel weights are made from 303 stainless steel which isn't 100% corrosion resistant. 316 has increased molybdenum which gives it the additional corrosion resistance. Weights from 316 are possible but 316 costs more and takes longer to machine and would probably cost twice that of the same weight in 303.
  12. Hi, First thing to do is check that the worm-wheel gear mesh is set correctly. It might have moved a fraction during your strip down or it was just a bit to too tight any way. If it's too tight it will bind the and cause the stepper motor to stall which is what the sound is in the video. Read the instruction on on the adjustment an setting on Astro Baby's website http://www.astro-baby.com/EQ6 rebuild guide/EQ6 worm alignment.htm
  13. The clutch couples the axis housing to the worm-wheel gear.
  14. You can get the collimation close with a camera but I always do the final adjustments at the eyepiece on an in focus mag. 1 to 2 star. Use a high magnification say x500. You should be able to see the Airy disc and a faint diffraction ring around it. Adjust the collimation so the ring and central star are concentric. You need a steady night as a lot of the time the seeing won't allow you to do this final step. In the eyepiece you should see some thing like this -
  15. Does the 'humm' noise change when you change the slewing speeds on the hand controller ? If the noise is that quiet it's likely it's not to be a problem. How tight are the belts? Too tight is bad! You should have 1-2 mm deflection of the belt with light finger pressure. @SiriusB comment is spot on. To evaluate tracking performance you need to record a guide log with the actual guide corrections turned off. i.e the camera is then recording the change in position of the guide star caused by the tracking errors of the mount - the PE. Then load that file in to EQ mod's PecPrec or PHD2 viewer. The graphs will tell you exactly what the errors are and where they're coming from.
  16. Hi, I can't quite tell from the video if the motors are stalling but that is what is sounds like. The motors can stall and make this noise when the worm and gear wheel mesh is too tight. Have a looks at http://www.astro-baby.com/heq5-rebuild/heq5-we1.htm for instructions on how to adjust the mesh.
  17. Hello All, The movement in the video is completely normal and as expected. That's the springs allowing the worm to move in and out of mesh. However the adjustment screws should be adjusted to make this movement much less. The amount of spring movement needed should be just enough to accommodate the eccentricity of the wheel gear. The eccentricity of the wheel gear is usually no more then 0.2mm . So the adjustment screws (labelled B, last page in the instructions) should limit the direction of movement shown in the video to this sort of range. If any one needs further help or advice setting the ZB assembly, drop me an e-mail. E-mail address on our website.
  18. Over packing is more of a problem in normal applications where the shaft and inner race of the bearing is spinning at 1000's of rpm. The grease heats up and becomes more of a liquid and the pressure of the balls running in the grease forces the grease passed the seals. But for a slow moving telescope mount it isn't much of a problem. Packing the bearing full will increase the drag of the axis, which mechanically isn't a problem for reliability but might cause tracking issues ?? When greasing this bearing I would leave 50%>75% space for the grease to move around the balls.
  19. Try a search for "face spanner" or "caliper face spanner" https://www.google.com/search?q=face+spanner
  20. How were you tensioning the belt that broke ? The damage is definitely from over tension.
  21. That looks like a DC servo motor with geared head fitted on the front of the motor for reduction. I would say the play in the gear shown in your video is the natural backlash you find on the output shaft of a gearbox of this type. It could be one of the internal gears has worn on it's shaft allowing more clearance between the internal gears and increasing the backlash. If that's the case, it is going to be quite an involved fix. The thing to try first would be to have a small imbalance in the DEC axis so the 'weight' of the scope keeps the gears pressed in one direction which will take up the backlash.
  22. Does the motor have an integral gearbox attached ? Can you post another photo of it.
  23. Or it could translate to - don't force on the allen key until it looks like a clock spring 🙂
  24. The pier is a re-purposed fork truck bollard used to protect the corner stanchions of a high bay racking. I used to look at them thinking they'd be perfect as a telescope pier. The warehouse layout was re-done, the bollards became redundant and I managed to squirrel a few away. It was many moons ago.
  25. The height of the gussets depends on the section & height of the vertical tube. If the diameter and section is substantial enough then the gussets can be kept short just the stiffen the joint between the tube and base plate. With piers it's diameter that's King 🙂 The bollard we used at the show would work well in real use.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.