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Horwig last won the day on October 16 2015

Horwig had the most liked content!

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About Horwig

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    Sub Dwarf

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  • Location
    Caernarfon, Gwynedd
  1. Thanks again Tony for putting up with my ramblings. Things are getting serious. New angular contact bearings are in, they make a difference, but have not solved the problem. I'd been noticing that when I dis-assembled and then rebuilt the drive, backlash would be different, and I couldn't work out what was changing, till I rechecked the worm to wheel centering, it was off, a lot of head scratching later, I hope I've found what's causing it, the slop in the stacked pillow blocks is so great that the wheel can twist against the worm, so before I get anything more done I'm going to have to replace the DEC trunion bearings with a pair of tapered rollers. Interestingly, with things as they stand, roughly half the backlash comes from the worm, the rest from the gearbox/belt drive, and most of that I suspect is probably from the gearbox. Huw
  2. That is one of the cleanest ASC images I think I've ever seen, very well done.
  3. I'm slowly getting a workflow together for jobs to be done. The bearings for the worm linked to above were larger diameter than the present ones, so would need a new worm block to house them, so I've found some angular contact bearings that match the size of the present ones: https://simplybearings.co.uk/shop/Bearings-Angular-Contact-Only/c3_4592/index.html If the worm block shows any sign of flex, I will the go to larger bearings and fabricate a new stiffer block. I've some left over 4 inch ali tube section with 3/8 wall thickness which should make a housing for the tapered bearings, and you are right Tony, I should address the single pillow block on the far side, I'll probably just replace it with the pair I'm taking off the driven trunion, should be better than what's there now. Huw
  4. An update, the preload was not as tight as I'd thought, tightened it, backlash is now closer to 16 arc seconds, getting there I think. I am still going to change the worm block bearings to angular contact, these are what I've been looking at : https://www.bearingboys.co.uk/SKF--FAG/7201BEP-SKF-Single-Row-Angular-Contact-Ball-Bearing-22415-p Also, the pillow block pack on the driven trunion is going to be replaced with a pair of taper roller bearings, these look possible: https://www.bearingboys.co.uk/Imperial-Taper-Roller-Bearings/HM-801346-X2310QVQ523-SKF-Imperial-Taper-Roller-Bearing-82351-p Any thoughts from anybody? Huw
  5. Thanks for taking the time to give such full answers both, lots to consider. Firstly, the mount is stripped back, the OTA removed, and the fork removed from the polar axis for ease of measurement. So all tests are done off load. Initial results this morning. The worm bearings are plain ball, but preloaded. Measurement just now shows end float of about 20 microns when changing directions on the motor, on a 21 cm dia. wheel I think that equates to about 40 seconds of arc. Could be the principal source of error. Also the pillow blocks show appreciable slop, resulting in about 100 microns displacement at the worm when push/pulling the trunion hard by hand, this also needs addressing, but is only going to give problems under heavy load. Engineers blue was applied to the drive, nice even pattern, no bottoming out exhibited. Bearing research starts now. Much appreciated both of you. Huw
  6. This is really a followup to a thread I started last year: Firstly, a big thank-you to everybody that helped me out then, the mount started behaving for the first time. HOWEVER... I tried to image on a few of night last winter and got pants guiding, so I sulked and left the problem for another day. That other day arrived this week. The mount is stripped out again, and a problem was found. The motor shafts are locked to the timing pulleys with grub screws against flats on the shafts, the DEC grub screw was loose. Will replace with a split spring pin, hopefully problem solved. Trouble is, I can't leave well alone. The new sprung worm blocks work well enough, with PHD2 sorting out the (nice predictable) backlash, but it would be nice to mechanically minimise if at all possible. Upshot is I've gone back to measure DEC backlash, and I can't get it under about 30 arc seconds whatever I do. (I measure it by using a dial gauge on a long metal rod clamped to the DEC axis, Sitech is set at 15 arc seconds per second DEC speed, there's 2 seconds dead time, seems to agree with 30 arc seconds). The DEC worm wheel has been re-checked to be square and centered to the worm. I have two obvious adjustments, the setscrew to set clearance, and the spring plunger to set worm to wheel pressure. I've checked the worm block hinge, it's free to move, and has absolutely minimal play, the backstop setscrew is set at 50 micron clearance, and I've experimented with spring plunger tightness over its full range. Nothing I do seems to change the 30 arc second dead zone, minimising the backstop clearance shows no improvement, upping the spring force to max makes it worse if anything. Grabbing the DEC axis trunion reveals no slop, but I still get the 2 seconds backlash delay. The only change I've done that improves matters was to change from thick lithium grease to a thin aerosol white grease, but the change was minimal. I've tried attaching a rod to the end of the worm as before, there's no dead zone there, it must be just the worm/wheel interface. Could it be that they just don't mesh? HELP! Huw
  7. Thanks for all the observations and kind words, it's good to get feedback. I processed this using batch pre-process in PI, and something went wrong somewhere, the results are peppered with black snow, especially when sharpened. When I get time I'm going to go back to square one and start again. I think this will be worth the time spent on it.
  8. What's interesting is that the main body of nebulosity is now under control, but compared to the original I'm not sure if the transition from dust to the illuminated region is as smooth, I guess I'll have to play some more
  9. No I have subs all the way from 10 seconds up, It's my cack handed work at the computer I'm afraid
  10. Agreed, it's a little bit in your face?
  11. This is my first image in over a year, I've nearly forgotten how to do them. This was taken over nine frustrating nights in January and February, some nights only one sub was kept! There was constant cloud fronts passing through, and as soon as I gave up and de-rigged the kit, the sky would clear, very frustrating. So anyway, finally got down to processing it, PI was not playing ball, (I had to get the book out I was so rusty). I kept getting black flecks, especially after sharpening, so in the end I gave up and manually removed them is PS. Kit was my usual, FSQ106 at 380mm with SX35 camera and Astronomik filters on AZ EQ6. Subs were from 10sec to 1200sec Lum, a total of 4 hours and 3hours of Ha in 30 minute subs. Software was SGP and PHD for aquisition, PI and PS for processing. The RGB had horrible halos from the brighter stars, so I didn't use it, instead borrowed some RGB from a four year old slightly wider image taken with a 300mm lens and this camera. There were camera issues when that image was taken, it affected the luma, but the RGB was OK. It's nice to have something to post after so long. Huw
  12. May I add my twopence worth to this thread. I've built a couple of light boxes for flats, here's the thread on the one I use on my refractor. To measure the evenness of illumination, I used a stills camera in a darkened room, not filling the frame with the lightbox, so as not to get affected by vignetting on the lens. Then stretch the contrast on the image in photoshop, a good visual way of doing it, but not as accurate as Oddsocks method above. Just my opinions?, naturally there are more ways than one of skinning this feline. Huw
  13. Horwig


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  14. Horwig


    It should, it's quoted at 88mm, I'm also using a reducer 645, so that should be good as well, here's the FOV, now that's what I call a widefield rig? The third lottery ticket would be for something like this to handle the stacking, wonder how PI would run on it, HP Z8, dual 28 core, 384Gig Ram We can all dream big (can't we?)?
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