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Horwig

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Horwig last won the day on October 16 2015

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About Horwig

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    Sub Dwarf

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  • Location
    Caernarfon, Gwynedd
  1. That is starting to look like a beast, what size cameras do you intend to hang off it? Keep it coming, it's good to see designs unfolding. Huw
  2. Just to clear things up, in my post above, I called the Gurley encoder an absolute encoder. IT IS NOT, what I'm sure I meant to write was mount encoder as opposed to a motor encoder. I'm not sure where my brain was when I wrote that post, apologies to those I mislead. Huw
  3. The Gurley I'm using (or not at the moment) is the 320K pulse R158 encoder, and it's £882 Huw
  4. If I may add my experience here with trying to add an absolute encoder to my Sitech controlled DIY fork, I bought a Gurley encoder as specd for Sitech (not cheap), and mounted it via a flexible shaft coupling to the RA axis, the body of the encoder was solidly mounted by bracket to the bearing block. I must have some axial offset in the centering of the encoder, it gives differing RA speed, dependant on pointing position, so will have to go back to the drawing board in its implementation. EDIT The encoder is not ABSOLUTE, don't know why I called it that!!! Huw
  5. Best of luck with this project, I've been fighting my equatorial fork mounted 400mm f3.5 Newtonian for more time than I care to remember Not sure, but I think the Sitech system can handle Alt-Az mounts, as well as guiding and de-rotation, see page 22 of this manual http://pgrasc.org/wp-content/uploads/2014/03/SetupManual1-1-a.pdf Huw
  6. Thanks Dave, it feels as if I've been at this forever. I did have triangular stars when I first built this scope (I called them 'mickey mouse ears' I seem to recall), they were caused by mirror edge clips too tight, then I had astigmatism caused by a safety strap araldited to the centre of the secondary. These also could be caused by pinching of the secondary I suppose, but there are no clips, just three blobs of silicone. Guiding was good, don't see many major spikes there. One problem solved causes another one to shine through, hey ho, the life of an engineer... Huw
  7. It started life as a Beacon Hill mount many years ago, looking like this
  8. First of all, a big THANK YOU to Tony Owen for his input on this rebuild. I'll post the latest news in case it is of benefit to somebody else building a mount. The DEC axis rebuild went slightly out of control, I ended up replacing the RA axis as well! Here's the new RA axis in it's bearing block. Here's the worm and wheel re assembled, note the red engine rebuild lube used to lubricate the worm, very clever stuff, the colour shows how well it distributes itself. And here's the fork re-assembled, note the new bearing block on the left hand tine. The hinges on both worm blocks have been replaced with flexors, as can be seen on the DEC worm block to the left of the mount awaiting re assembly. First results are promising, PHD2 is showing guiding of about 0.5" repeatably, and it's applying DEC backlash of about 175 ms. Last night I had a good PEC record run, and did a quick and dirty 300 second test frame before clouds came in. That's a single luminence frame, just stretched and a little noise reduction added. Guiding looks good, but is it my eyes, or do I have triangular stars? Huw
  9. Just what I need. My electricity bill for the dehumidifier in my dome over three months of winter was over £250. £2 for one of these and £15 for a tube heater sounds like a huge bargain: https://www.screwfix.com/p/dimplex-ecot1ft-wall-mounted-tubular-heater-40w/3951f Anybody want to offer me anything for a used dehumidifier?
  10. well said, now if everybody did the same..., well we all know the outcome... Nice one Huw
  11. Oh, Colclene certainly brings back memories, I was a young BBC VT engineer in the early 80s, it was used to clean tape heads back then, both 2" and 1" VTRs.... But back to the PSU in question, I'm using the exact same one in my obsy, and have been since 2009, it's not the prettiest, but mine still plods on. I'd think it's probably just a buildup of crud on the surface of the trimmer pots, doubt very much if there's any lasting damage there. Tweak the voltage set pot back to roughly where it was and everything should hopefully come good, it not give me a PM, I'll take mine to bits so we can compare notes. Huw
  12. Just a quick update on where we're at with this. The new trunion bearing is in, now at least I have repeatable results for DEC backlash, but it's not that brilliant, about 20 arc seconds or there about, with the gearhead on the motor accounting for something like half of that. After a lot of research I found some Japanese zero backlash gearboxes from KamoSeiko, and found one on ebay to play with, actually calling them gearboxes is wrong, they use ball bearings: Here it is on a Pittman motor compared to the Pittman gearmotor that's in at the moment. I just about have space to accommodate the extra length. New timing pulleys are on order, but there's a 15 working day delay, damn. Anybody out there come across the Kamo ball reducers? This shows potential, but is there anything I should know that would make it unsuitable? Huw
  13. 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
  14. That is one of the cleanest ASC images I think I've ever seen, very well done.
  15. 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
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