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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

  • Rank
    Sub Dwarf

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  • Location
    Caernarfon, Gwynedd
  1. If you can't find a suitable wall Adam, might I offer you mine Huw
  2. just one word:: SUBLIME Huw
  3. I gave up on the yoga mat quite soon. I do imaging from my garden, which is very dark, but the light blue yoga mat would reflect any lights into the optical train, far from ideal. I now stick to matt black Huw
  4. True, I've been trying to attack this itereratively, and it;'s sort of working. My latest challenge is a problem thrown up by the high res encoder on the polar shaft. The dc gearmotor is mounted to the worm block plate by its face plate, trouble is, under drive, the 3.5mm ali plate flexes, just a little, but it's enough, the encoder on the motor, and the one on the shaft fight, and an error of an arc minute or so throws the servo controler into a tiz, it tries to correct, and results in a 4 arc second bump, every few minutes, and yes, at 0.4 arc seconds per pixel, that's a lot. It's too cold and damp here to start diss assembling the mount, it can wait till warmer weather returns. I'm interested in your idler wheel tensioning the belt, is it adjustable, and if so how? Huw
  5. Nice one, battleships were produced with lighter stiffening
  6. Just a thought Rusted, is any of the movement you were showing in the video due to movement in the bearings on the axis? My mount, as was, had pillow blocks without any preload applied, and I was getting appreciable sideways movement of the shaft. I've replaced them on both axes with pre-loaded taper roller bearings and precision cut shafts, that, and the work on the worm block hinges solved the wobble for me. H
  7. the £800 is the cost of the encoder only (from memory), Sitech II is 900us, motors new about 150 us each, I got my motors second hand off ebay. Huw
  8. This might be getting OT () My mount is controlled by a Sitech II system, using dc motors with encoders. The beacon Hill RA worm has 'wonderful' periodic error, so I've mounted a second hi-res encoder directly onto the end of the RA shaft. They are not cheap at about £800, but give very smooth tracking with no PE. This is the raw unguided mount in blue, with guiding in yellow, and guided with encoder in pink:
  9. If I started this project all over again, my polar wedge would look totally different. The hinged plate model of Beacon Hill mounts might heve ben adequate for visual, but for high accuracy imaging it's pants. (My highest resolution imaging is 0.4 second per pixel on this scope). The lower part of the wedge is a commercial gate hinge welded to two steel plates, the fulcrum created by the adjusting rods at the top of the plates pushes the hinge apart at the bottom, any imbalance in the load when moving between East and West of the Meridian rocks the mount, hence the bracing plates. But it still sucks. If I were to start with a clean sheet, I reckon something like this as a polar axis would work: http://www.astronomyblogger.com/homemade-stuff/homemade-equatorial-mount/ but naturally, in 20mm ali, not 18mm ply Naturally, with so much invested in the mount already, and with so few clear nights this far West, it's a law of diminishing returns, so I'm fettling what I have, not stating anew. I've spent a fortune in this last year on an encoder for the Polar axis, this is going to be my last big spend on this mount. Huw
  10. Ahh, what's missing in that photo is a plate across the front, joining both side plates, just behind the box section. This solidified the mount enormously, maybe a further bracket from the worm block spacer box to that would make sense. Ta Huw
  11. I'm moving the worm block and motor as one unit, the 'hinge' is quite some way back from the worm/wheel. Rigidity is paramount. My dec assembly is quite sturdy, not so sure about the R.A. I've had to build up a 'spacer' from 2"x4" box section to put the worm at the edge of the wheel, not ideal. Huw
  12. Sorry Michele, my tech drawing skills are terrible, and I don't use any helpful drawing packages, just Photoshop, so here goes in 3d Does that make any more sense? The green is the 0.2mm strip of stainless, the blue is the part of the mount/worm block, and the brown/orange are the fixing strips. I find this works really well, having great stiffness to sideways and twisting forces, whilst allowing a relatively good hinge angle, since the max it has to open is the tooth depth of the worm. I first used flexors in a Clement focuser I built a few years ago: Huw
  13. Sorry to hear you're not well, keep safe and warm, health comes before telescopes. Huw
  14. Here's what my Beacon Hill worm blocks look like. this is from before last year's re-build, so still has the old hinge mechanism and stacked flange bearings. The 'U' channel has the ends chamfered back for wheel clearance, and the thickness of the end sections was cut back slightly so the plates on the end preload the bearings. The step in the worm shaft lines up with the inner dimension of the channel section, I assume yours is the same. With this old hinge design and the stacked pillow block bearings I was getting horrible movement of the DEC axis, work on both problems has brought it under control. Huw
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