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Robert72

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Everything posted by Robert72

  1. Hello Explorer42, sorry for taking so long getting back to you. I didn't continue with the restoration, I just decided to use it as is for now. I hope to get back to it at a future date. Now It's time to concentrate on completing my CF spider for my home made tube and get that project completed.
  2. I was just reading up on the Yolo concept, and wondered how the project is going Chriske? Any updates?
  3. I think it probably is a UNC. I am not too au fait with UNC, hence the reason for the post as people with more experience can help. That sounds good as it means i can probably source something. Thanks for all your help!
  4. Well, the good news is I got the broken thumbscrew out, by gluing a nut on it. I may have to go down the drilling and tapping route after all though, unless i can source M5.0 x 1.0.
  5. Looks like M5.0 x 1.0! Anyone know a supplier?
  6. Hello all. I bought a second hand Celestron C8, and the finderscope bracket thumbscrew has sheared. So i ground it down to get rid of the bad thread prior to attempting an extraction, and it turns out it is made of some kind of polymer. Anyway. I am trying to id the thread size. I have tried an M5, but it starts off OK then gets tight, and i don't want to force it. Having said that, the standard screws get tight as well, must be some kind of locking feature. Can anyone tell me what threads these screws typically have, and better still where I can get similar replacements?
  7. OK, so the sub assemblies are pretty much done.... A close up of the spider hub..... The adjuster plate with brass inserts and anodised bolts. I chose red to stand out under red lighting. There is a bigHead female bonded onto the back there to act as a kind of lock nut to resist rotation.... Side view of adjuster plate and bonded bigHead....... Assembled. Still awaiting compression spring....... Internal view of the angle thingy. This is where the spring will go. The bigHead makes an ideal spring rod, but i think i will need a bigger washer...... Candle holders make ideal spider stands........
  8. Here's a trial fit in the building jig....
  9. Now let's make a kit of carbon parts.... I've also made a rudimentary building jig. The outer ring and vanes are held by the adjustable quadrants of MDF. The inner ring is held by the steel dowel. Should be good for holding all the parts in position while bonding.....
  10. Hello, nice project. I was wondering what you were using for your layout drawings? I am also using the Baader Steeltrak in my project, and could do with that dwg for my layout.
  11. Here is the single vane equivalent, it's basically the same however the central box has been replaced with a 40mm tube. The tube and vanes are semi-slotted and bonded. Not sure about the ends, how important are they in terms of diffraction? If need be they can be integrated into the tube, this would give a very clean light path.
  12. I didn't mean the difference between thin and thick vanes, I meant the gap between the vanes. If I read your previous post correctly the gap between the vanes is the thickness of the thick vane. The gap between vanes on my initial design was 10mm. Does that even matter? I think someone in a previous post mentioned if the gap is small it has a larger effect. Regardless, I'm going to have a crack at a single vane design.
  13. Maskulator seems like a handy app. The double vane spacing seems quite small though (I don't know if it makes much difference).
  14. It is 0.25mm sheet - 10mm box at the ends and centre - 0.25mm sheet
  15. Thanks for all your input so far. The main reason for the dual vane design, is that it is so easy to design and build, although I had no idea they were so poorly regarded within the astronomy community. Back to the drawing board!
  16. Yes basically like that. Funnily I had already looked at this page, but due to the odd angle that the holders are in at the top left picture, I had assumed they were 3 screw. I feel it would be too much of a challenge for me to construct a 3 screw system due to the vane positions, as the site says, "With a four screw adjustment, each screw is centered between the spider vanes, making collimation adjustments a snap".
  17. I don't have a sketch, but imagine two plates being pushed together by a spring. And then 4 screws equidistantly spaced on one of them to push them apart. If the screws protrude a few mm, then there is angle adjustment available in both planes.
  18. Agreed. How about a 4 screw arrangement then where the 2 planes have distinct control? It may be a better way to de-couple tilt and rotation (to an extent).
  19. An interesting read. Thanks wimvb.
  20. After the height and rotation are set, then surely tilt is the only thing that requires adjustment? Adjusting rotation and tilt simultaneously with a 2/3 adjustment mechanism seems kind of un-intuitive. I was fairly convinced of this after reading this site (from which i stole the tilt mechanism). http://conradhoffman.com/secondary.htm
  21. Some of you may have seen my carbon fiber tube project, and I have decided to compliment this with a carbon spider. I did not intend to build a spider initially, however having sized up the spider i got with the mirror set, i found that it is slightly too short. Obviously I could purchase a spider, but a homebrew carbon version is in keeping with the DIY theme, and gives me a chance to try out something new. I was hoping to run the design past you fellows for a sanity check. This is not the most complex thing in the world, however there may be something i have missed as i have never actually had to set one up before. The vanes are 0.25mm CF, bonded with 10mm section box section. the tension bolts are aluminium, the nyloc nuts are self retaining within the outer boxes, no spanner required. The central spindle is an M6 x 80 aluminium bolt, locked into position with nyloc nuts. This should allow for rotation and +/- 5mm height adjustment. I have designed the tilt mechanism as a single bolt adjustment type, in order to de-couple tilt from rotation (I can't see the point of the 3 bolt adjustment types). The diagonal backplate is compressed by a spring, and pivots on 2 ball bearings. The remaining third position has a bolt in compression to do the adjustment. Hopefully this is clear from the side view. Anyway, here is the electronic prototype, i would really appreciate it if you could let me know if i have made any omissions etc.
  22. https://www.easycomposites.co.uk/vm100-black-methyl-methacrylate-adhesive
  23. Good question. When I said the finish is superb, it is mostly, but there are several flaws, uneven cloth, bubbles etc. Also the tube is a touch small for my tube rings, a slight blunder on my part. And the ends where you can see the foam core are a bit rough in my eyes. Having said that all these things do give it character, along with the hybrid cloth arrangement. However, I am quite keen on skinning as it will solve a lot of these slight deficiencies. I know, the whole point of making a mould is such that I shouldn't have to do this, but it is what it is. I will write a post at some point about my findings from the whole project, and give anyone advice if they are thinking of doing the same. For me this is only the first tube, I am keen on doing more, perhaps a large truss would be nice. Everything I have learned from this should make subsequent versions better/easier.
  24. Modified the moulding frame into a tube chop saw. This gives a nice square cut:
  25. Well, here it is, after allowing the part to stabilise for a couple of weeks the lid is finally off. The surface finish is superb, you can see that I have used a mix of standard carbon and carbon/kevlar. For several reasons however the tube will be getting skinned with a single layer of carbon. Here's the pics:
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