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Robert72

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About Robert72

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    Nebula

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  • Location
    Glenrothes
  1. John, There is a chap in Germany that makes Carbon tubes: http://klaushelmi.de/en/ Also take a look at these phenolic resin tubes, also from Germany, I like the look of these: https://www.gerdneumann.net/english/ Anyone got any links to tube makers in England?
  2. Just a quick update. So I have applied a few coats of resin primer, but not too happy with the roundness now. There is a difference of 2mm between the high and low spots. Also, as I thought it might be, sanding the tube is very tedious. So I have made the decision to convert the pattern jig into a mini lathe, using a router as a cutting tool. The drive motor for the tube is a stepper motor, the transmission is a bicycle chainwheel, chain etc. So far I have extended the ply end panels to accommodate the flange bearings that I am using to act as a bearing for the tube spindle. I have also fitted the flange bearings. Still have to make a spider to install the chainwheel and a drive unit to accommodate the stepper motor, bearings and sprocket. Included is a FreeCAD model of the drive end. The intention will be to install a 2020 V-Profile along each side with gantry bearings and gantry to support the router. Hopefully I will be able to get this lot up and running in the next couple of weeks to progress this build (with pictures), as once the pattern is done the mould should be quick to progress.
  3. On one of the forums a while back someone jokingly mentioned making a CF Focuser. Has anyone designed, or better still, fabricated such a thing? I am currently brewing up a few ideas and wondered what might be out there.
  4. Planetman what dia. tube is the base suitable for?
  5. Tube filled and glassed. These are two of the most tedious parts out of the way. Nice and cosy next to the rad, outdoor conditions not too conducive to curing today. I am very happy with the uniformity of shape and the surface of the GRP. Still a bit rough around the edges, nothing a little finishing won't get right........ Next stage priming. Hopefully I will get a bit more done before I have to go back to work.
  6. Spark erosion is ideal for making square holes...... or any shape for that matter.
  7. Mould tool converted into plug cradle with plug installed. Now comes the fun bit..... filling, glassing, priming, glossing, cutting and finally polishing. Then convert back to mould tool to layup one side.
  8. The mould tool. The end liners are 3mm polypropylene, and the same material in strip form will run down the sides vertically and horizontally to act as barriers for the flanges. I will post the plug cradle tomorrow, which is basically this tool converted with different end caps. Ed, thats a good reminder about tube length and car space - I must keep this in mind. I was planning on 1200 - 1250 mm, but i better double check the rear seat width.
  9. Just restarted Alan. Please excuse the tardiness of my reply, I didn't seem to get a notification. So yes, after work commitments and a minor project or two, the build has recommenced. I have started making the mould tool and plug cradle. Tonight I quickly assembled the mould tool to check the mechanical integrity and fit. Seems pretty good, stronger than I thought so no bracing required. For now, here is the kit of parts for the mould tool and plug cradle, I will try and upload a pic of the assemblies on Saturday.
  10. Morning Demon, this is an interesting question. Something seemingly simple, but frustratingly difficult to measure. I am sure someone on here has a good answer, and probably better than mine, but i'll give it a go. The best way I can think of to actually get a rough value is to turn that screw with a low range torque wrench/screwdriver at a low setting of torque. Make sure it torques out and then repeat with a slightly higher setting. Repeat until it stops torqueing out and that's your value. You may have to temporarily replace the screw with one that is capable of being driven by the wrench/screwdriver, in which case the different thread will give a false reading, however you should be in the ballpark. My school physics teacher taught a good way of visualising force (and therefore torque). Newton is associated with the falling apple, and the mass of an apple is about 100g (0.1Kg). Force =mass x acceleration. F = 0.1 Kg x 9.81 m/s2 = approx 1N. So the weight force of an apple in your hand is roughly 1N. Torque is force x distance applied from pivot. So 1Ncm would be 1 apple at 1cm from the pivot, although estimating this is, as you have eluded to, more difficult. To answer your original question, I cannot help with actual numbers of Ncm, in your particular application. Perhaps others may know ballpark figures to look for from previous projects. Don't forget you can perhaps use a gearbox to increase the torque (and reduce the step size) if required or if space permits.
  11. I use the Oxford Precision manual vernier that came as part of the "Precision Equipment Set" from my local Cromwell. I have had no complaints, it is superbly made and easily available at your local Cromwell outlet. They also do a digital set at around £50, but I can't comment on its quality. I have no affiliation or association with any of these corporations.
  12. Did you mention that these are AD Inventor models? Nice quality.
  13. Superb project Chriske. I would like to try my hand at an obstruction free scope one day.
  14. Rusted good question. I obtained a piece of 610 x 610 x 18 chipboard. Using a meter stick I drew lines (A) from corner to corner. Then I used a set square to draw horizontal and verticals lines (B) through the point of intersection of lines (A). Then I used a meter stick to draw lines (C) joining the end of lines (B). Then I used a set square to draw lines through the intersection of lines (A) and (C). This left me with four quadrants to cut out, with each quadrant having an 8 point star, the points of intersection being the centre. No measuring required. I then measured 100mm from the centre along each line to give the 8 hole positions. The centre hole is 30mm cut with a flat bit. The 8 large holes are 38mm cut with a flat bit. The small 8 holes are 10mm cut with a wood bit. The 8 large holes are to allow easy rotation of the plug on the upcoming plug bearer, when rollering etc. That carbon tube looks like a bargain for someone.
  15. Just a quick update. Managed to get the plug formers fabricated today out of 18mm chipboard. Please excuse the crudity of my workmanship. Now in plug with 30mm steel spindle. No more work for a few weeks, as I am off to BAE to do a course in Virtual Machines. I have started to draw up the plug and mould jig in FreeCAD though, and may upload a few pics in a week or two.
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