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[Login] Forum Archives · Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> ATM, Optics and DIY Forum Previous   Index   Next   Threaded   Pages: 1 | 2 | 3 | 4 | (show all) HandyAndy professor emeritus Reged: 01/11/08 Posts: 650 Loc: West Midlands and around Re: Truss pole termination idea [Re: HandyAndy]       #3413531 - 10/27/09 07:31 AM Attachment (10 downloads) Edit   Reply   Quote Quick Reply   Picture 2 -------------------- Monarch 8x42, Zeiss 10x50 WA 10mm F2, Pentax 60mm F5 City: 7" MN78: MK4#2, 10" F6.3: MK4#1, 16" F5 ParaCorr Country: 8" VISAC: (GP2) Car: 6" F5 MPCC: SP, 5" 127mm F7.5 (GP2) TV 55mm, Paragon 40mm, UO Pretoria 28mm B&L 32 Pl, Clave's 25, 8, 6, 2x Hyperions 5, 8, 13, 17, 24, 31 Nagler1 9mm, Meade 14mm 4000 UWA Antares 1.6x, 0.7x, 0.5x Post Extras:       HandyAndy professor emeritus Reged: 01/11/08 Posts: 650 Loc: West Midlands and around Re: Truss pole termination idea [Re: HandyAndy]       #3413533 - 10/27/09 07:32 AM Attachment (11 downloads) Edit   Reply   Quote Quick Reply   Picture 3 -------------------- Monarch 8x42, Zeiss 10x50 WA 10mm F2, Pentax 60mm F5 City: 7" MN78: MK4#2, 10" F6.3: MK4#1, 16" F5 ParaCorr Country: 8" VISAC: (GP2) Car: 6" F5 MPCC: SP, 5" 127mm F7.5 (GP2) TV 55mm, Paragon 40mm, UO Pretoria 28mm B&L 32 Pl, Clave's 25, 8, 6, 2x Hyperions 5, 8, 13, 17, 24, 31 Nagler1 9mm, Meade 14mm 4000 UWA Antares 1.6x, 0.7x, 0.5x Post Extras:       Glig sage Reged: 10/02/05 Posts: 370 Loc: Baltimore, MD Re: Truss pole termination idea [Re: HandyAndy]       #3413656 - 10/27/09 09:13 AM Edit   Reply   Quote Quick Reply   These pics are not clear at all. Pic 2 seems to be 2 separate truss tubes, capable of folding just a tiny bit. (like crushed tubes) Pic 3 seems to be only one truss tube. What is the purpose for the split ball inside of the truss tube? And if they are 2 separate truss tubes how do you get each half ball inside the tube? And the bolt running through the balls is attached to a thread insert? On the spider? What I really want to know is, what design requirements are satisfied with this idea? -------------------- Richard Caldwell Edited by Glig (10/27/09 09:20 AM) Post Extras:       Roy McCoy professor emeritus Reged: 10/13/05 Posts: 642 Loc: Glendale, AZ Re: Truss pole termination idea [Re: HandyAndy]       #3413746 - 10/27/09 10:03 AM Edit   Reply   Quote Quick Reply   Hi Andrew, I think these pictures are very clear. Thank you for drawing them, as I now understand your idea. Best Regards, Roy Post Extras:       HandyAndy professor emeritus Reged: 01/11/08 Posts: 650 Loc: West Midlands and around Re: Truss pole termination idea [Re: Roy McCoy]       #3414027 - 10/27/09 12:46 PM Edit   Reply   Quote Quick Reply   Hi, I would be interested in your proper CAD drawings taking into account the angles for a real world example for perhaps a 8 pole and a 6 pole example. I hope you can see now that all the forces will pass down the centre of the truss tubes which gives the stiffest result. The mirror and secondary cages should be designed to pass the forces through the triangle apexes with no residual twisting forces if possible. For the upper cage one can make a plywood ring to go inside the rolled 6mm ring and like wagon wheels of old heat shrink the rolled metal ring onto the plywood ring. The tension can then match the tension of stressed spider vanes and so cancel them out. It may be a bit stiffer to make a cut out where the tubes cross and have a bit of the full truss pole at the top to resist the cut out spreading under the tension on the bolts. I imagine a short length of a larger tube with the same internal diameter as the external diameter of the truss pole can be slipped over and welded or glued on, of sufficient thickness to make the cut out as strong as the full tube. My main design issue is with repeatability of the length between the upper and lower bolt shanks as I have to allow a clearance hole in the truss pole. If one can find a suitable solid plastic sphere to match the truss pole inner diameter then the construction is easy. A jig can be made to drill the truss pole clearance holes. The bolt clearance hole in the sphere can be machined up with a lathe accurately. A jig can be made to hold the sphere. Drill a hole the size of the sphere to drop it into. Drill a cross hole to line up with the bolt clearance hole. Push a wooden dowel through the drilled bolt clearance hole to stop it rotating. Cut the sphere in two using a router with a 6mm bit. Cheers. Andrew. -------------------- Monarch 8x42, Zeiss 10x50 WA 10mm F2, Pentax 60mm F5 City: 7" MN78: MK4#2, 10" F6.3: MK4#1, 16" F5 ParaCorr Country: 8" VISAC: (GP2) Car: 6" F5 MPCC: SP, 5" 127mm F7.5 (GP2) TV 55mm, Paragon 40mm, UO Pretoria 28mm B&L 32 Pl, Clave's 25, 8, 6, 2x Hyperions 5, 8, 13, 17, 24, 31 Nagler1 9mm, Meade 14mm 4000 UWA Antares 1.6x, 0.7x, 0.5x Post Extras:       Pages: 1 | 2 | 3 | 4 | (show all) Previous   Index   Next   Threaded   Extra information 14 registered and 13 anonymous users are browsing this forum. Moderator:  Don W, Mike I. 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