By remmie - 7/31/2014 9:08:28 PM
Hi, Looking for advice and thoughts; I'm looking to create a quarter circle tube, approx 1.3m diameter, 18ID, 20OD. Problem is it needs to be a fairly accurate circle as 4 pieces will be joined to make a ring (demountable prop guard ring for a drone). At the moment I'm thinking getting a mandrel made from aluminium tube; take it to metal workers and get them to bend me a 120 degree circle. My concern is would I be able to break the part from the mandrel even if it was a perfect curve without being able to apply any torque to it. Would I need to step down a size and apply a thin wall silicon tube to it to break away cleanly and handle any deviations in the curve? Layup schedule will be CF uni, 45/45 CF braided sleeve, 300g Eglass sleeve (need colour and want some sacrificial body), heat shrink tube for compression. The completed ring needs to make a decent effort of surviving 6kg of force slammed into the ground at decent speeds. Thoughts, comments, suggestions? |
By remmie - 7/31/2014 11:07:53 PM
Hi, By 'A' surface are you talking about atheistic or consistent OD/ID? My composite experience comes from boat building, CF is about strength/weight... not look!!  The quarter joins I was thinking male plug (aluminium insert or CF plug with an ali sleeve) on one end to ensure OD plug matches the ID of the main tube (as ID would be consistent, reverse the idea for a female mould). There's going to be inward struts for motor mounts and hub join (think wagon wheel) from mid point of each quarter, so it doesn't need to be perfect joint, a bit of movement is fine, it's more as a propellor (anything the propellor could hit) protector. What do you suggest for split mould technique.... I've seen the technique but never found details on what to use for internal pressure bag? Assuming it would get killed with each cast so what's cheap and effective? Been thinking over wash out cores (or even just CNC'ed foam male plug) but obvious fail for repeat performances. |
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