MikeQ Posted September 4, 2022 Share Posted September 4, 2022 (edited) Hello playing with a new toy, SLA printer. Also, about to start building a 3.5m Slingsby Petrel glider with an AllMovingTailplane. Similar to this thread ... I’ve printed up a bellcrank prototype but was wondering just how tough and durable SLA components would be. Its a big model but I doubt the AMT would be subject to huge loads in flight. Its not and F3F for sure. Any opinions on wether this is totally unadvisable or not an issue? cheers mike Edited September 4, 2022 by MikeQ Quote Link to comment Share on other sites More sharing options...
Brian Sweeting 1 Posted September 4, 2022 Share Posted September 4, 2022 I don't have a 3D printer but maybe one day, however, I believe that the strength should be there but make sure that the filament you use is UV resistant, you don't want it going soft in midair. Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted September 4, 2022 Share Posted September 4, 2022 2 hours ago, MikeQ said: Hello playing with a new toy, SLA printer. Also, about to start building a 3.5m Slingsby Petrel glider with an AllMovingTailplane. Similar to this thread ... I’ve printed up a bellcrank prototype but was wondering just how tough and durable SLA components would be. Its a big model but I doubt the AMT would be subject to huge loads in flight. Its not and F3F for sure. Any opinions on wether this is totally unadvisable or not an issue? cheers mike Some 3D printed parts I have come across have been easily broken by hand where the layers hadn't fused properly. An easy thing is to try is a destructive test on some parts to see if it withstand the duty you expect it to do. Quote Link to comment Share on other sites More sharing options...
MikeQ Posted September 5, 2022 Author Share Posted September 5, 2022 Hello I’d have to check my layer height but its much smaller than with my regular PLA printer. I only just got the SLA dialled in. Was a bit of a faff and so is all the cleanup etc, what with all the resin and that, but Im pretty impressed with the results. I wouldn’t attempt this with the PLA printer but the SLA component seems way more ‘homogeneous’, tougher and generally better all round. I’ll let you know how 8 get on ... hopefully not with a black bin bag collecting bits off the bottom of the slop 😳 Quote Link to comment Share on other sites More sharing options...
Graham Bowers Posted September 5, 2022 Share Posted September 5, 2022 My opinion is that it would be wise to estimate loads and environmental (temperature ) conditions and conduct some bench proof tests. I'm not experienced in SLA methods and materials so couldn't comment on the specifics. Quote Link to comment Share on other sites More sharing options...
Dave Garrett 1 Posted September 5, 2022 Share Posted September 5, 2022 Hi Mike Considering the amount of time & cost involved in building the Petrel, my advice would be, go with what Chris has put on the plan. Don't risk unknowns (3D printing) for such a critical part. Best Regards Dave Quote Link to comment Share on other sites More sharing options...
MikeQ Posted September 5, 2022 Author Share Posted September 5, 2022 (edited) Hello yeah, theres no arguing with that logic really. At the same time, we’d still be building models out of bamboo, nails and fish glue if no one tried anything different. Balsa was very definitely looked down upon as a new fangled fad back in the 20s and 30s by those in the know 😆 i printed a beefed up version, at 45 degees with support pads etc and whilst it was pretty strong in many directions failed fairly easy in one ... i guess the one that pried the layers apart at the right angle. So it will be brass tube as per ChrisWs wisdom for me 🤣 Edited September 5, 2022 by MikeQ Quote Link to comment Share on other sites More sharing options...
Dave Garrett 1 Posted September 5, 2022 Share Posted September 5, 2022 Ha HA 45 yrs in the aerospace industry tend to make one think conservatively.😀 Dave Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted September 5, 2022 Share Posted September 5, 2022 Interesting as SLA printing is supposed to eliminate layer failure by producing isotopic structures. Quote Link to comment Share on other sites More sharing options...
MikeQ Posted September 5, 2022 Author Share Posted September 5, 2022 Hi Not expert enough to argue the toss but maybe exposure time not enough. https://www.chitubox.com/en/article/support/indepth/troubleshooting/45 Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted September 6, 2022 Share Posted September 6, 2022 I was going to say while the flight loads may not be great, it can be subject to some twisting when you are pushing the tailplane halves on, a failure in flight wouldn't end well and even one on the ground would mean major surgery to repair. Quote Link to comment Share on other sites More sharing options...
Maurice Dyer Posted September 6, 2022 Share Posted September 6, 2022 I solved the same problem. Bought it from Balsa cabin / Slec Quote Link to comment Share on other sites More sharing options...
Jason Channing Posted September 7, 2022 Share Posted September 7, 2022 On 05/09/2022 at 18:05, MikeQ said: Hello yeah, theres no arguing with that logic really. At the same time, we’d still be building models out of bamboo, nails and fish glue if no one tried anything different. Balsa was very definitely looked down upon as a new fangled fad back in the 20s and 30s by those in the know 😆 i printed a beefed up version, at 45 degees with support pads etc and whilst it was pretty strong in many directions failed fairly easy in one ... i guess the one that pried the layers apart at the right angle. So it will be brass tube as per ChrisWs wisdom for me 🤣 Just finished working with some fish glue having never used it before and was amazed to how strong it is, Quote Link to comment Share on other sites More sharing options...
MikeQ Posted September 7, 2022 Author Share Posted September 7, 2022 You’re not really meant to sniff it Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted September 19, 2022 Share Posted September 19, 2022 The other thing that effects printed resin strength is the cure. Over-curing can make very brittle parts, which can be hard to avoid of course if the item is exposed to UV (the sun) a lot. This can be mitigated by mixing your own resin cocktail - one with a bit of flex mixed in proportion. I use my SLA printers for fine detail parts, and definitely wouldn't consider them fit for structural parts like this - I think you've chosen the right path! I actually think I'd trust a high infill PETG filament printed part way more than a resin part in this case. 1 Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted September 19, 2022 Share Posted September 19, 2022 It would seem sensible to print structural parts with provision to insert carbon reinforcement, this is how some of the fully printed airframes are done. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted September 19, 2022 Share Posted September 19, 2022 My concern is not so much the strength of printed components, in the line of the bead even PLA is really quite strong, but the overall weakness and brittleness resulting from the thin sections required to keep the overall weight within bounds. The light weight self foaming filaments are going in the right direction but do as yet have limitations. Overall most planes end up with a mixture of materials each suited to the required duty and in many cases actually bonded together in such a way that one imparts its properties to the other. IMHO printing a complete plane from a single material even with inserted carbon reinforcement is a long way from the ideal. Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted September 19, 2022 Share Posted September 19, 2022 4 hours ago, Simon Chaddock said: ... IMHO printing a complete plane from a single material even with inserted carbon reinforcement is a long way from the ideal. They work though... Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted September 20, 2022 Share Posted September 20, 2022 22 hours ago, Andy Stephenson said: It would seem sensible to print structural parts with provision to insert carbon reinforcement, this is how some of the fully printed airframes are done. For sure, on the airframes and bigger parts, it's definitely so-able. For smaller parts like that tailplane bellcrank, I'd be really tempted to try and make a 3d printed compression mould, and mould it from carbon. 1 1 Quote Link to comment Share on other sites More sharing options...
MikeQ Posted September 25, 2022 Author Share Posted September 25, 2022 Now thats an idea 😀 1 Quote Link to comment Share on other sites More sharing options...
John Minchell Posted July 21, 2023 Share Posted July 21, 2023 Sorry, but as an engineer and user of 3D printer, I would never make such a flight critical part as the elevator bell-crank out of anything which could be suspect. A local club's existence is potentially in the balance due to an elevator failure and crash into the farmer's garden. So personally I wouldn't make a bell-crank out of anything less than a sheet of G10 glass or carbon sheet - to ensure its mechanical strength and longevity. Also all the Micro Mold plastic bell-cranks I have in the spares box will remain in there now, as most of them are 20 to 40 years old and God (if there is one) only knows what the material degradation has been. Just my 2 pence worth. John M Quote Link to comment Share on other sites More sharing options...
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