Tim Kearsley Posted February 22, 2022 Share Posted February 22, 2022 This is probably elementary to you experienced builders - I have some magnets, 10mm diameter and about 1mm thick, which I intend to use to secure a battery hatch on a Cessna I'm building. How would you produce nice, tidy circular recesses in the balsa frame to hold the magnets, so that the magnet is flush with the balsa surface? Quote Link to comment Share on other sites More sharing options...
Nick Somerville Posted February 22, 2022 Share Posted February 22, 2022 Hi Tim, I have used a piece of sharpened tubing the same diameter as magnets I have, to cut a hole through the location. I then cut a plug with the same tube and then glue plug and magnet together into the hole so that the magnet ends up flush. Quote Link to comment Share on other sites More sharing options...
Tim Kearsley Posted February 22, 2022 Author Share Posted February 22, 2022 That sounds a neat idea Nick. I hadn't thought of going right through the balsa but that could be a very neat solution. Thank you. Quote Link to comment Share on other sites More sharing options...
Trevor Posted February 22, 2022 Share Posted February 22, 2022 I usually drill a suitable size hole in a piece of 1/16” ply, glue that onto the balsa, then epoxy the magnet into the hole in the ply. I like Nick’s idea though! Quote Link to comment Share on other sites More sharing options...
Matt Carlton Posted February 22, 2022 Share Posted February 22, 2022 For smaller diameter magnets, I have glued a disc of sandpaper to the end of a piece of dowel and chucked that into a drill. 10mm is a bit big for my drill though. Quote Link to comment Share on other sites More sharing options...
Stuphedd Posted February 22, 2022 Share Posted February 22, 2022 I do the same as Nick. I use 6x3mm magnets from ebay , cheap as chips and normal cyno glues them in the tube cut holes very well never had a failure yet . I do use them in pairs , ie one in the top and another in the bottom to give a very strong "bond" do the same in foam but do you foam safe cyno !! cheers Quote Link to comment Share on other sites More sharing options...
extra slim Posted February 22, 2022 Share Posted February 22, 2022 And to ensure decent alignment do one magnet and then place a tiny tiny piece of bluetak perfectly in the middle. Then place the other surface down onto it, lift and you have an exact centre to drill the other one.. works for me and means both are neat. 1 Quote Link to comment Share on other sites More sharing options...
Tim Kearsley Posted February 25, 2022 Author Share Posted February 25, 2022 For anyone interested I have found another reasonable solution. A clubmate has lent me a set of Forstner drill bits. They make a superb, clean circle which is almost flat-bottomed, with just a small indentation in the middle of the recess. 1 Quote Link to comment Share on other sites More sharing options...
john davidson 1 Posted February 25, 2022 Share Posted February 25, 2022 I recycle magnets from defunct motors ,glue one in with Por, cover with thin tape put another magnet on top , leave to set , then do the same on the other side. does that make sense bccause the lads have been in for a sessionn finishing with Jim Beam Quote Link to comment Share on other sites More sharing options...
kc Posted February 25, 2022 Share Posted February 25, 2022 (edited) I use the tiny hatch magnets and drill a hole very slightly deeper, put a blob of epoxy in the hole, then insert magnet and cover with a flat bit of steel covered in parcel tape etc. The magnet then pulls itself up level with the surface but the epoxy does not stick to the parcel tape. Using the same method it's possible to make magnetic saw guides in the manner of the Nobex saw guide. The saw blade but not the teeth can then run guided along a wood block with magnets flush with surface. Edited February 25, 2022 by kc Quote Link to comment Share on other sites More sharing options...
john davidson 1 Posted February 25, 2022 Share Posted February 25, 2022 I recycle the magnets from old motors, glue one in with Por, cover with thin tape , wait to dry then do the same on the other side, care fully lined up Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted February 26, 2022 Share Posted February 26, 2022 13 hours ago, kc said: I use the tiny hatch magnets and drill a hole very slightly deeper, put a blob of epoxy in the hole, then insert magnet and cover with a flat bit of steel covered in parcel tape etc. The magnet then pulls itself up level with the surface but the epoxy does not stick to the parcel tape.. . . . I use this method to get the first magnet flush with the surface, having drilled holes through the two mating surfaces clamped together, to make sure they match exactly. Then for the mating magnet I put a piece of cling film over the installed one, attach the mating magnet to it (makes sure the polarity is correct!), and then fill the hole in the mating piece of structure with epoxy and clamp it over the magnet until it's set. Quote Link to comment Share on other sites More sharing options...
Tim Kearsley Posted February 26, 2022 Author Share Posted February 26, 2022 Yes, getting the magnets oriented so that they attract rather than repel is fundamental! I made a hatch for a Warbird Replicas P51 last year and completely forgot this aspect. Would you believe, every one of the four magnets was in wrongly, so my hatch hovered a couple of inches high rather than provide a firm joint! Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted February 26, 2022 Share Posted February 26, 2022 Even the best manufacturers get this wrong. I ordered a replacement canopy for a Sebart Angel and after a lot of head scratching as to why it refused to seat I discovered that they had put in the opposite polarity magnets in the replacement. Quote Link to comment Share on other sites More sharing options...
PatMc Posted February 26, 2022 Share Posted February 26, 2022 (edited) For magnet fixing I always use either soft iron or tinplate on one side with one or two magnets on the other. Iron/tinplate is usually fixed at the rear of the hatch/canopy opening , with hole/slot to take a peg at the front. Magnet(s) are fixed with cyano usually to the hatch/canopy. One exception was my MPX Easyglider, which had 4 magnets cyanoed in place when one of the supplied plastic catches broke. Edited February 26, 2022 by PatMc Quote Link to comment Share on other sites More sharing options...
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