Keith Evans 3 Posted January 24, 2018 Share Posted January 24, 2018 I am considering a design that will feature a removable cowl .It will be split along the horizontal--from spinner to firewall .It is a 40 size model fitted with an I.C. engine .The bottom of the cowl will be permanently fixed to the firewall and it is the top half that will be removable .I would like to use niobium magnets .The question relates to the fixing of the magnets themselves . I am considering recessing them in the bottom and top halves of the cowl .Is it sufficient just to stick them in with either epoxy or cyno or do I need to cover them over with thin ply to retain them ? Are top and bottom magnets required or could one half be a ferrous material ?I can't give the size of the magnets required as I don't yet know the wood area of the cowl I have to play with .Size of suitable magnets for strength purposes would be helpful .I know this could be like how long is a piece of string , but any suggestions would be helpful . The magnets will be pulled apart and not be able to slide . Keith Quote Link to comment Share on other sites More sharing options...
Don Fry Posted January 24, 2018 Share Posted January 24, 2018 One point, use a magnet on one half, steel washer on the other. Use 2 magnets and the grip will be excessive. Common and nice system is a dowel peg(s) to locate the front, magnet to pull the back in, with a lip at the back to locate the rear, i.e. Stop it sliding about. Or use a screw. Quote Link to comment Share on other sites More sharing options...
kc Posted January 24, 2018 Share Posted January 24, 2018 Its an obvious point but easy to forget - if using two magnets together it's necessary to allow the other magnet to orientate itself. Leaving the top half of the hatch or cowl slightly proud - maybe 1/32 or 1/16 inch - will allow the fingers sufficient grip to overcome the magnets. Using a dowel at the front prevents the airflow from lifting the cowl and overcoming the magnets. Quote Link to comment Share on other sites More sharing options...
Geoff S Posted January 24, 2018 Share Posted January 24, 2018 I agree with the others about positive mechanical location needed and just using the magnet to hold the cowl in place. The magnet doesn't need to exposed. You can glue it/them in a recess and cover with 0.5mm ply. Using a magnet on both sides is OK but be very careful to get them oriented correctly or they'll have the opposite effect from what you need. Geoff Quote Link to comment Share on other sites More sharing options...
Keith Evans 3 Posted January 25, 2018 Author Share Posted January 25, 2018 Thanks for the suggestions .Peg ,Ply ,Washer ,Gap .and orientation all taken on board . Quote Link to comment Share on other sites More sharing options...
Keith Berriman Posted January 25, 2018 Share Posted January 25, 2018 Hello Keith. When I purchased some magnets recently there was a note inside to advise do not use the magnets touching together so I used some masking tape between the to stop metal to metal action when in use Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.