Magnetic door closures

Anything to do with mechanical, construction etc

Magnetic door closures

Postby patmorin » Mon Jun 29, 2015 2:02 pm

I'm planning a 5'x5'x8' teardrop that will have 3/4" plywood walls. I'd like to make the doors out of the same plywood and am thinking of the following design:

door.png
door.png (10.35 KiB) Viewed 480 times


  • The door will be shaped like a 36"x46" rectangle with 6" radius rounded corners
  • The door will be cut at a 15 degree bevel, so the inside is smaller than the outside.
  • I'll use a 36" stainless steel piano hinge for the hinge
  • I'll attach an inner door frame that is an inch smaller than the inner part of the door.
  • I'll use thin weather stripping on the inner (smaller) part of the door that will seal against the frame and outer part (or maybe I'll put this where the inner frame meets the wall).
  • Magnets in the frame, mated with screws or magnets in the door will be used to keep it closed tightly (magnets from here: http://goo.gl/I6pEjL)
  • A magnet in the wall, mated with a magnet in the door will hold the door open when we want to leave it open.
  • The magnets in the door frame give a place to attach an interior screen if we want to sleep with doors open.
  • I plan to seal the exterior and openings of the teardrop with West 105 so, between that and the bevelled/sealed door, I won't use any moulding around the doors. Any water that gets in the crack will get stopped by the weather stripping and drip out the bottom (exterior) of the door (thanks to the bevel).

I'd be interested in any feedback from the more experienced teardrop builders and woodworkers. Of course, I plan to build a half-scale one out of scrap plywood I have around before trying it for real.
patmorin
Teardrop Inspector
 
Posts: 2
Joined: Wed Jun 17, 2015 3:38 pm

Re: Magnetic door closures

Postby KCStudly » Mon Jun 29, 2015 2:56 pm

Not intending to discourage, just doing my best to answer the question and share the pitfalls that might need to be steered around.

I see no point to the beveled edge. It just complicates things unnecessarily. I believe you will find that even 3/4 ply will tend to warp some, and that you will need some stiffening to maintain a flat surface for the seal; 1x2 frame on edge works well. Of course, full disclosure, I am of the mind that these little campers should be stick built as lightly as practical (I am building a foamie hybrid, after all), so there should be no need for 3/4 inch ply anywhere. I mean, if you have to build a 1x frame to stiffen the door and opening anyway, then why not start with 1/4 ply in the first place and save some weight? But then again I understand the appeal of a fast build using simple plywood construction.

I say go ahead and place the magnets for the screen insert, but I would not rely on them for security or the ability to hold the door closed going down the road. Wind, bumps, and curious outsiders (lookie-loos or crooks?) kind of mandate proper locking door latches. I know, I know, if people... or bears... want in they are coming in, but we are talking about the opportunistic ones here, right? What if you are bopping on down the road, you hit a big chuck hole and have to swerve to miss the next one; meanwhile your duffel bag just jumped out the door and is bouncing off into the Tully whackers?

Okay, you may argue that there are some really strong magnets out there, but unless they have a switch to turn them off (...okay, okay, some do; but that's not my point...) how the heck will you be able to open the door that has magnets that are sturdy enough to keep it closed under the dynamic conditions of road travel? Might work okay for the hold open situation where less holding power is needed, but you will have to plan that out pretty well in advance to make sure that you can get the two to come together given any trim, windows, latch hardware, rain drip edge, etc. and that they have the exact strength needed to hold the door in light wind w/o being too hard to operate. All of that can change with a coat or two of paint, too. Magnets rust.
KC
My Build: The Poet Creek Express Hybrid Foamie

Poet Creek Or Bust
Engineering the TLAR way - "That Looks About Right"
TnTTT ORIGINAL 200A LANTERN CLUB = "The 200A Gang"
Green Lantern Corpsmen
User avatar
KCStudly
Donating Member
 
Posts: 9610
Images: 8169
Joined: Mon Feb 06, 2012 10:18 pm
Location: Southeastern CT, USA

Re: Magnetic door closures

Postby patmorin » Mon Jun 29, 2015 3:16 pm

Thanks KC. I appreciate the feedback.

I wasn't sure myself about the bevelled edge (in particular, how it will interface with the piano hinge), but I do want some way for water to run out.

Apropos the warping, I was hoping that by using an array of 3 or 4 magnets along the height of the frame, this would keep the door aligned and flat against the frame. On the other side, the piano hinge should keep it from warping.

Getting just the right strength will take some experimentation for sure. I'll build a model door before I start the project at all.

I'm not too worried about doors opening on the highway---wind is on my side. Security is a different issue, not one I'd worry about on a campground, but maybe when parked and unattended in a parking lot.
patmorin
Teardrop Inspector
 
Posts: 2
Joined: Wed Jun 17, 2015 3:38 pm
Top

Re: Magnetic door closures

Postby aggie79 » Tue Jun 30, 2015 8:52 am

+1 on what KC said. I might add that a general rule is that door seals / weather-stripping need to compress 1/4 to 1/3 of their thickness to be effective. It may difficult to do that with magnets alone.
Tom (& Linda)
For build info on our former Silver Beatle teardrop:
Build Thread

93503
User avatar
aggie79
Super Duper Lifetime Member
 
Posts: 5405
Images: 686
Joined: Tue Aug 07, 2007 5:42 pm
Location: Watauga, Texas
Top

Re: Magnetic door closures

Postby woodywrkng » Wed Jul 01, 2015 9:52 am

I considered sealing my doors in the same manner as refrigerators, or steel exterior doors, with magnetic weatherstripping. If you can work that into your design it could be pretty unique.
User avatar
woodywrkng
Silver Donating Member
 
Posts: 104
Images: 35
Joined: Sun Apr 22, 2012 3:54 pm
Location: DeSoto, Wisconsin
Top

Re: Magnetic door closures

Postby GuitarPhotog » Fri Jul 31, 2015 6:37 pm

The wind may not be in your favor. The airflow can cause a low pressure area that causes the door flap to open, especially if an accidental air intake up front causes a high pressure area in the interior. If I don't latch my top hinged window when traveling it will float open to almost 45 deg.

<Chas>
:beer:
GuitarPhotog
Silver Donating Member
 
Posts: 1779
Images: 55
Joined: Tue Feb 08, 2011 12:52 pm
Location: Grants Pass Oregon
Top


Return to Teardrop Construction Tips & Techniques

Who is online

Users browsing this forum: Google [Bot] and 15 guests