Plywood doors

[Sir Percy]

Hi,

I plan to make a pair of doors - outswinging, exterior, need to put up with a fair bit of abuse, rough dimensions 1000 x 250 x 36 (h x w x d) mm. Flush surface. Need to mount a lock.

So what I'm thinking of is two skins of ply 12mm thick, 980 x 230, centred and glued onto a slightly larger ply sheet, 990 x 240 to give me the thickness required and a tongue running along the centre of each panel edge, to fit into a hardwood edge (20 x 36) on top, bottom and sides. Edge has central groove 12 wide, 10 deep.

I don't have a router or table saw of my own, though may be able to have the use of these, might be able to get my hands on a plough plane.

Asking for advice, please:
Is this a good construction?
Is there a better / simpler way?

Apologies if I've used the wrong terms, or missed out any information.
They're for a narrowboat, btw.

Many thanks in advance.

 

[Zeddedhed]

If you make the middle piece of ply smaller all round by 10mm on each edge then you don't need a tenon.

 

[Sir Percy]

If you make the middle piece of ply smaller all round by 10mm on each edge then you don't need a tenon.

Maybe I've misunderstood, but the thinking behind having the middle piece of ply deliberately larger was to have something to fit into a groove, instead of just glueing the edge strip to a flat surface.

 

[Zeddedhed]

I get it. My bad.

 

[Sir Percy]

No problem, thanks for replying. Description probably wasn't that clear; I'd basically looked at a plan for making a frame-and-panel door and mangled it from there...

 

[monkeybiter]

If your gear is limited then that should work fine, saving work that might be trivial for more equipped/experienced woodworkers, dry fit it all prior to gluing to be sure of a good fit, I'd add plenty of glue [can clean up later] and plenty of weights [two or three bags of sand or similar] over a flat surface while glue is going off, probably glue the central piece into the frame first , then the outer panels to prevent creep/slippage and missalignment.
I'd also bang a load of 1 1/4" screws from the inside [in a regular pattern] but then I put screws in everything.

That said, experts will be along shortly.

HTH

 

[Sir Percy]

I'd add plenty of glue [can clean up later] and plenty of weights [two or three bags of sand or similar] over a flat surface while glue is going off

Ah yes, I'd read warnings about warping on other build blogs

probably glue the central piece into the frame first , then the outer panels to prevent creep/slippage and missalignment.

That's a good idea, had been worried about getting the panels lined up right.

Thanks for your help!

 

[AndyT]

I think your approach ought to be doable but it will be challenging to get the panels sized and square to the framing on both sides and then fit the doors to the hole.

A few other thoughts:

Plywood thickness is generally less than the nominal size, so measure what you are offered before you buy. 12mm ply may only be about 10mm thick.

Consider using thicker ply instead of building up in three fiddly layers. Your outside lipping could then be T section rather than U section which could locate tidily and would fit against the cut edge. Ploughing a groove is not easy into plywood but could be done with a circular saw and designed to match a whole number of layers.

A possible source of good thick ply would be a fire door blank - one would be enough to make your two doors and you could even use a slightly damaged one, sometimes available cheaply. However they might be too thick at 44mm.

The quality of much plywood is pretty poor these days and you will need quite a lot of work on surface prep before you can get a good paint finish.

Do plan ahead for how you will be jointing your frame at the corners. A full length mortice and tenon would be best. Second best would be stub M&T following the shape of the ply. Simplest but weakest would be mitres, like a picture frame.

You will need a way of covering the gap between the two doors when closed. The simplest way is to add a strip of wood or metal down the edge of the door which closes second. Alternatively you could work a pair of rebates but you might then want to adjust the width of the stiles so they look equal. This can also complicate your choice of lock!

Narrow boat doors do seem quite hard to design to be properly secure while still being easily opened from the inside. A big visible padlock and hasp can just say "there's nobody in, so break in now". Most boats I've seen rely on tiny little brass cupboard bolts to secure the doors, which seem pretty useless to me.

 

[mindthatwhatouch]

I am umming and aahhing about similar albeit larger doors.
Worried about the ply delaminating which would be even more of a concern on a boat.
External Fire door blank would seem the way to go.

 

[Sir Percy]

Do plan ahead for how you will be jointing your frame at the corners. A full length mortice and tenon would be best. Second best would be stub M&T following the shape of the ply. Simplest but weakest would be mitres, like a picture frame.

Hmm..had planned ahead - but had planned on mitres. Rethink.

You will need a way of covering the gap between the two doors when closed. The simplest way is to add a strip of wood or metal down the edge of the door which closes second.

Will reuse the metal strip off the old doors...

Narrow boat doors do seem quite hard to design to be properly secure while still being easily opened from the inside. A big visible padlock and hasp can just say "there's nobody in, so break in now". Most boats I've seen rely on tiny little brass cupboard bolts to secure the doors, which seem pretty useless to me.

Will be mounting one of these: http://www.amazon.com/NU-SET-2125-3-Locking-Deadbolt-Cylinder/dp/B007A4SP8I

Thanks

 

[Benchwayze]

Sir Percy,

You can always groove the edging and the edges of the door, after you are sure all is sized correctly. All you need do then is make a loose plywood tongue to fit the grooves, when you glue on the edging/framing. That will save you fiddling about allowing for a 'built-in' tongue. Just set the router to the required setting and work from one face, and you're golden.

When joining large plywood sheets, you will probably find the sheets 'creep' on the glue, as you try to clamp them up.
To avoid this, get the sheets dead in line with a dry run. When you have them in the right place, clamp them so they can't move and drive a screw at each corner. Then you can use the screw-holes as reference to position the sheets, when you come to glue. Saves a lot of heartache!



HTH

John

 

[Sir Percy]

Just set the router to the required setting and work from one face, and you're golden.

Good idea...just need a router!

When joining large plywood sheets, you will probably find the sheets 'creep' on the glue, as you try to clamp them up.
To avoid this, get the sheets dead in line with a dry run. When you have them in the right place, clamp them so they can't move and drive a screw at each corner. Then you can use the screw-holes as reference to position the sheets, when you come to glue. Saves a lot of heartache!

Good tip.

Thanks

 

[Benchwayze]

Sir Percy.

No problem ref a router. Trouble is I live in Brum.

Actually, I think you can buy a 'two month wonder' for a few quid. Good enough to do this one job at least, and may last you considerably longer!
Best of luck

John