# Help with birdsmouth joint please



## Gaz (1 Oct 2012)

Hi everybody, I'm looking for the best way to cut a self locating birds mouth joint from rafter to wall plate, something like the picture below, I don't know if anybody recognises it, any other suggestions are more than welcome,

Thanks in advance,

Gaz.


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## Jacob (1 Oct 2012)

I'd miss out the complicated toggle thing and just nail it. But if you really want to locate it what about housing the top or the face (or both) of the birdsmouth into the wall plate, just 10mm or so if it's for location only. Easy to do.


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## Gaz (1 Oct 2012)

Hi Jacob, thanks for the reply, I'm only looking to locate the joint for ease of assembly, these frameworks are to be supplied in kit form and I want the simplest form of assembly for my customers, I was thinking dominos or something completely different, I'm not too sure on this one, 

Cheers, Gaz.


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## Dibs-h (1 Oct 2012)

I'd give the self locating thingy amiss and screw, nail or peg it. 

I can't see anything to be gained by the "self locating" element - in a "completed" roof, little if any lateral forces act at the intersection of the the rafter\wall plate.

I appreciate the idea of ease of assembly - but it's not Ikea is it? :wink: 

Dibs


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## Gaz (1 Oct 2012)

Sorry guys, I didn't explain myself properly, these timbers are going to be machined and seen from the inside, these kits need to be high quality and need to be assembled easily by the customer, I'm looking at using insert nuts and flat Allen bolts for the fixings, the reason for the self locating joints are for the customers benefit, not having to use a tape etc and more importantly so the don't put the kit together wrong, hope I explained myself a bit better,

Cheers, Gaz.


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## deserter (1 Oct 2012)

Could you drill a hole of a dowel in both the wall plate and the birds mouth, and then the customer only has to push the dowel into each hole?


~Nil carborundum illegitemi~


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## Hudson Carpentry (1 Oct 2012)

Are the beams laminated?


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## Gaz (1 Oct 2012)

Deserter, I had thought of dowelling the joint, this might be the route I take, cheers, HC the beams are solid machined sapele 57mm x 100mm

Cheers Gaz


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## kostello (2 Oct 2012)

you are over engineering this...........................

of it is for your orangery roofs then all if needs is 2 screws down through the top of the rafter into the wall plate........

thats all the big firms do...... insert nuts etc is a waste of time and money.

just trying to be helpful...


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## Gaz (2 Oct 2012)

Thanks kostello, maybe I am going a bit too far with it, I'm just a bit worried customers will balls the installation and blame the product, I think I'll give it a go with a standard birdsmouth cut and see how people get on with it


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## deserter (2 Oct 2012)

Kostello, your absolutely right but let's look at this from another perspective. 

An accountant from Oxford buys one, his tool kit comprises of a hammer his dad gave him and a cheap screwdriver set from halfords. He decides he wants to get more hands on and do his own "grand design" so he opts to build an extension/conservatory. After a little research he discovers kits to help, so, armed with his new tool 'Stanley fat max 8m tape" from b&q he decides what size he beads and orders. 
Several months later he gets round to hitting the roof only to find these wierd cut bits of wood, that gave to be somewhere on a centre to something. 
Needless to say it goes horribly wrong. 
Now everyone here has a talent and can see where this guy went wrong. The problem is he will never blame himself, no it will be the kits fault, the tools fault, the weathers fault possibly even a small third world dictators fault. The point is, if it doesn't work for him, he'll tell as many people as he can who's fault it was. 

I say over engineer it, make it as simple as you can. That way basic things can't go wrong and ruin your reputation. 


~Nil carborundum illegitemi~


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## Dibs-h (2 Oct 2012)

deserter":2cc7pyy7 said:


> I say over engineer it, make it as simple as you can. That way basic things can't go wrong and ruin your reputation.



Over engineering costs money and could result in pricing your kit out of certain markets\sectors. You should clearly state who the intended market is (somewhere) and what the capability should be along with what tools would be needed.

Might be an idea to make the instructions\manual "stupid proof" - you only need to do that once and after that it's just printing.

Trying to "stupid proof" the assembly - unless folk pay for this over engineering, why should the maker?

It might be an idea to offer a range of kits - normal, delux and silly person proof? Priced accordingly.

My 2p worth

Dibs

p.s. What about the glazing - our Accountant from Oxford, how do you think he'll get on with that? :wink:


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## Jacob (2 Oct 2012)

Gaz":1qn3k8x7 said:


> Thanks kostello, maybe I am going a bit too far with it, I'm just a bit worried customers will balls the installation and blame the product, I think I'll give it a go with a standard birdsmouth cut and see how people get on with it


A little housing on the wall plate would do it for location. Need only be 5mm deep.


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## kostello (2 Oct 2012)

almost all the people who do this sort of thing have an infill piece that is fixed between the rafters on the wall plate which locates the rafters.

it also hides the bottom seal on the glass and gives somewhere for the lower glass support to clip in or the step on the sealed unit to sit.


no need for housing or anything else.......

i think that Gaz may need to do a bit more research into the correct glazing of these structures......????????

just guessing


see no gaps......


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## Sgian Dubh (2 Oct 2012)

Dibs-h":2zhx5xom said:


> It might be an idea to offer a range of kits - normal, delux and silly person proof? Priced accordingly.
> Dibs


Ah, but even if something is silly person proof, there's always a dumber silly person out there with enough native wit and the low and cunning ingenuity to find new ways to somehow screw up any given job, ha, ha. Slainte.


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## Dibs-h (2 Oct 2012)

Sgian Dubh":xp565atg said:


> Dibs-h":xp565atg said:
> 
> 
> > It might be an idea to offer a range of kits - normal, delux and silly person proof? Priced accordingly.
> ...



Yes - that'll be the one that requires the delux* &* silly person proof kit. :wink: :lol: 

Dibs


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## Peter T (2 Oct 2012)

I used to work for company that made electro-mechanical switchgear for aircraft. One of the old lags there had a saying -

You can make something fool proof, you might even be able to make it silly person proof, but you will never, ever make it c*nt proof.

Pardon the bad language,


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## plug (2 Oct 2012)

Jacob":3vz4jmd7 said:


> A little housing on the wall plate would do it for location. Need only be 5mm deep.



A lot of old buildings I repair or demolish have notches in the wall plate, mostly the oak timber framed houses.


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## Gaz (3 Oct 2012)

Thanks a lot for your advice guys, your opinions have really helped, I can see I would be wasting my time over complicating the joints, I think I will use dowelling joints throughout the assembly like deserter mentioned and include some high quality furniture fixings to hold it together and a tube of glue, some simple dowelling jigs should make it a pretty easy build, I don't want it to seem like a home base product but on the other hand I don't trust Dave down the road having a go with his hammer and nails, there is a fine line aye, kostello I see what you mean I bout the infill, I think I might chamfer the wall plates at the rafter angle and rebate the tops to locate the birds mouth, I have glazing and bar assembly's sorted, I was going to use an aluminium bottom rail to support the glazing but won't need that now  dibs good idea ill be mocking it up in softwood first so if the result is acceptable ill think about a cheaper range, Peter LOL, plug, good shout ill give that a try out, 

Just wanted to thank everybody, I've been on a number of forums and left pretty sharpish, bad advice and arrogance, this is a great forum you've been a massive help

Cheers, Gaz.


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## kostello (3 Oct 2012)

I have seen the wall plate cut at the same bevel as the roof pitch which the gives you a 90 degree cut on the bottom end of the rafter.

It would be simple thpo cut a small housing in the wall plate and a stub tenon on the rafter......

Not sure where the fixing would go...probably into the end grain from the outside..

Might look nice



ETA. I've just reread you post and realised this is exactly what you are talking about oops.


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## Gaz (5 Oct 2012)

Lol, yeah I think that's what I'm going to do, I'll do a mock up in soft and check it for looks and strength, I'm sure ill be asking some more questions at some point, next stage making some jigs :-/


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