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Mutley Racers

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Hi, is there a rule of thumb on how much timber you buy for projects with wastage etc?

Is there also a rule of thumb on calculating depths, quantity and the thickness of tenons on work pieces.

Say for a 4 panel door.

Thanks for all your help guys.

Hope you have a great weekend
 

Droogs

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Hi Mutley
with regard to wastage it depends on if you are using rough planks (upto 50%) or prepared stock (about 20%) roughly, wood type dependent as well.

general rule of thumb for mortices is the rule of 1/3s. Usually the tenon will be about 1/3 the width in thickness and once the thickness is over an inch then you can start doing double mortices. In terms of how deep they should go roughly 2/3s if a closed m/t or just go all the way through with a wedge on the outside face or draw-bored pegs if prefered.

hth
 

MikeG.

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Stick to two or three different types of timber, and deliberately over-order every time you buy.* That way you'll build up a stock of wood such that little bits and bobs don't involve going out and buying wood specifically. Too few people here have stocks of wood. My view is that workshops should be more about wood, and less about tools and machinery.

* Beginners generally make the mistake of not having enough spare wood built into their buying and cutting lists, meaning a misplaced flaw in the timber can either wreck a project, or that they're forced to go back to the stockist and buy more.
 

deema

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For a door, I’d order order rough sawn stuff 1/4” larger in width and depth to the finished size as a minimum on good joinery grade wood. I allow 10” on each length for both machine setup and any jointer snipe. If it’s not stuff I have in stock I order an extra length for a style in case of any faults.

M/T are set to 1/3 depth as stated and no wider than 6 times their depth. For the bottom and middle rails that usual required twin tenons linked by a circa 1” deep stub / haunch tenon. On the bottom and top rails allow at least a 1” wide and circa 1/3 of the stock deep haunch. With the panel rebate it usually means that the haunch is c1 1/2” long, the same as the stub tenon. This works nicely with 4” wide styles.
 

Jacob

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That 1/3 rule is just a rough guide - basically you don't want a mortice to be much more than 1/3 or it'd be weakening the construction. Less is OK. You don't want a tenon to be much less than 1/3, ditto. More is OK.
Usually it's dictated by the size of the mortice chisel - most common being 1/2" and most doors have 1/2" M&Ts with tenons thinner than the rule e.g. 13mm on a 44mm rail.
May not be central - position may depend on other details such as rebates and mouldings.
 

AndyT

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If you are making a door with through m+t joints at the corners, the usual practice is to leave extra length of an inch or two beyond the mortices, at least it is in trad hand work.
This helps prevent the last bit of end grain splitting out when you are cutting the mortices. It also leaves "horns" on the door which prevent any damage in transit or handling. You saw them off when fitting the door into the frame.
So that's a bit more length to allow for on each stile.
 

Mutley Racers

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Hi everyone. Thanks for all the advice. I have been searching my books people have bought and the web for info on sizing mortices and tenons etc. Should really have come here 1st.

Will try a few different woods at 1st to see which I like the pattern of and work ability of it and then stick with 3. Good advice that. Best to have too much wood than too little. Well, as much as space allows!!
 
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