Woodwork Joints

Carcase construction

Geoff's Woodwork

for Students of Woodwork

Woodwork Joints For setting out joints see the paper 'Basic Setting Out 1' here and follow the articles through. When you have cut down the shoulders of a tenon properly, removed the waste of a halving and chopped out a mortise all these skills are repeated for most of the other types of joints. Remember to cut the shoulder lines with a sharp knife and 'vee' it partially to get a good joint. A tight joint is not needed, just fitted well. If it is too tight the glue will be forced out and any minor imperfection will throw the frame out and into 'winding'. There are numerous 'rules' for beginners and improvers to learn and at times it seems like there are too many. They are not my rules. The 'rules' however, are the techniques handed down as the most effective way of doing things. They reduce your error and allow you to work more efficiently and above all - safely. Later when you have learnt the techniques and you work effectively you may find 'other' ways. But you will understand and know the penalties when things do not quite go as they should and why! An important set of rules is the order of work see here. On many occasions if you cut a shoulder for instance before you have worked the groove or rebate you may find it difficult or tricky to use the plane or router, etc. on the reduced length. These rules make it easier and reduces error. How to actually cut the joints is well covered in the 'Stanley's how to sheets'. These are excellent for getting the basic techniques. If you read, understand and practise these techniques successfully you are 70% a woodworker. You then need to know about cabinet construction and lots of practise and experience to become proficient. I would like to add just one tip ~ when sawing to line or shoulder it should be well defined with a sharp H2 pencil, or gauged or in the case of shoulders, pre-cut with a sharp knife AND then saw as close to the line, on the waste side of the line, as possible. Your aim actually is to try and cut the line in half ! It is a mistake to leave a little on to trim to the line later. This is wasteful and the longer you rely on it you will never cut a straight or accurate line or shoulder. Remember if you are using powered saws, the 'kerf' could be as thick as 4 to 5 mm's thick.

The basic joints:

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Carcase construction

To see detailed isometric drawings of how the mortise and tenon joints are constructed see the three different frame joints here. a. Through haunched Mortise & Tenon. The haunch is to prevent the joint becoming 'bridled' and by reducing the width to 2/3 rds it reduces the tendency of the tenon cupping and thus putting the frame in 'winding'. see paper on M & T here. b. Secret haunched Mortise and Tenon. The secret haunch is achieved by cutting it at 45 degrees. This is needed for instance when the top of the frame is exposed such as a cane seat on a stool, etc. c. Secret Haunched Stub Mortise and Tenon. The Stub hides the end grain of the tenon coming through. The M & T mid way to receive a rail or runner, etc. would not need to be haunched. However, it is prudent in all cabinet work to have a small shoulder top and bottom of say 2 to 3 mm to hide any 'blemishes' that may be exposed on cutting the mortise. d. Corner rail to leg. The M & T is 'bare-faced' to allow the cheek of the rail to line up with the outside of the leg or stile. The meeting tenons are mitred to gain the maximum length. Note that it is also 'haunched' to prevent the joint http://www.geoffswoodwork.co.uk/joints.htm (2 of 5)7/27/2004 7:42:55 AM

Carcase construction

becoming 'bridled'. ( A lower rail would not need the haunch - see above) e. Corner or 'L' bridle for a carcase frame. f. Corner or 'L' dovetailed bridle, similar to above but stronger. Some chair seat are done like this. g. 'T' Bridle, Stile to mid-rail. A mid leg is often jointed like this on a half round table.

h. Corner halved or 'L' joint. With countersunk screws to reinforce it. For Carcassing quality work, etc. i. 'T' Halved Joint - For Carcassing. The 'X' or cross rail halving is similar where two rails cross but both rails continue. j. Mitred corner joint - hides end grain, suitable for table top mouldings and picture frames, etc. k. Halved corner Mitre Joint. As above but stronger. Use where the end grain may be hidden.

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Carcase construction

l. Butt joint. often nailed with round headed nails from the rail in a 'dovetail' fashion. This is called 'skew' or 'tosh' nailing. Low quality carcase ~ carpentry. m. Square through housing. Carcassing and carpentry. Often strengthened with nails as above. n. Stopped Housing - the stop or 'lap' is to give a better line of view. o. Dovetailed housing - helps to pull the carcase, etc. together. p. Stopped or 'lapped' housing or 'dado' for shelving or partitions, etc. May be vertical or horizontal. q. Stopped or 'lapped' dovetailed (single or double) housing or 'dado'. As above for extra strength and resisting pull. P&q above are often used vertically as a divider. (turn the illustrations 90 degrees left CCW). The stopped part of the joint should be to the front to hide the dado or housing.

r. Common halved 'T' frame dovetail. For Carcassing - the dovetail resists the lateral pull. Soft wood ratio is 1 : 6 and hard wood ratio is 1 : 8. There are other ratio varieties for decorative purposes. s. Common dovetail ~ corner joint. t. Lapped dovetail ~ corner joint. Note that for drawers the pins are much smaller and the face mark and face edge are indexed on the inside. Numbers aid the correct jointing and assembly. More Joints text and grafics © G.E. Malthouse ~ all rights reserved reference sources: Furniture Making - E Joyce, Purpose Made Joinery - P Brett - Collins Woodworking Manual - Carpentry & Joinery, Porter & Rose - Woodwork Joints, Charles H Hayward

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29th December 2003

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