Carcass Joinery Orientation

[Roy Wall]

Hey all,

Is there a right/wrong way to do this???

Say HB DT"s showing on the side faces of the box, etc...
or
HB DT's showing only on the bottom and tops of the carcass
or
Through DT's with the tails on the top/bottoms thru the side pieces..
or
Through DT's wit the tails on the sides that go thru the bottom/top pieces...

and if the joints are snug....do you really need clamps for the pressure or just adjust for squareness and let it dry....

Thanks!

[Mark Singer]

Roy,

The correct way is for the pins to be cut in the top of the carcass so the weight is resisted by the geometry of the joint. Now I have done it the opposite way for appearance...because a dovetail is a strong joint for carcass construction and the back is a strutural member also. HB or thru that is up to you....Make a sample corner and try it.... It is good practice anyway.

[Bob Smalser]

I think you're looking at it from the wrong point of view.

Instead of searching for rules of thumb, visualize where the potential tension will be greatest on the piece and orient your dovetails accordingly.

The tension (as opposed to compression) on a drawer is at the knob, so the tails face that direction regardless of what type dovetail used. On a chest, the tension is at the handles....and in a large carcase like a bookcase base, the tension is at the sides as the weight of the books attempts to rack or splay them outward.

[Mark Singer]

This is the correct way structurally assuming there is weight in the cabinet and it is supported from top bottom or back...pictures help

[Roy Wall]

I'm thinking the tail board would be the sides(vertical pieces)....pins on top and bottom (horizontals)...like you guys said. I guess those would show the beauty of the joint whether they were HB's or Thru's... and the weight of the box (and contents) would be opposed and held by the desgn of the joint for sure.

I just got to thinking about Box Joints / DT joints and their various strengths.

[Roy Wall]

Mark,

Yes, photos do help! That's what I thought....

Also, I notice "Half Pins" on the edges are generally "thicker" on carcass joinery as they need to be stronger to bear the weight?

[Mark Singer]

I like thick tops and bottoms esthetically....on small cabinets a lot ofthis is overkill...I try to get every component to add strength...

[Mark Singer]

Roy ,

This one I made with a sub top that is dovetailed ...buy hidden..

http://www.sawmillcreek.org/showthread.php?t=5421&highlight=shedua

[Roy Wall]

I think I got it.....

The thicker top ( and bottom) held the HB Pins....tails on the sides...

so the weight ( and pressure as Bob S. alluded to) is held in check by the nature of the joint........

Nice work!!:)

[Mark Singer]

Roy,

I must say I love your approach... you are very interested in details and I know we will see some beautiful cabinets from you...you are asking all the right questions. Just think the whole cabinet out in your head and make sketches of all the connections...piece by piece...


I think I got it.....

The thicker top ( and bottom) held the HB Pins....tails on the sides...

so the weight ( and pressure as Bob S. alluded to) is held in check by the nature of the joint........

Nice work!!:)

[Alan Turner]

Roy,
For a free standing piece of furniture, such as a chest of drawers, the traditional way to cut the carcase DT's is for the pin boards to be the sides of the carcase. All of the pressure is down, to the floor ultimately, and so the Dt joint is used to keep the sides from cupping, and hence the pins in the vertical members resist this force. They are "locked" to the endgrain of the top and bottom and can't move. Unless you want to display the joinery, then lapped DT's are the traditional approach. Use a sub-top and this will allow you the traditional overhang of the top to the sides, but on a piece such as a slant front writing desk, where there is no overhang to the top, but rather just a square corner, the top of the piece displays the tails of the DT joinery. And, of course, the bottom does as well, but is not visible. A wall hanging cabinet is different, and the approach is for the pin boards to be the horizontals, since hte greater force is to carry the weight of the unit. The top carries the weight of the cabinet, and the bottom carries the weight of the contents.