Replies

1. 
   Danford_C._Jennings | Jan 16, 2002 08:32pm | #1

   *
   Tris,

   Awhile back FWW had an interesting article on joint strength, in short the conclusion was that dove tails with narrow pins were the strongest and that there was no difference in strength between the "traditional" ratios of 5:1 vs 8:1.

   As to your last question; I lay out my tails first using a marking knife, cut just to the mark so that I
   i have
   to use a paring chisel to clean up with. The pins are layed out using the tails, again with a marking knife, cut or chopped using a paring chisel to the line. The first cut is the last cut. Generally, hardly any fitting is required. When I get a perfect fit first time every time, then I will give it up.
   b ;)

   Dano

1. 
   Tris_White | Jan 16, 2002 11:47pm | #2

   *Dano, thanks for the input. I'm still not sure about spacing the pins. Is there a point where they are too close together which would make the tails too narrow? Is there a general rule of thumb for determining how many pins are necessary to provide enough strength ie how many pins would be needed for a drawer that is x inches high?thanksTris

1. 
   Danford_C._Jennings | Jan 17, 2002 12:41am | #3

   *Tris,There really aren't any "rules of thumb" for dove tail spacing or number for a given width, at least that I am aware of. I do know that the tail spacing is limited by the thickness of my dove tail saw.b ;) As stated previously, I layout the tails first, so the pins are laid out from the tails. Perhaps what I was not clear on was the symmetry. I start from the center and lay out the tails of equal dimensions so that half a tail is on top and bottom of the side of a drawer, for example. The main thing I think is to not use a 8:1 dove where it is so narrow that it is weak across the grain where it narrows down.Dano

1. 
   David_McCaulley | Jan 18, 2002 07:30pm | #4

   *When I do my dovetails I use a piece of scrap and do a layout with a pencil. I use one of two sizes on the tails (small end) of 1/4" or 1/8" depnding on how many I need. Dano, like you I use the 5:1 ratio. You can get a share ware programs for dovetail layouts that will help you learn how many you need, the sizes...etc.

1. 
   ben_malamed | Jan 18, 2002 09:36pm | #5

   *Don't space your tails closer together than the width of your narrowest chisel. If you do you will find it very difficult to remove the waste. Not something you want to tackle on your first dozen dovetails.

2. 
   Danford_C._Jennings | Jan 18, 2002 09:57pm | #6

   *Good point, Ben. When I want a more decorative dovetail with "thin" pins, I use a plane iron. Another plus for having Stanley planes with their original irons. b ;)Dano

3. 
   John_Adams | Jan 22, 2002 03:55am | #7

   *....And while we're on this subject.....how many out there remove most of the waste between tails with a coping saw; and on half-blind, remove most of the waste between pins with the coping saw, or better yet, a forstner bit? Just curious ...as four generations of my family have done it this way, and perhaps farther back ... but there's nothing that old left we can disassemble ... that we can attribute to an Adams!John in middle Tennessee

4. 
   Sgian_Dubh | Jan 22, 2002 06:33am | #8

   *I prefer a plunge router with a side fence to remove that pesky waste in hand work. Mr. Chippendale would have approved I'm sure. It saves a bunch of time, and doesn't detract from either the aesthetic's or the strength. Slainte, RJ.

5. 
   Larry_G | Feb 08, 2002 08:01am | #9

   *Half-blind dovetail question? Any tips on the easiest way to lay out and hand cut halfblind dovetails for drawers? What about cleaning out the half- blind portion? Should I simply use a dovetail saw and chisel? Tips on keeping the joints clean and artistic looking in 3/4" drawer fronts where the sides are through 1/2" thick tails would be appreciated. Thanks. Larry G.

6. 
   Sgian_Dubh | Feb 08, 2002 12:35pm | #10

   *After cutting and shooting the end grain square to the faces and edges, a shoulder line is marked on both pieces to be joined with a cutting gauge. *1 On the drawer front the inside face is marked the thickness of the drawer side. (Workers vary in their preferences, but I set the gauge a bare whisker less than the thickness of the timber. This just prevents the outside face of the side sinking below the level of the pins in the drawer front during assembly of the joint, allowing easy additional cramping if needed.)*2. The ends of the drawer front are marked so that the tails of the side extend about 2/3 to 3/4 of the way through to the front face. b This setting just described,*3. is used to mark the length of the tails in the side. *2. Set out the tails in the drawer side piece first. Decide how many tails are required. b For the sake of discussion here, let's say four.*3. Pick a convenient width of bevelled edge chisel to fit between the tails.*4. Mark approximately 2/3rds of the chisel's width on the shoulder line to locate the half pins on both edges. Carry one of these marks along the edge of the board with a pencil line (use the 'pencil in the fingers' marking gauge method.)*5. Hold a rule at an angle between the lines marked at *4 above to find a convenient multiple of 4. Mark these points and carry them to the shoulder line with a pencil and set square. These marks set the centre point of the tails between the full pins.*6. Hold the width of the selected chisel to bisect this point, and mark lines either side of the chisel across the shoulder line with a 0.5 mm mechanical pencil.*7. Hold the stock of a set adjustable bevel gauge on the end grain, and pencil in the rake (bevel) of the dovetails.*8. Square the raked lines across the end grain and cut the dovetails from one side, using only the two marked lines as a guide; trust your skill. Clear the waste, define the shoulder line and use the cut dovetails to transfer and mark the positions of the pins on to the matching piece. Now cut these. *9 In both parts of the joint you can often set up a small (plunge?) router with a small cutter and side fence to remove a lot of the waste. The tool can not only speed waste removal, but is handy in defining the shoulder line, and with lap dovetails it will define the depth required between the pins worked in the drawer front. Laying out the joint this way provides that,*1. The gap between the tails is just right for your chisel.*2. The rake of the dovetails is adjustable to suit the job in hand. For carcase construction and softwoods, a rake of about 1 in 5, or 1 in 6 is typical. A steeper rise than this leads to weak short grain. A rise of 1 in 8, or 1 in 9 is the norm for fine work (e.g., drawers, delicate boxes) and hardwoods. Much less than 1 in 10, and the locking property of the dovetail begins to wane, and the accuracy required to cut an effective joint rises significantly.*3. The number of tails and pins can be adjusted to provide a balance between strength and aesthetics. In most carcase constructions the joint is largely cut for strength, so the tails might only be twice the width of the pins, thus increasing the long grain to long grain gluing area. In drawer work wide tails and small pins are generally preferred, so some strength is sacrificed for a ‘refined’ look.*4. The quantity and width of tails and pins can be varied to break up the regularity of the standard layout for visual impact.Through dovetails are marked out in a slight adaptation of the above methodology to suit the somewhat different form. The blue link below is the same image as pops up here. No need to click on it. Slainte, RJ.

7. 
   Sgian_Dubh | Feb 09, 2002 11:57pm | #11

   *Larry, I'd forgotten that I have this image to hand, which with luck graphically reinforces my earlier description. It's for through dovetails, but the marking out is almost exactly the same for the lap dovetails you were asking about. Anyway, here it is. Slainte, RJ.View Image

8. 
   Larry_G | Feb 10, 2002 07:49am | #12

   *Sgian Dubh, Thanks for the great lesson in dovetailing. You are encouraging me to tackle the task with hand tools. I appreciate the details with drawings, etc. Thanks again. Larry G.

9. 
   Sgian_Dubh | Feb 10, 2002 08:06am | #13

   *My pleasure. I mostly just copied and pasted. Sslainte.