Replies

1. 
   Samson | Mar 12, 2007 10:14pm | #1

   One thought is to try to avoid tight spots in the first place by marking more before sawing both tails and pins.  Specifically, when cutting in 4/4 having the cuts square (as in perpendicular to the end grain) is especially critical.  For example, the cut at the end grain marked from the tails for example, may be right on, but tight spots can happen if the but is out of square in any manner.  The answer for me has been careful marking of those lines on the long grain with a knife and square (saddle square or DT market with similar feature is especially useful).  The knife line shows me just where to pare if my saw line has strayed at all. 

   As far as finding tight spots graphite powder can help in light woods and chalk powder can help in darker woods like walnut. 

1. 
   jrogerh | Mar 13, 2007 06:03am | #4

   "One thought is to try to avoid tight spots in the first place by marking more before sawing both tails and pins."

   Certainly an ideal solution.  In my case I am too afraid of cutting wide and leaving a gap (which I have found very difficult to patch with a perfect color match) so I err on the tight side.  I'm sure with more practice I could get to the ideal cut but right now I am trying to "creep up" on the exact cut. 

   I have seen those saddle markers.  They seem like they would be a great marking aid.

2. 
   pinsortails | Mar 12, 2007 10:28pm | #2

   If you are saying the boards will not engage, I'd have to offer the suggestion that you need to crowd the knife mark of the pin profile a little tighter.  Once you have sawn, coped & trimmed the tail (without undercutting anything), superimposed it over the end of the pin board, indexing flush at one end and outside face, scribed the edge of contact, that mark defines the edge of the kerf when you saw the pin to the baseline. 

   Sometimes, especially with walnut, I rub a little blackboard chalk into the knife marks, then wipe the excess away with a damp T-shirt, making it easier to saw right down the line.  Any trimming is limited to the saw-tooth marks that are compressed as you bring the joint together.  Strive for no trimming, except the minor paring along the  baseline where your coping saw has failed to stay on the line.  I always seem to progress slightly away from the line, in fear of cutting below the mark.  That cut is well below my line of sight, since I don't reposition the board after making the initial pin-cut.

   John in Texas

3. 
   BG | Mar 13, 2007 12:21am | #3

   jrogerh,

   When you absolutely want your dovetails to be perfect I think the way your doing it is the only way. Experience and a sharp eye can detect where its rubing a bit harder on the pin and a thin shaving can be taken...and then gently try to fit.

   One minor trick is to remember what part of the pin actrually shows in the final outcome and you can be a bit more agressive(undercut) elsewhere on the pin surface. In other words, I stay away from the top and front edge when paring and take it from the sides and only take a tiny bit from the edge...sometimes with a file. 

   I can postion the marking knife such that the pins will fit well on the first attempt or maybe after a minor shaving or two. However, when marking that way if my saw blade wanders a tad I need to live with or repair that outcome also. 

   
   

   ---

   Edited 3/12/2007 5:51 pm ET by BG

1. 
   jrogerh | Mar 13, 2007 11:53pm | #5

   Thanks BG.  Good advice.  My real problem is the number of pins I have to fit.  I have 12 pins on each of the side-to-top joints.  If there is only one tight fit none of the pins will engage.  Sometimes I can  detect a single tight fit by rocking the board and seeing where the point of contact is.  If there are two or more tight spots it becomes very difficult to see where they are.  Also, if I mark all the tails with chalk to try to highlight the offending pin I find that ALL the pins get chalk rubbed off on them.  I think my best solution is to, as you suggest, restrict my trimming to the unseen areas of the pins.

1. 
   mwenz | Mar 14, 2007 07:42am | #6

   Not trying to invalidate your design choice. Structurally I don't think that many are needed. I think I would choose to cut fewer pins/tails. Not because of the degree of difficulty having 12 pins may entail, but rather I don't think that many is necessary for the application.

   The plus side is that if you can master that...you can do about anything to do with DTs.

   Take care, Mike

    

1. 
   jrogerh | Mar 15, 2007 05:13am | #9

   Mike.  I think you're right.  Even though this unit is going to house large drawers full of magazines I could probably have gotten away with fewer pins/tails.  I will probably master dovetail joints sooner than I will master the art of design.

1. 
   mwenz | Mar 15, 2007 06:01am | #11

   Hi Joe,

   There really isn't too much "right" or "wrong" about it. Just an economy of work. That said, you really will be more proficient and understand the fitting aspect better after this than another may.

   From then on, as long as you keep doing them, DTs will become more a second nature than if this one had just blown together. At least that's how these types of problems have been for me. Seems I often need to walk around kicking the tires sometimes to understand what's happening with certain processes.

   Take care, Mike

4. 
   JAurand | Mar 14, 2007 07:48pm | #7

   One trick that helped me was to chamfer the inside edge of the tails starting about 1/16" from the end. This chamfer won't show in the finished joint, and may be enough to start bringing the joint together. If you can get the joint started, you should be able to detect tight spots using graphite powder, chalk, or just looking for the shiny surfaces.

   Good luck!!

1. 
   philip | Mar 15, 2007 03:02am | #8

   Definitely....that small chamfer saves a lot of grief: enables one to get the fit started, which allows one to see the tight spots which have a different appearance-more so with some timbers. Also, when separating the joint after trial fitting the chamfers prevent split-out. Also when driving the joint home the glue "wiped" along, and at the end there is somewhere excess glue to go
   And it is a quick and simple matter to do the chamfer with a short chisel.Philip Marcou

   Edited 3/14/2007 8:03 pm by philip

2. 
   jrogerh | Mar 15, 2007 05:16am | #10

   I certainly will try using the small chamfer to get the pins started.  I think this will give some visible evidence of where the bind is.