Replies

1. 
   Samson | Sep 04, 2009 06:40pm | #1

   How long are we talking.  8" is no problem, but 20" is a serious issue in my experience.  If you are going to taper, I think you ought to match the tapers because the point of the taper is to essentially make the parts mate fully, just not until fully driven home (the narrow end is loose until the last inch when it fit perfectly (same for every point in the tail).

1. 
   miserybob | Sep 04, 2009 09:19pm | #3

   I think the longest is only about 10" wide - plus they'll be stopped (blind?) dovetails, so maybe only 9".

   So you wouldn't bother to taper with something that short?

   Thanks!

    

   Chris

1. 
   Samson | Sep 04, 2009 09:46pm | #5

   It kind of depends on how you like to make them and the results of that process.  I recently made some stopped sliding dts for some shelves about 6" wide.  I cut the slot with a router (template guide collar running against a straight board clamped to the workpiece).  I made the tails with a handsaw (for the shoulders) and chisel.  It wasn't the perfection of a router table, but it was very sound with lots of gluing surface - i.e., lots of room for minor error as no one will see it and it is VERY strong). 

   View Image

1. 
   Michael503 | Sep 04, 2009 10:00pm | #7

   Why not make it straight and only glue it only at the ends?
   apply glue to socket at the far end and to the pin at the near end and slide them together. just glue the outer 2-3" and let the middle float. A good fitting one only needs glue to hold it in place, right?-Michael

   Edited 9/4/2009 3:01 pm by Michael666

2. 
   WillGeorge | Sep 04, 2009 07:17pm | #2

   I taper both 'sticks'. Just one #matching# edge. Never tried just a taper on one stick but I would think you would loose much of the surface contact and have poor alignment. Especially on something like a long shelf. I find that the taper can be very slight and still work. Even with a full length glue line. I must admit I never tried to hand cut a long tapered dovetail. That is why I bought my routers! OK, so I can hand cut short ones. Maybe about 6 inches or shorter. I have tried something like 24 inches handcutting and it just takes more time that I want to spend on doing it. AND the router fit is way better!

   I only mention one edge #above# because I know somebody that tapers both edges #As in a wedge#. Not sure why he does it that way. Extra work and maybe he just enjoys making them that way?

   In fact I have to do several tomorrow, or the next day, for a large book case. For shelves #obviously.. not adjustable# I love tapered dovetail slots. Glue the edge, slide it in, pulls everything in alignment and holds it there while you do the next shelf or cabinet part. And I do the cabinet 'box' with a Lock-Miter bit for the same reason.

   YES! I do check things for square also but usually just a tweak to square up things before the glue dries.

1. 
   miserybob | Sep 04, 2009 09:22pm | #4

   What method do you use to taper?  The simplest I've seen is just an edge guide and two passes - the second one slightly skewed by a thin strip.  That same strip is then taped to the male end, which is shaped on the router table.

   All that seems fairly simple if a little crude.  The hardest way I"ve seen was on Pat Warner's site...  fairly complicated, but probably perfectly accurate and safe.

   Thanks for the input!

    

   Chris

3. 
   bakesale1 | Sep 04, 2009 09:57pm | #6

   I was taught to taper the female side only.  But this was for a bench hook.  We drove the batten in without glue.  I have a drawing somewhere of the layout, which I'll try to post for you. 

4. 
   Jimurock | Sep 04, 2009 10:08pm | #8

   Use polyurethane glue or a slow epoxy -- they don't bind.  No need to taper.

   Jim

1. 
   roc | Sep 05, 2009 05:14am | #10

   >polyurethane glue or a slow epoxy -- they don't bind. No need to taperJim,
   Good job ! You beat me to it.Chris,Doesn't bind because doesn't swell the wood ( unless you put on water to activate the poly.
   I was going to say poly glue or epoxy acts like a lube to help slide the parts together.One problem I got into was I was making some quickOdickO book shelves from Home Depot lumber and the 9"x3/4" had some cup across the width. Caused major problems. The idea was to make the book case so I could knock it apart and move it. Floor to ceiling book shelves.They worked in the end because the material was thin enough to flex flat and I gave it a bit more room with the router passes for compensation but a bit gappy. No work of art just utility. So for nice work the stock needs to be stabilized and flat. Dahhhh like for anything else. That's what I get for buying thicknessed stock that is less than fully dry.I didn't glue; in fact I waxed so I could knock down latter. Use candle wax not bee's wax.rocGive me six hours to chop down a tree and I will spend the first four sharpening the axe. Abraham Lincoln ( 54° shaves )

   Edited 9/4/2009 10:19 pm by roc

1. 
   Jimurock | Sep 05, 2009 05:40am | #11

   As long as you don't hang around too long you can water one of the parts, and the dovetail still slides in easily.  Last one I did was about 26" long for a chest top, a tight fit, and it slid in like a rat up a drainpipe.  For some reason most people are reluctant to try it.

   Jim

1. 
   flairwoodworks | Sep 05, 2009 06:33am | #12

   Jim,That technique sounds just like putting dowels or tenons in hot sand before assembly.Chris @ http://www.flairwoodworks.com and http://www.flairwoodwork.spaces.live.com)

    - Success is not the key to happiness.  Happiness is the key to success.  If you love what you are doing, you will be successful. - Albert Schweitzer

1. 
   Jimurock | Sep 05, 2009 04:27pm | #15

   That's a new one on me.  I think I have a dowel jig hiding in a drawer somewhere, but I can't remember using it.  I might have a hard time finding hot sand too -- there hasn't been any all summer here in S.W.Ontario ;^/

   Jim

2. 
   flairwoodworks | Sep 05, 2009 09:38pm | #17

   I just recently made my first sliding dovetail, a monster at about 56" long and straight to boot for a chain rack (think chain saw). I made the mistake of shooting for a really, really precise fit (read too tight). It was too snug, but with a lot of pounding, I was able to seat it without splitting the female part. No glue required.Chris @ http://www.flairwoodworks.com and http://www.flairwoodwork.spaces.live.com)

    - Success is not the key to happiness.  Happiness is the key to success.  If you love what you are doing, you will be successful. - Albert Schweitzer

3. 
   Jimurock | Sep 05, 2009 11:12pm | #18

   I suppose with a tight joint you never need glue, because the mechanical hold is so good, and in most applications the sliding dovetail is horizontal anyway.  Really the PU glue is more for lubrication than adhesion, to make life easier for yourself.  I wonder what they used back in the day?  You do see older furniture where the female part is cut full, but there's only a half dovetail on the male part, with a wedge at the end to hold the joint tight.

   Jim

4. 
   WillGeorge | Sep 06, 2009 04:17pm | #19

   It was too snug, but with a lot of pounding, I was able to seat it without splitting the female part. Did you hug her first?

   I make my sliding dovetails about 2 inches longer.. Dry fit and mark before the glue-up.

   A woman should NEVER be pounded upon even if she asks! I HARD hug will do!

5. 
   Michael503 | Sep 06, 2009 05:18pm | #20

   "A woman should NEVER be pounded upon even if she asks! I HARD hug will do!"LOL ... good one Will.-Michael

6. 
   flairwoodworks | Sep 06, 2009 05:38pm | #21

   Thanks for the tip(s).Chris @ http://www.flairwoodworks.com and http://www.flairwoodwork.spaces.live.com)

    - Success is not the key to happiness.  Happiness is the key to success.  If you love what you are doing, you will be successful. - Albert Schweitzer

2. 
   roc | Sep 05, 2009 06:47am | #13

   Sounds like you make some very precise components and joinery !26 " !Way to go !I would be scared it would get stuck half way.rocGive me six hours to chop down a tree and I will spend the first four sharpening the axe. Abraham Lincoln ( 54° shaves )

1. 
   Jimurock | Sep 05, 2009 04:21pm | #14

   Well, it's always scary because you can't dryfit it.  If you can fit the first 5 or 6 inches in without binding too badly, then it'll work with the glue if you've cut the mating parts consistently all the way along.  I always check the depth with a router plane, inspired by fear.  Sometimes you'll need a tap with a hammer, and it doesn't hurt to have long clamps ready in case the case sides are bowed, but I've never had a failure, and believe me I'm no super craftsman.

   Jim

5. 
   hammer1 | Sep 04, 2009 10:12pm | #9

   Don't jump to conclusions without trying it. I use sliding dovetails quite a bit and seldom taper them. You can't make the joint too tight but there isn't any need to, either. The nature of the dovetail means it won't come apart, even if there is some play. As long as your stock is straight and the cuts made accurately, long sliding dovetails can go together without problem.

   I typically cut the male dovetail with a horizontal router table. It's easy to go back for another pass and you may not need to change the setting. Just like any other joint that may need a touch of shaving for a proper, unforced fit. The glue will have some swelling effect. If the fit is too sloppy, a gap filling glue, pins or other solution could be used but it isn't too difficult to get a fit that doesn't need anything extra.

   Tapered sliding dovetails require a jig that is specific to the size work. They can bind before going home, too. Correct fit is critical with tapers just as with straight. Adjusting the fit, if necessary isn't quite as easy as making another pass on a table.

   The taper won't make your shelf tilt. The male and female part should marry, both would be tapered, one side or both. They just stay loose until brought home. Otherwise, the dovetail will only fit tight in the last portion of the dado. It's good to think things through but there is no substitute for practice. Give them both a try, then draw your conclusions. With either, good woodworking practices are a must. Things need to be flat, straight and of equal thickness if you want accuracy, consistency and repeatability.

   Beat it to fit / Paint it to match

6. 
   Jfrostjr | Sep 05, 2009 05:12pm | #16

   Here is a post of mine from '06. Hope it helps. Just go to Advanced Search and enter the post # at the bottom.

   1250.11

   Frosty

   "I sometimes think we consider the good fortune of the early bird and overlook the bad fortune of the early worm." FDR - 1922