Replies

1. 
   Dave45 | Apr 24, 2006 03:57pm | #1

   Your dado bit is made for the undersized plywood that is sold these days.  If your panel stock is a full 3/4" (or more) try making two passes to cut your dados - raising your cutter slightly for the second pass. 

   Practice on some scrap to get the fit just right.

2. 
   charlesm | Apr 24, 2006 04:27pm | #2

   John,

   Plywood varies in thickness too much for a single sized bit to be correct every time. I recommend that you run a second pass with the bit that you have if possible to make the groove wider.

   Charles M

   Freud America, Inc.

1. 
   Stephenson | Apr 24, 2006 08:37pm | #3

   Thanks for the advice, I figured I would have to make a second pass I just didn't want to.

    

   Thanks, John.

1. 
   John_D | Apr 24, 2006 08:46pm | #4

   ...and this is why I find it difficult to make grooves to fit ply with a router bit. :)My goal is for my work to outlast me.  Expect my joinery to get simpler as time goes by.

2. 
   SgianDubh | Apr 24, 2006 08:57pm | #5

   You could take an altogether different approach, and the end result is stronger too.

   Rout a groove or housing (dado) at something convenient, say 1/2", whatever cutter you've got close to that. Do it in one pass.

   Then work a matching tongue on the end of the shelf, or whatever it is, by creating a tongue on the end or edge of the board. The tongue naturally would be just a bo'hair shy of 1/2". If you happen to leave the tongue a bit fat a couple of skims with a rebate plane will make it fit. This way it doesn't matter if the plywood is a full 3/4" or a thin 3/4".

   It's stronger because there are more returns on the joint adding mechanical strength and you get extra glue line length. It also follows the age old principle of making the (female) mortice, groove, housing (dado) part whatever is conveniently cut by the chisel, router bit, blade kerf, etc, and making the (male) tenon, tongue, etc, to suit. 

   Personally, I can't ever recall trying to create full housings for plywood/ man made board constructions, and I've been doing these types of jobs for, well, over thirty years now. I've always used the tongue and housing or tongue and groove method method I've described. Slainte.Richard Jones Furniture

1. 
   Stephenson | Apr 25, 2006 06:45am | #7

   This cut is for a pannel in an entry door. I will want it to be able to be loose to allow the mortise and tennon frame that surraounds it to moce, correct? If not can I just glue in the pannel?

   There will be no decorative molding to cover the joint. It will be a simple shaker style pannel.

   Thanks for all the help, John.

1. 
   SgianDubh | Apr 25, 2006 10:28am | #8

   You know John, I'm not sure how I missed the point that you were making the groove for a panelled door.

   It was pretty glaringly obvious now that I look back to your original question. Sorry for the bad steer.

   I can only guess I was half asleep or my attention wasn't fully switched on somehow. It looks like a second pass is your only solution.

   I think I'll go and flagellate myself lightly with hazel twigs to remind me in future to be more attentive. Slainte.Richard Jones Furniture

2. 
   Stephenson | Apr 25, 2006 05:59pm | #10

   Well Richard lets just consider that some good advise for my future wood  working.

   I've made the second pass and everything is looking as though it will work out.

   Thanks for all the help, John.

3. 
   Dave45 | Apr 25, 2006 04:30pm | #9

   I wouldn't glue the panel even though it's plywood.  Anything made up as a frame and panel assembly needs to be able to expand and contract without tearing itself apart.  That's why panels are supposed to "float".

   The only glue I ever use on a panel is in the middle of the top and bottom.  That fixes the position of the panel but still allows free expansion & contraction.

3. 
   notDusty | Apr 25, 2006 01:49am | #6

   John ,

                  Richard has offered a great solution for this application . Not only will it work but , it will create more glue joint and strength if done crisply .

                I am not familiar with the dado blade you have , but am assuming it is a fixed width without individual blades that can be shimmed for a perfect fit , a good reason to use the standard style dado blade sets .

                     good luck                dusty