Replies

1. 
   woodguy | Mar 10, 2003 08:02pm | #1

   I just did a counter top for my son and used a 3/8 laminate triming bit. you will have to clean up the inside corners with a file. I have never heard of using plywood for a sudstrate for tops. mdf would be much better suited fof this application. Woodguy

1. 
   jcutrer | Mar 10, 2003 10:19pm | #2

   i chose plywood because of the span of the top-the top wil be 5ft. x 26" and there is very little support for the top other than the end panel and front panel-some local guys recommended plywood in this situation

2. 
   BobLang | Mar 10, 2003 11:41pm | #3

   A flush trim router bit will leave you with a rounded corner. If you are going to trim the laminate before putting on a finished edge, there is a smaller diameter single flute, solid carbide trim bit that will cost you less, work faster, and leave a smaller fillet in the corner. A block of wood with 80 grit sandpaper stuck to it will work to remove the corner, work down from the top & in to the corner. Plywood should work OK, but you may need to add some reinforcement to the bottom of the top to keep it from sagging.

   Bob Lang

   http://www.craftsmanplans.com

3. 
   johnhardy | Mar 10, 2003 11:50pm | #4

   I'm going to suggest something different here.

   Seems to me that you need to get the laminate and the underlying plywood cut into an exact 90 degree corner ... at least that's what you're describing.

   How about having the underlying plywood be pieces of plywood so that you can get a crisp corner in the substrate. If the desk is to be 60 inches by 24 inches, with the cutout being 12 inches deep, cut three pieces of plywood ... 60 by 12 and two pieces that are 12 by 12. If you put those together you'll have a 60 by 24 piece with a 12 by 36 piece cut out of the middle. To get strength, I'd make the substrate two levels deep. For the layer under this one, I'd cut two pieces 12 by 24 (the outside pieces), and one piece 12 by 36. Done accurately, the lower layer will be an exact mirror of the top level, but the joint lines will be in a totally different place.

   Glue all of this together and make sure it's absolutely flat when doingso. Then you can glue laminate on the edges, getting everything tight and clean, and you can put the laminate on the top as the last thing you do. When you trim the laminate the inside corner won't be totally square, and you can use Bob Lang's approach to fix that one last item.

   If it were me, I'd use MDF as the substrate, since it's flatter.

   John

4. 
   DennisS | Mar 11, 2003 10:30am | #5

   I offer the following comments since it appears installing plastic laminate may be new to you. If not, no condescension intended -

   On plywood, or MDF for that matter, be sure to apply two coats of the contact cement to the surface letting the first coat dry before applying the second coat. This seals the surface and provides a better bond. Only one coat is generally requred for the laminate since it's not as porous as the wood material.

   The edge detail is something you should give some thought to if you haven't already considered it. A straight laminate trimming bit will leave a relatively sharp square edge. If you don't think it's sharp, I'll send you a picture of a few scars! (hehe) You'll need to knock off this sharp edge with either a single cut mill file or a block and sand paper. If the top is to be self edged (laminate on the edge as well as the surface) you can use a beveled trimming bit but you'll only be able to bevel the edge the thickness of the laminate, obviously. To achieve a more beveled edge thus a more 'arm friendly' edge for the desktop, you might consider edging the plywood with hardwood before applying the laminate. That way you can run a 45 degree piloted bit along the edge to get more of a chamfer and provide a more comfortable edge.

   I agree with the suggestion(s) to double the thickness of the substrate. Not simply from the perspective of strength. I think visually the 3/4" thickness will be too weak (again, visually) for the size of desktop you're building. A 1 1/2" thick top would, in my opinion, look better, visually stronger. With the added bonus of giving you more vertical surface to run your trimming bit against.

   If indeed you've not applied laminate before, be sure to have copious numbers of small thin slip-sticks available. After two-coating the wood and coating the laminate, lay the slip-sticks on the top close enough so the laminate doesn't sag down between them, then lay the laminate on the sticks. (I use old venetian blind slats). Get the laminate aligned where you want it then start from the middle removing one stick at a time and working all the air out from under the laminate as you go. The contact cement bites fast and hard.

   You only get one chance.

   ...........

   Dennis in Bellevue WA

   [email protected]