another dumb question for you cabinet pros.

a year or so ago, I made my wife a small work center for her sewing room.
Problem is, I made it with desk portion lower than bottom storage cabinets and she needs the top all one level.
Im not cutting anything down as it wont work, Im just rebuilding the bottom cabs.

my question.

I need to make an L shaped top, around 5 feet on one wall, and 4 feet on the other wall. It will be approx. 22 inches deep.
Id like to make the top and laminate something onto it, like formica, or something easy for me to do.
I figured Id use mdf? and cement on a top. Not sure exactly what material on top, something easy.

and second, how do I cut the mdf perfectly in the inside corner so when I laminate over it, its even and smooth.

any tricks, or just do my best with a track saw finished with jig saw?

My sons top was much longer, so I just made two tops and attached them to the bottoms.
Id like my wifes to have no seams on the top, but I need a perfect cut if I want to laminate, or even if I go with oak plywood and stain it, how do I cut one piece and make the cut perfect?
I know, silly, 7 years doing this, and I don't think Id get a good enough cut with a jig saw. is there a trick or something I missing?

Do you have a table saw? If so, you can cut that out of 1 sheet of MDF. Just set your saw for 22" and rip it to 22" from the end. Flip it over, then turn it 90 degrees and cut that side to the 22" mark. You should then have an "L" shaped piece of MDF that will be 48"X96". Cut the 96" leg off at 60" and that's it. If you don't want any seams in your formica top, glue a full sheet to the top. If you try to cut the "L" like you did the MDF, it'll break before you can lay it. DAMHIKT

When you're finished cutting, you should have a piece of MDF and a piece of formica approximately 26 X 74 left over.

Good luck.

Last time I did Formica was many years ago, but I remember a trick that really worked. Everybody was looking for the seam at the diagonal. I did not make a diagonal seam. I made the connection around the corner about an inch back from one side - close to the point where the front edge of the sheet of Formica from the other side would have fallen. Not only was it easier than a miter corner, but practically nobody found the seam. I cut as straight as possible, then beveled the cut back slightly with a hand plane, so the top was in tight contact, not held apart by any roughness of the cut or the lower part of the Formica.

My hints, in no particular order.

You make the cut perfect by using a jig of some sort.

Either jig the wood and slide it accross a cutter, or make a jig for the cutter to slide across the wood.

You make the cut perfect by being careful and measuring twice.

You make the cut perfect by allowing for the saw kerf, especially on the corner cut.

You make the cut perfect by making a test patern out of cardboard.

Use a tablesaw or a hand held circular saw in a jig to make the cuts.

Use a blade rated for MDF to cut the MDF.

Be careful of walls that are not at a true 45 degree angle, hense the cardboard template.

Use a router to trim the formica.

With so many pretty Formica patterens and colors, I'd go with that before sanding and finshing plywood.

I would use plywood under the formica, mdf tends to swell with moisture.

You don't need to cut the core for the top out of one piece. Butt them together, run your buildup through to tie it to the other piece.

Use particle board. It's more stable than mdf when it comes to humidity changes. Plus it's not as miserable to work with.

The laminate will cover with one piece, also helping hold the two pieces of core together. You won't need to seam it.

I think I would lean toward particle board as well. The single piece of laminate would probably be easier than trying to seam 2 pieces.

There is a particle board product called "sink deck". It is made specifically for laminate work. At one time I believe it was the only substrate that laminate manufacturers would guarantee their products over.
Anyway, that said, as others here have stated 2 piece your deck to size. Now over size the piece of formica by about an inch to allow it to overhang all the way around.
If you need to seam make yourself a mirror jig and using a new bit run it through the 2 pieces of laminate simultaneously. This will create 2 pieces that "mirror" each other and fit perfectly together. Looking at your dimensions though you should be able to get a 5x8 or if you make the 5 foot leg 4'-11" instead then get yourself a 5x5 piece leave it overhanging an inch off the back and run your laminate trimmer around the inside. This will give you the needed overage for trimming afterwards. Be conscious of the overhanging extra stock and use that for your edge trim. Then, trim the edges first, trim them flush and THEN do the top.
To finish off the corner use a laminate file with a down stroke so you don't chip out the corner, again, being cognizant not to scratch the laminate on the face.
If its a small section then you can used tape to hold the seam together when you cement it down.
I would shy away from MDF for pretty much anything. It creates some really nasty dust for one. It has formaldehyde that is released when cut, reeks havoc on your shop, dc, and gets everywhere, and imo is just plain junk.