Mitering large countertop

[Mike Hoyt]

Hey everyone, I have a new issue that I'm trying find the best approach to. I am making a L-shaped top to serve as a bartop, it needs to be mitered for the L piece obviously, it is 8'6" long and 26" wide. How would you go about cutting such a long panel ? Im guessing use a staightedge guide of some sort and my circular saw. Would a 40t blade be fine enough and in your estimation would this method yield a good enough cut to make that glueup.

Thanks,
Mike H

[Bill Huber]

I am sure not an expert on the subject but here is what I would do..

Flip it over so you are cutting it from the back.
Use a 60 tooth sharp blade.
Use a straight edge to guide the saw.
Don't force it, just cut it slow and smooth.

[Ray Newman]

Only saw it done once.

Shop owner had a dedicated saw & carbide blade for such tasks. He first scored the final cut line, then cut it a bit oversized, and finally took a light a trim cut down the the line.

[Don Alexander]

clamp a piece of 1/2 ply on the laminate side of the cut and use a quality carbide blade to make the cut at .....least 60 teeth and preferably something like freud's laminate cutting blade which is designed for cutting countertops and melamine covered particle board

make the cut right through the plywood scrap obviously use a straight guide to guide the circular saw

this system has worked well for me for years HTH

[Mike Hoyt]

Sorry I should have been more specific about the material. It is actually 5/4 mahogany not a laminate like material at all if that makes a difference to your responses

Thanks again,
Mike

[Gene Howe]

Not a problem with 5/4 material. Make an accurate template of 1/4 MDF, cut with a guide as you suggested in your post, only an 1/8th long. Trim with a 2" trim bit in your router.
Don't have a 2" trim bit? Use a pattern bit first then turn the work over and use a trim bit following the cut made by the pattern bit.
Make sure your pattern is a true 45.

[Bob Carreiro]

1) Cut both pcs to your 45 with a circular saw - regardless of blade type - a quarter-inch oversized on both pcs.
2) Clamp both pcs together at 90 degrees (the 45's against ea other). Measure the angle with a framing square to make sure it's at 90 degrees (adjust clamping as necessary).
3) Using a 1/2" straight bit in your router, clamp a straight edge parallel to the joint so that your bit straddles the cut line thru its length. Set your bit height to an appropriate depth (don't cut thru the entire thickness in one pass) and make the passes in one smooth movement. More than 3 passes is unnecessary as long as router HP and bit sharpness are sufficient.

Good luck and happy WWing,
Bob

[Jamie Buxton]

Big miters in solid lumber may not be the best construction practice. The problem is that as the countertop shrinks and expands with changes in humidity, that 45 degree cut changes angle. That isn't intuitive, but it is absolutely true. (This is why the miters in door casings sometimes open up.) If you firmly fasten both mitered counter pieces to the cabinets below, you're likely to get gaps opening along the miter. If you must use a miter, let one end of the resulting L-shaped counter float to accommodate the change in angle. A third (and easier) way to deal with it is to make the joint a big butt joint, not a miter.

[Eiji Fuller]

Festool saw and track make this an easy task.

[johnny means]

What type of material is your top? Wood, Solid surface, self-edge laminate. post-form laminate? Different materials will call for different techniques and tools. Any type of laminate or solid surface should be cut with a sharp router bit and guide. Wood is more forgiving and can be cut with a saw.

[Erik Christensen]

here is what I would do to get a perfect joint.

use a guide & circular saw with the best high tooth count carbide blade you can find (I have a festool track saw so that is what I would use) - cut both miters oversize by 1/2 the width of the saw blade, join the 2 pieces together & clamp securely, then run the saw down the joint line for a second pass centered on the joint line itself so you cut equal amounts from both pieces. any slight inaccuracies in a true straight cut will not be noticed as the 2 pieces will fit together perfectly

I wish I was clever enough to think up stuff like this but I got this idea from john lucas and the few times I have used it it has worked out pretty slick

we even did this with a right cut on a soapstone kitchen counter top and other than having dust all over the place it came out great

[David Helm]

Big miters in solid lumber may not be the best construction practice. The problem is that as the countertop shrinks and expands with changes in humidity, that 45 degree cut changes angle. That isn't intuitive, but it is absolutely true. (This is why the miters in door casings sometimes open up.) If you firmly fasten both mitered counter pieces to the cabinets below, you're likely to get gaps opening along the miter. If you must use a miter, let one end of the resulting L-shaped counter float to accommodate the change in angle. A third (and easier) way to deal with it is to make the joint a big butt joint, not a miter.

I fully agree.