Mike Corwin

Bevel cuts on really long boards

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Hi Everyone - I'm making some 48" wide plywood cabinets and would love to miter all the corners so the grain waterfalls and covers up the ply's at the same time, problem is I've never figured out how cut the bevels on long boards.  If I was making small box sides I'd use a bevel sled on the tablesaw or think about using a lock miter set on the router bit table, but since the boards are 48" wide these methods don't really work since the boards are so long.  Do people use a circular saw and guide for this sort of thing?  That's the only way I can see doing it, problem is the repeatability in terms of accuracy seems precarious.  Any ideas welcome, thanks very much.

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The track saw was born for this job, but it can be done old school with circ saw and straight edge.  Make sure it's a very straight edge, and do some test cuts to make sure you're dead nuts 45.  Long miters can be tricky joints.

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Yes, although my cabinet sides are 12" deep by 48" long so while the 12" section is getting the 45 miter, I've got roughly 40+ inches hanging off the router table as I push the board past which seems like it'd be impossible to control.

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17 minutes ago, Mike Corwin said:

Yes, although my cabinet sides are 12" deep by 48" long so while the 12" section is getting the 45 miter, I've got roughly 40+ inches hanging off the router table as I push the board past which seems like it'd be impossible to control.

If you want to try this way, a couple of roller stands might be the trick for support and even though the track saw is the best way, a couple of good roller stands would be less costly.

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If you had multiple boards to cut you could clamp them together like a panel glue up and bring the router to the boards. Use a straight edge as a fence and add some sacrificial boards to each end. 

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K Cooper, only because 40" or more would be hanging off the table saw and would be inviting kickback.  

byegge, that's an interesting idea for sure

 

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Don't bother with the router.  That's a much more difficult way to do it.

Get one of these and a really good square...

zoom.jpg?c=1480922091

 

Put a good plywood blade on your circular saw and make the cuts.  The key to long miters is making sure your cuts are square.  Just the slightest bit out will make for some ugly joints.

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My Ridgid miter saw will do 16". You could flip it on a miter box that won't do the full 12"

 

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I'm confused - is the bevel on the 12" edge, or the 48" edge?

 

If it is the 12" edge, I suggest a tablesaw sled.

If its the 48" edge, I second@Eric. , with a small modification. Use 2 straight edges to trap the circ saw base, so that it can't wander at all.

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I have done this several different ways over the years. The key is practice cuts however you decide to do it !  I have made those cuts in a driveway with a new circular saw and an expensive blade. Extremely careful setup of the straightedge plus practice is key. It's possible on a router table too, but practice on less expensive ply until you get great results, then cut the good stuff !

Today I personally would use my tracksaw. And even after 40 + years I would make a few test cuts in cheaper material or scrap before I made the first cut in the specific material for the job. My absolute best square to set up the track , repeated measurements using a magnifying headset, and exactly the same pressure on the saw to keep it against the track. Your stance or how your jaw is clenched matters too.  I am building 12 tabletops from white maple B-2 ply right now and I bought 13 sheets just to cover my ass. Don't be cheap, have enough material to loose a strip to mistakes cause they are going to happen ! I spent a few hours today sharpening my edgebanding trimmers, cleaning  blades and adjusting my saws. Constant attention during each cut is nessacary. The face veneer on ply these days is very thin and any wobble or misstep can affect the cut. 

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I just had to do this on the 20" side of a 20"*40" piece of 3/4 ply. I used a table saw sled and found no problem with it although I got some tearing at the end of the cut but I'll attribute that to the cheap general purpose blade on the TS. Just keep your downward pressure closer to the cut, I clamped it down on the sled. 

On a 12", a sliding miter saw would be ideal, but a track saw, skillsaw+straight edge, router can all do this. 

Just be careful and you should be fine with either method. If you can, practice it on a scrap first.

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1 hour ago, wtnhighlander said:

I'm confused - is the bevel on the 12" edge, or the 48" edge?

 

If it is the 12" edge, I suggest a tablesaw sled.

If its the 48" edge, I second@Eric. , with a small modification. Use 2 straight edges to trap the circ saw base, so that it can't wander at all.

I too am confused. I see, after going back that he wants to bevel all four corners (sides), and the 12" edge would present the biggest concern. But if I were going to cut a 48" piece of 1x4, or 2x8 or ply, at at 45* angle, I would do it  with the blade set at 45* on the ts. What am I missing? If it's due to lack of outfeed support for the ts, then there lies the problem.

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Sorry for the confusion.  The bevel is on the 12" side.  My biggest issue is having the 40+ inches hanging off my tablesaw to the left of the blade if I used a sled since my shop is small and something that long would hit another table I have.  Ideally if I had a larger shop a sliding table saw would be the easiest way however it looks like the track saw method seems to be the route I'll take.  

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Sorry for the confusion.  The bevel is on the 12" side.  My biggest issue is having the 40+ inches hanging off my tablesaw to the left of the blade if I used a sled since my shop is small and something that long would hit another table I have.  Ideally if I had a larger shop a sliding table saw would be the easiest way however it looks like the track saw method seems to be the route I'll take.  

 

 

I guess no one like using a miter box. . .

 

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8 hours ago, QHC said:

I guess no one like using a miter box. . .

You're gonna cut 12" miters in plywood...in a miter box?  First of all I don't think I've ever seen one that big before, and even if they exist...sounds like torture.  For you and your saw.

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You're gonna cut 12" miters in plywood...in a miter box?  First of all I don't think I've ever seen one that big before, and even if they exist...sounds like torture.  For you and your saw.

 

Yes, thats what I'm saying. My ridgid will do a 16" crosscut. Easy peasy! Flip it over on one that won't so 12". Not a big deal, really.

 

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11 minutes ago, QHC said:

My ridgid

Oh, you're talking about a sliding compound miter saw...not a miter box...those are two different things.  This is a miter box...

 

MiterBox-inuse.jpg

 

13 minutes ago, QHC said:

Flip it over on one that won't so 12".

 

Yeah...good luck getting a perfect, clean miter doing that.  You realize we're talking about plywood so you can't just pop it in a shooting board to clean up the miters.  Even the slightest deviation from perfect will create a sloppy joint...and flipping a piece over like that is a recipe for sloppy every time.  I'll mail you a topless picture of my wife if you can produce a video proving it...four sided box, 16" deep, gapless miters on all four corners.  Godspeed.

But yeah, for a 12" cut...if you have a nice SCMS that's tuned dead nuts and it has the capacity to make the entire cut in one pass, then you can probably pull it off.

Regardless, the track saw is the man for this job.

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Yeah...good luck getting a perfect, clean miter doing that.  You realize we're talking about plywood so you can't just pop it in a shooting board to clean up the miters.  Even the slightest deviation from perfect will create a sloppy joint...and flipping a piece over like that is a recipe for sloppy every time.  I'll mail you a topless picture of my wife if you can produce a video proving it...four sided box, 16" deep, gapless miters on all four corners.  Godspeed.

But yeah, for a 12" cut...if you have a nice SCMS that's tuned dead nuts and it has the capacity to make the entire cut in one pass, then you can probably pull it off.

Regardless, the track saw is the man for this job.

 

If course you can clean up the miters with a hand plane if needed. I would run a spline down the length of the miter and glue it up. You work the point of the miter with a burnisher as needed while in the clamps. Take it out of the clamps, sand lightly and you're done. I could cut them on a band saw and xlean them uo with a plane and you'd never see a crack. I'd put a mitered four sided top on the box if you'd like.

 

Here are some lighted shelves that are boxes using cherry 3/4 MDF, using the same process. Granted these were only four inches tall but the process would be the same. I definitely would prefer MDF over ply. The long sides were done on the TS, the short ones on the miter saw. If the piece was 40" long, 12" wide, I'd do the 45 on the miter saw.ff56ff0caf956d51c614135f0f1b1dd6.jpg

 

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Yeah...good luck getting a perfect, clean miter doing that.  You realize we're talking about plywood so you can't just pop it in a shooting board to clean up the miters.  Even the slightest deviation from perfect will create a sloppy joint...and flipping a piece over like that is a recipe for sloppy every time.  I'll mail you a topless picture of my wife if you can produce a video proving it...four sided box, 16" deep, gapless miters on all four corners.  Godspeed.

But yeah, for a 12" cut...if you have a nice SCMS that's tuned dead nuts and it has the capacity to make the entire cut in one pass, then you can probably pull it off.

Regardless, the track saw is the man for this job.

 

Sorry about the terminology on the miter box vs saw. Your miter box looks like it's a Stanley like mine at 35 years old or so

 

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Sorry about the terminology on the miter box vs saw. Your miter box looks like it's a Stanley like mine at 35 years old or so

 

Sent from my SM-N920P using Tapatalk

 

 

 

All that being said I have no problem with the track saw either should work fine.

 

Sent from my SM-N920P using Tapatalk

 

 

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16 minutes ago, QHC said:

Granted these were only four inches tall but the process would be the same.

Not if the pieces were 16" deep and you tried flipping them over to complete the cut.  Try that and report back.  If you can pull it off accurately you're a better woodworker than me.  And I hesitate to believe that you can shoot 16" plywood miters on a shooting board.  I'd be happy to be proven wrong...but until I am, my position is that it can't be done well.  My experiences with trying to hand plane plywood have been...disappointing.

All these techniques that you offer are totally valid for little 4" pieces...I never claimed they weren't.  You threw in the "16 inch flip the board over" aspect and I'm skeptical it can be pulled off effectively.

That miter box is a Lie Nielsen and it's not mine...pulled from the LN site.

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Using a hand plane on plywood is very hard on the edge. It's  marginally successful only a very few passes with an extremely sharp blade then the blade and the results decline rapidly and neither is easy to recover from.

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