Large miters

[Ron Swanson Jr.]

I'm doing a custom shelf project for a friend. 

The shelves are 10" wide and are joined with a miter in the corner of the room. (Inside corner)

It's actually sets of shelves, one on top of the other.

Anyway, I measured the corner of the walls at 89-1/8°. And since I'm not super confident in being able to set a miter saw to precisely 44-9/16°, my plan is to cut one of the 2 mitered shelves here at home.

Then bring it to the job site and hold the other, uncut shelf underneath it and Trace the angle from the first, pre-cut board.

I feel good about this approach, but thought I would see if anyone has any other ideas? Obviously I need the miter to be air tight.

Also, I'm going to use some biscuits in the miter joint. I've never cut a miter that's anywhere near this large, and I feel like a couple biscuits will help with alignment, etc during the installation.

If anyone has thoughts or other strategies they'd use in this situation, I'd sure love to hear about them.

Thanks

[drzaius]

I think I'd glue up both the shelves at 90*, then take them to the site & scribe them to fit the wall. There is no guarantee that the wall profile will be the same for both shelves anyway.

[pkinneb]

45 minutes ago, drzaius said:

I think I'd glue up both the shelves at 90*, then take them to the site & scribe them to fit the wall. There is no guarantee that the wall profile will be the same for both shelves anyway.

This is what I would do as well I can almost guarantee the wall will not be 90. I would use a hand plane to dial in the angle

[Chet]

What is mentioned above is a good way to go.

55 minutes ago, applejackson said:

my plan is to cut one of the 2 mitered shelves here at home.

This wouldn't work.  Unless you cut the two miters to equal degrees the front edges of your shelves won't line up, one will be set back some from the other. 

[..Kev]

Scribing the wall is probably the best option.  Another would be to use a bevel gauge and a track saw.  I've done a couple large slabs this way and it's worked well for me.

Good luck!

[Ron Swanson Jr.]

Thanks all. It sounds like scribing is the way to go here. @Chet thanks for pointing that out. I would have been sick after putting a fair amount of work into these things, to have a fatal mistake during the install. I am going to test that theory - I am sure you're right but in my mind it seems like it would work. Sometimes I have to see something with my eyes in order for it to really sink in. 

@Kev thanks - I dont have a track saw so I will have to scribe it. I appreciate the suggestion though. 

@pkinneb and @drzaius - thanks fellas. 

I will cut (2) 45's and join them (Still going to use biscuits) and then scribe the long shelves to fit the wall. 

Very much appreciate everyone taking the time to reply here. 

 

[JohnG]

Good luck! Be sure to report back to let us know how it turns out. 

[curlyoak]

Buy some door skin. Cheap plywood an eighth inch thick. Rip it up 3" rips. Bring the rips along with a hot glue gun to the job site. Bring a block plane too. And a tin snip. Scribe each piece to the wall. Then glue a lap joint in the corner. Then a piece or 2 diagonally. Now you have a template to duplicate.

Cut each mitre big by an eighth. Then set up a router with a straight edge to clean up the joint. Do the biscuits or dominoes. You can glue on clamp blocks to bring the joint tight.

A ledger board fastened to the wall either temporary or permanent will be easier to make the template. Or 2 more hands...

[Ron Swanson Jr.]

10 hours ago, JohnG said:

Good luck! Be sure to report back to let us know how it turns out. 

Will do, sir! I'm hoping to install on Sunday, but not sure if I will have the finishing completed by then or not. 

These are going to be huge miters, something like 16". 

Hope it goes well. 

 

[Ron Swanson Jr.]

6 hours ago, curlyoak said:

Buy some door skin. Cheap plywood an eighth inch thick. Rip it up 3" rips. Bring the rips along with a hot glue gun to the job site. Bring a block plane too. And a tin snip. Scribe each piece to the wall. Then glue a lap joint in the corner. Then a piece or 2 diagonally. Now you have a template to duplicate.

Cut each mitre big by an eighth. Then set up a router with a straight edge to clean up the joint. Do the biscuits or dominoes. You can glue on clamp blocks to bring the joint tight.

A ledger board fastened to the wall either temporary or permanent will be easier to make the template. Or 2 more hands...

I *think* I am following you there. I was just going to bring a couple long 1x4's to make a template out of, but plywood is probably a better call. why the tin snip? 

[drzaius]

1 hour ago, applejackson said:

why the tin snip

For cutting the  1/8" ply.

[drzaius]

As @curlyoak suggested, cleaning up the cuts on a large miter with a router & straightedge is a great way to go. I did a couple of wood counter tops with mitered corners. They were about 34" long & with my circ saw & straight edge, I just couldn't get a smooth enough cut. Cleaning up with a router left an extremely tight joint.

A good track saw might be good enough, but the router will make it perfect.

[Ron Swanson Jr.]

Thanks, @drzaius. I am packing a router with a bearing guided flush bit and a straight edge, for sure.

 

[Ron Swanson Jr.]

Thanks all - for your great suggestions and advice. 

Here is my revised plan of attack. 

1.  I am going to cut the miters in my shop - each at 45*. 
   1. I am probably going to cut them on the table saw, though I may have to clean up with a router and guided flush cutting bit.
   2. On the larger of the 2 set of shelves, the shelves are each 70" from the corner of the room. 
   3. The smaller set are each 38" from the corner of the room. 
2. I will transport them, unassembled, to the job site. 
3. I'll use 1/8" plywood, and a compass to scribe the walls and make a template. 
4. Transfer the template onto the shelves. 
   1. I'll be bringing a host of tools for the cuts needed to conform to the scribed lines: belt sander, block plane, jig saw, hand saws, chisels, etc. 
5. I'll use biscuits to keep the miters aligned. 

I think that should do it. 

I will post pics, and (I am hoping) an account of a successful install after I am done. 

Thanks again, all. The check is in the mail.... 

 

[curlyoak]

I would bring the template to the shop. My best work is in the shop. On the job it is more difficult. I would fine tune it on the job. Except the visible ends, I would bevel cut the back edge so I have less wood to remove scribing. Assuming you use a ledger board. I would glue and clamp in the shop too. Also I would want to sand and finish in the shop.

[Ron Swanson Jr.]

@curlyoak: 

Bring template to the shop? Check.

Bevel on back edge? Check. 

Sand and finish in the shop? Check and check. 

Thank Curlyoak for advice? Check.

 

[curlyoak]

I would also bring roughly a 1 x 2 sanded with a routed edge and finished. And a mitre saw and/or a coping saw. And install right under where the shelves go. That will make it easier to make the template and hide the beveled edge. And install the shelves. Have you figured a bracket design? Stop your bevels before you get to the visible ends...

[Ron Swanson Jr.]

@curlyoaknot sure I follow you on the 1x2? Is it just to give something to set the template-stock onto? 

I will def be bringing a miter saw and coping saw and a slew of other tools. 

As to brackets, the client ordered some fairly hefty steel brackets. 

There are two styles. 

1 style is like so: 

 

 

 

And the others are identical to those, except the part that you fasten to the wall sits underneath the shelf, and not above the shelf like in the picture. 

He wants the lower shelves to be co-planer with his desktop, so we're going to saw off the part of the bracket that comes up on the sidegrain on the front of the shelf. 

[drzaius]

It looks like they hold the shelf out from the wall far enough that you may not even need to worry about the corner being less than 90*. The back edge of the shelf will probably be 1/2" - 3/4" off the wall.

[G Ragatz]

2 hours ago, drzaius said:

It looks like they hold the shelf out from the wall far enough that you may not even need to worry about the corner being less than 90*. The back edge of the shelf will probably be 1/2" - 3/4" off the wall.

+1  Just make the shelves narrow enough to give yourself a little bit of play inside the bracket, and you should be good.

[curlyoak]

No bevel needed.No scribing needed.Install the brackets. See if 90 will work. With extra space in the bracket 90 should work.

[Mark J]

On 3/22/2019 at 2:27 PM, applejackson said:

we're going to saw off the part of the bracket that comes up on the sidegrain on the front of the shelf. 

Use a thicker board and you won't need to cut down the bracket.

[Ron Swanson Jr.]

Howdy all. A quick update. Finally ready to install these this coming weekend. Had a few week's delays and some design changes. I wasn't able to come with a good way to miter a 10" wide work piece on the table saw, and too big for a miter saw. So I went old school and pulled out the skill saw and a speed square. Results weren't acceptable to me. Miter was ok, not great. So I ended up ripping the pieces in half, and using a miter jig on the table saw for the now 5" wide pieces and edge gluing back together. The glue is drying and the joint is perfect. I've hung the brackets already so the install should be pretty straight forward. I'll post pics when it's done.

Thanks all

 

[drzaius]

Glad it's working out, but rough cutting with a circ saw & then cleaning it up with a straight edge & router is much easier, faster, and you're guaranteed a perfectly jointed edge.

[Ron Swanson Jr.]

2 hours ago, drzaius said:

Glad it's working out, but rough cutting with a circ saw & then cleaning it up with a straight edge & router is much easier, faster, and you're guaranteed a perfectly jointed edge.

Yep. Tried that. Sounds easy but in execution it was anything but. Didn't get a good result. But then, it don't do a lot of hand routing Unless just putting an edge profile or something simple like that. Thanks for the suggestion though. Take care