Author Topic: mitered plywood joints  (Read 1099 times)

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Offline Packard

  • Posts: 854
mitered plywood joints
« on: October 11, 2021, 02:58 PM »
In the past, I have made boxes for various purposes using plywood and mitering the edges to be joined.  I then use packing tape to join them in a flat sheet.  I add glue to the joints and fold up to make the box. 

I am planning on doing the same shortly for a small rolling stool with storage. 

When I have done this on the table saw I would first cut all the pieces to size.  Then I would make a sacrificial fence with a relief cut in the bottom so that waste would not kickback.  I would raise the blade at 45 degrees until it was slightly buried in the fence.  The relief is taller than the waste and about 3/16" wide so plenty of room for the waste to rattle around.  I do stand clear of the waste but I have never experienced any kickback.

Fast forward to 2021.  I have a Festool track saw. 

Do I cut the miters along the length of the sheet with the track saw? And then cut the mitered board into the four pieces I need?

Or do I use the track saw to make the blanks and use the table saw to make the miters. 

The stool will be about 16" x 16".  It will have casters and an upholstered lift off lid.  The finished height will be 18".  I guess the cut height will be in the 15" range. 

So if I am using one long board it will need to be 60 + inches long by 18" wide.

Any thoughts?

To check my 45 degree angle, I would cut a piece about 12" wide and rip it into four equal-sized strops (about 3" x 12").  I would fold that up and make sure the joints all closed nicely.

I have never made any angle cuts using the track saw.  Anything I should watch out for?


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Offline GregorHochschild

  • Posts: 29
Re: mitered plywood joints
« Reply #1 on: October 11, 2021, 03:26 PM »
Interested to hear about others thing. I would prefer a good table saw in most cases. But if the piece is to difficult to handle on the table saw, I would use the track saw. I find it harder to get the perfect miter because the saw tips over so easily when the blade is at 45 and because it’s easier to perfectly locate the cut (or creep up) on the table saw. A separate guide rail for miter cuts might make that easier because the painter guard perfectly aligns.

I would, however, use the track saw when I need a crosscut miter on a long panel.

Offline Packard

  • Posts: 854
Re: mitered plywood joints
« Reply #2 on: October 11, 2021, 03:36 PM »
I think I will just cut the blanks to size with the track saw.  I am comfortable with that.  In the beginning, I was cutting rough blanks and then cutting to size on the table saw. 

What sold me on cutting to final size is that the cuts are cleaner with the Festool, especially since I've been making scoring cuts first.

It also saves time. 

I have the miter cut system down pat on the table saw. I was not aware of the tipping issue.  Thanks for that.  I don't want to use edge banding.  The mitered woodgrain looks much better to me.   


Offline Peter Parfitt

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Re: mitered plywood joints
« Reply #3 on: October 11, 2021, 04:12 PM »
If you have a Kapex then cut the pieces for width on your tracksaw cutting station (TS 55) and then take them to the Kapex for perfect mitre cuts:



Peter

Offline Rick Herrick

  • Posts: 603
Re: mitered plywood joints
« Reply #4 on: October 11, 2021, 04:46 PM »
If you have a Kapex then cut the pieces for width on your tracksaw cutting station (TS 55) and then take them to the Kapex for perfect mitre cuts:



Peter
Hey Peter, don't you also have a video using just the track saw and one of your Parf tables to make those miters?  I think you had a scrap piece at the end (with a miter on it) and you used it as a guide/gauge.  And then you flipped each of the four sides under your track.  I know I have seen something like this but not sure where (in your videos list).

Offline woodferret

  • Posts: 137
Re: mitered plywood joints
« Reply #5 on: October 11, 2021, 05:49 PM »
I find it difficult to cut long pieces at an angle because I tend to stop/start if this is a middle-of-the-board cut. Doesn't help that the TS55 is tippy.  That can be alleviated somewhat using the limit stop as an anti-tip



Personally, I'd cut it into sections first for grain matching and then cut the bevel into it.  That cuts down on middle-of-the-board cuts too and keeps the bevel cut manageable.

Offline Michael Kellough

  • Posts: 5305
Re: mitered plywood joints
« Reply #6 on: October 11, 2021, 06:05 PM »
@Packard   I take it you have a right tilt table saw?

My saw is also right tilt but I cut bevels with the workpiece to the right of the blade so it’s still riding the long hard fence and no sacrificial fence is needed. To keep the fresh cut bevel from creeping under the fence during the opposite cut a couple strips of tempered hardboard are double stick taped to the table.

When cutting bevels with the tracksaw I try to start with stock that is about a foot longer than needed because I need a little extra distance at the beginning to get a comfortable stance and get the lean pressure consistent before pushing the saw through the keeper stock. A little inconsistent pressure will adversely affect the cut and joint and the guide rail itself is springy so it’s largely on you compared to making a 90 degree cut.

In both cases I over cut the bevel slightly (45.1 degrees) so that the outside of the joint closes up tightly.

Offline Packard

  • Posts: 854
Re: mitered plywood joints
« Reply #7 on: October 12, 2021, 08:53 AM »
I try to get to as close to 45 degrees as possible.  I always make a test to check the assembly.  If the edges are a hair open (which I do see no matter how careful I setup), I run a round shaft screwdriver shaft gently up and down the joint.  This will close up the gap. 

The joint is surprisingly strong.   For a 3/4" thick piece of plywood, 3/8" is going to be face grain to face grain, so not a bad joint.  If I am making a box, I cut a groove along the bottom to glue in the bottom panel.  If I want stronger joints, I will glue in a length of 3/4" poplar or pine cut to a triangular shape and it runs the length of the joint.

But mostly the joint is strong enough as is.

The advantage of cutting the joint as I do, is that the cut blank becomes the exact size of the finished piece.  So no calculations are required.  (I mostly mess up when I have to use a ruler or have to make calculations.)

I think I will cut the blanks with the track saw and the miters on the table saw.

Thanks for the input.