Bevel Cutting Plywood

[George Brown]

Gentlemen

Have a need to bevel cut 1 inch plywood at angles steeper than 45 degrees. That means the cut is going to be deep and at angles that saws do not tilt as much. Also, the pieces are large, almost a full size sheet, so they are also heavy.

Been working on this for several days, but have not been able to figure out how. Any suggestions, or is this impossible?

Thanks

[Kent A Bathurst]

It is the size of the sheet that makes this difficult - but you knew that. I'm scratching my head along with you.

Could you make an auxiliary foot plate for a circular saw which would change the effective cutting angle? Attach it to the saw's plate, and go from there.

Along the same lines, could you build an outboard support for your TS that will change the effective cutting angle? This would sit above the plane of the TS table, obviously.

[johnny means]

Tilted router plate, think laminate trimmer.

[glenn bradley]

Angled shoe jig for your circ-saw.

[Matt Meiser]

A guy was just telling me last weekend that they made a shim to go under the Festool rails that let them cut a little past 45 degrees.

And depending on what you are trying to do, remember that, say 60 degrees is 90-30. So maybe you can make up a fixture that holds the workpiece at 90 degrees and cut at 30 degrees.

[Stephen Cherry]

I vote for a supersized table saw raised panel jig-- one where the tip of the blade is burried in the jig so that any wrong moves are into the waste. plus plenty of feather boards, and at least one helper. Start with the blade low, make a couple passes, watch out for pieces of scrap shooting out the front.

[Sam Murdoch]

Other than Matt's suggestion - and I think you would need the big Festool track saw - I wonder if you could just cut the desired bevel on some 2" or 3" or 4" rips on the TS, then reattach the rips to your sheet with biscuits or dominos or splines? If this is a paint grade project this would be easy. If you are doing stain grade you will need to be more precise but still might be worth a mock up.

[Mike Cutler]

George

Uhmm,,,,, how accurate do the cuts need to be?
If you have a guided circular saw system you will need to make a carrier for your saw that has the additional angle you need.
Where you're going to run into some trouble is that a 7 1/4" circular saw has a max cutting depth of ~ 1 1/2" when mounted on a guided rail, at least mine does. The hypotenuse of the cut you're making will be probably exceed a 7 1/4" circular blade at that angle,so you may need a larger saw. I use an 8 1/2" worm drive on EZ rails, but I made the base for it. I can also go past 45 degrees with it if I need to, but it takes a little setup time. Once setup though I can split a pencil line across a sheet of ply.

I will tell you that if this is pre finished cabinet ply to be very careful of that beveled edge. It will cut very deeply, even through Kevlar gloves.
Yep, it hurt really, really, bad when I did it, and took a long time to heal.

[Matt Schroeder]

Could you gin up a way to hold the plywood vertically on the floor (maybe clamped to the side of your workbench) and clamp a long 90 degree L-shaped "table" to the edge of the plywood so you have a nice wide base for a circular saw that could be set at 30 degrees (for example) to get a 60 degree bevel on the sheet? You could even add a small guide rail on the outboard side of the L to guide the shoe of the saw. This is along the lines of Matt's idea above. You could make it sort of zero clearance by making the table wider than needed and cutting off the excess with the saw set at it's appropriate angle for the first cut. I would want to figure a way to raise my standing height rather than holding the saw at chest height standing on the floor (maybe by standing on my workbench or setting up a plank on a couple sawhorses), and keep the sheet between me and saw blade just in case anything bound up and tried to kick during the cut.

I am not sure you could make it a full 8 feet long and only clamp it at each end, but if you can screw it to the sheet you could go the whole way at once, or put in a few intermediate clamps that you have to stop and reposition during the cut.

This is not something I have ever done, but it would be what I would try first if I had to do this. I would be concerned about the stability of the thin edge with a steep angle in plywood. That last little bit will only be one of the plys and will likely chip easily. How is this going to be used? It that edge needs to be robust, then gluing on a hardwood edge that can take the angle would be best, I think.

[James Pallas]

Cut 45's on two pieces. Stack them together with the 45's in line with each other. Set the increased angle on your circ saw and run it on the 45 cutting the bottom piece. This should give you enough surface for the saw plate to run on on both sides of the blade to get a good cut. I have never used a track saw but I guess it may be possible to set th track on the edges of the stacked pieces.

[scott vroom]

That's a tough one. First off, how much right of fence capacity do you have? Sounds like you need close to 48" if you're planning to rip 4 x 8 sheets.

My thought would be to build a sled that props the sheet goods at an angle, then run it through the 45 degree blade setting to get your 65 or whatever it was. I'd use paste wax on the bottom of the sled and the saw table....I've trimmed cab face frames this way (at 90 degrees, without the prop up); the wax allows the piece to glide effortlessly.

Good luck.

[George Brown]

Thank you all for your input. I'll try to come up with a jig to hold the saw, but the depth of cut may be a problem, which could be 3.75 inches. A saw that cuts so deep is very heavy and impossible to hold sideways. Even with a jig it might be impossible. Plus, each piece is at a different angle. Router bits don't cut that deep either. The only good part is that the edge quality or chipout does not matter.

[ian maybury]

I've made long cuts along the edge of a birch play sheet at 45 deg using a Festool track saw in 3/4in ply with very good results - a nice clean edge that could be glued to another the same to give a 90 deg corner with no chips.

The extra angle makes it a bit more complicated. It'd be necessary to tip the rail up to get the angle, but it'd need to be firmly held for safety and accuracy - in that the extra angle would result in a force that would tend to skid the rail across the sheet. The other issue is that the outboard side of the saw base would end up lower than the surface of the ply, so the cut would have to be right at the edge of the ply.

If you didn't mind drilling holes for a few screws in the rail you could probably make some angled packing pieces and screw them to longish flat strips of ply. The strips of ply could then be clamped to the ply sheet at the opposite edge to locate everything. The sheet of ply you were cutting would need to be well supported so that it was accurately flat and unlikely to move under some side force too.

Watch out for the depth of cut, the smaller Festool saw is limited to something like 50mm or a bit less.

You could get by with some sort of DIY rail and another variety of circular saw, but the big advantage of the Festool rail for a cut like that is that the ridge that locates the saw is in the centre of the rail, which means that it doesn't get in the way - plus the saw is located to both sides.

Another option might be to find somebody with a long sliding table saw, and to mount a fixture from the T slots in the slider. It'd need to have a proper panel support frame fitted to prop the sheet from though, it'd take a carefully made set up that prevented any possibility of movement, and getting it up in place would be a multi person job...

ian

[Steve Peterson]

I vote for a supersized table saw raised panel jig-- one where the tip of the blade is burried in the jig so that any wrong moves are into the waste. plus plenty of feather boards, and at least one helper. Start with the blade low, make a couple passes, watch out for pieces of scrap shooting out the front.

And do this in a shop with at least 12 foot ceilings with 2 helpers standing on top of the saw when cutting the ends. Sounds scary, especially if you wax the top of the saw. I hope Stephen was only joking. :)

Steve

[Larry Browning]

Would it be possible to rip off a 90* piece of the plywood parallel to the desired angle, say about 6-8 inches. Then make your desired angle rip on that piece on edge. Then re-join the ripped piece back to the larger section with a spline joint?

I'm not sure I described that very well, but I can see it in my mind.

Using a table saw is the other assumption.

[Jeff Duncan]

Is this a one-off, or multiple pieces? If multiples I'd start by calling local shops with CNC capability and see if they can handle it for you. Not sure exactly what your trying to cut, but something the size of a full sheet of plywood that's 3-3/4" thick is not going to be easily moved anywhere....least not over a table saw???

good luck,
jeffD

[Erik Christensen]

something from out in left field - how about a router sled that you could set at an angle to horizontal? You could do very shallow angles with that and move the tool instead of trying to maneuver a heavy sheet of ply past some cutting tool

[Paul Murphy]

Thank you all for your input. I'll try to come up with a jig to hold the saw, but the depth of cut may be a problem, which could be 3.75 inches. A saw that cuts so deep is very heavy and impossible to hold sideways. Even with a jig it might be impossible. Plus, each piece is at a different angle. Router bits don't cut that deep either. The only good part is that the edge quality or chipout does not matter.

Ok, reverse engineer from what you've told us. A 3.75" face on 1" material gives us a 74.5° angle (or 15.5° from the adjacent face).
What you really are talking about here is much like cutting a scarf joint.

A short cut can be done with a handsaw, but it doesn't sound like that is your situation.
A sawsall, or better yet a hand held bandsaw could work: http://www.plumbersurplus.com/Prod/Milwaukee-6232-6-Deep-Cut-Portable-Band-Saw/63794/Cat/165

Being that we are woodworkers and own routers we might even build a ramp style jig of the proper angle, and rout that bevel on a sheet of plywood.
If I had a lot of sheets to cut I would be talking to the CNC router shops, or to someone with a bandmill who would jig sheets at the proper angle and gang-cut them in batches.

Edit: I see you have many different angles, so any single jig would have to pivot about a hinge. Determine your range of angles and go from there.

Further edit: You could build an angle "T" jig to use this large circular saw [that can hopefully be rented]:
http://www.amazon.com/Makita-5402NA-16-5-16-Inch-Circular/dp/B0000614UR

[Sam Murdoch]

Obviously my original suggestion of beveling 4" rips or so offers no solution with this new information. Consider using a hand held power plane?

[Paul Murphy]

Ok, I'll try to attach a pdf concept sketch for router and saw...:)

[Rod Sheridan]

Funny, I did this last year for someone.

I used a 45 degree bevel cutter tilted 15 degrees in my Hammer B3 Winner, worked great, I just cut the plywood about 2 mm oversize and used the sliding table.......Rod.

[Rich Engelhardt]

Consider using a hand held power plane?
That's what I'd consider - mainly because I have one though & it'd sure be nice to find something to actually do with the thing.. :D.
I don't want to say "useless" ....but...even though I picked mine up on a super clearance price, I've spent $20.00 better by stuffing it into a slot machine...l).