Edging Luan with a router

[EZ]

Seeing as a lot of you guys like to use a flush cut bit in a router for various things I thought I would try it out. I made a nice foam-core door with Luan and 1 Xs and made the sheets a little oversize so that I could cut them flush with the router. Seems that luan doesn't like to be cut cross-grain very much and resulted in some minor or worse splintering. Since my luan roof was going to be trimmed all around (all cross grain due to 5.5 foot width) I am thinking that either this may not be a good idea, I had better come up with a new material for the roof or maybe, just maybe there is a handy-man's secret like masking tape or something that I don't know about. Anyone have a tip?

Ed

[mbader]

Try a brand new (sharp) carbide cutter of 1/2" or 3/4" dia. and go slow.

[mikeschn]

Ed,

Luan is a cheap, splintery wood. Even with a sharp blade you are going to get this...


Just knock the splinters off with some sand paper.

If you don't like that you could cover the edge with an aluminum or wood molding, or even rope like Ira did. If you are going to paint it, you could finish it with bondo or epoxy filler, and sand smooth.

It's time to use your imagination.

Of course, like you said, you can always switch materials.

The Lil Diner, with a birch plywood roof cleaned up very nicely...

Mike...

[Ken A Hood]

You can always score the top with an exacto/razor knife to minimize splinters, masking tape also will work.

[AmyH]

I'll reiterate what Ken said, score with a razor blade first, then do the cut, it should reduce the tear-out significantly. I have tried this and it works great. I have also heard (but not tried) of taking two razorblades and separating them slightly with a washer in between (to get about an 1/8" between the razor blades), and then scoring two adjacent lines side by side. If you aim to cut between the scored lines then you'll get a nice tear-out free cut.

Amy

[travbickel]

A spiral cutting bit will give a cleaner cut than a straight bit, also.

[Mitheral]

A spiral cutting bit will give a cleaner cut than a straight bit, also.

Down cutting if you can find one.

[cracker39]

I have hardly any experience using a router on thin plywood. I've only cut my 1/4" oak plywood from my side template with the router, using an old and probably dull, 1/4" straight bit. The plywood was put face to face and held tightly together with screws and I had no splintering at all. The cuts were very clean. Luan may be a little different. But, I don't plan on using the router for the luan. I will cut the sheets close to the required width using my circular saw, leaving only an eighth or quarter inch overhanging the sides and will remove most of that escess with my belt sander using 80 grit, then finish it with 100 and 120 grit in my orbital sander.

[Steve Frederick]

I seal it w/epoxy, just the edge, and cut away!! No splinters! For finish layers, same technique, 'cept, I use a round-over bit..

[Steve Frederick]

A spiral cutting bit will give a cleaner cut than a straight bit, also.

Down cutting if you can find one.

Try MCLS
I have all of the spiral bits. I like the down cut bits for thin ply.

[cracker39]

I think MLCS is one of the best places to get router stuff. I bought T-track and mini T-track from them to use on my router table that I built, and other accessories like the table base on my router in my pictures, router feather board, etc.

[TomS]

I trimmed mine with a router and a brand new flush trim bit and got very good results. My roof is a 2-ply bendable luan.

[EZ]

Leaving just a small bit of overhang and using a belt sander might work well. I am not sure a new router bit (it is) would help but a new more expensive bit might. Or maybe a spiral bit (never used one of those).

Scoring really isn't an option since the ply will be glued to the sides and can't tell exactly where to score. That's the point of using the flush cutting bit on the router.

I intend on soaking the corner with epoxy but after it is trimmed flush. Or I could use some real wood......

A lot of good ideas. Thanks guys.

Ed

[cracker39]

If I was using an edge trim, I wouldn't worry about how the edge looked, but I'm not. I would prefer to cut the sheet to fit flush, but, then, if I made any error at all starting it, when it bends down, if it is off even an eigth of an inch, it will show and need filler, so I guess allowing a little extra and sanding it flush is the easiest way to be sure...at least for the first piece on the front. If I get that one straight, the others will go on straight too. The flat front and back sheets won't be a problem to line up straight.

[Artificer]

A spiral cutting bit will give a cleaner cut than a straight bit, also.

Down cutting if you can find one.

Try MCLS
I have all of the spiral bits. I like the down cut bits for thin ply.

The problem with the spiral cutting bits is that they are not flush trim bits. You could set up a C-shaped guide, like a laminate trimmer, to get a flush cut. Another option is the following from MLCS Shear angle bit

The shear angle give some of the benifits of the spiral bit, but still gives you a guide bearing for flush cutting.