Haven’t used a router much before but am running into a problem that I haven’t seen discussed anywhere. I’m using a straight up/down spiral bit to cut 3/4″ plywood. the routed edge is perfectly straight down it’s length but some of the ply layers stick out further than others such that when two pieces are butted together, they meet on some of middle plys and not the top or bottom veneer edges. I actually bet a flatter cut (through the thickness of the ply) with my table saw (80 tooth blade). Anyone have any suggestions?
Lance
Replies
I'm trying to understand why you're cutting ply with a router instead of your TS?
Good question. I'm building cabinetry and have to butt two pieces together and need a joint that isn't visible as this is in a highly visible location where I'm matching figured teak veneer plywood. It's tough to run a 26"x48" piece throught the saw and get a perfectly straight edge, particularly on a small 8" saw. A crosscut sled to accept a 26" width would have to be huge. I can set the router fence up to be perfectly aligned with the matching grain and get a beautifully smooth cut...except that a couple of the inner layers of ply must be harder than the others, at least that's the only thing that I can think of to account for it, although it isn't logical. The router bit should whack everything straight down.
Lance
If it's a used bit or HSS, it's not unusual that it's pulllng end grain from the middle of your ply. Try a new, good quality carbide bit, as the resins used to bond the plies are rather abrasive. A larger diameter bit (~3/4") will give you better shearing action than a smaller one.
what about putting a 1° angle on your cut so only the top edge butts?edit: to all, not to just you SG
Edited 5/13/2006 7:35 pm ET by storme
But that would leave a gap on the "B" side of the joint, wouldn't it? That doesn't seem like an acceptable trade-off to me and it would unnecessarily complicate glue-up/clamping.
Storme, Is this a problem you've seen before? The 1 degree angle is a great idea, except that I'm using a hand router.
Splintergroupie, I'm using a brand new Whiteside up/down spiral bit. The Whitesides came up as the best cutting bit in a test of a bunch of brands in a Jul/Aug FWW evaluation, so don't think it's the bit. After I encountered the problem, I tried a test cut with another brand of straight bit and had the same problem.
After experimenting a bit, turns out I can lightly sand the edges and get an acceptable joint. Just seems odd to me though, that there is a problem at all.
OK, it's your ply, not the bit. I've done what you're doing and had it work fine, so since you haven't posted much, i made a WAG you might be newer to woodworking and unaware all bits are not created equal. Pardon my assumption.If you have a jointer or access to one...I cut ply just a hair short of the line and sneak up on it on the jointer, even cross-grain.
Actually I've only done a modest amount of woodworking but the FWW site has such an incredible amount of information available; poke around a bit and suddenly you seem smart - like picking good router bit brands! Although I've got the plywood issue, the Whiteside bit makes a beautiful cut, top and bottom. I've got a 3/4" dado bit from them and it cuts beautifully as well.
You're probably right about the joiner, accept I dont have access to one. Actually I tried using one once and found it really tricky, at least for me. In any case, my light sanding of the joint (keeping off the top veneer face is working acceptable well. I only have one really critical joint that I'm working; the others aren't so visible.
You have tenacity and a streak of perfectionism, and those are the best tools in the rack. BTW, if you're gluing the butt joint, consider masking off the veneers with tape before spreading glue. If the veneer absorbs the glue, you can end up with a permanent splotch you can't scrape out. Good luck!
How much are you trying to take off with your cut? If your taking more than a 1/64 or1/32" try a cleanup cut with just a very light pass. Sometimes with large panels and oddball angles, I'll rough cut with a circular saw and come back and do a cleanup with the router. It may take a couple of passes to get an acceptable edge.
You may be lifting the grain in the center ply. Try routing the edge and then come back across with a climb cut.
Jack
If you look at the spiral bit it is tapered, so that would tend to not give a perfectly straight cut (vertical) unless you make passes that get deep enough for the bit to get to its straight profile. While you mention not being able to run the sheet goods through a table saw, if you set up supports to feed it once you have made the initial cut a little proud , you can then set up a sacrificial fence slowly raise the running saw blade into the fence so just a fraction of the tooth is exposed to the sheet goods and you have a poorman's joiner.
I have yet to see a spiral bit thats tapered, the spiral grind can be deceiving. He says he's using an up/down spiral bit, Sometimes called a compression cutter. Probably the best bit for this application if the Ply is veneered on both sides. There is a remote possibility that the opposing shears might be ground slightly off. I would mike them up to either prove or disprove that possibility and continue on from there.Work Safe, Count to 10 when your done for the day !!
Bruce S.
Bruce,
I did a test cut with a straight bit as well and had the same problem, so I don't think it's the bit.
The problem with that version of the "poor man's jointer" is that the outfeed table (so to speak) is the same height as the infeed, so as you get toward the end of the cut, your stock will tend to rest against the fence after the blade, pushing the cut slightly out of true.
If you want to dress the edge, why not just set your fence width to the width of your board, minus the amount you wish to remove? Then you're always registering against the straight fence and can push straight through. If you haven't got a good edge to use against the fence, temporarily attach a straight edge to the right side of your board to reference against the fence.
If you want to do what you're describing, you could run a partial cut along the bottom of your fence, so the "outfeed" portion is proud of the "infeed" portion. It could take some fiddling but you could get it cut so that you had level support on the outfeed side.My goal is for my work to outlast me. Expect my joinery to get simpler as time goes by.
I have to agree with Johnd on this one.
Jack
Thanks all for the help. For now I've got an acceptable edge by carefully sanding down the raised plys, but I'll try some of the ideas on future cuts.
Lance
Jack,
that actually looks like what is happening (raising the grain), but you've hit me with a new one...what's a "climb out"?
Lance
Normally you run the router across the wood left to right so the spin of the bit helpf pull the router into the wood. A climb cut, is running the router right to left, often used with dificult grain problems. It's a little harder to hold because the router will try to climb out of the wood. So what I sugessted trying was to run the router across as usual then run it back across in the oposit direction without moveing you guid. See if that helps.
Jack
For a similar cut that you describe, let me make two suggestions, both requiring a good straightedge. See: http://www.amazon.com/gp/product/B0000224DM/qid=1147690784/sr=8-1/ref=pd_bbs_1/104-8102472-5900765?%5Fencoding=UTF8&v=glance&n=228013
1) Get a finishing blade for your circular saw, this may be all you need. you can do the following :
A) Cut from the top, light cut to score the veneer, deeper cut to finish, OR:
B) Cut from the back, one cut should do it.
2) If you don't like that, or the veneer tears anyway then cut it close, say no more then a 1/4" with the circular saw and straight edge again, then use the router with a good (Amana, Freud, Bosch) down shear bit to clean up the edge and effectively "joint" with the router and straight edge.
Method #1 will probably work, although you may have to do a bit of experimenting, method #2 definitely will work. I used it many, many times.
Oh, the straightedge that I recommended is a wonderful thing in that it grips the edge of the material and actually works!
Let me know if I can be of any help. Good luck!
John
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