A small finger joint bit/cutter?


A friend has a 80" x 37" cherry table they let several candles burn down on. It actually burnt out maybe an eight inch of wood. The top is 1 1/4" thick, but I think sanding the damage out is probably hopeless; presumably the wood will be discolored deep into it, and it might be 3/8" to find clean wood. Turning the top over won't work either, as the bottom surface is quite imperfect. That leaves ripping the damaged 12" out, putting new boards in, and sanding it down. The problem is the joinery used. The top is all 2" wide boards that have a sort of finger joint between them. It is flat for an eight of an inch at the top and bottom, and then 4 pairs of fingers, each about an eight of an inch. They are rounded, and project about an eighth of an inch.
Getting an exact match is too much to ask for, but I can't find anything even close. Any suggestions, either on the cutter or alternate methods? I will take a router bit, a shaper cutter, or maybe even a molding head for my table saw.
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How objectionable would it be to use a patch on the places that are damaged? Like I have seen used by Norm on a couple shows to fix defects in desktops. He uses a bowtie shaped patch, glued into the same sized hole routed into the top and then sands it down to be flush.
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methods?
Like you said, it seems like it would be really tough to match up finger joints. I think I might try routing down just a little ways in the area immediately around the burn, then inlaying some similar wood, and sanding/scraping/planing down to flush. If the bowtie/butterfly shape mentioned above is too small or wouldn't work decoratively, I'd be inclined just to use a plain rectangle, possibly directly along the existing joints between boards. In other words, could you use a straight bit set 1/4" deep to rout out a section of each burned board, and inlay new wood? Or get a table runner, or a nice centerpiece/candle stand that covers up the marks. Good luck, Andy
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You might want to make an irregular shaped dutchman, it will be easier to hide. Or, inlet several as decorative features.
irc. There are good instructions in one of Matlack's router books. Mine are packed away right now so I can't chack and say for sure.
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I'm having a little trouble following the rounded finger-joint thing, but will assume you want a flat top.
You might take to routing the top as follows:
If you have two very flat boards [MDF?] for the router to ride on, you can rout out all except for some very narrow ridges to support the boards and router while getting out most of the material, setting the router the 1/8" below the present top [perhaps 2 passes of 1/16"]. You can remove those ridges close to the new surface by hand with a sharp chisel. Then sand with a sanding block until happy.
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is this a glue up edge joint? Why do you need to match the profile? Does it extend and become the perimeter edge also? Could you not just glue it up with biscuits or dowels or just straight glue up?
I'm probably missing something here.
I have a three flute edge bead shaper cutter that cuts 1" that sounds similar to what you have described. But it is three not four beads, with a top and bottom flat.
Frank
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wrote:

If it were mine I would do just that. But it is seen in the edge, she thinks it is decorative and wants to match it.

I did a search and found one. http://www.amanatool.com/shaper/960.html Is that what you are talking about? Is there a mating profile? If that existed, it might be close enough to work.

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Similar. the outside (top and bottom) flats are slightly deeper than the flats between the flutes.

cutter, so I doubt there is a reverse or female profile.
If your friend can stand to lose a quarter inch or so all around, you might just glue in the replacement panels and then put an all new edge profile on the table with a router beading bit. Seems to me it is going to be hard to get a really good edge match on the glue up anyway pre cutting the end on a shaper or molding cutter head.

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[...]

Something like http://www.axminster.co.uk/recno/4/product-Perform-Finger-Joint-Cutter-22968.htm or a bit cheaper but less flexible http://www.axminster.co.uk/recno/4/product-Perform-Finger-Joint-Cutter-22968.htm
Or if you insist on "rounded": http://www.axminster.co.uk/recno/3/product-Omas-Glue-Jointing-Block-20415.htm
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writes:

http://www.axminster.co.uk/recno/4/product-Perform-Finger-Joint-Cutter-22968.htm that has a 3/4" bearing. Would it still work (ie. would the pieces still mate) with a 1" bearing? If so, it might be close enough.
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patch as suggested by others.
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The finger joint doesn't matter.... simply joint the edges of the remaining boards (they will have sawn edges based on your plan) and glue in new pieces.
Perhaps a bit of archeology is warranted here. Take a carving gouge and carefully see just how deep the damage is in the wood. One way or another you are going to remove that section or Dutchman it so the gouge work isn't hurting anything. You may find the damage is relatively shallow and not warrant drastic measures.
Personally, with 1 1/4" of solid wood to work with, I'd be inclined to surface the entire table rather than mess with cutting out the damaged section. I wouldn't sand it all away though, I'd start with a scrub plane and work towards a smoother. Completely removing the discoloration isn't needed as it could be masked in the finishing process.
John
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Or you can "antique" the rest of the table, calling the burns "features".
Don't laugh...
Barry
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wrote:

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Personally, I wouldn't even try to get an exact match.
To me, "close, but no cigar" looks *worse* than an obvious patch.
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http://www.frontiernet.net/~toller/routerbit.jpg
I contacted one router bit company and they said they could make a custom bit for a reasonable price. I'll let you know how that goes...
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A few ideas come to mind...
1. If you have access to a wide belt sander, run the whole top through the sander multiple times till you get down to good wood.
2. Rip the top into widths that will fit through a planer (12" typically), plane down to good wood, then reglue the top together. Sand and refinish.
3. If you do not have access to either of the above tools, you may be able to build a "sled" of sorts to flatten the top with your router and a straight bit. LOTS of passes back and forth, but it should work in theory.
4. Flip the top over and try any of the above methods. Depending on whether the top is worse than the bottom, this might be a good option.
5. 80" isn't that long. You should be able to cut out the damaged section and replace it with a single board.
6. Assuming this section isn't on the edge of the top, the joinery won't show anyway. Use scarf joints, or slots and splines to join boards together. Then cut out and replace the damaged section.
7. Depending on the construction of the table, maybe you could just cut out the damaged section and make the table smaller? For example, 80" x 35". It's unlikely anyone would notice a couple of inches difference.
8. Forget about repairing this top and just build a new one from scratch.
Anthony
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