Flatten and end grain board


wtnhighlander

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Ahhhh, I think I see my confusion now. Turtle is concerned with problems in removing the rails at the end of the process, not with the flattening process. Is that correct?

No, I am concerned with the safety of getting a clean consistent flat cut.  You need to keep your reference surfaces tight to the table top, that means downward pressure is needed to keep the reference boards in contact with the table the whole time.  This is the pressure I am concerned about.

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No, I am concerned with the safety of getting a clean consistent flat cut.  You need to keep your reference surfaces tight to the table top, that means downward pressure is needed to keep the reference boards in contact with the table the whole time.  This is the pressure I am concerned about.

OK, then I am confused again. The glued-on rails ARE the reference surface. Since they are wider than the cutting board blank's thickness, all pressure applied to the rail is transmitted directly through the rail to the table. No downward pressure need be applied to the board blank at all.  If you feel that the rails do not provide enough surface area to manipulate the rig from above, just screw a piece of plywood across the rails, and you have the entire surface area to work with.

This is exactly the same process as using a router sled to flatten a large slab, only inverted to use the router table with smaller pieces.

The only thing I can see that might prevent a clean, flat cut is if the axis of the router bit is not perpendicular to the table for some reason.

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OK, then I am confused again. The glued-on rails ARE the reference surface. Since they are wider than the cutting board blank's thickness, all pressure applied to the rail is transmitted directly through the rail to the table. No downward pressure need be applied to the board blank at all.  If you feel that the rails do not provide enough surface area to manipulate the rig from above, just screw a piece of plywood across the rails, and you have the entire surface area to work with.

This is exactly the same process as using a router sled to flatten a large slab, only inverted to use the router table with smaller pieces.

The only thing I can see that might prevent a clean, flat cut is if the axis of the router bit is not perpendicular to the table for some reason.

And as it is just like flattening a large slab, would you put together a sled for that with hot glue?

 

There will be shear stress at the joint, that is why it was glued after all.  Now I guess you might get resonable safety by only pushing it through the bit and if it chatters up and down let it.  Though that would also provide much higher stresses on the glue as any movement dramatically increases stresses this might not be so good either.

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So we are talking about the flexibility of hot melt glue and the uplift caused by the cutter. I assume the uplift is negligible. I also assume that hot melt the length of the rail easily equals turners tape. Wear your safety equipment because a catch could bother, but don't panic. 

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  • 3 weeks later...

One more comment on the hot melt glue: I did another board blank, using this same method. I chose to pry the pine runners off, rather than saw through the glue line. The hot melt glue actually pulled chunks out of the pine when I pried the board away, and I had to chisel them off the blank. Now, if I was not in a hurry, I would certainly prefer to use wood glue, as it cleans up easier. But I have no fear of the hot glue failing.

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  • 2 weeks later...

I can see ponders concern here. It's not quite the same as routing above for a few reasons. 1. Your hands arent behind the cutter like they are with a normal sled. 2. You are not applying pressure dirrectly over the cutter like a traditional sled ( IE: Chatter which can lead to a catch is looming) 3. Its risky because you cant see the operation. Personally, while I think it was ingenious, making a conventional sled wouldn't take much more work and is way safer.

 

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If you adjust the bit too high, thats when things can get nasty. It can go smooth 100 times, but you have meat pinched between the fence and the bit on the initial pass, which is a climb cut, and breaking the "rules" of safe router table operation. It's no different than dropping a piece over a strait bit to create a groove (like a drawer side) which always gives me pucker factor.

In this case, the one thing you have going for you is, the board is large and your hands are pretty far back. 

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