Thread: Table top bowed with dominos?

What happens if you alternate every second piece 180 degrees to have the bottom become the top


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Is your square square?

Does it sit flat if you take the dominoes out, with no spaces (top or bottom) between the boards? That will tell you if the boards have been accurately jointed. If it's flat at that stage, then the problem is with the domino holes not being parallel to the top/bottom surface, whichever is your reference face.

For a table top of that thickness, I don't think you should need dominoes.

Cheers,

ajw

Originally Posted by forrestmount

What happens if you alternate every second piece 180 degrees to have the bottom become the top


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Dang too late to try that I glued it used 2 aluminium bars to keep it flat

Originally Posted by elanjacobs

Is your square square?

I think so, I checked it against another square (a framing square) and it is correct. But I suppose the framing square could be off...

Originally Posted by ajw

Does it sit flat if you take the dominoes out, with no spaces (top or bottom) between the boards? That will tell you if the boards have been accurately jointed. If it's flat at that stage, then the problem is with the domino holes not being parallel to the top/bottom surface, whichever is your reference face.

For a table top of that thickness, I don't think you should need dominoes.

Cheers,

ajw

it sits flat without the dominos.

I wouldn't be trusting a framing square for much...

The bast way to check a square it against itself; mark a line with it on a piece of board, flip the square over and see if it lines up. Any deviation from the original line will be double the error of the square.

Just checked with that technique - its spot on.

It must be either the domino tool or my technique. Is there a way to check the tool? It doesnt go beyond 90deg right? You flip the reference plate all the way down as far as it goes and lock it down.

I plunge slowly so it doesnt bite and I ensure that the reference plate is perfectly flat with the top of the board

argh

The domino fence was not all the way to 90°, it must have been at 89.(something)°

I was really careful and checked that when I was setting it up but maybe I screwed it up somehow :S

when cutting the slots, could the domino base plate be hitting the bench? This is s typical problem with biscuit jointers

I find technique makes a huge difference.

Hold the front knob hard down on the surface, then hold the tail right at the back near the cord, lifting ever so slightly.... just to reduce the gravity.

When doing smaller pieces I've found putting them on a bit of MDF for support and balance gives good results.

Ian's point of hitting the bench is spot on (or lifting the tail as my fingers get jammed between domino and bench). Done that many times!

It's such a great machine.

I had the boards suspended by two pieces of pine so I don't think its hitting the table - I'll check on weekend to confirm though. In terms of technique, I was pressing hard down on the fence and I was worried it would lift the tool so I also pressed down slightly on the tool to try and keep it square. Maybe I was trying too hard lol

For the concave result that you have, the slots would need to be sloping down from the face. ie cut with the power cord far end of the cutter raised. Or the cutter is at greater than 90 Deg to the foot plate.
If the cutter did not cut deep enough, the biscuits would bottom out and the result would be convex. If the cut was to narrow for the biscuits, they would jam and likewise give a convex result. Also convex if the cutter was at less than 90 Deg to the foot plate.

Cutting disc alignment to the plate, being grater than 90 Deg, is my best guess.

If you are having strife, this manual is incredible: http://thedovetailjoint.squarespace....%20reduced.pdf


Additionally, you can ensure a perfect 90 degrees by using one of these, or making your own (of MDF):
Domiplate for 1/2" and 3/4" nominal ply | Seneca Woodworking

Why people insist on using domino's etc in table tops, I have no idea. It is just one more thing to go wrong or create complication. What is wrong with a simple, well glued butt joint?