Problem with conical disc sander

[BuckeyeDennis]

For some reason, the video that algale posted won't play for me right now. So this may be redundant. But keep in mind that the SS main table is not terribly rigid in the horizontal direction. So, whenever you are doing an operation that needs a close tolerance in the horizontal direction, you want to stiffen it up. Assuming that you have a 510 or a 520, this is easily accomplished buy mounting the auxiliary table, and coupling it to the main table with the connector tubes. Somewhere there's a video of Nick doing this and using a dial indicator to show the improvement.

You can't connect the main table to the aux table when using the conical disc, since the main table needs to be tilted to approximately 4 degrees to the left left in order for it to be square to the conical disc surface. But your point about rigidity is still a good one. If you try to take a big bite with the conical disc, there's a chance the table is going to deflect. So use the right grit and take light passes.

Oh yea, duh, forgot about that.

I suppose that one could just butt the main table up against the aux table, and get some improvement in stiffness.

[JPG]

If the table is deflecting, feed rate can affect this. Slow at the ends but faster at the center will likely cause more deflection at the center. A repeat pass may help. If the above is accurate, the second pass will remove more material at the center while removing minimal amount at the ends. Repeated passes may completely eliminate the convexity.

BTW how much fatter at the center.

[tomp]

I appreciate the help and suggestions from all of you.

I did use a square to align the table to the disc, and I did happen to have a floating table attached.

I still believe that Dusty was correct; I was trying to use the disc to dimension the wood, and using quite a bit of force on the board.

Finesse, finesse, more finesse

One question for ERLover regarding: read the instructions on how much to remove per pass based on grit!!!

Just where did you find that?

[charlese]

Maybe that is it, Dusty, because I was trying to remove the 1/8 inch of chipped wood using multiple passes at 150 grit.
Tom

Probably nothing wrong with your setup, Tom! Dusty was absolutely correct!!!
As you witnessed, the jointer chipped out some places because of grain figuring. This means there are "hard places" and softer places along the edge. The sander sees these hardness differences the same way as the jointer knives.

Patience is the key! You will be helped by both smaller takes on BOTH the jointer and the sander. It's more work but pays off in the end.