Problem with conical disc sander

[tomp]

I'm trying to join boards for a table top. Through the jointer, they line up perfectly, except the wood is figured along the line, and it chipped out. Decided to use the conical disc sander. Lined it up perfectly square with the table. Ran the board thru, and then it was slightly convex. Went back to the jointer; nice and straight. Back to the conical disc sander; slightly convex. The convexity is in the long direction of the board. It was flush against the fence the entire time.

I don't understand what I am doing wrong.

Tom in MT

[dusty]

Make absolutely certain that you are remaining tight against the fence. Take off very little. You should not use the conical to dimension the work piece; only to finish sand it.

[ERLover]

Trying to understand, is the table set, I think at 4*, which would make it 90 to the disc. I set mine with a square, table to disc. Is the table set higher then the center line of the disc?
I have one, used it a couple times, but not for what you are doing and I am away from the shop geographically.

[tomp]

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

I need to buy another conical disc when they next have a special, maybe 2, so I don't force things.

I set the disc square to the table, but was a little higher than midline; sandpaper badly worn. Does it matter that I wasn't exactly centered on the disc?

Tom

[ERLover]

1st table and disc 90*
2nd read the instructions on how much to remove per pass based on grit!!!
3rd table needs to be above center line, read instructions on that.
4th in doubt read instructions again.
5th you can go to SS site I think to get a net copy of instructions to read.

[jsburger]

1st table and disc 90*
2nd read the instructions on how much to remove per pass based on grit!!!
3rd table needs to be above center line, read instructions on that.
4th in doubt read instructions again.
5th you can go to SS site I think to get a net copy of instructions to read.

That is true but as you mentioned in another post the main table must be tilted 4* left per the instructions to make the table and disk 90*. Just wanted to clarify for those that are a bit confused.

[algale]

If you are still having issues, review this video.

[youtube]https://www.youtube.com/watch?v=UO7eejezyu8[/youtube]

[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.

[algale]

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.

[JPG]

Not sure I understand your 'issue', but be aware the angle is not actually 4°.

More like 3+.

Use a square to set the table angle(square against the disc on a line that vertically passes through the center of the quill and the other leg(square) aligned to a line on the table top that is parallel to the quill axis.)

Make sure the workpiece is against the disk grit only(anywhere from the paper edge nearest the center to the periphery.

Taking more off the ends than the center(convex)? How straight is the back edge(against the fence)?