Conical Disc Sander and Jointer

mandoboy · Post by **mandoboy** » Tue Oct 16, 2007 8:28 pm

Question 1:

I got my conical disc set up with 150 grit and sharpened my jointer blades. They seem great when you look at them. They are very sharp with a nice straight edge. I set them in the jointer and made them even with the fixed bed so that there is only a slight "touching" when spun with a piece of wood held on the fixed table. This "touching" is even from side to side and blade to blade. The jointer seems to work very well, but I seem to be getting a some weird irregularities in the surface of the piece. These are not straight, so they are not in the blade. It almost seems as though something is getting caught between the blade and the piece and moving around. The chips are flat spaghetti like pieces. Anyone know what might be wrong?

Question 2:

I am using the conical disk to sand a piece of wood. I put the table so that it is square to the disk at the center. On my machine, this is about 3 degrees not 4. I am not sure why it reads this as the table reads 0 when it is square to a blade. When I sand a 1x2, the top of the wood is sanded, but not the bottom. Which means that the angle needs to be less than the 3 I get when it is square. That seems weird to me. Any one know why that is or the proper way to get it to sand square?

Thanks.

Jeff

bkhop · Post by **bkhop** » Tue Oct 16, 2007 8:44 pm

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charlese · Post by **charlese** » Tue Oct 16, 2007 9:08 pm

Hi, Jeff - I can answer your number 2 question right away. When sanding the edge of a board with the conical disk sander, the table should be set a 4 degrees. Why? because the angle of the conical disk is 4 degrees, and you want a 90 degree angle from the bottom of the board and the sanded surface. Checking with a machinist square is not a bad idea! Especially if your index on the table trunnion is off a little.

mandoboy · Post by **mandoboy** » Tue Oct 16, 2007 9:11 pm

bkhop,

That is what I am doing to square the table to the disk. It is square, but still sanding the top third of the 1x2.

Thanks . Jeff

bkhop wrote:Jeff -
When you're setting up the table to the disk, put a square on the tabletop and then the ruler up against the disk. Takes all of 30 seconds to square it up properly. Right on, every time.

bkhop · Post by **bkhop** » Tue Oct 16, 2007 9:24 pm

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mandoboy · Post by **mandoboy** » Tue Oct 16, 2007 9:32 pm

I was surprised too. It seemed like it should work great.

I used it to sand the marks from the jointer only to get my piece out of square. Bummer.

Jeff

bkhop · Post by **bkhop** » Tue Oct 16, 2007 9:35 pm

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mandoboy · Post by **mandoboy** » Tue Oct 16, 2007 9:35 pm

Thanks Chuck.

My index reads 0 when the table is square to the blade and 3 when it is square to the disk. That is what doesn't make sense. It should actually be less than 3 based on the way it was sanding. That is what I don't understand.

Jeff

charlese wrote:Hi, Jeff - I can answer your number 2 question right away. When sanding the edge of a board with the conical disk sander, the table should be set a 4 degrees. Why? because the angle of the conical disk is 4 degrees, and you want a 90 degree angle from the bottom of the board and the sanded surface. Checking with a machinist square is not a bad idea! Especially if your index on the table trunnion is off a little.

dusty · Post by **dusty** » Tue Oct 16, 2007 9:39 pm

Jeff, it might be helpful if you could post a photo showing the conical disc, table at tilt and the square.

It seems that you are doing what all of us say to do but your evidence is compelling. If you sand only a part of the vertical surface that is "against" the disk - it sounds as though the surface you are attempting to sand is NOT parallel to the surface of the conical disk (not perpendicular to the main table).

The edge of the 1x2 is cut square correct? In other words, it is 90 degrees to the main table before sanding.

charlese · Post by **charlese** » Tue Oct 16, 2007 9:40 pm

Jeff - your question number 1 had me head scratching a bit until I read you used a piece of wood on the fixed table to set the blades. Slight touching on a piece of wood is a pretty rough measurement method. (Good enough to set a saw blade or a router bit, but not good enough for jointer blades)

As you already know, it is pretty hard to tell just when a jointer blade touches a piece of wood used as a feeler. Also the feeler must be "straight" with no irregularities. A piece of wood may look straight, but usually it has small irregularities. Instead of wood - use a 12" metal straight edge ruler standing on it's edge and protruding over the edge of the fixed table exactly 2". If a jointer blade, when turned by hand, moves that ruler more than 1/8" it is too high. The reason for extending the ruler exactly 2" is so all parts (edges and center) of each blade will strike the same piece of the ruler - thus eliminating any irregularities in the ruler's edge. You can get such a ruler by buying a cabinet maker's square and removing/using the sliding ruler that is part of that tool.

My guess is, the core of your problem is the height of the blades. They are a little too high and also one of the blades is higher than the others. This causes the wood being jointed to jump and slap back down in time for another blade to hit it. If an edge or two of a blade is a little higher than the other (probably caused by gaging with a piece of wood) it would produce an irregular pattern.

Best wishes to you in getting the jointer adjusted well. As I know, this is a difficult operation. Maybe not so much difficult as it is time consuming and frustrating. But when done - and the jointer makes nice smooth cuts, - the job becomes very satisfying!