Difficulties trying to joint the face of a board
I’m trying to join the face of a hickory board. It is about 84 ” long, 3″ wide and 1.5″ thick
The jointer is a new 8″ jointer with a 76″ set of beds. After running the face through the jointer several times, taking 1/32″ off each time, the face has formed two flat surfaces which intersect. Running the board across the jointer more times doesn’t make a flat face – it always enlarges one of the two surfaces. I’d like to take a clean cut between the two edges of the face. The board doesn’t lay parallel to a plane between the edges.
I’ve been thinking of clamping shims to the infeed and out feed to force the board to lay in the plane I want
I’ve checked to make sure the blades are parallel to the outfeed table and at the same height. Maybe I need to check closer?
I’m making a workbench that will have about 20 of these boards, so I need to solve this problem. Otherwise, I’ll be taking a taking a lot of material off the boards and still not getting flat faces.
Thanks
Replies
I'm not understanding exactly what you're describing, so it could be one of several issues. Most likely, either your outfeed table is not set correctly to your cutterhead knife height, or your infeed and outfeed tables are not co-planer.
Are you getting two completely different 'facets' on the face of the board, or something else.
When facing a board for flatness, it's important that once a portion of the board is run over the cutterhead, that downward consistent pressure be applied on the outfeed side of the cutterhead as the board passes through the entire facing cut. If you're outfeed table is higher or lower than the height of the knives, it will not produce an accurate cut.
One way to check this (CAUTION---BE VERY CAREFUL WITH THIS) is to use a known flat edged board, and very, very slowly slide it over the cutterhead from the OUTFEED side. SLOWLY!!! If you hear just the slightest little feathering sound, that is the knives just barely knicking the wood. If you get nothing, the outfeed table is too high. If you get a louder noise, then it is too low. PLEASE BE CAREFUL with this.
Adjust accordingly.
Report back.
Jeff
Report back
Jeff
Using a flat edged board, I slid it according to your instructions... both at the back and later at the front of the table. I observed minute contact with the blades. Also, resting the board, on the outfeed table, over the blades, I can turn the blade, clockwise, and the board moves maybe a centimeter each time a blade passes underneath ( due to contact with the blades ). This happens when the board is positioned at the rear or the front of the table.
For the next experiment, I attached a flat MDF section of board about 8" in depth to the outfeed table, with its right end resting over the blades, and started the jointer. The result was very fine removal of material ( maybe 1/100" ) at the right/rear edge of the corner, but little to none at the right/ front. So it seems the outfeed table and blades are not perfectly parallel from front to back. With this, I will be removing 1/100" more near the fence than near the front of the jointer. With repeated passes, this will add up.
Question - what accuracy should I expect to be able to attain as I adjust the outfeed table to correct its front to back elevation?
Thanks much
I'm not understanding exactly what you're describing, so it could be one of several issues. Most likely, either your outfeed table is not set correctly to your cutterhead knife height, or your infeed and outfeed tables are not co-planer.
Are you getting two completely different 'facets' on the face of the board, or something else.
When facing a board for flatness, it's important that once a portion of the board is run over the cutterhead, that downward consistent pressure be applied on the outfeed side of the cutterhead as the board passes through the entire facing cut. If you're outfeed table is higher or lower than the height of the knives, it will not produce an accurate cut.
One way to check this (CAUTION---BE VERY CAREFUL WITH THIS) is to use a known flat edged board, and very, very slowly slide it over the cutterhead from the OUTFEED side. SLOWLY!!! If you hear just the slightest little feathering sound, that is the knives just barely knicking the wood. If you get nothing, the outfeed table is too high. If you get a louder noise, then it is too low. PLEASE BE CAREFUL with this.
Adjust accordingly.
Report back.
Jeff
Jointers should be set up so that blade height differential between the knife at TDC (top dead center) and the outfeed table should be under .002, using a dial indicator. If your knives are set so that the fence side of the knife is a different setting than the front side, you will initiate twist. Also, if the infeed and outfeed tables aren't co-planer, or dead flat, with no twist, to each other, you will also have problems.
It sounds like your setup is all wrong. I have 2 jointers in my shop, and both are set the same way. My outfeed table is less than .001 under TDC, so I get real flat results.
Using a magnetic base, a dial indicator, and a known straight edge of decent length (4 feet should suffice), you need to test the setup of your jointer tables. Make sure the infeed and outfeed tables are in the same plane, and that they don't ramp up to the cutterhead in each direction. Also, make sure that when the infeed and outfeed table are set to the exact same height as TDC (no wood removal when passing a board over) that front side and back side are of the same depth.
Once you achieve this, you should automatically solve your problem.
Jeff
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