How to Joint/Plane long boards?

[Chris Dodge]

I have owned a jointer and planer for about a year and a half now and have become very proficient with making very straight boards that are four feet or shorter. No problems there.

Where I am having problems is when I need to make a cabinet door that is six or seven feet long. My jointer has a 75 inch bed so it should be long enough but still the long boards often curve by 1/8 - 1/4 inch sometimes. How do I get a perfectly straight long board?

[James Phillips]

When jointing the most important thing to remember is to not push down to hard. This can cause some bowing. Be sure the stock is flat to the outfeed table, and apply pressure more against the fence. Also check the tables. Make sure they are EXACTLY coplaner. This will cause bows that will be more apparent in long stock.

[Jim Becker]

An alternative for edge jointing long stock is a router with a guide, either a commercial solution or one you make from a "known" straight edged piece of material.

[Chris Dodge]

When jointing the most important thing to remember is to not push down to hard. This can cause some bowing. Be sure the stock is flat to the outfeed table, and apply pressure more against the fence. Also check the tables. Make sure they are EXACTLY coplaner. This will cause bows that will be more apparent in long stock.

I am careful not to push down hard and just guide along the fence. That is why short boards are easy. I can push down on the front and just let the rest of the board be cut wherever it makes contact with the blades. But when the front of the board leaves the end of the jointer I no longer have that part of the board to use as a reference for the rest of the board. Does that make sense? Is there anything else I can do to ensure flat boards?

Also, I have checked the tables and they are coplaner.

[Chris Dodge]

An alternative for edge jointing long stock is a router with a guide, either a commercial solution or one you make from a "known" straight edged piece of material.

I might need to clarify a bit. My boards are straight along the edge but the long boards are not always flat. That is where the problem is. Any sugestions?

[Andrew Williams]

I face joint by hand before using the powered planer. I always work on the concave side, which means I am removing material from both ends rather than the middle. Throughout the process I am frequently flipping the workpiece over onto the workbench surface (which is pretty flat) to check it. This has been fine so far, and the only thing I can think of that would make it better would be to own a very long precision ground straightedge (big bucks!). If I were using a powered jointer, I would do the same, focusing on only the high spots in the board. Honestly I have never used one though (never needed one, the handplanes are quite fast once you get used to it).

If I have a really bad piece then I screw it to a sled of MDF with shims under the bowed spots and run that through the planer until I get a flat side.

[James Phillips]

Long boards not being flat can be tricky. If over half the board is off the end of the tables, you are correct that you are forced to push down more to offset teh gavity pulling in the end og the board. Also the overhang can cause the board to flex a little and this can cause the bowing you are seeing. I would try and outfeed roller or two that are very carefully set to the same height as the outfeed table. Might Work.

[Al Willits]

Think James hit a good possibility.

Haven't had much trouble with the jointer, but I did have some sniping with long boards on the planer, added in and outfeed rollers and they helped quite a bit.

[Jim Becker]

I might need to clarify a bit. My boards are straight along the edge but the long boards are not always flat. That is where the problem is. Any sugestions?

Yes, I should have commented on that. Sorry. Face jointing can still be done on your existing jointer with many light passes and extra infeed/outfeed support. (I've successfully done this) It also helps to start with material that is nearly flat if you can. Further, for components that are nearly 7' long, if you start with a largely flat board, you can probably get away with just surfacing both sides with your planer since you have enough material to bring things together while clamping square and true. Judgment call...

Projects like this sometimes require a little more scrutiny on material selection because of machine limitations.