Help Jointing 6 foot long boards

Hi,

Sorry to be a pain again but I'm in the process of building a gas fireplace enclosure/mantel and need some encouragement on jointing longer boards. I decided to build the whole thing out of solid maple with some cherry shelving. I have most of the stock milled down but find I need a few boards that are 6 ft long and I'm unsure the best way to do this. I have the Delta X5 jointer with a 46 inch long bed. Some of my attempts on scrap wood seems to be producing boards that are thicker in the middle. Any guidelines?

Thanks,
Tim

[Ron in Richmond Hill]

Length of jointer bed is fine for 6' boards. Would you say the boards are tapered. If so, its syptomatic of the outfeed table being too high relative to the knives (or the knives being too low). If you start with a board that has a high spot in the middle, it is difficult to remove that on the jointer as there is a tendancy for the board to rock as you move it across the knives. Can you turn the board over so the concave side is on the bed and straighten it?

Hi Tim,
Convex edge sounds like the tables are not level. (assuming your technique is good

Tim - I have the same jointer and had the same problem until I got serious and checked the setup. Check the archives on this forum for a good discussion of jointer setup titled 'jointer "Technique" problem' initiated on 20 Aug 2004.

I followed the composite of the points raised in that thread and now get a straight edge.

Jointer Tune Up.

Thanks for the info guys. I must agree that it does appear to be an alignment issue, but I recently spent several hours resetting knives and tables, so I'm pretty confident on the setup. I am able to joint 3 ft boards or less without issue. Ma me wonder if there is a technique to jointing longer boards. I'm not getting tapering which would indicate my outfeed table is out of whack, I'm getting a situation where the middle of the board is thicker, than the ends.

Thanks

Hi Tim

How bowed is the board before you start face jointing? If it's bowed, your jointer will take material off the ends before the middle. you'll end up with a board thicker in the middle. It becomes more noticeable when face jointing longer boards.

Try to select boards that are good and straight for long boards, save the bowed boards for shorter pieces

Mike

Hi Tim,
I still wonder if your tables are level. What your are explaining is exactly what happens if they are not. Just to be are clear, by level I mean that if both tables are adjusted to "zero" they form a perfectly level (flat) surface down the length of the tables.

If this is the cause and you are lucky you can true the tables with the adjustment gibes. If the tables themselves are out because of warpage or poor machining your SOL.

This is tough to measure with a 36" ground straight edge. Perhaps you could clamp trued spacers of equal height at each end of the tables and stretch a couple of fishing line between them. Now you can measure from the table to the line. Far from ideal but it might work if you're patient and gentle.

Sorry to waste your time if you've already covered this but I hope it helps. I feel for ya man, jointers that don't joint are a pet peeve of mine.

As Mike says if you are jointing with the bowed face down [as you should] you have to end up with a board thicker in the center and you need to select the straightest boards for long pieces. If you put a straight edge from tip to tip, the distance from the straight edge to farthest distance of the bow will be about what you take off of each end of the board. When selecting stock check and rough cutting to length, make sure you are cutting off the end with the most amount of bow.

The one technique issue is to be careful that you are not "pushing" the mid point of the board down while jointing. This will result in a board that never gets flat. The longer the board the lighter the touch you need in the midsection.

If you are using some kind of safety push pads try to keep as much of the force forward as possible. You can usually tell if you are pushing down too much if when you change hand position the board loses contact with the cutter head. You really need to have a good slippery outfeed side so you can have a light touch.

This might not be the issue but it's something to think about.

Shane