Jointing technique help

[Martin S.]

OK, it has been a long time since I used a power jointer.

I finally got dust collection hooked up, so I have started trying to do some woodworking when I am home.

I am building a roubo bench.  I am working on the legs.  The jointer has been tuned to factory settings by a factory representative.

I know that you start holding the wood at the infeed end, then as it passes over the blades, you transfer your hold to pressing down the wood on the outfeed side, just past the blades.

Here is the problem I keep having.  Instead of a straight line, I get a "u" shape, in other words, a slight crown in the middle of the jointed edge.

Or, I get one end that is up "off the table".  If I hold a straight edge to the board, the outfeed end will have maybe 5-10 thousands of a gap.  I am guessing, as I don't have a feeler gauge, but I am going to buy one.

It seems like the tail end of the board is "off the table".

So what am I doing wrong?  I have jointed wood before, and don't remember having this problem.

I have watched some videos, but can't seem to identify what I am doing wrong.

I am open to your suggestions for improvement.

[JGrout]

it is likely a table issue

follow the instructions to troubleshoot it 

Joe

[MikeBob]

If all is set up correctly on the joiner, it the face you are jointing is high in the center that will happen, you want to clean the face of the wood that is concave in the center to get it flat on the jointer. Then clean up the convex side, high in the center, in a power planer or table saw to width.

[Martin S.]

Thanks, Joe and Mike!

The out feed table was just a very tiny bit too high.  

When I lowered it just barely, the problem was solved.

Thanks for your help, I was beginning to wonder if I had forgotten how to joint a board!


Now I need to figure out how to clean up a board in fewer passes so I don't end up with tapered boards.

[MikeBob]

Kinda basic but the best I can do at 221am!!
http://www.shopsmithhandson.com/archives...y_tips.htm

[MichaelMouse]

Table problems would provide consistent errors. It's your technique, I believe.  If the outfeed were high, you'd butt into it because you haven't removed enough wood. If low, the leading edge would tip because you took too much, leaving a gap.

The jointer is just a powered plane in technique.  You take off the high spots to gain an approximate straight edge, then run full length.    Sight the edge.  If it has a belly, joint only the belly until mostly gone.  This demands moving the guard out of the way to start the cut just prior to the belly - pencil helps here - taking a pass, moving forward, taking a second, sighting until the belly is gone.  A safer approach is to joint the concave side of the board.  Joint a short pass from end A, the another short pass from end B. Sight, repeat until approximately straight.  Try that, if the table has been set properly.  http://forums.finewoodworking.com/node/94670

[JGrout]

Thanks, Joe and Mike!

The out feed table was just a very tiny bit too high.  

When I lowered it just barely, the problem was solved.

Thanks for your help, I was beginning to wonder if I had forgotten how to joint a board!


Now I need to figure out how to clean up a board in fewer passes so I don't end up with tapered boards.

Tapering is inevitable if you have excessive bowing in the face or edge and you do not work from the middle outward 

There is one part that I have to mention here that gets overlooked when jointing stock:  that is rough cutting the stock to lengths +1~2" longer than the cut list callout. It is possible to flatten stock that is as long 8-14' long but it requires relatively straight stock and a good feel for what you are doing. I encourage you to cut lengths then go to the jointer  

The way to minimize this is to work from the middle outward in both directions from a bow (grain direction is not as important in the roughing phase in either face or edge preparation until the bow is nearly out so do not be so concerned with tear out at this juncture) The key is to take equal amounts out of the bow or crown as I said is to begin in the center and move outward with the cutting. In the case of a face you will want to shut off the jointer pull the guard back set the stock on the jointer start the jointer then begin feeding the stock forward. I put my down pressure on the stock much further back on the board so I am not manually pushing the bow out  (in fact if the end of the stock is on the jointer infeed table I set my hands nearly at the rear end of the piece) then proceed to feed the stock forward. do not expect the stock to be cut at the start in fact it may not cut until you get close to your hands at the end of the board once the cut begins hold the stock down and if you get cutting action of say plus 12" move your lead hand to the out feed table holding down pressure. finish the cut and repeat the process until you are cutting nearly from the center of the stock to the end Once  you accomplish this flip the stock end for end  and work the second half to the same condition 


Now you should have a nearly flat face or edge with just a bit in the center to be removed I will look at the face or edge at this point determine the grain direction for the smoothest cutting set that face or edge so it leads into the jointer and feed it in so I can make an entire cut the length of the stock You may have to do this a few times but it  should cut the entire face in a pass or three .  then it is off to the planer (to finish off the second face to parallel or the TS to cut the edges parallel 

If you have any questions please ask I am happy to help 

Joe