Replies

1. 
   forestgirl | Jul 16, 2003 08:56am | #1

   According to earlier posts made in various jointer-method threads, it seems the majority here think it's safest to place the board with the concave face down on the bed (crown up, right?).  All the books I've read while learning about jointer techniques have indicated that is the preferable (safest!) approach, because the board has much more in contact with the jointer bed and so will be more stable.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl   ;-)

1. 
   eddiefromAustralia | Jul 16, 2003 11:11am | #2

   I was trained as forestgirl says, purely from a safety point of view.

   As well, in the early stages of flattening, the board could rock on the crown and give you a twisted face for the first few passes.

   If I recall correctly, my textbook when I was training said crown down, but even the instructors cautioned against it. - correction - found my book - crown up was what it said

   Cheers,

   eddie

2. 
   JohnWW | Jul 16, 2003 04:44pm | #3

   I've run into comments about this technique before and while I haven't tried it myself, this is what I have read:  Apparently, many boards with a crown will straighten out and lose at least some of their bend if the crowned side is run through the planer first, presumably this releases tension in the board and allows it to relax.  The advantage to this is that the board will need to have less stock removed to flatten it out, resulting in a thicker board after both surfaces are planed flat and parallel.

   I don't see much of a safety problem with this technique since it is no more likely to cause kickback or leave the operators hands at risk.  Running the crown down does mean that the board is harder to control especially on the first pass or two, but I have done it on occasion, for other reasons, and never found it all that hard to control the board.  One way to stabilize the board for the first pass is place a wood shim under the trailing edge of the board.

   John W.

1. 
   DavidP52 | Jul 16, 2003 11:58pm | #11

   That is going to depend on the reason the crown exists, would it not? As well as grain direction. Too hard to try to predict that one in my view. Frankly, I've never noticed any straightening. Ultimately it becomes for me a question of how much planer knife I want to sacrifice for a piece of wood that's going to cost less than resharpening. Not good economix in my book. If it were a piece of cocobolo, maybe. Would you agree.

2. 
   Telemike | Jul 17, 2003 08:07am | #12

   One advantage of a drum sander is that I can put a board in with the crown up and take light passes.  The pressure will not flatten the board like the rollers in a planer so the crown will be removed.  When the board is pretty much flat, I run it through a planer to flatten the other side and make it parallel.

   This only works if there is not twist or bending up or down in the board.  That is best removed with a handplane (on which side?) and finished with a planer or drum sander when the first side is flat.

3. 
   Len | Jul 16, 2003 05:00pm | #4

   I've heard that same thing that you can release the tension on a crowned board by planing the crown side. But I always heard that in conjuction with using a hand plane. It would be more unstable than running the board crown side up.

   I will admit, I have run a crowned board through my planer with a shim under the crown to keep the rollers from compressing the board. It worked just fine.

   Len

1. 
   johnnyd | Jul 16, 2003 07:05pm | #5

   Get the best of both worlds by running the crown through the TS blade, concave edge against the fence.  Take just a sliver off, then over to the planer.  Or flip the board, re-adjust fence, take the concave out, now you've got parallel edges, and just clean up at the jointer.

1. 
   PlaneWood | Jul 16, 2003 07:23pm | #6

   I've never had much luck straightening the crown edge of a board on my little jet 6" (more than 1/8" out).  I first straighten it up on my table saw or band saw.  Snapping a chalk line works pretty well for the bandsaw and a straight guide board for the table saw.

   PlaneWood by Mike_in_Katy (maker of fine sawdust!)PlaneWood

2. 
   Len | Jul 17, 2003 08:37am | #14

   That would work for a narrow board but it's a little scary. I'm not sure I would want to  run a 3/4 stock on it's edge with the blade raised up that high.

   Or am I misunderstanding your post

   Len

1. 
   johnnyd | Jul 17, 2003 04:04pm | #15

   Looks like throughout this thread, folks are using the term "crown" to mean different things.  One post used three OTHER terms, warp, cup, and bow, to describe various ways in which boards end up twisted.

   When I use "crown" I'm speaking of the variation from straight that you see when you site down the EDGE of the board.  Like when you put in floor joists you always try to put the crown up.

   I machined 500 bd feet of butternut ceiling boards using the table saw as a jointer.  Long, straight 2X6 clamped to the table as a fence with integral plywood in and out feed surfaces.  Five different finished widths, so I had to keep stacks of 1/2 done boards handy (crown ripped off with the concave edge against the fence...some boards with alot of crown were demoted to the next narrower width at this point) and then re-set the fence to the finished width in stages for the final passes.

   The boards were nailed to the rafters just like that. Results look great...if rustic...very little seasonal change which is an attribute of butternut.  Finish was half and half thinner and linseed oil.

   The thin trimmings from the rip/joint operation kept me in kindling for two winters.

1. 
   forestgirl | Jul 17, 2003 08:46pm | #16

   Seems like "crown" could be used with respect to the convex side/edge of a crook, a cup or a bow.  When I responded above, I was assuming, perhaps wrongly, that David was referring to a board that was cupped -- one face concave and one face convex, running lengthwise.

   A board with a severe crook would certainly be easier to fix on a tablesaw.  The other two ugly-board options, a bow and wind (twist) are ones that, as a novice, I try not to deal with.  Since I work mostly with inexpensive woods such as oak and alder, I'll usually cut up a bowed board to try and get to something useful.  I hate twisted boards -- even the mildest twist seems impossible to mill out properly.  Very frustrating!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl   ;-)

2. 
   johnnyd | Jul 17, 2003 09:03pm | #17

   OK, so we should standardize on "crook"  "cup" and "bow" and use "warp" or "twist" for combinations of the above, with "crown" applied to all.  Fortunately, the butternut I used mostly only exhibited crook.  The stuff that didn't make it was ripped narrower and cut into shorter pieces for trim.

   Got a new Freud "Industrial" rip blade...24 tooth.  $50. Goes through old hard white oak like butter...easy to sand the few light saw marks out with 100 grit on a belt sander.  Nice sharp corners.

3. 
   forestgirl | Jul 17, 2003 09:42pm | #18

   The terminology is already standardized, it's just that it's often not used consistently.  In face-to-face conversations, that's probably not so much of a problem, but when we're "typing" to each other, things can get pretty confusing without carefully chosen words.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl   ;-)

4. 
   johnnyd | Jul 17, 2003 11:07pm | #19

   Judging from your picture, you must have camped out during the 1st earth day as a child with your parents.

2. 
   forestgirl | Jul 16, 2003 07:29pm | #7

   Len, I like that idea.  Seems like running the board through a planer, with shim(s) as you indicate, would be more likely to do a good job and less likely to do something unfortunate to the wood.  There's always the 6" x 48" belt with some 40-grit paper on it too!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl   ;-)

3. 
   Mach70 | Jul 16, 2003 07:29pm | #8

   I always thought the crown (convex) side was stretched or under tension relative to the concave side which has shrunk (shorter/compression) causing the curve.  Seems to me shaving some off the top would only relax the wood cells making the condition worse.  Is my thinking more warped than the board?

1. 
   DavidP52 | Jul 16, 2003 08:55pm | #9

   I do both, but with crown-up, if it is badly warped you'll get too deep a feed at the start edge because the egde is projecting BELOW the infeed table. When that happens, look out for shrapnel. Wear you Kevar!!

   OTOH, if a board is that bad, it should be firewood anyway. If warpage is within 1/8" per foot, I have no problem. Otherwise I cut it in little pieces and burn it. Jointing is an art, not merely machining.

   WHEN DOING IT CROWN UP, START YOUR FEED real slow.

   Edited 7/16/2003 2:01:44 PM ET by boatman

2. 
   JohnWW | Jul 16, 2003 09:14pm | #10

   The original discussion was about dealing with curvature along either the length of the wide face of the board (bow) or across its width (cup), not along one of the edges (crook), I don't know if planing the crown would work on edges, but it seems unlikely.

   MACH70's analysis is correct, at least in regards to cupping, I think the technique is primarily meant to be used on boards that bow.

   John W.

   Edited 7/16/2003 2:20:04 PM ET by JohnW

3. 
   Len | Jul 17, 2003 08:31am | #13

   Nope your thinking isn't warped. It shouldn't work but sometimes it does. It really depends on the type wood, the grain as well as the moisture content. At least that's my story and I'm sticking with it.

   Len