Planing question?

[keith micinski]

So, I finally got to buy my first batch of rough sawn wood. I took it over to the jointer and jointed the face on one side and jointed one edge getting everything perfectly square and true. I then took the boards over to my new DW 735 and started running them threw to get them planed down to 3/4. Everything turned out really nice except for one thing. After planing some of the boards had a slight bow in them on the side that I planed. It was nothing I couldn't work around and probably better then the refinished boards I was buying before. But I started wondering should I have run the board through the planer and then flipped it over and run it through on the other side and keep repeating this process until I get to my desired 3/4 thickness?

[Darnell Hagen]

Yup, but there's no gaurantees.

You've removed wood and released internal stress. Sometimes it helps to go back and forth between the jointer and planer. You can sometimes use this to your advantage, joint crown down and use the stresses to straighten out a banana.

[Bryan Berguson]

It depends on the wood for me. If it's a species that tends to pick alot like hard maple or hickory, If I get a good side then I'll leave it alone. If it's pine, oak or cherry, I'll flip the boards each time I run them through the planer. It's still possible the board will bow though, they can have a mind of their own...:rolleyes:

[Frank Martin]

Removing equal amounts from each face helps keep the board straight during the dimensioning process.

[keith micinski]

I really was happy with the wood overall I just have never used a planer before and wasn't sure. The next time I use the planer (hopefully tomorrow) I will flip the board over since it cant hurt anything to do it that way anyway.

[Van Huskey]

One thing that can help is never finish milling your lumber in one day, let it sit for several days after the initial milling before going to final size.

[keith micinski]

I thought about that also but l figured with the quality of wood I was using before this was going to be a step up from that anyway. I am probably over thinking it because it was still really nice finally working with wood that was all the same size.

[Brian Tymchak]

Keith,

You didn't mention if you had waited a while after getting your material in the shop to start milling it. If not , I'd recommend waiting at least a couple weeks. Even though it may have been kiln dried, the moisture level in the air at your lumber dealer is probably different than at your shop. Wood will move a bit as it comes to the same ambient moisture in it's surrounding. If it was air dried, it may be quite a ways off and need a lot longer time to come down to a workable level.

And then, even after that, particularly on heavier (8/4) and wide stock, I follow Van's recommendation of rough milling pieces and then let them set a day or 2 before taking them down to final dimension. When you cut a large board, it is likely that the exposed "middle" is slightly higher in MC and needs to acclimate a bit longer.

I also tend to remove stock evenly from both sides unless there is a really good reason not to.

Brian

[Scott T Smith]

Keith,


You didn't mention if you had waited a while after getting your material in the shop to start milling it. If not , I'd recommend waiting at least a couple weeks. Even though it may have been kiln dried, the moisture level in the air at your lumber dealer is probably different than at your shop. Wood will move a bit as it comes to the same ambient moisture in it's surrounding. If it was air dried, it may be quite a ways off and need a lot longer time to come down to a workable level.

And then, even after that, particularly on heavier (8/4) and wide stock, I follow Van's recommendation of rough milling pieces and then let them set a day or 2 before taking them down to final dimension. When you cut a large board, it is likely that the exposed "middle" is slightly higher in MC and needs to acclimate a bit longer.

I also tend to remove stock evenly from both sides unless there is a really good reason not to.

Brian


+1. I'll take a moment to explain why.

I operate a kiln, and one thing to keep in mind is that lumber does not dry evenly across the board. Usually there is at least a 1% delta between the interior and exterior moisture contents of a board during the drying process. At the end of the kiln run, it is customary to "equalize" the load, whereby you increase the RH inside the kiln to bring the shell back up to match the MC% in the core.

However, every tree is different, which means that every board is different, which means that they don't all dry exactly the same. Some boards may be a percent or two higher or lower MC than the next board in the stack. It's just the nature of the beast.

If wood comes out of my kiln at 8%, give or take, and then sits in someone's garage for a few weeks and increases the shell MC% up to 12%, chances are that if you used a high quality meter to measure each 1/10" you will notice a deviation of a part of a percent, or more from the exterior to the interior of the board.

So, the core may be at 8%, halfway in-between the core and the shell it may be at 9%, 25% in from the shell it may be at 10%, with the shell at 11%, etc. This same thing happens as the board starts to lose moisture.

In essence, the board absorbs, and loses moisture from the outside in, and depending upon the species it can take quite a while for the MC% to work its way in - or out of the board. Also keep in mind that the wood cells will grow when they pick up moisture, and shrink as they lose moisture.

When dimensioning a board, based upon my perspective of the drying process it is always best to joint one side smooth, then plane the opposite side approximately the same amount, and then alternate between the two sides. By taking off approximately the same amount of wood from each side you are keeping the MC% roughly equal on both faces of the board. If you only take 1/10" off of one side, and 1/4" off of the other side, then the surface moisture contents will be slightly different from side to side and as the wood equalizes, the cells on one side of the board may shrink more than the cells on the other side, thus causing the distortion.

This is not a perfect science though, because usually a rough sawn board is not perfectly flat and one part of the board may clean up with 1/8" removal, and another part requires 3/16". Turn the board over, and odds are that it will be the exact opposite.

By removing equal amounts from each side of the board, you should end up with surface MC%'s that are somewhat equal, thus minimizing the amount of subsequent warp. However, because the board wasn't perfectly smooth to start with there will be slight deviations in the new shell MC, hence the movement.

Back to Van and Brian's advice, by removing a portion of the wood, and then allowing it to re-acclimate for a few days before removing more, you are allowing the wood to obtain a more consistent MC% across it, which will minimize the subsequent distortion.

Scott

[keith micinski]

Well, I have 5 board feet out in my garage that I plan on making a small end table with tomorrow, but maybe I will get it joined and let it sit for a day or two to acclimate but that is going to be hard to do. Usually once I start getting the wood all dimensioned up I want to start making stuff. Also, this makes me sound ridiculous but for some reason I really like making tables so it is even harder for me to stop once I get going.

[glenn bradley]

should I have run the board through the planer and then flipped it over and run it through on the other side and keep repeating this process until I get to my desired 3/4 thickness?

That is generally what I do. I flip the board end for end as opposed to side for side to keep the grain orientation correct. Your cutting edge, planer, jointer, hand plane, etc., should be cutting "downhill" (http://www.newwoodworker.com/readgrain.html).

[keith micinski]

You know one thing I read about was jointing and planing with the grain but I have tried it both ways and to be honest with you I couldn't notice any difference in the cut quality. I still try and make sure I am going with the grain though.

[keith micinski]

Ok, so now I have a new problem. I have some 8 inch wide 4/4 boards and I only have a 6 inch jointer. I am putting three of these boards together to make a top and I don't want to add extra seems so I would like to keep all three boards 8 inches wide. When I run them through the planer they are cupped a little bit and I think the pressure of the feeder rollers is flattening the board out so that the cup cant be totally taken out. Is there something else I can do to get one side of these boards flat other then rip them down to 6 inches wide and face joint them? I don't have any hand planes or anything so that is not really an option either.

[glenn bradley]

Ok, so now I have a new problem. I have some 8 inch wide 4/4 boards and I only have a 6 inch jointer.

Two words:

Planer Sled (http://www.sawmillcreek.org/showthread.php?t=58735).

[keith micinski]

I was afraid someone would say that. I don't think that the board is bad enough to make a planer sled. I would almost rather rip the boards down to 6 inches and face joint them then. I just don't think I would use the planer sled enough to justify making it and the space it would take up since sadly, my shop is starting to get full of to much stuff.

[Scott T Smith]

I was afraid someone would say that. I don't think that the board is bad enough to make a planer sled. I would almost rather rip the boards down to 6 inches and face joint them then. I just don't think I would use the planer sled enough to justify making it and the space it would take up since sadly, my shop is starting to get full of to much stuff.


Keith, what about seeing if there is a SMC member near you that has a wider jointer?

[Danny Burns]

Ok, so now I have a new problem. I have some 8 inch wide 4/4 boards and I only have a 6 inch jointer.

http://www.finewoodworking.com/SkillsAndTechniques/SkillsAndTechniquesPDF.aspx?id=32132

If you can see the very small photo, they have made a plywood blade guard, in the style of most European blade guards, and clamped it on the fence.


Here is a picture of the Jet J/P with a European guard.

http://www.globalindustrial.com/site/images/grid-large/708475.jpg

http://forum.canadianwoodworking.com/showthread.php?t=25713

[keith micinski]

Well, I have tried everything I can to figure this out and I am just not getting it. Does anyone have a better picture or a better description of what he is trying to say?

[Myk Rian]

Does your jointer have a rabbeting bed?
You can joint an 8" board on a 6" jointer. Then you tape the rabbet to a flat board, run the un-jointed side through the planer.
Remove the board and joint the remaining face so the rabbet is gone.
It's been discussed many times here.

[keith micinski]

I understand the concept now. I guess I just don't see how this stops the feeder rollers from pushing the cupped board flat as it runs threw the planer. I could see how this would help a board that was warped end to end but not how it would help a board that is cupped.

[Glen Butler]

Keith,

The cupped board will be run across the jointer frowny style. Run the wide board through your jointer using the rabbeting function. This will face 6" worth of the board that will no longer be cupped. Rip a peice of plywood, mdf, or particle to over 6". You don't need to use double stick tape. Glue a thin stop to the front edge of the plywood. This will cause the rough stock to pull the plywood withit. Because the 'crown' width ways of the board is up as it goes through the planer the feed rollers will have no choice but to apply pressure between the red lines in the image below.

[Glen Blanchard]

I understand the concept now. I guess I just don't see how this stops the feeder rollers from pushing the cupped board flat as it runs threw the planer. I could see how this would help a board that was warped end to end but not how it would help a board that is cupped.

If a flat piece of plywood is placed ONLY under the portion of the board that has been jointed, you have a flattened surface against a flat reference (the plywood board) against the flat surface of the planer. The unjointed portion of the board is elevated above the planer table so it has no influence in the planing process.

Make sense?

[keith micinski]

I get the concept now. The drawing in the previous post is incorrect though. The feeder roller is going to apply downwards pressure across the entire top of the board. If you have the cup facing down this would work but if you have it facing up it would still press the unsupported end down and then allow the board to spring back up once through the planer. I've got it now.

[Glen Butler]

You are correct, the rollers will apply pressure to the entire board. I guess I was more demonstrating the how the reference surfaces will transfer to make the planing work.