Another milling process/acclimation thread

[Jakub Wegrzyn]

I bought some wood and it warped, now I want to do it right the second time. I read some threads on this topic that answered some questions but raised new ones

Longer version: I bought some 4/4 cherry for a coffee table (from Austin Hardwoods in Denver, FWIW. Denver has pretty consistent humidity but who knows what the wood went through before). I had it finished S3S becuase at the time I didn't own a jointer. Within a few days in my garage -- stored on metal shelf bracket wall rack -- the wood had warped. I thought I could "force" the bow out by aligning with cauls during glue-up (against the advice of most of the internet) but that just yielded a twisted panel (just as the internet predicted). Couple months later, I got a jointer, resawed the panels, and re-milled a couple of the boards, but now am concerned they're too thin to use in a ~40" table top (one is down to ~5/8")

I went back and got some 5/4 cherry to give myself more leeway (1-straight-line-ripped, rough otherwise). I also plan to cut to approximate length so I'm only jointing/planing at most ~40" at a time

Guy at the store said that I should have used the wood right away, rather than letting it rest in my garage

This begs several questions

• Did I really need to use the wood right away? Is that just the limitation of buying rough-cut and having it surfaced at the store, vs the seemingly perfect but also quite expensive S4S boards, or having access to gear to mill on one's own schedule?
  
  • Should I be getting my wood elsewhere?
  
  
• How to best handle the new 5/4 stock?
  
  • Currently it's in the garage, on sawhorses, on edge. I will move it to the wall rack tonight. Should I keep it on edge? Flat on stickers? Does it not matter?
  • How long to wait before cutting to approximate length? Before jointing/planing?
  • Should I mill to needed size at once, or joint/plane to the thickest flat size first, then wait some more, then plane to needed thickness? If the latter, how long to wait between the steps? It sounds a little wasteful to be common practice, but what do I know...
  
  
• Once milled to final size, how long do I have to glue up the panels, do joinery, and finish? I'm a weekend warrior at best and moving slowly -- no way can I go from rough-cut to sealed/finished in a weekend
  
  • Should I consider sealing/finishing individual panels before moving on to the next panel to limit further movement (except the areas that are going to be cut in joinery), or should they be more stable if I properly rest/mill the wood in the earlier steps?
  • Based on this experience, it seems that the proper approach is to joint/plane individual boards as needed, rather than to do all the milling at once -> all glue-up -> all joinery. Is that correct?
  
  

Thanks - I'm still a relative beginner at this, despite having read a lot of the internet...

[Robert Engel]

Did I really need to use the wood right away?

I never use lumber right away.
IMO if the wood is not acclimated, it wants to move whether its on a shelf or in a project, in which case it either puts forces on the project or cracks or bows.

On rough wood I cut to appropriate lengths, do an intial face joint and skip plane, then sticker for 5-7 days.
I repeat the process once or twice more, stickering each time for at least 3-5 days, never taking more than 1/16 EQUALLY off each side.
I wait to do the final thicknessing when I'm ready to start work.

I've also learned WHERE you store the wood matters, too. I try to keep from stacking against a wall or in the direct line of a fan, etc. I will generally use thick, straight timbers as cauls on either side of the stack with either weights or clamp the whole stack, especially with wide boards. If you live in the humid south like me, there can be huge humidity swings that can make boards move overnight!!

I never stack on edge always horzontally. I think with weight of the wood on the stack helps during acclimatization.

S3S wood is usually kiln dried but wide boards can still cup.

Should I be getting my wood elsewhere?

Not necessarily. I would look at your shop climate, where & how you stored the wood because more than likely therein lies your issue.

Once milled to final size, how long do I have to glue up the panels, do joinery, and finish? I'm a weekend warrior at best and moving slowly -- no way can I go from rough-cut to sealed/finished in a weekend

You need a stable environment if there are long gaps between work. One of the easiest, best ways I've found is to store your parts in a sealed plastic bag.

Finish has little influence on wood movement.

Based on this experience, it seems that the proper approach is to joint/plane individual boards as needed, rather than to do all the milling at once -> all glue-up -> all joinery. Is that correct?

I generally do all the milling at once. The parts I am not working on either stay stickered or moved to the plastic bag.

There are other more experienced people here that will probably give you more/better advice, but this is how I do it and it works for me.

[Kevin Jenness]

Ideally the wood will be in equilibrium with the relative humidity with its final location as well as your shop. You need to know the moisture content of the wood coming in, which means using a moisture meter, and the RH of your shop and the destination,which can be found with a hygrometer.If the lumber is more than a couple of points off from the equilibrium moisture content where it is going you may well have significant movement in service, so you need to acclimate the lumber to that point on stickers. Heat and air movement will accelerate the process.

I like to rip the pieces first to approximate width (+1/4" - 3/8") to release any tension and minimize the twist that has to be removed. If there is a lot of twist in the lengths, I will crosscut parts at least 1" over finish length. If there is sufficient thickness I will flatten and thickness the lumber at least 1/8" over final size prior to acclimating. There are some pieces that are just spiteful, so it is a good idea to have some extra stock so you can afford to toss the bad ones. Milling in two steps gives you a chance to see what the wood is going to do, especially for critical parts like door stiles and rails.

If your shop conditions are significantly different from those expected in service, you need to minimize the lumber's exposure to shop conditions. You can work in stages, milling the lumber for the top and gluing it up in one stage, doing the milling and joinery for the frame in another session, and keeping the parts stacked tight and covered in between times to minimize moisture exchange.

Most wood movement is caused by moisture content changes, so keeping that as constant as possible is important through the building process. Some is just inherent in the wood or induced by poor drying or stacking, and that is where dicing up your parts early in the process can help to sort things out.

[John TenEyck]

You will get every opinion imaginable, as it sounds like you already have. I know a pro woodworker who swears he never has trouble taking wood from his unconditioned storage shed to his conditioned shop and working it immediately. Whenever I've done the same thing I've had problems, especially if I resaw it. Those things have cupped like bananas. So I always bring wood (and I'm talking KD wood) into my shop and let it sit for at least a week or two before using it. I also religiously use a moisture meter, and the actual time I wait is determined by what the MM is telling me.

When I start working the wood I try to mill everything at once, or at least everything for each phase of a project. I'll mill all the faceframe material, for example, or all the material for a table top. If the wood is at EMC with my shop I don't have troubles with it bowing or cupping, etc., unless I hit a board with stress in it, in which case it gets used for something else, or thrown in the firewood bin if I can't even get short/narrow pieces out of it. I face joint and thickness plane to near final dimensions, then bring it to final thickness through the drum sander. If the wood is at EMC there's no need to mill oversize, wait, mill, wait, though there's nothing wrong with doing so it just takes more time. Some people swear they have to do that or the wood moves. I say it's because they didn't wait for the wood to reach EMC with their shop before they started milling it. But there is a valid argument to be made, and this may apply to you, for folks who have a shop where the RH is moving all the time that milling oversize is probably a sound strategy. My shop is in my basement, with temp. and RH control, so the conditions are nearly constant day to day and only change slowly during the year, so waiting is unnecessary. You have to design a strategy that works best for your conditions. If you don't know what the conditions are in your shop, buy a thermometer and hygrometer, and hang them on the wall next to a graph of RH vs. EMC of wood. Keep track of the RH a couple of times a day over a few weeks to see what's going on. Adapt to it.

Between milling, joinery, etc., I place the boards on edge or lean them against a wall so that air can circulate evenly around all faces. Even in my well controlled shop I've had boards cup that were left flat on my bench overnight. Typically, they will straighten back out again after a day or two on edge, but it's a pain to have to wait.

John

[Andrew Pitonyak]

Jakub, you did not mention where you live. Are you also in Denver? Do you expect that there was a large change in humidity when the boards were moved from the supplier to your place?

If I lay a board flat onto some surface, then the top portion of the board is more able to release or absorb moister than the part on the flat surface. This will encourage warping and such. I am not saying that this is what happened, but, it is possible.

When you cut or mill a board that contains "stress", it may move. I have had boards spring together while I was trying to cut them on the table saw and I could no longer push the board forward. My point is that sometimes it is not related to moisture, but simply internal stress on the wood. Quarter sawn wood is generally more stable than flat sawn. Wood with lots of wild pretty grain is less stable.

If you can keep the board stabilized while it acclimates, that helps. You probably noticed that a previous poster mentioned that he has things stickered (allows air movement so more uniform air movement) and then he secures things down (which pushes back against movement I suppose).

[Andrew Hughes]

My thoughts are you should have used it right away.I always start with rough I pick the best boards for the top.Then mill at least twice.While I build the other parts I keep one eye on the top stock.When I have a apron and legs ready for the top.I get out the top stock for final milling and glue up the same day.Next morning I start the finish.

Picking the best boards for the top is the part you will have to learn from experience.
No books,videos or a black belt in Google fu will teach you that part.

[Joe Jensen]

If you have a jointer and a planer in the future you would buy the wood rough. I use the following process;
1) Pieces from the rough stock slightly longer and slightly wider than the parts need to be in the end. If the end parts are shorter and/or narrow I will rough cut pieces large enough to get several parts from one piece.
2) Flatten one face with the jointer
3) Flatten one edge with the jointer
4) Thickness with the planer
5) Rip to width
6) Square one end
7) Cut to length.

If you have any warp in a long board and you have it surfaced at the dealer you will end up with a smooth warped board.

[Mark Rice]

Stickering has been mentioned in this thread but not really described. I mill a lot my own wood. Right after I mill it I sticker it. I stack a layer of planks then put down 2X2s across then another layer of planks. I have 4 sets of 2X4s with holes drilled in them. I put 2X4s (with the holes in them) on the bottom underneath the planks. I put them about every 3 feet. After I get done stacking I put some 2X4s with the holes on top of the stack. I put 3/4" all thread through the holes and tighten the allthread so the boards can't warp. I then cover it with a tarp to keep the rain off the top boards. Some people use weight or straps to do the same thing. I have very little warping. Another factor that can cause warping and cupping is how sharp the blade is if they are using a large circular blade for a saw mill. I had a guy mill some logs for me and his blade beats it's way through the board more than it cuts. He doesn't sharpen his blade very often. The whole 1000 BF of wood was pretty sad, even after being stickered. I haven't seen that problem with any bandsaw mills. I don't plane any wood until I am ready to use it. If it does any strange stuff I can sometimes fix the problem with the planer before I use it. If I plane it first then I lose that option.

[Danny Hamsley]

A garage is usually not climate controlled. So, if you put kiln dried wood in a garage with the wood at 8% equilibrium moisture content, the equilibrium moisture content in the garage from higher humidity might be closer to 15%, so the wood will gain moisture and this can cause wood movement. Best to store the wood in a heated and cooled space where the humidity is controlled.

When I make a table, the very last thing that I do is mill the boards for the top, glue up, sand, and put the top on the base as soon as possible. Many people build the top first, but that is the wrong sequence. Also, as has already been mentioned, never store lumber with one face flat on a floor, workbench etc. where one face is exposed to the air and the other one is not. This can lead to bow, cup, and warp if the moisture content of the wood is changing.

If you are milling rough lumber for a project and the wood is in equilibrium with the environment, you are fine. However, with s4s wood that is already at final dimension, it is best to use it immediately because if it moves and at all, there is nothing you can do to fix that, as there is no more meat on the bones to take out any warp, bow, or cup.

When working with wood for furniture and projects, it is all about equilibrium moisture content with the environment that the wood is in and the environment the piece will reside in, and it is all about timing.

[Jakub Wegrzyn]

Thanks, all. Really appreciate all the responses, especially as this is probably a topic that's been addressed in some form countless times

On rough wood I cut to appropriate lengths, do an intial face joint and skip plane, then sticker for 5-7 days. I repeat the process once or twice more, stickering each time for at least 3-5 days, never taking more than 1/16 EQUALLY off each side. I wait to do the final thicknessing when I'm ready to start work

This is what I'm going to do. Conveniently enough I've been busy with work and outdoor yard work so I can let the wood rest and monitor any changes over time.
So far, one of the re-jointed boards has bowed maybe .003-.005" over ~40" and is sufficiently thin that i can flatten it with relatively slight pressure. That's less than my work bench surface or kitchen island, which is fine for me visually. Is that as good as one can hope for, or worth another pass through the jointer (given a non-industrial jointer and intermediate-at-best technique)?

I never stack on edge always horizontally. I think with weight of the wood on the stack helps during acclimatization.

I was referring to horizontally, but on edge. Not vertically on the end, and not horizontally flat on the face. If you still recommend the last, what's the reason for this? I would have thought that on edge would have less tendency to bow due to weight. Or this might not be an issue if stickered properly, e.g., every 12-18"?

You will get every opinion imaginable, as it sounds like you already have...
...Between milling, joinery, etc., I place the boards on edge or lean them against a wall

Yup...

Finish has little influence on wood movement.

How about sealing? If it didn't play a role, then why the advice to finish/seal the same way on both sides? (this could be a very rookie question)

When I make a table, the very last thing that I do is mill the boards for the top, glue up, sand, and put the top on the base as soon as possible. Many people build the top first, but that is the wrong sequence

I had not thought of that but it makes a lot of sense. Duly noted

If you are milling rough lumber for a project and the wood is in equilibrium with the environment, you are fine. However, with s4s wood that is already at final dimension, it is best to use it immediately because if it moves and at all, there is nothing you can do to fix that, as there is no more meat on the bones to take out any warp, bow, or cup.

That was my main lesson learned, and one that resulted in the purchase of a jointer and a move up to 5/4 rough stock

[Philip Rodriquez]

Hi Jakub,

Austin HW is where I have been buying most of my wood for the last 20 years. However, you have to keep in mind that they are buying wood from all over the world and it does not always have a chance to acclimate, to our, climate before it is sold.

Additionally, wood moves (forever) and internal moisture content, seasonal humidity, internal tension, etc. will always be factors even in a perfectly good looking board - it is the simple nature of the beast. For example, a your flat .003" board can turn into a banana after you run it through your table saw and the same can happen when you resaw a board.

You asked about sealing - Boards should always be finished/sealed on all sides. This results in evening out how quickly a board will react to seasonal wood movement. If you only finished a board on one side, like the top of a table, your tabletop would curl like a potato chip within a year or so. Since you are new, I would also do some research on wood movement and cross-grain issues.

Lastly, I live in the e-470/Arapaho road area. PM me if you are in the area and I would be happy to get you started on your project.