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Flatsawn Lumber Is Not So Flat: How To Fix Cupped Wood

Quartersawn lumber stays flat, but flatsawn lumber does not (ironic, I know). Flatsawn lumber cups during the drying process and it even cups after it’s dry if not cared for properly. Wide boards are especially fussy and panel glue-ups can be a giant pain in the tuchus.

I deal with cupped lumber all of the time, and I was reminded of this common problem when a friend of mine was trying to figure out why his wide panel glue-ups had cupped. Whenever I am asked about this, my first question is always, “How did you store your panels after they were assembled and surfaced?” The answer is usually that they laid the panels flat on a table. A quick bit of logic says that a flat panel on a flat table should stay flat, but that isn’t how it works, at least not with solid wood.

Solid wood needs to expand and contract evenly, on both sides, to stay flat. If the panels are placed flat on a table, they can breathe on one side but not on the other. The bottom side will remain as dry or wet as it started, but the top side will shrink or swell depending on the ambient humidity in the room. Usually, this  problem arises when lumber is moved from a non climate-controlled environment (like a garage or barn) into a dry, climate-controlled shop, so the top of the panels will shrink and the lumber will cup up and away from the table as it dries.

This glued up panel couldn't breathe on the bottom since it was flat on a table. The top dried out a touch after processing and the panel cupped.

This glued up panel couldn’t breathe on the bottom since it was flat on a table. The top dried out a touch after processing and the panel cupped.

 

In a perfect world, rough lumber would be stored for months in the exact same, hermetically sealed environment where the processing is going to happen, but since we don’t live in a bubble, that’s not really possible. Even if you store the lumber in your climate-controlled shop and build in your climate-controlled shop, the climate still changes – in small increments from day to day and more dramatically from season to season. And, since you know that these changes will make your wood expand or contract, it is even more imperative to store surfaced lumber and panels properly to make sure your flat work stays flat.

Again, storage is the key, and there are two approaches to keep things flat. The most common way is to store the wood so that it can breathe on all sides. This is done by keeping it stacked flat on sticks or by storing it upright at an angle, perhaps leaning against a wall. The other approach is to not let the wood breathe at all and keep it wrapped or covered in plastic. I commonly use both tactics, leaning panels against the wall for short-term storage, usually during a day of processing and then covering them with a sheet of plastic for longer storage. Note that dramatic changes in flatness can happen in just hours if the conditions are right (or wrong, in this case).

From fresh sawn lumber (in this photo) to finished product, storing wood on sticks is the best practice.

From fresh sawn lumber (in this photo) to finished product, storing wood on sticks is the best practice.

For short term storage (hours to days) standing wood upright is a great choice. Make sure air is able to get to all sides.

For short-term storage (hours to days) standing wood upright is a great choice. Make sure air is able to get to all sides.

Now, let’s say you didn’t follow this advice and your panels developed a cup in them. They were planed and sanded flat and ready to be put into the door frame before you left the shop, but when you returned the next morning they had a noticeable rock. Since everything was already to final thickness, what options do you have? There is no meat left to machine flat and the wood can’t really be bent back into shape… or can it?

No, it can’t really be bent back, but it can be coerced back by doing the reverse of what caused the cup in the first place. The key is understanding the cause of the problem.

First, you need to identify the wet side and the dry side. If you are looking at a cupped panel from the end and it is shaped like a rainbow with the legs down, then the bottom side is the drier side. It is drier, tighter and smaller, and the outside edges are pulling together. The top side is wetter, looser and bigger, and its outside edges are pushing apart. These two forces, one pushing and one pulling, are working together to make a cupped panel.

After you have identified the problem, the solution is to treat the panel to the opposite conditions. This can be done by drying the wet side or wetting the dry side, but since almost all problems in woodworking are from wood that is too wet (at least around here), you should choose to dry the wet side.

I recommend to use a hairdryer for convenience, but on nice sunny days you can put the sun to work for you too. Both work fine, but the sun can fix a lot of panels at a time, quickly and quietly. The sun works great because it focuses all of the drying energy on just one side, and it focuses it on the entire side, not on just one spot like a hairdryer. (Be aware that some woods, like cherry, change color quickly in the sun and may be a better choice for inside drying).

The process is simple. Put the dry side down on a flat surface, one that restricts air movement across the bottom of the wood. The wide board or panel will be sitting like a rainbow, with the two legs down and the center up. Then just proceed to dry the top side, either with the sun or a hair dryer. If you are not in a hurry, you can simply move the wood to a drier environment, like the inside of your house on a cold winter day and let it dry out on the top side overnight. Any way to dry the top side while the bottom remains as it is should do the trick.

Use a hair dryer (like in this photo) or put the panels out in the sun with  the wetter side of the wood up to reverse the cup.

Use a hair dryer (like in this photo) or put the panels out in the sun with the wetter side of the wood up to reverse the cup.

Keep an eye on the panels and check them regularly. With a hair dryer you will probably end up propping it up in a position to blow on the panel and check it every thirty minutes. In the sun, check the progress every hour. If you just move them to a drier environment, check them once or twice a day. Even with regular checks it is not uncommon to go too far and overcorrect. If you let the wood bake too long on one side and it starts to cup the other way, just flip it and dry the other side. Eventually, you will get a feel for how long it takes and end up with a flat panel, and now a drier panel (both good things).

Follow these guidelines for flat wood:

  1. Build with quartersawn lumber. Quartersawn wood doesn’t cup.
  2. Store lumber in the rough. If the lumber goes wonky you will still have extra thickness to machine flat.
  3. Store lumber and build in an environment similar to where the piece will end up.
  4. Quickly build with lumber after it is machined. Don’t give it a chance to move on you.
  5. If you can’t build immediately, store wide boards and panel glue-ups properly. Give them air on all sides or no air at all.
  6. Make sure assembled furniture stays flat by finishing both sides of solid wood panels the same. This is especially important on wide glue-ups like tabletops.

Remember, wood moves and changes size all of the time. It is your job as a woodworker to understand how these changes happen, how to prepare for them and how to control them. And, luckily, in the case of wide wood, you may even have the chance to correct them.

How to Make Realistic Worm Holes in Wood

If you want to make something look older, just add some worm holes. Sounds simple enough, but there is a major difference between just poking holes in the wood and making the holes look authentic. Now that the all natural, rustic wood look is in style, even new, or at least not very old wood often benefits from more character, and I am here to show you how to really do it.

First off, let me assure you that I have a lot of experience in this field. I often build pieces that need to be “wormed up” in some regard, either to make new wood look old or to make old wood look even older. Especially on projects like beams and mantels, worm holes help add a lot of age to a piece.

Much of the wood that I use already has worm holes in it because I let the logs sit awhile outside before I mill them into lumber (sometimes even on purpose), so I have a head start, but there will still often be spots without bug holes where the wood needs a little extra love, like in the following video:

To get things started, it helps to first look at truly worm-eaten wood. There are consistencies even in what looks to be very inconsistent patterns. Here are a few principles that hold up in most wormy wood:

1.) Hole sizes vary: Even similar-sized holes are not the same. Your method for creating holes should easily produce random results.

2.) Worms tend to focus their efforts: Holes will usually have an area of focus, with more holes in the center of an infected area fading out to fewer holes.

3.) Not all holes are perpendicular to the surface:  While most holes are just that – holes, many are oblong and some are more like trails.

4.) The bugs that make the worm holes often enter around defects in the wood: Soft or punky wood, spalted wood, cracks, and sapwood are all areas that will focus worm activity. Good, strong, solid heartwood is the last area to be bug infested.

5.) Small holes outnumber the big ones: Older wood that has been attacked by multiple insects will have lots of tiny holes (1/16′ diameter), some medium-sized holes (1/8″ diameter), and just a few big holes (up to 1/4″ diameter).

Here are some photos of authentic worm holes. If you can copy any these patterns you will be off to a good start.

This section of pine shows a nice array of hole sizes from large to small. Notice how the long holes follow the grain.

This section of pine shows a nice array of hole sizes from large to small. Notice how the long holes follow the grain.

This section of hickory has holes that make short lines. They are also very dark and almost seem stained.

This section of hickory has holes that make short lines. They are also very dark and almost seem stained.

This section of maple shows a mix of holes and short trails.

This section of maple shows a mix of holes and short trails.

The holes in this white oak are larger and have stains around them where the wood has started to decay.

The holes in this white oak are larger and have stains around them where the wood has started to decay.

 

Here are some of my tricks for achieving realistic results:

  1. A scratch awl, normally used for marking projects, is the perfect tool for making small to medium-sized holes, after being sharpened to a long, tapered point.

    A scratch awl, normally used for marking projects, is the perfect tool for making small to medium-sized holes, after being sharpened to a long, tapered point.

    Small holes. You’ll be tempted to use a drill bit for the smallest holes, but it isn’t the best choice. Tiny drill bits break easy and the size is too consistent. Plus, they pull out wood fibers that make the edge of the holes fuzzy. Instead use a nail or a scratch awl sharpened to a long fine point. A scratch awl is the best choice because it can be used without a hammer and produces speedy results. The long point will make different sized holes depending on how deep it is pushed into the wood. Push the scratch awl in the wood at different angles and different depths.

  2. Large holes. Use a twist drill bit for the larger holes. Be sure to drill deep enough that you can’t see the bottom of the holes and to vary the drill angle. Put the bigger holes in the softer wood. Sapwood, punky wood and areas around defects are a good place to start. Mix up the sizes in the 1/8-3/16″ range for a more natural look.
  3. Oblong holes. Some of the larger holes tend look like small jelly beans. Drill in fairly deep and then use the side of the drill bit to cut a short trail. The result is similar to two holes drilled right next to each other.
  4. Trails. Trails are often left just under the bark in bug infested logs and sometimes inside the log. Use a twist drill bit about 1/8-3/16″ in diameter and drag the bit in different lengths of crooked lines. Be sure to make some of the areas have more depth. Think of the trail as a river with shallow areas and deeper pools. Trails can have one, both or none of the ends finishing in a hole. Mix it up and have a few ends disappear into holes made with the same drill bit.

One of the most important things to remember when making worm holes or using any other techniques to age wood is to really go for it. You won’t destroy a piece of furniture by adding a few more holes or dents, and you can only miss by doing too little to the surface.

I often see furniture, especially mass-produced furniture, that will have some sort of distressing that looks like it was just phoned in. Usually, someone quickly takes a chain to the surface or pokes a few holes and calls it a day. Don’t do that. Pay attention to Mother Nature’s work and try to duplicate it. And, most importantly, have fun doing it.

 

 

Barbie and Dan Lend a Hand Holding a Door Open

This past year I got some help in the shop and on installations from Dan, a friend of mine that entered the carpentry/woodworking field as a union framing carpenter. He is a hard worker, gets things done quick, cares about the quality of his work, and most importantly, taught me a few of his tricks.

His most recent bit of advice saved me a day or two of work and only took me minutes to complete (I really like that guy).

I have a relatively new house. It’s about three years old, and overall, I am happy with it. Since the beginning, though, there was one thing that drove me crazy, and I could never figure out an easy solution. My daughter Mira’s bedroom door was hung way out of plumb, it is leaning into the opening about 3/4″, and if left alone, it will swing almost closed. You open the door and it closes on its own.

I am sure the carpenter that installed the door let it slide because the door casing butts into another door casing and the straight casing looks better than casing with an angle cut. At least that’s what I tell myself. Truth is, he was probably flying along throwing up doors and plumb wasn’t too much of an issue. Either way, it is still annoying.

The only way I could see to fix the problem was to rehang the door. That meant remove the casing, remove the door frame and start over. That also meant hours of finish work including caulking and painting. And, after all of that work, I would still have an unsightly, uneven line in my casing. Not to mention that I had an almost new house that I just wasn’t in the mood to tear apart. What to do?

While I waited for divine inspiration to strike, I came up with a couple of temporary fixes. I started with a small stack of books which did not make it through Mira’s approval process, and then I moved on to a regular old brown doorstop, but lacking the mandatory pink color made that one a no go as well. One of my favorite solutions was to get someone to simply hold the door open. I chose one of our family friends that is always at the house without much to do (that one made me chuckle a bit).

Barbie did a great job of holding the door open.

Barbie did a great job of holding the door open.

Amazingly enough, Barbie did not get cleared either and was quickly given her walking papers. So the door swung shut, again and again. We lived with it, and lived with it, and kept living with it, and it just got more and more annoying.

One day when I was working with Dan, I mentioned the stupid door and the stupid carpenter and the stupid level that he didn’t bother to use. Dan casually said, “Just bend the hinge.”

My first thought was, “What?”

That was much too simple. I needed to get in there and take care of this professionally, and it didn’t include just bending the hardware. His plan was too pedestrian for me.

“No,” Dan said, “Just hit it with a hammer a couple of times. No one can tell and the door won’t swing shut.”

That’s all it takes. Instead of lubricating the hinges and making sure they swing easily, just do the opposite. Put a hinge, or in my case, two hinges in a slight bind, so there’s a touch of resistance.

I started by heading to the garage with the first hinge. I put it down on the concrete and gave it a whack on the barrel, but it didn’t make a difference. It didn’t bend and it didn’t bind. I hit it a little harder and still nothing. Then I really hit it. Finally, it started to offer some resistance, but not much. I ended up flattening the barrel down the entire length, but just a bit. I didn’t want it to look deformed, just a little out of round and not noticeable.

Hit along the barrel of the hinge until it binds, but still operates.

Hit along the barrel of the hinge until it binds, but still operates.

I reinstalled the the hinge, but it wasn’t enough. The door almost stayed open, but it still wanted to close. I took a second hinge out to the garage and treated it the same way, flattening the barrel just a touch down the entire length. That made all the difference.

Now the door looks good, stays open and works like any other regular door. And, the fix only took a few minutes (probably less time than it took to read this post). Thanks, Dan and Barbie, for all of your help.

 

Woodworking And Sanding Go Together

Sanding is one of those things that is low on the priority list but high on the necessity list. Very few of us want to do it, but we all know that we have to do it. And, even though most of us aren’t excited about it, the quality of a sanding job can be the difference between a masterpiece and a large paperweight. Poor sanding techniques cannot only ruin the actual piece but can also ruin the finish. No single tool in the shop can be so disastrous (note that I didn’t say bloody).

It all starts with the right mindset.  Often sanding is viewed as an obstacle, something that gets in the way of actually finishing, but it is the opposite. Sanding is finishing. Treat is as a separate and integral first part of the finishing process.

Be happy about it. If you break a woodworking project into two halves, the second half would be the finishing, which starts with sanding. Celebrate that your project is more than halfway finished and sand with a smile on your face. If you aren’t happy about it, at least try to fake it.

Don’t be lazy. Laziness shows up in the worst ways. Hard to reach areas will still have saw marks. Wide open areas will have chatter marks from the planer. Glue joints won’t be flush. If you don’t want to put in the time to sand, don’t be a woodworker!(Wow! That was harsh.)

Be disciplined. Don’t sand just because you are supposed to. Sand with a purpose, achieve the goal, and stop. Lack of discipline only creates more problems. Sanding through veneer, sanding through topcoats or stain, sanding across the grain, and rounding off edges too much (and this is only a partial list) all come from a lack of discipline.

Obviously, I think sanding (good sanding) is critical. Think about the four points above next time you are sanding and see where you land. It may be the difference between woodworking success or failure.

Woodworking With Gloves: Am I Crazy?

Before you answer that question, let’s discuss.

This photo was in a recent newsletter from Fine Woodworking. Notice the gloves?

Everything I read regarding safety in the shop says don’t wear gloves when operating machinery. Gloves can get caught in moving parts and suck you in. It makes sense. Don’t wear loose clothing, tie back your hair and don’t wear gloves. But, I am not one to just let things go unquestioned. Are gloves in the shop really that dangerous?

These are the gloves that I currently wear from Home Depot.

I almost always wear gloves in the shop, even while operating machinery. They are tight-fitting cloth gloves with nitrile-dipped palms from Home Depot. I like them because they are inexpensive, fit great, aren’t too hot, and give me excellent grip. I especially like to wear them when I am using the jointer, but I find the grip to be helpful any time that I am pushing smooth-planed wood through a tool like the table saw.

I use the jointer (mine is 12″ wide) to flatten the wide face of all of my lumber before it goes through the thickness planer, leaving it flat and straight. On wider, longer and heavier boards it takes a lot of force to move them across the jointer. Often, I am really leaning into it and the gloves are the only way that I can get enough grip. I know push blocks are recommended, but they are slow and very cumbersome to use when you are faced with several days of jointing rough lumber.

On the table saw and router table, the enemy is smooth wood. I constantly envision myself losing my grip and pushing my hand right into the action. Guards, of course, would help, but we all know that there isn’t one on my table saw and there probably isn’t one on yours either. On the router table it is easier to cover the cutter and be productive, but I still want a good grip, so that I don’t jam my hand into the bit. I think gloves are the answer.

So, why are gloves dangerous? They are dangerous because if you accidentally touch that table saw blade, instead of just getting cut, you will get cut, sucked in, and cut some more. To that, I say, “Well, don’t touch the blade.” I have been doing this a long time and I still get a little nervous when my hand is getting in the vicinity of the blade. I pay attention, think about what could go wrong and try to avoid it. I always picture myself at my college bakery job at 3 a.m. making donuts. I am tired, the floor is covered with grease, my knees are locked and I am leaning forward over a boiling vat of death. But, no matter how tired I was, I knew that if I lost my balance and fell forward, I was going to catch myself on the side of the fryer and not in the bottom of the hot oil. The thought of my hand frying like a donut goes a long way to making me focus and so does the idea of sticking my hand in the table saw. Gloves aren’t an issue if you keep your hands out of the saw.

Now that I have tempted fate and thrown it out to the universe, let’s say my hand does go into the proverbial “fryer”. If I am wearing a glove, is my result guaranteed to be worse because of it? I have heard stories from friends of friends and distant acquaintances on the internet about how things were bad because of a glove. But, what about the times that an accident was averted because of gloves? It is certainly possible. Nobody is going to tell a story of how they didn’t put their hand in the saw because they had a firm grip and everything went smoothly. There is no gore there, no tale of doom to pass down from generation to generation.

I would only use these loose-fitting gloves for moving lumber. Not for work around tools.

With this in mind, I tried to be more scientific and find studies about gloves in the workplace. The one that I found to be the most relevant only asked questions of people who were injured on the job and whether they were wearing gloves or not. They really needed to ask glove wearers about specific times when the gloves either made their outcomes better or worse. But again, worse outcomes are going to get more airtime because you can’t identify when things went better or nothing went wrong.

For now, I am still wearing my gloves. They make me feel confident when I am close to the tools, and I think that goes a long way towards safety. In the meantime, I hope to find more scientific data and plan to do some tests by sticking gloves in the tools to see how things go. I just need to find some volunteers.

Let me know your thoughts and if you have any first-hand accounts.

Pattern Guides On The Table Saw: Fast In The Straightaways

I’ve never seen it done before or demonstrated on any woodworking shows, and this would be the last thing that I would come up with on my own. But, thanks to Don Snyder, a fellow St. Louis Woodworkers Guild member, I can now add using a pattern to cut pieces on the table saw to my playbook. It sounds simple, and it is, once you understand what is happening.

The outside edge of the auxiliary fence and blade should line up for square cuts.

Don’s program was provocatively titled, “How to cut polygonal shapes.” I initially thought that there was going to be a lot of talk about angles – and there was. The information was “informative”, but seemed like something I could figure out on my own if I needed to. I could figure out the angles necessary for a 32-sided shape; but I was looking for a trick, something that I hadn’t seen before, and Don delivered.

This fence is for short pieces. Make sure the auxiliary fence is long enough to start and finish the cut with the pattern against the fence.

The reason for using a pattern on the table saw is to produce exact copies of shapes with multiple sides quickly, accurately and repeatedly. This is necessary for making more than one simple project or a lot of pieces for a complex project. Don got in deep, even showing how to use this method to make three-dimensional shapes like polyhedrons.

The first step it to make a pattern, a perfect pattern, of the shape that you would like to repeat. For this method, especially on the table saw, all the sides of the shape need to be straight lines. The table saw is not good at curves. The pattern is cut from 1/4″ thick material, which is easily worked and provides enough structure to run along a guide. MDF is fine for short runs. Plywood is more durable and a better pick for longevity. Solid wood is not a good pick because it is not dimensionally stable. Remember, accuracy is very important.

Top views of the pattern and an end view of the fence and blade show how the alignment of the three makes a perfect copy, one edge at a time.

The next step is to secure the pattern to the wood that will be your final piece (or, of course, a test piece). This can be done with nails, double-stick tape, spray adhesive, etc. as long as the pattern can later be removed and not damage your final piece. You want the pattern to stick firmly to the piece you are cutting. If not, the lumber could twist on the sawblade and cause a violent kickback (this is something you want to avoid).

All that is left to do is to make your auxiliary fence for the pattern to follow. This fence will attach to your regular fence and extend over the blade so that the outside edge of the fence is above and in line with the outside edge of the table saw blade. Set the blade to just clear the thickness of your final material and set the auxiliary fence about 1/16″ above the blade. The auxiliary fence should extend well beyond the front of the blade so that the pattern can engage the fence before the final material is cut (this is also for safety, as well as accuracy). The same is true on the back of the fence to allow for a safe finish on the cut.

Cutoff pieces will accumulate under the fence. Stop the saw and remove them.

To cut a piece like a pentagon, first make a perfect pattern then attach it to a board. Put the pattern against the auxiliary fence well before the blade and push it through. Rotate the pattern to the next side and make a similar cut. Do this for all five sides and you have a pentagon exactly the same as the pattern. Watch closely for cut off pieces accumulating under the fence and remove as necessary. Don said he turns off the saw and removes the cutoffs after every cut to avoid them binding in the enclosed space and kicking back.

This setup ends up working like a router with a bushing that follows the pattern, with a couple of major differences. The router can follow curves, as well as straight cuts, while the table saw method will only work on straight cuts. However, the table saw can be set to cut at an angle, which is essential for joining three-dimensional shapes like a polyhedron. The table saw method also allows the pattern to be followed with only one step, while the router method usually requires a rough cut beyond the pattern (done with a saw) before the finish cut with the router. Both methods have their advantages, but the table saw wins on the straight cuts, which was Don’s focus. As a matter of fact, Don started his presentation showing several pictures of woodworking with organic shapes and all of them were crossed out with big X’s. Don doesn’t like curves.

The Slippery Truth

When you are working in your shop it is important to have control of your work. Work surfaces, especially tables, should support your lumber and provide as little resistance as possible. This makes your job safer, more accurate, causes less fatigue, and just makes it more enjoyable. It is not instinctual to make your work area slick. But, in the right place, slick is exactly what you need.

For making surfaces slick there are two excellent options–one temporary and one permanent. The temporary solution is to apply something to the surface, like wax. There are also sprays available made with different compounds, but I recommend good old Johnson’s Paste Wax.

You can use wax for all of your tools with metal or wood parts. I use it on all of my fixtures and jigs where I want less friction, especially my crosscut sled. You should wax every stationary power tool table in your shop. The obvious ones are the table saw, jointer, router table and planer. I also use it on my hand power tools, including the jig saw and router. If you want the wood to glide along nicely, wax it.

No need for wax here. The planer board has taller sides and an UHMW surface to keep the boards going through smoothly and without end snipe.

The planer board has a piece of plywood mounted to the bottom to hook the bed of the planer. This is all that holds the board in place and makes for easy removal when you need the extra width.

The outfeed side of the planer board can be longer than the factory table for more support. This board is 48" long, but could be longer if you have the space.

The permanent solution is to use UHMW (Ultra-high molecular weight) plastic. I have found this most useful on the planer. As a matter of fact, setting up a table board with a sheet of UHMW was one of the first things I did once I got my new planer up and running. I used a sheet of 3/8″ thick UHMW plastic on top of a box made from 3/4″ plywood that is easily removed from my planer. The only adjustment to the planer was to move the bed rollers all of the way down and out of the picture. I was happy to do this because I think bed rollers are a terrible solution to the problem of boards getting stuck in the planer.  No matter how they are adjusted they make the ends of the boards snipe every time. In contrast, boards never, never, never get stuck on the UHMW and having a flat bed with no bed rollers eliminates the snipe. Lumber just goes in one end and out the other with no dip on the ends.

The UHMW is available in sheets and adhesive-backed strips. The strips can be applied to fences and jigs where friction can be a problem. The strips and smaller pieces are available at Woodcraft or Rockler and the larger pieces I purchase from Regal plastics here in St. Louis. They aren’t cheap (a 36″ x 48″ pieces cost about $50), but well worth it.

Before you start your next project, wax your work surface or add a piece of UHMW plastic. You will wonder why you hadn’t done it sooner.

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