Actually, I guess my question isn't really about gluing the panel, but getting it ready to glue.
What do you consider when you're arranging the boards to be glued into a panel? I'm thinking not so much about aesthetics as strength and stability.
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Actually, I guess my question isn't really about gluing the panel, but getting it ready to glue.
What do you consider when you're arranging the boards to be glued into a panel? I'm thinking not so much about aesthetics as strength and stability.
Michael,
This question pops up every few months, on almost all forums, so if you do a search I'm sure you'll come up with several that'll help you out... a bit. The reason I say this, is that most pro woodworkers will tell you they aim for aesthetics, while others will cite the need to flip your boards around so the growth rings alternate. Their argument falls along the line of needing to average out the slight seasonal warpage caused by moisture changes. Then, you'll receive the advice from some for ripping otherwise stable wide planks into 4" wide boards and flipping every second one over to alternate the growth rings.
Myself, I'm with the aesthetics group and use full width boards. Just make sure to store your newly glued up panels standing up against your shop wall so air can move freely on both faces to limit warpage until you can get the panel into its frame, or onto its base if it's the top of a cabinet or table.
One other consideration. It is easier to plane the glued up panel, if the grain direction on the faces of the boards is the same.
I just learned the part about grain direction the hard way, when I put together a panel for the bottom of a drawer. When I started to flatten and smooth it, I quickly realized I should have paid attention to that. Fortunately, I had only two boards so I could work on half of it at a time, just having to deal with the different grain direction at the joint, but that's not an ideal way to do it.
I've seen the advice about alternating the way the growth rings are aligned, but I've wondered whether it really makes that much difference, so I wanted to see what people actually do. I've found several areas of woodworking in which the common, often repeated advice doesn't work for me or in which there's conflicting advice (card scrapers come to mind!), so I like to collect information from people on this board. Like someone who says he pays more attention to aesthetics than direction of the growth rings. Thanks!
As expected, we have different responses for different reasons. I too am in the aesthetics camp where I go for looks and just don't use material that is going to cause me trouble. Folks heavy into hand tools benefit greatly from grain direction (some power tool folks too). Painted pieces, where the wood figure will not be shown, frees one to make decisions without considering the figure appearance.
All that being said, yes there are many articles on reversing growth rings, ripping to a narrower width, using breadboard ends, using cleats, etc. Each of these methods can be considered based on the design and your material/environment challenge. I do not believe there is one answer or even a 'golden rule' for this. A structurally sound, poor looking panel is of little use to me outside of shop fixtures and I generally use plywood there. ;-)
Check on the grain direction!
Some times that is the major factor in arranging the boards.
Aesthetics depends on where. A table top much diff than drawer bottom, for example.
As for alternating grain, I've done it and not done it the biggest thing is wood stability and keeping the panel stable after glue up.
I'm a big fan of wrapping panel in plastic till final assembly. Really depends on whether shop is conditioned or not.
Just a thought.... be sure to check the mating surfaces of the edges using the spin or twist technique. Be sure to give it a little ( very little ) spring in the middle. Look down the edges of the mating boards when you get to just right but not quite and train your eye to spot square and dead flat surfaces. You eye can usually see what the spin technique will indicate and soon your eye will get the idea.
As far as grain direction, I think matching grain direction on the top surface of a joining board is most important. It will ease you work effort to flatten after the glue up and it will give the assembled board more than adequate stability IMO.
Enjoy the shavings !!
Sorry....the "spin or twist technique." What's that? But I do know putting "spring" in the middle. Thanks!
I think they are referring the practice of placing the joints together on edge upright. If there is a bow on one edge or both, the ends will easily spin apart. If they mate with out rocking or spinning, you have a good joint. I use a sheet of paper to check for a slight gap in the middle for a spring joint. I don't want to be able to slide the paper between the boards at either end.
I have glued up a lot of door panels. I am staring at a few of them right now. I always try to match the grain so it looks like one wide piece of wood. I don't alter the stack up for strength or stability reasons. I have never machined the edges to produce a slight gap anywhere in any of them. Some of these panels are 30 years old and all look just fine. What is the purpose of the gap? I saw the technique demonstrated on a woodworking video some where but I never understood why. It seems to me the technique is a solution still looking for a problem.
In commercial shops ,or anywhere more than one person uses a jointer the machine tends to cut joints with slightly open ends. No one wants to use a jointer that starts off removing a sixteenth then climbs and cuts less at other end,that can cause a "nervous breakdown" in some. In fact most don't check out feed adjustment after changing knives.Too much trouble.So table too low is ok with them and that tends to leave joints slightly open at ends and with a high failure rate. I have always used sprung joints and never had an end of panel open interior or exterior. Sprung joints are never going to become popular but they do prevent joints from opening. I do agree sprung joints were more necessary with air dried wood. I've glued air dried panels that shrank so much overnight that the clamps fell off and were on the floor next morning. But the joints ends did not open. Sure some here have seen the same thing.
Other than shop projects, my first priority is aesthetics. For stability, I'm not sold on the idea of alternating growth rings. With plywood or a glue-up with many pieces, it may help but my glue ups are rarely more that 4 boards and often just 2 or 3.
The most common I see movement is related to the growth rings. Boards tend to cup in the opposite direction of the rings. This is the reason quartersawn stock is so nice for tops. The rings are perpendicular to the face. Anyway, imagine rift/flat sawn stock that wants to cup in a specific direction. When we glue 2 of then together with the rings facing the opposite way, one cups up and the other cups down. With 3 of 4 boards, we may get a wavy effect. This doesn't seem ideal to me and IMO is not any stronger.
Instead, I want to predict as best as I can the movement and arrange the boards to they move in a way that is easier to counteract. For example, a table top glue-up with the rings aligned will want to cup across the entire width. This is really no problem at all. The normal process of attaching the top to the table frame will pull the top flat. Not so with alternating rings. Than 'S' shape or wave shape is not going to pull flat as easy.
In addition, I like leave some extra thickness, so I can re-flatten the part after the glue-up. IMO, most stock will find a balance and want to remain in that shape. Often we can create flat stable pieces by giving the stock time to move and then flattening, re-flattening.