Replies

1. 
   rob_ss | Jan 13, 2021 02:06am | #1

   It's a beautiful piece, isn't it.
   I had a quick look at the article and could not find accurate dimensions for the panels.
   I recall hearing that the dimensions are not usually added by the original woodworker, but rather later so oversights and inaccuracies are common.
   This occurs fairly frequently in woodworking plans so it is always best to take dimensions off your finished pieces - make the frame parts first THEN make the panels.
   You will need some wiggle-room as you put it, though how much is a matter for dispute in any woodworking pub.

   TBH I wing it a bit so I'm probably not the best to answer exactly how much. I generally put in as much allowance as the design will permit - if I have a 12mm beading around a panel then I can allow for 6mm all round without any risk of the gap being visible. The key is not to have gaps appear when the wood dries out, if you can help it.

   https://www.finewoodworking.com/2013/08/29/calculating-for-wood-movement gives a guide. The problem is that you still need to know the variance of moisture.
   If you can measure the moisture content of some wood in your home then you are on to a winner, especially if you do it several times through the year and record the differences.

   If we assume a very reasonable 5% variance across the year in your home (the 10% used in the example was a bit extreme as it took into account the possibility of travel to very moist climates), and that the wood is acclimated to your home, the movement for quarter sawn white oak calculates out at 0.0018 x 5 x 40 inches = 0.36 inches for the back panel. You need to incorporate about that amount of wiggle somehow, one way or the other.
   If you put in more then it will cope better with a change from drier to wetter climates, but you may find the design compromised with gaps appearing in dry weather.

   Perhaps @mikepekovich might chime in on this one, as he designed and built the original.

   
2. 
   lat_axe | Jan 13, 2021 04:44am | #2

   The back panels are tongue and groove. Normally such panels would be fitted together with a small gap between the tongue and the groove to allow for expansion/contraction. Often, a bead or a chamfer is used in the T&G interfaces to help take the eye off any gap opening and closing, as such gaps would be quite small.

   The individual panels are not that wide .... but the fully-enclosed-in-a-frame side panels would benefit from some wriggle room. 1/16" each side would probably be enough.

   The outside edges of the two rear panels on either end could have their vertical edges glued into the legs. The T&G gaps between the other back panels would deal with any expansion/contraction. Gluing the vertical panel edges of the end panels of the back into the leg grooves would add a bit of extra strength to the whole carcass too.

   ********
   Whilst a plan is a good way of understanding the construction, no plan should be assumed to be perfect or complete. Basic woodworking practices (such as giving solid wood panels room to wiggle in enclosed frames) should always be performed, in the plan or not.

   Lataxe

3. 
   esch5995 | Jan 13, 2021 08:20am | #3

   I applaud you recognizing that wood movement needs to be allowed for and will try to explain why it is seldom accounted for in plans.

   There are several factors that will determine how much wiggle room needs to allowed in construction A major factor is what is the humidity in the shop you are building compared to the final location of the piece. With most American homes being air conditioned today we don't see the wide fluctuations in humidity levels that were once common, but it still needs to be accounted for, while most shops aren't.

   Your goal is to have the wood in an environment as close as possible to the one where the piece will reside to enable you to anticipate and allow for wood movement. It is also this unknown that makes it difficult for designers to specify how much "wiggle room" to allow for. A piece built in a shop with 75% humidity but placed in a location that has a humidity typically in the 30-40% range is going to see shrinkage and should be built with very little wiggle room. Conversely, if the shop is 30% and the final environment is 75% the wood will expand and needs to be built much looser.

   To help me know how much play to leave I keep a humidistat, less than $15 on Amazon, in my shop so that I always know what the humidity level is and I also have a dehumidifier that maintains the humidity level between 40-55% to help approximate the typical American home humidity level.

   As a new woodworker, I don't know if you are aware that you should purchase your wood a minimum of 2 weeks, preferably longer, ahead of actually starting to build and store it in your shop in stacks off the floor with stickers between boards to allow the boards to acclimate to your shops humidity level. You could also lean it against a wall vertically if you shop ceiling is higher than mine. If you do this and know your shops humidity level at the time of construction and have some idea of what the final environment is going to be relative to your shop the last thing that must be accounted for is the species of wood, Hard Maple shrinks more than Red Oak, and how it is cut, flatsawn wood will move more than quartersawn, only then can you plan on how much "wiggle" room to allow and why it can't be specified in plans.

   A good source of wood info online is https://www.wood-database.com/

1. 
   thebardowl | Jan 13, 2021 12:51pm | #8

   A cogent, well-presented reply. Thank you from the peanut gallery. I’ve always struggled a bit with the “how much to allow for” question, and your description of your own practices is very helpful. Much appreciated.

4. 
   ysu65 | Jan 13, 2021 09:08am | #4

   What I have done many times without problems is to put a small dab of silicone adhesive in the grove to limit movement or rattle. The silicone is compliant and holds panels in place but allows movement due to humidity changes.

5. 
   DRBWWing | Jan 13, 2021 10:41am | #5

   A good rule of thumb is 1/8" per foot maximum for lumber that is 12% or less.

   In most cases, you can expect wood to shrink, not expand when it moves inside.

   That said, you have to take into consideration the time of year the your local climate. For example, building in the winter (low humidity) you would expect expansion, the opposite for summer.

   Or if you live in Colorado or Nevada, you may not need to do anyting :-)

   Take this into account when you make the drawers. Good idea to make them a tad loose in the winter/a tad tight in the summer.

6. 
   jpe52 | Jan 13, 2021 11:22am | #6

   Thanks all for these very useful comments. I should have mentioned that I purchased the digital plans and so knew the various dimensions. I did not know that it is common for plans to not include allowances for shrinkage/expansion. While I am generally aware of things regarding moisture content, relative humidity in shop vs. home, my on-the-ground experience is minimal at this point. Indeed, that is what makes this forum so helpful.

1. 
   john_c2 | Jan 13, 2021 11:55am | #7

   Plans often have errors, and we make errors in construction. If you have 6 stiles and 5 panels, a tiny bit of error on each part multiplies into a real problem. As someone said above, use the plans as a guide, to a point. In this instance, construct the rails and stiles, dry fit, and then figure the true dimensions of the panels, factoring in the wiggle room.

7. 
   gary_vaiskauckas | Apr 01, 2021 01:24am | #9

   This article by Christian Becksvoort explains seasonal wood movement and how to calculate allowances based upon species of wood, grain pattern, location and season.

   "FWW #187–Nov/Dec 2006 Issue
   Stop Guessing at Wood Movement Figure out exactly how much of a gap to leave in doors and drawers, no matter the wood or season
   Author By Christian Becksvoort #187–Nov/Dec 2006 Issue"

8. 
   elmaduro | Apr 01, 2021 09:35am | #10

   Consider pre-finishing those back panels as well. As they ‘move’, raw wood won’t be exposed.

9. 
   Cayman | Apr 06, 2021 10:55pm | #11

   I've made a number of solid wood floating door panels applying small rubber 'barrels' between the panel and the stile. The barrels absorb the seasonal movement and keep the panels tight all year. I think they are available at most woodworking retailers.

10. 
    _mj_ | Apr 07, 2021 03:33pm | #12

    I've used snips of 1/4" foam backer rod the same way, it centers the panels nicely.

11. 
    hoovermd | Apr 07, 2021 10:23pm | #13

    1/8" per foot across the radial grain.

12. 
    [email protected] | Apr 08, 2021 06:51pm | #14

    I have put a pin or nail in the center of each panel after allowing 1/16 between panels.The narrower each panel the less you need to worry about expansion of each panel

13. 
    mikaol | Apr 08, 2021 07:12pm | #15

    I love plans. If woodworker A, in Atlanta, in summer, uses mahogany for a project 4' x 3' and allows for 'x' amount of movement, that amount of movement would not apply to me using pine for the same project in winter- time Iowa.
    I agree with those who use plans as guidelines "not carved in granite."
    Mikaol

14. 
    mikaol | Apr 08, 2021 07:19pm | #16

    Oh, lest I forget, mentioning Fine Woodworking on Maverick Abrasives' site will earn you a discount.
    Mikaol