Wood movement thoughts

[Dan Oliphant]

I have a client that would like a Walnut storage unit 10 feet long. This unit will be 24 inches high and 28 inches deep. Far left section (30 inches) will be three (7) inch full extension drawers, center section (58 inches) will be storage behind two arched doors,( wide screen TV will set on top in this area) far right section will be one (7) inch full extension drawer over a storage area behind two arched doors.
With that all said, my concern will be the top, not sure if I will be using 6/4 or 5/4 kiln dryed walnut, equalized for two to three weeks prior to machining. The top will be 28 X 120 inches, with bread board ends.
This unit will stay (for several more years) in the high desert of S. Ca were the Rh stays between 10% and 25% most of the year. The client may take it to the Palm Springs area (low desert) at some time in the future.
So after all that, does anyone have any thoughts on the top (long term issues?)

[Vaughn McMillan]

Dan, I don't have any input regarding your question, but I was wondering where you purchase your hardwoods. I live somewhat close to you (40 miles or so from Palmdale) and so far the only hardwoods I've found locally are in Pasadena. Do you have any good sources out your way?

Thanks -

- Vaughn

[Jim Becker]

Dan, if you construct your breadboard ends correctly and fasten the top on the cabinetry so that it can move (usually to the back), you shouldn't have any problems at all. Wood moves. Just plan for it and you and your customer will be happy campers. In the case of this top and assuming the grain runs the length of the piece, your movement will be almost all in the front to back dimension, not in the length.

[Don Baer]

Dan;
I wish I could help but most of the research I have seen deals with larger changes in humidity and humidity level in excess of 20%.

Not to hijack your thread but you might be interested anyway.

Vaughn,
have you tried Peterman Lumber for hardwoods. They have a very large yard and I find there prices are good. They are in Fontana, that about a 40 mile drive for you. Take 10 Fwy east I think it's the Cherry ave exit.

Here is a link to their web site.

http://www.petermanlumber.com/products.htm#Imported_Hardwoods

a neighbor of mine is a cabinate maker and he says that they buy all of there material from them.

[Dan Oliphant]

Vaughn,
Check out Kelly-Wright hardwoods in Anaheim. I have had an account with them for several years now. From Anaheim to Palmdale is a cartage fee of $30, materials are delivered to my door within 3 days of order.
Jim,
Thanks for the info, can you be a little more descriptive as what you are thinking on front to back movement control? I'm sure others would like to know your thoughts.

[Jim Becker]

...can you be a little more descriptive as what you are thinking on front to back movement control?

Well, firstly you can't "control" it...the wood will move. So you need to do two things:


1) Build your breadboard ends correctly as originally suggested in my first reply. I have a narrative of the process on my site (http://sawsndust.com/a-breadboard.htm). (no pics, unfortunately)


2) When you fasten the top to your cabinetry, make sure it can still move. The actual project substructure will dictate what method you use, but for example, it might be something like this:

Let's say it's a more traditional cabinet structure with aprons at the top all around. In the corners, you might put some triangular blocks to provide "screwing" capablity...these are set down from the top edge ever-so-slightly. You might also have some cross pieces spaced across the cabinet since it's so long to tie the cabinetry together. These cross pieces are fastened between the front and back apron, have the grain running in the same direction as the end aprons and are also slightly recessed from the top of the aprons.

You now drill some holes to accomodate the screws that will hold the top in place. The holes in the very front of the piece in both the corners and in the cross pieces get round holes that pretty much fit the shaft of the screws. The holes to the back of the piece in those corner blocks and in the cross pieces have elongated holes, with the elongation front to back. This allows you to screw into the top to hold it down, but the screws can slide in the slot (elongated holes) as the top expands and contracts front to back. You make the fixed holes in the front as that is where you most want the top to stay in exactly the same position no matter what the season...it's the shadow line that gets seen. If the back extends beyond the cabinet slightly in the hot, humid time of year (to whatever degree that is, even if minimal) nobody will notice.
Any other fastening method would still obeserve this same basic premise...allow the top to expand and contract while still holding it down to the cabinetry.

And don't put the screws through the top...pick the right size the first time! (correspondingly, don't drill your pilot holes in the top all the way through, either...hee hee)

[Howard Acheson]

Go to www.woodbin.com and click on the "Shrinkulator". Input you species range of relative humidity and starting width. The output will be the expansion/contraction you will need to plan on. That said, with the very small change in relative humidity annually, you really will have little movement.

As to the breadboard ends. You have some choice as to where you want the mismatch of the field to breadboard to be. In many cases, the breadboard is fixed in the center of the panel and floats at the end of the breadboard. This will mean that mismatches will occur at both the front and back of the panel. For the item you are building, consider fixing the breadboard at the front edge and letting the center and back float. This way all the mismatch will be at the back which may be less noticeable.

[Dan Oliphant]

Jim,
Thanks for the added detail, very informative and constructive.
Howard,
I hadn't thought about gluing the breadboard on the front portion and allowing the mismatch to be directed towards the back, I like that approach for this project.