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View Full Version : How much expansion on 5 1/2"x 10 1/2"...



Joe Tonich
05-29-2004, 5:07 PM
x 7/16" Curly Maple panel? Would 1/32" be enough or should I go with 1/16"?

Thx,

Joe

David Rose
05-29-2004, 8:17 PM
Joe, more info would surely help. Do you have any idea what the relative humidity ranges are for: where you are producing it and where it will end up? That's a lot to ask if you don't have some hygrometers sitting around.

Mine never gets under 25% nor goes over 55% either in my shop or house. With those ranges as extremes, the movement will be .25" per 12 inches across the grain.

For convenience I almost always just allow an 1/8" per side on the "average" panel.

Sugar Maple will shrink almost exactly 10% from green to oven dry. Of course that has little to do with your question.

I bought a couple of cheap hygrometers from Radio Shack and put one in the house and one in the shop. They record minimums and maximums. Then I downloaded a shrinkage rate calculator free that is online. It helped me get rolling when I was starting. That is probably overkill, but relatively cheap. I think the hygrometers were around $15-20.

David


x 7/16" Curly Maple panel? Would 1/32" be enough or should I go with 1/16"?

Thx,

Joe

Joe Tonich
05-29-2004, 10:21 PM
Joe, more info would surely help. Do you have any idea what the relative humidity ranges are for: where you are producing it and where it will end up? That's a lot to ask if you don't have some hygrometers sitting around.

Mine never gets under 25% nor goes over 55% either in my shop or house. With those ranges as extremes, the movement will be .25" per 12 inches across the grain.

For convenience I almost always just allow an 1/8" per side on the "average" panel.

Sugar Maple will shrink almost exactly 10% from green to oven dry. Of course that has little to do with your question.

I bought a couple of cheap hygrometers from Radio Shack and put one in the house and one in the shop. They record minimums and maximums. Then I downloaded a shrinkage rate calculator free that is online. It helped me get rolling when I was starting. That is probably overkill, but relatively cheap. I think the hygrometers were around $15-20.

David
David,

Sorry, I really suck at describing things, but, here goes. I'm making a music stand for my son. It will be 24"x14"x7/16" and will have 4 bookmatched panels divided by 3/4"x7/16" cherry rails & styles and the sides being 1 1/2" wide. It's all tongue & groove. I didn't really want a large gap between the panel & dividers if possible. I don't have a moisture meter to check the MC but it has been kiln dried and in my garage for a while. It will be used in my house and the humidity is about the same as my garage. (I HATE air conditioning)

Thanks,

Joe

Mark Singer
05-29-2004, 10:33 PM
If you make a loose panel it can move in the dado and you won't see the gap. Wood moves primarily across the grain .25% to .5% should be enough. The key is in the design...allow it to move and you won't have problems.

Joe Tonich
05-29-2004, 11:04 PM
If you make a loose panel it can move in the dado and you won't see the gap. Wood moves primarily across the grain .25% to .5% should be enough. The key is in the design...allow it to move and you won't have problems.
Mark,

The panels have square edges and a tongue all around. If I leave room between the tongue and the groove in the dividers & sides, would I still need a gap between the edges? :confused: :confused:

I thought I had this figured out , but.... :(

Thanks,

Joe

Dennis Peacock
05-29-2004, 11:26 PM
Joe,

1/16" to 1/8" on each side for expansion would suffice nicely in your case. Just make sure it fits snuggly enough to not rattle when moved.

David Rose
05-29-2004, 11:31 PM
Joe, I think I see what you are asking. If I'm wrong, correct me. You want to know if you can do this?

rail Gap1 panel
__________ _______________
__||
Gap2 ||_
__________||_______________

I'm terrible with ascii drawing. With "Gap1", you want a minimum space and Gap2 you are hoping will contain the movement? If this is what you mean, it won't work. The gap at all three points would need to be great enough to not come under compression when it expanded or open to excess if it shrunk. See what would happen if you closed Gap1 and left space at Gap2 and the bottom? As it compressed the top would bow out and pop joints most likely. That is one purpose of raised panels. The taper allows you to have a slight flat area exposed without it looking bad. Also the taper itself can go into the groove some without damage to the rail/stile. Is this clear? Sorry, but my drawing program is to old to convert files to something I can post here.

____________ _________
__|___/
||__
____________| \___________

See how this would work?

David


Mark,

The panels have square edges and a tongue all around. If I leave room between the tongue and the groove in the dividers & sides, would I still need a gap between the edges? :confused: :confused:

I thought I had this figured out , but.... :(

Thanks,

Joe

David Rose
05-29-2004, 11:40 PM
Sorry, Joe. The ascii drawing didn't come through as it was drawn. At any rate, you need gaps at the center, top and bottom surfaces as viewed from a lower or upper edge. Some sort of taper or curve would distract from the fact that you were leaving a gap. If you didn't break it into panels, you could do it all with edge glued boards and maybe bread board ends. But panels need a gap showing.

I am treating like you don't understand one purpose (besides decorative) for raised panels. If it sounds like I am speaking "down" to your experience level, I'm sorry. That is not what I am trying to do.

David

Mark Singer
05-30-2004, 1:24 AM
Joe,
If you trap the panels in a dado and don't glue them, they can move. If you are going to use a rabbet and stops ...just let the panel free and the stop will secure it ....like a glass pane in a sash window. Hope that helps. If you want I can make a drawing.