Replies

1. 
   highfigh | Jul 21, 2006 06:12pm | #1

   It's probably metric. 1/2" is 12mm, 5/8" is 15mm, 3/4" is 19mm, 1" is 25mm, etc.

   "I cut this piece four times and it's still too short."
1. 
   kostello | Jul 21, 2006 07:28pm | #2

   1/2" is 12.7mm 5/8" is 15.9mm3/4" is 19mm1" is 25.4mmjust being pedantic :-)

1. 
   highfigh | Jul 21, 2006 11:28pm | #4

   Those are the actual conversions. When you go to a yard for 3/4" baltic Birch plywood, most of the time, it'll be loose in a 3/4" dado because it's metric and not the metric version but a rounded off size.
   "I cut this piece four times and it's still too short."

2. 
   gb93433 | Jul 21, 2006 08:51pm | #3

   If it comes from a foreign country it is metric. If it laid up in the US it can be American sizes. Both are on the market.

3. 
   DougU | Jul 21, 2006 11:41pm | #5

   did

   I just went out in my garage with my calipers and measured about 20 different pieces/places.

   Got anywhere from .460 to .485  When I build drawer boxes out of the stuff I consider it a full 1/2" so  that it gives me the play that I need to comfortably fit the drawers guides. A little light is better then being on the strong side.

   My BB has been sitting around for awhile, don't know if some of it had been sanded or if some has drawn some moisture and swelled a bit.

   Doug

4. 
   seb | Jul 22, 2006 02:13am | #6

   I measured some and it is .494 to .502

   Bud

5. 
   cowtown | Jul 22, 2006 08:55am | #7

   It is as close to spec as any imperial measure (inches) is, and likely a tad more close when you measure tolerances.....

   First off you gotta get yer own calipers. Even cheapo calipers if you must. You will soon find them indespensible.

   If yer making BB drawers, why not just figure out yer rabbets etc based on what is left, as opposed to how much you cut out.... Simple to adjust yer thinking that way.

   Example, You gotta make a drawer box 21 3/4 wide by 22" deep.

   You rip a bunch of 1/2" stock to depth say 4 1/2", and cut two sides 22" long.

   If you cut your front and back 21 3/4" less 3/4" (yer gonna use about a 1/8 rabbet) and then you cut yer bottom the same width, and the bottom piece at the same exact 21" width and then at 22" les 3/4"= 21 1/4" then with scrap pieces, you just set yer dado head to close to 1/8", cut two pieces, and set them back to back and see if what's left is 3/4" adjust to achieve this "left over" -as opposed to trying to make a precise 1/8" rabbet.

   Front back and bottom are all the same width, so you can glue and tack them together, and if yer width of the rabbet is set up to be precisely the thickness of yer stock, the sides should set in place with nary a gap showing. If there is a gap, it's gonna be small, and oftentimes judicious clamping will make it disappear, or worst case is, you pop of a front, pull the pins, and shave off a 64 or a 32 off the bottom on the jointer and reassemble.

   When I'm making drawers this way, I presand the pieces with 120 on the flat and use a 50 dollar pneumatic sander in the drill press to sand the edges to a slightly radiused profile.

   I pop-spray em with laquer, sand, and spray on another coupla coats.

   What I'm saying, is don't think about what yer cutting away, think about what yer leaving, and problems with variance in thickness disappear.

   Hope that helps.

   Eric

   I've never had much of an issue with thickness, using this system,

   What I have encountered frequently is that the sheets are slightly out of square.

   Ergo, never assume factory edges are either straight or square.

6. 
   TomT226 | Jul 22, 2006 01:25pm | #8

   1/2" is 15/32", and 3/4 is usually 23/32".  I've seen it vary between "Russian" Birch and "Baltic" Birch, so watch your rabbets.