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View MrRon's profile

Since when did plywood go metric?

by MrRon
posted 03-15-2016 03:51 PM


16 replies so far

View Pezking7p's profile

Pezking7p

3217 posts in 1771 days


#1 posted 03-15-2016 04:02 PM

Just the way of plywood I guess. I’ve gotten used to it. It’s one of the reasons I cut plywood dados with a dado stack instead of a router. An exact size dado jig would be even better.

-- -Dan

View jmartel's profile

jmartel

8127 posts in 2269 days


#2 posted 03-15-2016 04:06 PM

It hasn’t been a full 3/4” for many years now. Use an exact width dado jig as was said.

-- The quality of one's woodworking is directly related to the amount of flannel worn.

View MrRon's profile

MrRon

4991 posts in 3363 days


#3 posted 03-15-2016 04:38 PM



It hasn t been a full 3/4” for many years now. Use an exact width dado jig as was said.

- jmartel

I realize that, but it was always 1/32” less in thickness. Router bit makers made bits that were 1/32” less to match the plywood. This “metric” plywood is still smaller yet. The only way to cut dados is with a dado stack set or a smaller router bit and a jig.

View WhoMe's profile

WhoMe

1564 posts in 3363 days


#4 posted 03-15-2016 04:43 PM

Ahh, more perils of being one of only 2 countries still not on the metric measuring system.

Personally, I think it is the manufacturers trying to squeeze out as much wood without actually going down a physical size in plywood thickness

-- I'm not clumsy.. It's just the floor hates me, the tables and chairs are bullies, the wall gets in the way AAANNNDDD table saws BITE my fingers!!!.. - Mike -

View Ger21's profile

Ger21

1075 posts in 3250 days


#5 posted 03-15-2016 04:54 PM

If you bought enough sheets, I think that you’d find that the thickness can vary by more than .01”

I’ve done jobs with 100+ sheets, and found that dados that fit with the first 40 sheets were much too small on the next bundle.

-- Gerry, http://www.thecncwoodworker.com/index.html http://www.jointcam.com

View LiveEdge's profile

LiveEdge

593 posts in 1740 days


#6 posted 03-15-2016 04:54 PM

Was it birch plywood? That traditionally comes in mm because it comes from Northern European countries.

View sepeck's profile

sepeck

351 posts in 2260 days


#7 posted 03-15-2016 04:59 PM

Random from memory the Wood Whisperer had an exact width dado jig.
http://www.thewoodwhisperer.com/videos/exact-width-dado-jig/

I have seen ads for router bits sized for these, but yet another investment and I don’t have any.

-- -Steven Peck, http://www.blkmtn.org

View b2rtch's profile

b2rtch

4863 posts in 3168 days


#8 posted 03-15-2016 05:07 PM

I have a set of undersized router bits from Freud just for this reason

-- Bert

View hotbyte's profile

hotbyte

991 posts in 3095 days


#9 posted 03-15-2016 07:09 PM

I think MrRon is saying he now needs an undersized, undersized bit :(


I have a set of undersized router bits from Freud just for this reason

- b2rtch


View bbasiaga's profile

bbasiaga

1240 posts in 2114 days


#10 posted 03-15-2016 08:40 PM


I think MrRon is saying he now needs an undersized, undersized bit :(

I have a set of undersized router bits from Freud just for this reason

- b2rtch

- hotbyte

Or an oversized 18mm bit…. :)

-- Part of engineering is to know when to put your calculator down and pick up your tools.

View SignWave's profile

SignWave

440 posts in 3154 days


#11 posted 03-15-2016 09:07 PM

It’s been a long time since I’ve seen plywood marked as 3/4”. It always says 23/32. That would be .71875 which is pretty darn close to what you measured. Was it marked as 18mm?

-- Barry, http://BarrysWorkshop.com/

View MrRon's profile

MrRon

4991 posts in 3363 days


#12 posted 03-17-2016 04:04 PM



It s been a long time since I ve seen plywood marked as 3/4”. It always says 23/32. That would be .71875 which is pretty darn close to what you measured. Was it marked as 18mm?

- SignWave

The plywood came from Lowes and labeled “Top choice”. It was stamped on the edge stating it was .710” thick. It has 11 plies, but the face layer is the thinnest I have ever seen on plywood.

View marshallLaw's profile

marshallLaw

17 posts in 919 days


#13 posted 03-18-2016 06:24 AM

MrRon, you answered your own question – the reason you see a difference is your buying source. The big box stores are buying bulk, lower quality plywood.
If you check regular, honest to god lumber yards you will find better quality 3/4” plywood measuring in at 23/32”. They are known for under selling which causes grief for customers coming in wanting us to price match them I gently inform them that we can ‘t price match because our quality is better.

View tomsteve's profile

tomsteve

808 posts in 1338 days


#14 posted 03-19-2016 11:55 AM

yer shopping for plywood at lowes and expecting cabinet grade quality maybe?
it is “top choice”..... for lowes.

ive been workin on afew projects with plywood from menards. not needing super high quality 13 ply for the projects, so menards ply will work.
i found the thickness in one sheet varied 1/32”.

View Logan Windram's profile

Logan Windram

347 posts in 2581 days


#15 posted 03-19-2016 01:41 PM

Buying stock from lowes was the biggest problem.

View MrRon's profile

MrRon

4991 posts in 3363 days


#16 posted 03-19-2016 03:07 PM

I agree with your comments about “big box” plywood. I used this plywood because it will be painted, so I don’t want to buy more expensive material at a lumber yard.

It s been a long time since I ve seen plywood marked as 3/4”. It always says 23/32. That would be .71875 which is pretty darn close to what you measured. Was it marked as 18mm?

- SignWave

The plywood came from Lowes and labeled “Top choice”. It was stamped on the edge stating it was .710” thick. It has 11 plies, but the face layer is the thinnest I have ever seen on plywood.

- MrRon


yer shopping for plywood at lowes and expecting cabinet grade quality maybe?
it is “top choice”..... for lowes.

ive been workin on afew projects with plywood from menards. not needing super high quality 13 ply for the projects, so menards ply will work.
i found the thickness in one sheet varied 1/32”.

- tomsteve


I originally called this 11 ply because the outer ply was so thin, I didn’t consider it to be a ply, but just a prime coat.

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