Now 3/4 inch MDF is not 3/4 inch.

[Bill Huber]

I hated it when they change plywood from 3/4 in. to what every it is now something close to 23/32, again I say close.

Now today I got some 3/4 inch MDF, I like to keep it on hand for jigs and the like. Well its no longer 3/4 inch, its something like .712 and not .75.

Whats next, will a 1/4-20 screw only be .243-19?
How about a 5 gallon bucket only 4.82 gallons.

I just can not see the point in it, why do we have to change it now. I would pay a little more if they would put out 3/4 stuff. I can understand board sizes, a 2x6 is 2x6 before its milled, I don't like that but its been that way for a very long time.

[Chris Padilla]

Interesting...any idea of the origin of the 'not dead nuts on 3/4 inch' 3/4" MDF?? I bought some 5/8" several months ago from the orange box...dead nuts on at 5/8".

Incidentally, I do not think 3/4" plywood has EVER been dead nuts on at 3/4"....

Some thoughts from Norm: http://www.thisoldhouse.com/toh/asktoh/question/0,,459293,00.html

[Steve Clardy]

Incidentally, I do not think 3/4" plywood has EVER been dead nuts on at 3/4"....



Well maybe not in your lifetime little bro. :D
Everything used to be on 1/4's, 1/2's, and 3/4's


Ocassionally I will get in some oak ply that is a full 3/4. [Columbia forest products]
It really screws up the process sometimes when you've gotten used to using 11/16" and 23/32" ply.

[Jason Beam]

This might be more of a metric size with an imperial name. 18mm = .708661417" ... that's dang close, eh?

[Todd Burch]

Where did you get this scant MDF? Was it on sale?

[Peter Quinn]

I see a fair amount of MDF made in those "Metric" parts of the world, i.e. every where but USA. 18MM is pretty close to to .712", could be that. If its consistent throughout I'd be thrilled. At this point I don't care what it measures, as long as it all measures the same, which is more than I see from most sheet goods these days. Sorry to say it Bill, but it seems the US doesn't run the world any more?

[harry strasil]

I have a full sheet of real plywood from the late 80's left over from when I bought this house and its not dead on either, by my digi caliper its. .760 at 55% humidity. That's what the dehumidifier says it is down here in the basement. and they are about 18 inches apart.

[Matthew Hills]

Maybe its going like laundry detergent and you bought the new, ultra-concentrated MDF (now with 20% stronger formaldehyde) -- less is more.

But who cares about MDF, anyways. I'm still trying to figure out what happened to those last scoops of ice cream in the half-gallon containers.

(and for the more serious here -- is there going to be a new lineup of router bits for the undersized MDF?)

Matt

[harry strasil]

ICE CREAM GREMLINS, when I had 4 kids at home I had to lock the freezer. LOL

[Steve Clardy]

But who cares about MDF, anyways. I'm still trying to figure out what happened to those last scoops of ice cream in the half-gallon containers.



Me too. Darn ice cream bandits. :mad:

[Paul Atkins]

Anyone in the US buy gas by the liter? (yet)

[Peter Quinn]

Maybe its going like laundry detergent and you bought the new, ultra-concentrated MDF (now with 20% stronger formaldehyde) -- less is more.

But who cares about MDF, anyways. I'm still trying to figure out what happened to those last scoops of ice cream in the half-gallon containers.

(and for the more serious here -- is there going to be a new lineup of router bits for the undersized MDF?)

Matt

LOL. I just bough some ice cream that was buy one get one free, and it looked deceptively like a half gallon, but the first one seemed to go rather quickly. Half way through the second I started thinking "Is my spoon getting bigger or is this ice cream getting smaller?" Sure enough, my spoon is the same size (I measured it with calipers) but my ice cream is exactly one pint smaller! Same old price, new smaller size. The American consumer HATES to see food prices rise, but apparently we are to stupid to notice a significant reduction in volume? When they shrunk my OJ I adapted, but now they have come for my ice cream, and that isn't funny. I'm going to start making my own again. I have a very nice gelato machine in storage from my restaurant days. I'll show them.

But some of my recipes use large eggs and quarts of cream. Is a large egg still large? Does a quart of cream still contain 32oz? Come to think of it some of my best recipes come from Italy,Spain or France, and those are all in grams, so I suppose all is not lost?

[Frank Drew]

I'm still upset that they only give you 13 ounces of coffee in a 1 lb. can; what the heck is 13 ounces, and when did that become a unit of measure?

One nice thing about working on old houses is that you occasionally get to see real 2x4s.

[Steve Clardy]

Folgers coffee in the red plastic container[used to be 3#] is now 2lb. 1.9 oz.


:mad: Grrrrr

[Ed Sallee]

What's the big deal..... Measure twice, cut once...

[Mike OMelia]

Anyone in the US buy gas by the liter? (yet)

I remember back in the early 80's (after Carter inflation) when gas stations in NC tried selling gas by the liter to make the price "seem" more palatable. Problem was, when you said fill'er up, it still cost the same, by the gallon or by the liter. Stupid marketeers.

Mike

[Zach England]

Not sure about the thickness, but a while ago I got some mdf that was 49 inches wide. I didn't need a lot of precision for what I was making, so I cut it assuming the factory edges were 48. It took me forever to figure out why nothing fit.

[sean m. titmas]

What's the big deal..... Measure twice, cut once...


so simple, yet for some, not so easy.

[Matt Armstrong]

Not sure about the thickness, but a while ago I got some mdf that was 49 inches wide. I didn't need a lot of precision for what I was making, so I cut it assuming the factory edges were 48. It took me forever to figure out why nothing fit.
49x97 is industry standard for a 4'x8' sheet of MDF.

[Zach England]

Interesting. Other sheet goods I have bought have been 48x96.

[Chris Padilla]

Interesting. Other sheet goods I have bought have been 48x96.

Yep, MDF has always come 49" x 97". Due to its density, its corners are often damaged so you get a bit extra to trim off....

[Eiji Fuller]

Yep, MDF has always come 49" x 97". Due to its density, its corners are often damaged so you get a bit extra to trim off....

I think the real reason is that it makes it easier to lay up a 48x96 veneer or laminate. They only carry the damaged goods at Lowes and HomeDepot.

[Rod Sheridan]

I hated it when they change plywood from 3/4 in. to what every it is now something close to 23/32, again I say close.

Now today I got some 3/4 inch MDF, I like to keep it on hand for jigs and the like. Well its no longer 3/4 inch, its something like .712 and not .75.

Whats next, will a 1/4-20 screw only be .243-19?
How about a 5 gallon bucket only 4.82 gallons.

I just can not see the point in it, why do we have to change it now. I would pay a little more if they would put out 3/4 stuff. I can understand board sizes, a 2x6 is 2x6 before its milled, I don't like that but its been that way for a very long time.

Actually Bill, it'd probably the vendor rather than the product.

You probably purchased 18mm MDF, and the vendor chose to put a 3/4" sign on the pile.

Most of the world is metric, the US is one of the last bastions of the British system, and the US actually has the old British system, which is why your gallon isn't the same size as the British standard. (Something to do with the Revolutionary War no doubt :) ).

I finally gave up working in fractions and now do my woodworking in the metric system, far easier to find the center of a 430mm wide panel than 16 59/64".

I even ordered my planer with a digital thickness gauge, there was a learning curve, however the rewards are worth it.

The tablesaw has a dual scale tape, so it's easy to work in either system.

It all started with a set of kitchen cabinets using the 32mm system. I had to purchase metric bits and a tape measure and ruler, and found that the design was well engineered and simple. I carried the metric aspects into my next project, and haven't looked back.

Yes, I still occasionally use the Imperial system where required, however it certainly isn't as convenient.

Regards, Rod.

[David Keller NC]

"What's the big deal..... Measure twice, cut once..."

Well, one issue that comes into play here is the relative size of router bits to sheet goods. If you're trying to cut a dado in one sheet of MDF so that another one will fit in the slot, off-sized sheets may make the dado too tight or too loose, which forces you to rabbet the adjoining sheet - in other words, more work. No big deal for cabinets, fine furniture, and other high-end projects, but it can be dang irritating for shop jigs.

By the way, guys, this is the story I've been told regarding "undersized" plywood:

A while back, perhaps in the 60's and 70's, industry-wide specifications were adopted for plywood sheets - thickness, width/length, number of plys, slip/book matched, "A", "B" and "C" sides, VOC emissions, etc...

Because plywood is made from rotary-sliced pieces of real wood (at least "veneer" ply - in other words, not veneer-over-MDF ply), the compression/expansion response of the wood to the glue and the tons of force placed on it in the press and then the expansion when the force is released resulted in some unpredictability in the thickness of the finished product.

THerefore, the thickness specifications in the standard were listed as "mean +/- deviation" - in other words, the plywood was still in spec as long as it was within a range of thicknesses centered around a nominal measurement. Like 0.75 +/- 0.04, for "3/4 of an inch plywood", for example.

However, manufacturing processes and modern process control has considerably improved the predictability of the thickness of the final product since the standards were put in place.

Some clever manufacturer figured out that the mean thickness of their production could be lowered, and would still remain within the industry standard for thickness of a nominal size. Since thinner means less material and more yield from a particular tree, most manufacturers followed suit and lowered the mean thickness of their product within a particular class - resulting in plywood that rarely measures the thickness that it's named for (like three quarters of an inch).

[sean m. titmas]

Well, one issue that comes into play here is the relative size of router bits to sheet goods. If you're trying to cut a dado in one sheet of MDF so that another one will fit in the slot, off-sized sheets may make the dado too tight or too loose, which forces you to rabbet the adjoining sheet - in other words, more work. No big deal for cabinets, fine furniture, and other high-end projects, but it can be dang irritating for shop jigs.

Whiteside makes a set of bits for undersized plywood dados. it makes a two step process (dado and rabit) and makes it a one step.

[David Keller NC]

"Whiteside makes a set of bits for undersized plywood dados. it makes a two step process (dado and rabit) and makes it a one step."

Yeah, I'm aware of them (and have a couple). One problem, though, is that it seems the manufacturers are constantly adjusting the target. One batch of plywood I bought from a big-box store was even more under-thickness than the bits. This ply was made in China, and I'm not clear as to whether it just didn't meet industry standards, or it was just riding the bare minimum thickness spec. In any event, it reeked of formaldehyde, so I returned it.

[Jim Foster]

I've got some old, but nice, Walnut harwood plywood from the mid seventies. I just measured its thickness with a dial caliper. .745. I also have an old sheet of Birch; its .740.

[Edwin Bennett]

If we carry the progression to its conclusion, we'll be paying for nothing. It used to be that the manufacturer would increase the price and not change the commodity specs. Now, they are using a new psychology.

[Mike OMelia]

I like to call it the "candy bar pricing scheme"... the technical jargon has it as the "hidden price index". It is far more complex than this, but it goes like this: Price the product, then reduce the content, keeping the price about the same, then do it again, then maybe increase the content, holding the new price the same. And so on.

http://www.foodtimeline.org/foodfaq5.html#candybar

Thats all that is going on here. The make hides price increases by reducing content. Gets you used to the content, rewards you with more content at an increased price that does not appear to have increased.

Mike

[Matthew Hills]

THerefore, the thickness specifications in the standard were listed as "mean +/- deviation" - in other words, the plywood was still in spec as long as it was within a range of thicknesses centered around a nominal measurement. Like 0.75 +/- 0.04, for "3/4 of an inch plywood", for example.

The borg ply doesn't skimp here -- we get the full thickness tolerance, especially over the inner ply lap joints.

Matt

[Curt Harms]

Yeah, I'm aware of them (and have a couple). One problem, though, is that it seems the manufacturers are constantly adjusting the target. One batch of plywood I bought from a big-box store was even more under-thickness than the bits. ....

I made one up like those found around the WWW. Put one edge on a line and clamp it. Put a piece of the shelf-or-whatever against that edge. Move the other side of the jig against the shelf-or-whatever and fasten it. Take the shelf-or-whatever out and employ a router with a top bearing pattern bit smaller than the dado. It seems to work well and takes material thickness out of the equation. The limitation is the jig only works with dados wider than the narrowest top bearing router bit.

[Greg Deakins]

HA! that candy bar thing made me remember something. Earlier this year while doing a big job, I was consuming a snickers bar every day to keep up energy levels, I would eat half at one time, and half a little later on. Then Snickers decided to "help me out" and whipped up a grand new idea. They would cut it for me! Then they would sell me two smaller pieces that fit in the same package, with advertising all over the package claiming this was going to solve the complicated issue of holding two ends and snapping in half! The inside ingredients therefore could be skimped on, for the addition of a small amount of extra chocolate to coat the two new ends. This really got to me, I mean REALLY got me! At five a.m. in the convienient store on the way to a long day, little things will set me off, so I switched to dark chocolate snickers, which apparently was still "behind the times" and an actual whole bar. Well, they didn't taste as good so I dropped the staple altogether. I wonder if Snickers lost any more regulars because of that?

[Sean Nagle]

I like to call it the "candy bar pricing scheme"... the technical jargon has it as the "hidden price index". It is far more complex than this, but it goes like this: Price the product, then reduce the content, keeping the price about the same, then do it again, then maybe increase the content, holding the new price the same. And so on.

http://www.foodtimeline.org/foodfaq5.html#candybar

Thats all that is going on here. The make hides price increases by reducing content. Gets you used to the content, rewards you with more content at an increased price that does not appear to have increased.

Mike

Pretty soon we'll see "Fun Size" sheet goods ;)

[David Keller NC]

"I made one up like those found around the WWW. Put one edge on a line and clamp it. Put a piece of the shelf-or-whatever against that edge. Move the other side of the jig against the shelf-or-whatever and fasten it. Take the shelf-or-whatever out and employ a router with a top bearing pattern bit smaller than the dado. It seems to work well and takes material thickness out of the equation. The limitation is the jig only works with dados wider than the narrowest top bearing router bit."

I'm certainly not saying that it can't be done - just that it shouldn't be necessary. Particularly not with MDF, which behaves in a much more predictable manner - the manufacturer can't use "unpredictable wood expansion/contraction" as an excuse.

[David Keller NC]

I like to call it the "candy bar pricing scheme"... the technical jargon has it as the "hidden price index". It is far more complex than this, but it goes like this: Price the product, then reduce the content, keeping the price about the same, then do it again, then maybe increase the content, holding the new price the same. And so on.

http://www.foodtimeline.org/foodfaq5.html#candybar

Thats all that is going on here. The make hides price increases by reducing content. Gets you used to the content, rewards you with more content at an increased price that does not appear to have increased.

Mike

Well, there's one good thing about this at least - it's the revenge of the manufacturers against consumers that consider price above all else and don't look carefully at quality or quantity.

[sean m. titmas]

One batch of plywood I bought from a big-box store was even more under-thickness than the bits. This ply was made in China, and I'm not clear as to whether it just didn't meet industry standards, or it was just riding the bare minimum thickness spec. In any event, it reeked of formaldehyde, so I returned it.

thats why i dont buy, made in China, sheet goods from the Big Box for any quality project. sometimes, in a pinch and for projects that dont require a high degree of quality i'll use them but thats it. it has caused more problems due to the inconsistant thickness, internal voids and instabliity or the core. now I buy metric plywood from Canada from my local cabinet supplier.

[Chris Friesen]

I hated it when they change plywood from 3/4 in. to what every it is now something close to 23/32, again I say close.

Now today I got some 3/4 inch MDF, I like to keep it on hand for jigs and the like. Well its no longer 3/4 inch, its something like .712 and not .75.

MDF can be had in many thicknesses..."normal" 3/4" MDF is actually 19mm. They probably brought in some 18mm stuff either by mistake or to make a bigger profit.

[Chris Padilla]

I dunno...19 mm is 0.748". All the 3/4" MDF I've ever gotten has been dead nuts on at 0.75"....