Shopsmith Forums

I took out the HF caliper and found the plywood to be a minimum of .051" different in thickness. The handy panel I got varies all over the place in thickness, it was cheap so what can I expect. The worst case I found it was off by .060".

For those that are challenged by this sort of numbers remember that 1/32" is .03125" and 1/16" is .0625. So it is no wonder the top/bottom shelf would not fit the dado.

Already hot and humid and I have some medial tests to go to at 1:00 so I'm taking the day off from working on the shelf today. Weather maps shows heavy rains coming in about 5:00 tonight so that should cool things off and make working on this better tomorrow......... I hope.

The other plywood is actually slightly undersized which has caused some bumps where the kreg screws are. Garage shelf so no big deal but next time I'll look for another brand of plywood. I mean 3/4" plywood is already undersized, how low can they go and still get away with advertising it as 3/4"? Maybe kreg will have to come up with a new screw size soon as the 1-1/4" length is clearly a little long for this material.

Ed

reible wrote:... I mean 3/4" plywood is already undersized, how low can they go and still get away with advertising it as 3/4"?
Ed

The 3/4" size in a nominal measurement. Nominal sizes of lumber and wood products have always existed. Maybe MDF is an exception (sometimes), but the nominal size is always less than the stated size.

for example, 4" wide lumber measures about 3 1/2".

Don't be surprised when plywood manufactures use thinner layers in their product.

Although this discussion is about weight scales, the idea applies...
http://www.mymarketresearchmethods.com/ ... val-ratio/

Plywood used to be very exact.

Then along came 'metrification' and a rash of imported stuff. None of it(mostly) was targeted to be 'imperial'

Also a mind set also came along that interpreted X±y to mean making stuff to X-y(+very little - nothing) was an acceptable thing to do.

I.e. the goal was no longer the 'nominal' X, but something barely above the lower limit of X-y.

It all is the result of greedy irrational thinking.


Oh for the good old(rational) days when a spade was a spade.

Yes well aware of the nominal sizes but finding almost a 1/16" difference is more then I expected.

Earlier this year I got some 1x6's expecting them to be 3/4 x 5-1/2 and learned that this batch was 3/4 x 5-1/4.......... not happy with that either.

Looks like its time to take a caliper with when shopping.

Like I said I sized the dado's to fit the thickness of the one sheet of plywood and they fit good. How ever when putting the frames together in some cases you can see the bump from the kreg screw tip.

The Kreg instructions are to use 1-1/4 screws for 3/4" material. The next size down screws are 1". I guess I could also have alter the prescribed depth for the drill bit but I drilled all the holes before assembly. Didn't notice the bumps until I was all finished and turned the panels over.

Thinner plywood has these "added" issues that while not insurmountable one has to be even more vigilant then ever.

Next project is a inside the house one and for that I don't want to see any of these issues. I'll pay more for better plywood provided I see it is actually better and not something that cost more.........

Ed

JPG wrote:Plywood used to be very exact....

I.e. the goal was no longer the 'nominal' X, but something barely above the lower limit of X-y.

It all is the result of greedy irrational thinking.

Taint greed - 'tis efficency

reible, 1st, stay dry?
Yesterday I picked up a bunch of Baltic Birch Ply, 1,2, 3/8 and 1/4", I just measured all up with my dial veneer, all 1/64th thinner then its nominal size. So for your indoor project I would suggest BB ply if using ply and it finishes a nice honey with these, BLO and MS 50/50, or MinWax Natural Stain.

charlese wrote:

JPG wrote:Plywood used to be very exact....

I.e. the goal was no longer the 'nominal' X, but something barely above the lower limit of X-y.

It all is the result of greedy irrational thinking.

Taint greed - 'tis efficency

I disagree!

Efficiency is getting the same result with lesser effort.

Getting a lesser result is a different thing altogether.

I surmise the effort is the same.

To say nothing about the lesser raw material.


I consider it all to be a shameful sham.

I have no problem with calling 12 mm plywood 12 mm. Just do not call it 1/2".

I measured a bunch of pieces I have from over the years. Both Baltic Birch and Fir. Most of it was 1/32" under with a few 3/64" under. One piece of "3/4" Baltic Birch was a 1/16" under (surprising).

Interesting that Whiteside sells a set of router bits for plywood. They are all (1/4, 1/2 and 3/4) 1/32 under. It makes one wonder why if plywood is all over the place. 1/32 must be the standard but a lot of manufactures apparently don't adhere to that.

I suppose it depends on the quality control of the manufacture. As Ed said, take a caliper when you buy plywood.

.

I have bought some 1/4" ply, sanded one side, that was 3/16" at the BBS.