" 3/4 inch ply "

[Bill Fields]

Help--I'm starting a large CMS station and will be using 3/4 ply quite a bit. It will oak veneered both sides.

When I measured a couple of scraps with a micrometer I got readings of .690, .701, etc. Should I measure every sheet to get accuracy?

What about glue? Does a good glue in a compression clamped joint add much?

Thanks

BILL FIELDS

[Kelly C. Hanna]

Unfortunately it is not unusual to have this happen with today's ply. I measure every sheet and then plot their use so that the joints are tight....DAMWIDTN (Don't ask me why I do this now)....

[Bill Fields]

Thanks, Kelly. I will use my digital micrometer for this purpose on every sheet.


BILL FIELDS

[Steve Clardy]

Just about all manufacturers are running veener sheet stock at 1/32 under 3/4 now. PB, MDF is still 3/4.

[Bill Fields]

Thanks Steve:

Maybe MDF is the answer. It's cheaper, much heavier and less sturdy.

Gotta think about it.

Bill Fields

[Chris Padilla]

I learned the hard way to measure my "high grade" (yeah, right) plywood.

I had spent some time to set up my dado blade to get snug dados/grooves and then low and behold, I couldn't get some sheets of plywood into the dado/groove! I was like, "Huh?!" and then the calipers came out and told me the real story. I was able to widen the dado and get my snug fit. It would have been worse to have a very loose dado so my error wasn't too awful to deal with.

I'm more careful now and take more time and more measurements to be sure. It makes one want to make everything with MDF which is ALWAYS dead-on at 0.75" (+/- 0.005"). How would you like to deal with 3/4" plywood (okay, it is really 23/32", which is 0.71875") but the tolerance on my plywood is nearly +/- 1/16"!!!

Bill, let me caution you, I don't MDF is very good for structural material. If you plan to use it, laminate two sheets of 3/4" together for your carcass for the miter box station. I built a rolling bench from MDF (It was on the front cover of American Woodworker in 2000-2001) that has served me well but I there are certain parts of the bench that I would not use MDF for again. The torsion box part was fine and the top section part was fine but the main carcass that created 3 storage sections hasn't fared well. I think I clamped against it too many times and it is all out of square. When I rebuild my rolling bench, I will used two laminated sheets of 3/4" plywood for the main carcass supports...not MDF.

Also, keep in mind that most wood screws don't grip well in MDF...you need Confirmat (sp?) screws. Check McFeely's for these.

[Jim W. White]

I would go with 3/4" Baltic Birch Ply instead for this application. Much stronger and the sheet dimensions are very consistent.


my 2 cents,

Jim in Idaho

[Tim Sproul]

How would you like to deal with 3/4" plywood (okay, it is really 23/32", which is 0.71875") but the tolerance on my plywood is nearly +/- 1/16"!!!

Did you purchase those all from a single supplier from the same unit?


Yes, plywood thicknesses can vary depending on the manufacturer...but I've found they're pretty consistent as long as you get the sheets from a single manufacturer and your best bet on that is to pull all your sheets from a single unit. ~50 sheets of 3/4 ply per unit.

[Michael Gabbay]

I try to test fit all of my ply and adjust the dado stack with shims. But even within a sheet you can get some inconsistencies. For the final dry fit, I tweek the fit with a shoulder plane on the piece that is inserted into the dado. I set a fence at the same depth of the dado (3/8") and take one or two passes with the shoulder plane until they fit nicely. If you set the fence to the depth of the dado then you will probably not notice the cut on the final fit.

my 2 cents

[Chris Padilla]

Tim,

Yep, a forklift grabbed 11 sheets right off the stack and put them in my truck. I did as Michael did and fine tuned some sheet with my crappy little plane that I have (I have better ones since) along with adjusting the dado stack.

[Dale Thompson]

I would go with 3/4" Baltic Birch Ply instead for this application. Much stronger and the sheet dimensions are very consistent.


my 2 cents,

Jim in Idaho

Jim,
My son got me a sheet of 3/4" Baltic Birch Plywood due to a local plant closing. I think that it is either 15 or 17 ply. I can't count that high because I only have 11 fingers (or is it twelve)? It's GREAT but I would guess that it costs more than San Josey's shoe laces. Is that true?

Dale T.

[Bill Fields]

All--tx for all the advice-

I will use pre-measured good ply on this project.

Re: the project--I have a "new" concept on a combo station and portable set up, and will advise as it is built and tested.

But, for now I went to HD and purchased the Ridgid Miter stand.

I paid the full price, and after setting it up and giving it a trial run, all the previous accolades are warranted. Also, it is worth the $165 that was paid.

So, my new big 12" sliding compound MS is snug in a storage configuration vertical setup about 20" x 30" by 4 ft. high.

Great advice from all--and I needed it!

Thanks

Bill Fields

[Jim W. White]

Dale,


The baltic Birch is sold in 5' x5' sheets. 3/4" in my area runs about $45. While this is certainly not cheap, Bill said he was considering using A-1 Oak plywood which is quite spendyas well, nowadays and most likely would have been a wash pricewise. The baltic birch plywood is very stout stuff. I don't think it has an equal for shop carcus/fixture construction; but could easily be overkill for some applications.

I wish someone would drop by my shop and just leave me a peice unexpectantly!!

...Jim W

[Chris Padilla]

The A-1 maple plywood I picked up was $80/sheet...but it was also not a consistent dimension across a sheet or across 11 sheets!