More Wood, More Problems! Advice?

[CatBuilder]

My love affair with wood continues (sarcasm).

I just took my 1x2's and some 2x4's of the stack off the stack of plywood that Lowes delivered to my shop. They packaged all that and the other lumber was weighing the plywood down (keeping it in shape). It's all 3/4" plywood.

Well, here's what the first 8 sheets (out of 20!) look like:




Have I mentioned how much I hate working with wood?

So what do I do about this? I assume this is critical, since I spent days getting my mold strongback and supporting frames to within an 1/8" tolerance. The curve in these sheets would move my stations about an inch in any direction.

What do I do?

Also, another problem has developed. The hull shape takes up nearly an entire 8' long side of a plywood sheet, leaving only an inch on each side at the center of the keel and at the deck join areas. An inch doesn't give me enough room to cut a notch for my 1x2 to fit into the mold station.

Ideas?

[gonzo]

That's CDX plywood. The only way you will get anything worth using is to pick them out of the stack at the store. You need to add strongbacks to the stations to keep them from warping. I usually rip a sheet to about 10" and use that horizontally.
I don't really understand what the other problem is. A 1X2 is 3/4" thick. One inch should be enough for the notch. If you need a longer piece for the station, butt joint a piece of plywood.

[CatBuilder]

Thanks, Gonzo. Wood continues to be a mystery to me. Thankfully, I won't have any to deal with after the mold.

I got the store (Lowes) to come take back the first 10 sheets of the CDX. I see, so I can add some extra strongbacks or "gussets" or whatever between the stations to sort of pull them into place, taking care of any small warping that way?

My actual strongback can be seen above in the picture with the jigsaw. It is on the ground over to the right.

I was just double checking here, as I want to get everything to come out perfectly so the layup has no built in problems.

[rasorinc]

Big box stores do not carry quality Ply unless you order by brand and then you pay to much.
I can always beat box stores prices using local lumberyards--Always. I do know lumber and can talk their vocab. If using X go with ACX-PTS does not cost much more than CCX--I never use a D grade for anything. PTS means plugged (no voids , or less voids ), touched, and sanded.

[michael pierzga]

If you like messing around with wood you really should see out a good timber merchant. They care for their stock..even the cheap stuff. You will seldom get junk from a timber merchant

[TeddyDiver]

Two possibilities.. both are related to humidity. Either the humidity of the individual plies of the ply was different during the production or they are that now. In the latter case wrap it to get them even.. Same thing works with wavy paper stacks..

[gonzo]

I assume the plywood is for building stations and not for actually building the hull

[rasorinc]

20 sheets is a lot off stations--must be a big boat. Still if you know ply there is very good ACX almost full marine quality with zero voids (filled with adhesive) though the 3/4" is pricy retailing for about $34.00 a sheet. Bid price less. Do you know of an inexpensive tool for detecting voids?

[PAR]

If you're dry in the build area, why are you fooling with CDX. It's the worst material available. Use MDF or other reasonably stable, flat material. Of course you have to have reasonable shop conditions. If not, and going "commando" then your form quality will need to go up, to deal with the environment.

I find it's usually cheaper to use cheap solid stock for station molds, then plywood, unless the protect is small. You can cobble together any size mold or form from solid stock (1x6's, etc.) with plywood gussets and buttresses to keep it all nice and square.

Stan the least expensive and most effective tool for finding voids and other internal defects is the human eyeball. It takes some practice, but with experience you can find just about everything wrong with a sheet, just by looking it over. Low angle light helps a good bit too. The shadows get longer and it's easier to pick out a problem in mid sheet.

[alan white]

5/8" or 3/4" Advantek is a little over $20.00-$22.00. Much more stable than plywood. This isn't wafer board. It is much better stuff. All the box stores carry it.

[rasorinc]

PAR, I've used my eyes that way many a year but over the last 2 years I've lost almost 50% of my field sight. Night driving is now a nightmare for me and I can no longer really trust my color judgment. Ah, the golden years. I've got a machine for ground density and moisture. However, you have to drive a steel stake in a sleve then 16" into earth. Just not adaptable to wood and it contains uranium.

[AndrewK]

MDF would have been a better choice, exchange it if you can. Also your equivalent of 16mm is enough.
Make the butt join in the bilge a removable section so that it can come off to do the overlap join along the keel when doing the external laminate. In your case 18"?

[CatBuilder]

Straight.birch. ply was $45/ sheet and lowes employees have never heard of advantek. Trying home depot.

Home Depot had advantech. Looks like good stuff. Current price is $31.49 per sheet.

[alan white]

Originally Posted by CatBuilder

Straight.birch. ply was $45/ sheet and lowes employees have never heard of advantek. Trying home depot.

Those employees know next to nothing except what they are trained to talk about---- any carpenter knows about Advantek. Lowes has an identical product called something else--- you'll see. The Advantek name is like kleenex or Sawzall. The first to manufacture a certain kind of panel, most carpenters call it Advantek.
Home Depot has a similar product. Nearly all homes are now decked with these panels. Good luck.

[CatBuilder]

It sure seems unbelievable, but those guys know less about wood the I do! Ha ha ha
I got the advantech and it's perfect. Thanks for the help. Straight as an arrow, which should save several hours of pointless extra fairing.

Originally Posted by alan white

Those employees know next to nothing except what they are trained to talk about---- any carpenter knows about Advantek. Lowes has an identical product called something else--- you'll see. The Advantek name is like kleenex or Sawzall. The first to manufacture a certain kind of panel, most carpenters call it Advantek.
Home Depot has a similar product. Nearly all homes are now decked with these panels. Good luck.