When making door stiles out of laminated SOLID lumber is it best to use 3 layers of wood ( face to face )with 2 glue lines or 2 pieces of wood with one glue line ? I see lots of Euro windows using 3 layers of wood ( I realize their windows and doors are much thicker than ours ) but what is the bottom line to obtain THE STRAIGHTEST MATERIAL POSSIBLE ? Stave core is great but I would like a proven alternative for situations that stave core does not fulfill or if a customer simply doesn't want it.

In my opinion, it makes no difference. One, two, or three layers, it's all good.

John

Do you have/use a joiner? This is the best way to get dead straight materials. It is fundamental for making doors.

Beyond that.....

One, two, or three glue lines doesn't matter too much, as long as all the same MC and species.

I do have a great 12" Oliver (built in 1944 and I have owned for 30 years) which I hope to share my grave with. Thank you David for your reminder though. Speaking of which: I am constantly amazed at videos I see of " Experts" using joiners where they are applying pressure only on the infeed table ! Who taught them that ??

Good to see some love for the older iron. In my book, I mention it as simple logic. Observe carefully, and you will learn all you need to know to operate effectively..
I teach joining with one finger. Sort of. Set the board on the infeed table, hold it down with gentle left hand pressure. Keep it from bouncing. Push it into cutter with one right index finger. Continue same hold only pressure onto outfeed table. I also will demonstrate the futility of pressing a bow out of a part on infeed table, then across the head with heavy, deformity pressure, then release after the cut to see the bow us still there. Damn machine. No good.

Every time I’ve done two layers the doors have warped badly. I’ll do stave core occasionally but For the most part I’m a traditional solid wood man now.

David: I just ordered your book through a small bookshop in NY to try and help small book sellers. Looking forward to reading it ! So glad you decided to put all your wisdom down on paper and sharing it with the woodworking community out there.
Cheers, Gary G.

2 layer laminations for door stiles is a bad idea. It’s ok for shorter parts like rails but not stiles.
I typically use 3 layer solid for my 68mm thick doors and sometimes 56mm thick when I cannot get suitable solid material for these. For 1 3/4” thick doors 3 equal layers is not a good idea. I prefer solid or engineered stave core for these.

Important on the 3 layer construction is to alternate the grain of the 3 laminations. For 68mm thick I use well faced and planed 5/4 24 mm thick. Blanks are 72 mm thick and faced and planed again or sent through the straightening moulder. For 56 mm thick similar process using 20mm thick material.
Quartered and rift material preferred but not always possible with the wide range of materials we use.

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Joe, I would be very interested in why two and three piece laminations are a bad idea. I would have thought that the more laminations there were the more balancing out of individual board stresses would occur.

Tom I was saying 3 piece is good for 2 1/4 and up. I tried 3 equal pieces on a 1 3/4” thick door a few times and was not satisfactory. For 1 3/4” if you have to laminate I think the 1/8”skin and stave core is better. Never found 2 piece to be good either. Early on a few shops here tried that and most gave it up.

I cannot explain why the odd number of laminations are more stable but probably why plywood always has a odd number.

The reason in plywood it's always odd numbers is because of the outer veneers. They have to be going in the same direction. x/y/x/y will warp. x/y/x/y/x will have a much lower chance. The outside veneers have the most "pull" on the panel.

Those properties are really obvious in composite panels like you would make out of fiberglass.

Using a jointer productively is a skill that takes experience. Get a carbide insert if you want to be efficient. You can take deeper passes in either direction with no tear out.