gluing planks together to make a laminate.

[jackieschmidt]

I have a urge to build a Rail Gun Top out of wood. It would duplicate my current top, just being made of wood rather than aluminum.

I can buy finished 3/4 x 12 x 24 finished hardwood planks at Lowe’s. I could them atop each other to produce a piece thick enough to machine the top and the barrel block out of.

Or, would it be better to use thinner pieces and having more laminated layers to achieve the needed thickness.?

What would be the best choice in a adhesive to glue these pieces together to form a solid piece.

 

[Just Say Moe]

Titebond 3 has some water resistance. Epoxy resin would be tougher than the wood and you could dye it black to have a nice joint line highlight.

 

[tac284]

I wonder if TotalBoat epoxy would be a good choice…? I don’t know it well enough. I‘ve used there penetrating epoxy with success.

 

[joshb]

Hi Jackie: The 3/4 will work fine but which wood are you looking at?
Maple is a good one.
Titebond 2 is a great glue that I use almost exclusively. Use lots of clamps.

 

[ricco1949]

I suspect your Lowes 1x12s may be plain sawn.

I recommend you rip those 1x12 to the thickness that you desire and glue them together in butcher block fashion with the grains alternating....net result is quarter sawn with alternating grain.

The risk you run with lumber yard material is that it is kiln dried and will move moisture via osmosis through wood cells that are are not adequately collapsed in kiln drying vs air drying.

 

[jackieschmidt]

I suspect your Lowes 1x12s may be plain sawn.

I recommend you rip those 1x12 to the thickness that you desire and glue them together in butcher block fashion with the grains alternating....net result is quarter sawn with alternating grain.

The risk you run with lumber yard material is that it is kiln dried and will move moisture via osmosis through wood cells that are are not adequately collapsed in kiln drying vs air drying.

After the machine work is done, I plan on finishing it with TrueOil. Would that keep the moisture out?

 

[Intheshop]

Generally,the "faster" a piece of wood is dried,the faster it reacts to moisture change. So air dryed is the way to go on any engineering requiring stability. With a mighty few exceptions,I would never use "kiln dried" on stocks or bows.

Epoxy,when used for laminated projects.... glue ups; you're going to get a black line whether you like it or not. It's partly the fact that there's no light coming from under the surface.

Smooth-On EA40 has been a go-to epoxy for traditional bows 50 years. We used to buy it by the gallon units(building bows).... get the pint sized from any bow supply place.

 

[Greg Brooks]

I use West Systems epoxy to do laminates. Tough to find a better one imho, just works. The two parts are 105 and 207.

Arrow Wood Finish is the best oil I’ve found, I’d just send it to BC’z though .

Five part laminate of Tiger maple.

 

[JoeDuke]

Jackie, i use this product when gluing up stock blanks.
If ultimate strength is ur goal, find some baltic birch plywood. You can find it in places catering to cabinet makers. It can be bought in 1/2” thick by five feet square. Cut it to the width you want and glue up the layers. Reverse the direction of each piece as the best of sheets may still have a bit of twist. As someone said, use lots of clamps. If there are spots in the middle where u can hid it, drill a hole and use a bolt through it to clamp out in the middle where normal clamps wont reach.

T-88

T-88 is a high-performance, non-brittle, two-part epoxy adhesive designed to give superior results under adverse conditions.

www.systemthree.com

 

[JoeDuke]

Baltic birch, also called russian birch is a nice smooth, void free plywood used by cabinet makers. 1/2” is actually 12mm thick. It was used extensively in wartime to construct russian airframes.
It comes in five foot squares rather than our 4x8 foot size. I was told it is that size because that is what the typical Russian woman could pick up and carry in the construction process. Might be a fable but it sounded good.

It is a good product. Various lumber suppliers around the houston area carry it. Mason Mill and Lumber is one but they are on the other side of town from you.

 

[Jonnyofalltrades]

Baltic birch plywood is amazing stuff. I have a sheet of 12mm in my shop right now. A joy to work with. Excellent value for the price.

I have seen a few stocks laid up from the stuff, and they look really good.

 

[Twdmar]

I second joshb's reccomendation of titebond 2. Its easy to work with and may be a better choice than titebond 3. It's also a tad cheaper. One nice thing about a pva glue like this compared to epoxy is that it's very difficult to starve to the joint of glue. With epoxy, clamping pressure needs to be better controlled.
One thing I would suggest is that your laminations are milled flat so that you don't have to clamp so hard. Even though it looks flat, the wood probably isn't.

 

[ricco1949]

After the machine work is done, I plan on finishing it with TrueOil. Would that keep the moisture out?

Jackie:

I can't say for sure one way or the other...
but I doubt it. Stocks move in differing climatic conditions. It seems that the slightest amount of twisting in your laminate rail would be detrimental.

It appears that @Intheshop has the same perspective in his reply above.

IIRC, learned about air drying vs kiln drying and cell osmosis from an article in Precision Shooting years ago. You may recall it. It was about the purchase of one walnut tree for $500k...and grossing $1 million in blanks. Blanks need to air dry minimum of 5 years to collapse cells.

Below is a photo of an LR BR stock I have in process utilizing alternating grain.

 

[rickiesrevenge]

I would think thinner planks would be more stable. No science to back that up. I would also consider putting a layer of carbon fiber between the planks.

 

[DShortt]

I concur. If strength and stability is the ultimate goal thin laminates in various grain directions would be best. A fellow could drive himself way off in the weeds with that idea though. There comes a point of diminishing returns.

 

[Ggmac]

Tite bond II is all I’ve ever used and no , zero problems . I used the Lowes laminated Birch , made in USA. Dont use Home Depot laminate, it has thinner plys but made in china and has more voids than wood . Exaggerating but its crap .

 

[LVLAaron]

If you are lucky enough to have Menards, they always have REALLY excellent 3/4" maple boards. They're sold as "rough" and usually have on unfinished edge... but they're cheap and flat as an arrow.


Another option is Woodcraft. They generally have some nice hardwoods. Overpriced for what it is... but it's convenient and accessible.

Lumber

Woodworkers are loving Lumber

www.woodworkerssource.com

 

[TaperPin]

I would strongly advise against carpenter glue (Titebond, PVA of all kinds) - as a professional woodworker I’ve seen dramatic failures of it at only slightly elevated temperatures. In 100 degree weather, leaving a cabinet assembled with pva glue out in direct sunlight further raising the wood temp is asking for a quick self disassembly. I personally watched a new piece of furniture that took 160 hours of work, just fall apart at the joints while being carried after being left outside in the sun on a 105 degree day.

This is an easy idea to prove for yourself. Take a couple of 2’ boards and run a bead of glue across one far end covering 4-6” and clamp until dry. Set it in your car in the middle of summer for an hour and the roughly 140 degrees plus added heat of direct sun will allow the boards to be easily pulled apart by hand.

 

[TaperPin]

In cold conditions during glue up, I’ve had failures of two part polyester resin to fully harden, which is normally a reliable structural adhesive, so if the label says use above 55 degrees, that’s why. Not only did it fail to harden by the next day, it never hardened and a large bent lamination had to be scraped, sanded and reglued.

Polyurethane is good for cold weather glue ups and, while not as strong as epoxy or polyester, is stronger than the wood.

Epoxy comes in different viscosities and the thinner the better for glue line visibility.

Wooden airplane propeller makers use epoxy or powdered plastic resin glue. The plastic resin is a ureaformaldehyde and is mixed with water as needed - strong in elevated temperatures and moisture resistant.

 

[TaperPin]

When gluing up important pieces I try to use boards that have acclimated to the current weather conditions, which only takes a few minutes a day. On each board simply measure with a dial caliper at both ends and about every 2’ and write the measurement on the board. I write on the spot of the original measurement so additional measurements can be made on the same place. The ends of the board shed or absorb moisture 10x as quickly as the middle and measurements taken just a few days apart will show this. Most wood at retailers is poorly dried and has extra moisture - I would predict the ends will be shrinking a measurable amount every day during the dry months, or growing if during the wet months in states with big humidity swings. The ends will eventually stop moving, but the middle will take many more days or weeks.

During the kiln drying process if temperatures and humidity aren’t kept within proper ranges, many different internal stresses can build up that will stay with the board - often generically referred to as case hardening. If a board has a lot of extra movement during a cut, like dramatically pinching the blade or spreading out, it’s best used for small or thin areas, or cut up and used in the smoker.

USDA has researched all aspects of kiln drying to the point it’s very well understood. If anyone is curious about it, there’s a great free publication online.

Dry kiln operator's manual

www.fpl.fs.usda.gov