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Cross Grain Situation

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Forum topic by Lenny posted 09-27-2009 04:56 AM 3812 views 0 times favorited 11 replies Add to Favorites Watch
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Lenny

1298 posts in 2281 days


09-27-2009 04:56 AM

I am in the middle of making a cupola for my garage roof. The wood species is cypress. I will post more photos and provide details of the build once I finish. This photo shows my first dry fit. I am wondering if I need to be concerned about a cross grain situation. As you see in the picture, the grain of the four posts runs vertically (up and down) while the grain of the four boards that wrap the posts runs horizontally (side to side). In furniture making this is a classic cross grain situaton and caution needs to be taken in terms of glue and fasteners. As I conceptualized this project I pictured myself gluing the boards to the posts and perhaps adding some brads or screws. I am concerned that the boards (12” wide) will want to expand and contract up and down and if they are glued to the posts, they won’t be able to causing a crack in the board. The posts are 1 3/4” square.

Some alternatives would be to just glue a small section (say 3-4 inches) at the bottom, top or middle of the four boards. This will allow the remainder of the board to expand and contract. I have seen Norm Abrams do this on some of his projects. Of course, each post abuts two sides. Do I only apply the glue to one side or both? Another idea is to skip the glue altogether and from the post side, use two to three screws in each post drilling elongated holes that will allow the boards to move. I could also drill and screw from the outside but I would then have to counterbore and bung the screwholes. A woodworking friend suggested that this is like building a house and carpenters don’t worry about cross grain situations, cabinetmakers do.

What would you do fellow LJers? Thanks.

-- On the eighth day God was back in His woodworking shop! Lenny, East Providence, RI


11 replies so far

View papadan's profile

papadan

1156 posts in 2122 days


#1 posted 09-27-2009 05:02 AM

Gluing only partially will allow the wide boards to warp. I would glue full length of the posts and add a few brads to boot. Make sure everything is sealed well from the weather and don’t worry about expansion.

-- Carpenter assembles with hands, Designer builds with brains, Artist creates with heart!

View John Gray's profile

John Gray

2370 posts in 2639 days


#2 posted 09-27-2009 05:37 AM

Lenny,
What about Stainless Steel pocket screws? If I remember right the screws will allow enough movement for the boards to expand and contract with the seasons. Or regular pocket screws with the holes plugged as I assume you will paint it inside and out.
Or you could use screw slots, elongated, as you mentioned above.
It looks like it’s going to be 1st rate and your choice of wood is excellent.
John

-- Only the Shadow knows....................

View Dick, & Barb Cain's profile

Dick, & Barb Cain

8693 posts in 3053 days


#3 posted 09-27-2009 01:26 PM

I would dado a groove in the verticals, fit them in the groove. There would also be less exposure of the end grain to the elements. I think it would add to the looks of it with the vertical piece exposed from top to bottom.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN. http://www.woodcarvingillustrated.com/gallery/member.php?uid=3627&protype=1

View cypresswoodworker's profile

cypresswoodworker

89 posts in 2100 days


#4 posted 09-27-2009 06:57 PM

Lenny
I make cypress swings, chairs, benches and anything else you could imagine. All the builds have cross grain situations and i still full glue and brad the joints. Tite bond II or Tite bond III (if you want the joint totally waterproof) You may get alittle movement over time yet it will be ontop of the building and you would need binoculars to see the small cracks ! Alot depends on the moisture content of the cypress and the grade.
Your project is comming along great and you should be proud to have that cupola on your roof. As far as fininhing if you going to stain and finish it. stain both sides yet only finish the outside, you do not want to totally seal cypress, if it can’t “breath” it will rot. There are alot of natural oils in cypress which make it insect and rot resistant just don’t seal both sides. Great job long live cypress!!

-- If at first you don't succeed...Buy another tool !!

View Beginningwoodworker's profile

Beginningwoodworker

13347 posts in 2427 days


#5 posted 09-27-2009 08:10 PM

I really dont like using wide boards, because they might wont to warp and twist, you might wont to rip them in have and reglue them and add biscuits for strenght.

-- CJIII Future cabinetmaker

View Lenny's profile

Lenny

1298 posts in 2281 days


#6 posted 09-27-2009 09:11 PM

Thanks everyone for your replies. I appreciate and respect each opinion. I have decided to simply glue the boards to the posts and add some brads to hold them in place while the glue sets. As you will learn when I post the finished project, I am making this cupola the same as one I made over 25 years ago. I couldn’t remember how/what I did regarding the cross grain situation, but I know I was not knowledgeable of the cross grain issue back then and wanted to take it into consideration this time. Wait until you guys see the roof that is awaiting this project!

Charles, I think it is time you change your name on LJ. You are making observations/comments like a veteran woodworker. The wide boards pictured ARE a glue up of one 8” board and one 4” board using biscuits.

Ron, thanks again for your input. I do not intend to stain the project, only seal it. I will take your advice and only seal the exterior. Any particular product you would recommend? Fine Woodworking, in a recent edition, rated outdoor finishes that they put on 5 wood species and then left them outdoors in Oregon, New Mexico, Louisiana and Connecticut for one year. The one that had the best results in terms of maintaining color and weathering was Epifanes high gloss marine varnish ($22/quart). A representative at Woodcraft recommended System 3 Marine Coatings which is a spar urethane. It costs a whopping $45/quart. Some like the weathered gray but I prefer wood to retain its natural color. I will try to keep applying the finish as frequently as necessary to prevent the graying. Or at least so I say now!

-- On the eighth day God was back in His woodworking shop! Lenny, East Providence, RI

View Chris Wright's profile

Chris Wright

536 posts in 2235 days


#7 posted 09-28-2009 06:51 AM

I doubt you’ll have to worry about it. The slats look thin enough that they wouldn’t expand so much that they’d crack. And if you think about it, there’s a lot of antique furniture that uses mortise and tenon joinery and those joints run cross grain and they don’t (typically) crack.

-- "At its best, life is completely unpredictable." - Christopher Walken

View firecaster's profile

firecaster

557 posts in 2172 days


#8 posted 09-28-2009 01:16 PM

I can’t wait to see the finished product.

-- Father of two sons. Both Eagle Scouts.

View cypresswoodworker's profile

cypresswoodworker

89 posts in 2100 days


#9 posted 10-01-2009 01:48 AM

Larry Epifanes is great if you like a gloss. I like General Finishes wipe on urathane, tough yet satin finish. Can’t hardly wait to see the roof that deserves such a nice piece on top!!!

-- If at first you don't succeed...Buy another tool !!

View cypresswoodworker's profile

cypresswoodworker

89 posts in 2100 days


#10 posted 10-01-2009 01:51 AM

sorry lenny can’t type to well

-- If at first you don't succeed...Buy another tool !!

View Lenny's profile

Lenny

1298 posts in 2281 days


#11 posted 10-01-2009 02:01 AM

No problem Ron. Thanks for the input. I am not too keen on gloss finishes. I want something that will protect well and be as long-lasting as possible.

-- On the eighth day God was back in His woodworking shop! Lenny, East Providence, RI

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