Scarf joint on 8" wide board

[Al Killian]

I need a three boards 17' long, which I can't get. So I was thinking maybe a miter joint or scarf joint. Which would you do and how? The project is a three sided beam cover. The final size will be around 7-1/2" by 16'-7" x 3 boards. There is drywall covering the load bearing beam now and they do not like it. I plan on romoveing the drywall on one side so the wood will sit flush w/ the rest of the drywall. I asked this on a different form and I am fishing for different ideas. The look that they want is of one soilid beam so, I plan on using a locking miter joint to joint the boards. Was considering a pocket hole jig, but I was told it does not work well on 1/2" thick stock.

[Jim Becker]

A scarf joint would typically be used for this. In fact, I may need to do it for some trim I'm installing under the nosing of our loft floor in the great room.

[Gary Herrmann]

Al, if you have a miter saw, you can do a bevel cut. Simplest is two opposing 45s which you can then slide together - don't know if you intend to glue them. If your saw tilts far enough (don't think mine does) you can do a 30 and a 60. When I did chair rail, I did 2 45s.

If you want a longer glue surface you can try something like a 15 and a 75. For that you'd need to use a hand saw or a band saw.

If you need a stronger joint and you do 45s, you could try a spline - much like you'd do on a box, but obviously the resulting joint is 180, not a 90 degree box corner.

[Paul Girouard]

So your wrapping the beam like a "U" only with square corners ?

Or your covering one side of the beam only and can't buy a planks 7 1/2" x 17' ?

Is it paint grade or stain grade?

And when you pull off one face of drywall you'll be , MTL,( More Then Likely) be removing a corner metal and will lose that "clean " edge.

If I understood , more clearly "what you where talking about" it would be result in a better , or more right answer. As right now we have two dissimilar solutions IMO.

[George Bregar]

So your wrapping the beam like a "U" only with square corners ?

Or your covering one side of the beam only and can't buy a planks 7 1/2" x 17' ?

Is it paint grade or stain grade?

And when you pull off one face of drywall you'll be , MTL,( More Then Likely) be removing a corner metal and will lose that "clean " edge.

If I understood , more clearly "what you where talking about" it would be result in a better , or more right answer. As right now we have two dissimilar solutions IMO. What I think he wants to do is surround a strutural member to make a faux beam...like I have in my lake home. We had the same issue...used a scarf joint to "lengthen" the boards.

[josh bjork]

http://buildyourguitar.com/resources/tips/scarfjnt.htm

[Paul Girouard]

What I think he wants to do is surround a strutural member to make a faux beam...like I have in my lake home. We had the same issue...used a scarf joint to "lengthen" the boards.


Maybe , but if it's paint grade , or even some stain grade woods getting 18 foot or longer stock would be the best option. There are of course species that are hard to find , if not impossible to find in that length stock.

So I was making sure we know what we really are attempting to do and with what specifically we'd be doing it out of / with.

Scarfing is commonly done in wooden boat build , generally , not always , the looks my not have to be say good , but AGAIN that depends on the builder's skill / and or the specific result required / intended/ desired.

[Lawrence Smith]

I would definitely go with scarf joints to achieve you required length. I have used them many times when I recently build a boat. They are not hard to do and are extremely strong. When done properly and sanded they are almost invisisble even if your finished project is clear coated.

I do them a little differently than has been described so far. I use a scarf angle that goes from zero to one inch over twelve inches of plank. Since your planks are only 1/2 inch thick, your scarf joint will only be six inches long. The advantage of using this acute angle is you are not gluing largely to the end grain in each plank but you are using the long grain which results in a much stronger joint. Use West System epoxy for gluing. I've tried cheaper epoxy but ended up having problems. Proper clamping is a must. Always double check the alignment of your joint prior to clamping. This will result in a very strong bond. I have stretched scrafed planks into shapes where I thought surely the board was going to break and never had a problem.

For more detailed information go online to the Wooden Boat Store. They have books that cover this method. It is a very common joint in wooden boat construction. It sounds complicated however it is very easy to do. I learned this method at the Wooden Boat School. The only tools required to make the scarf are a power and hand plane. It can be done in less that a half hour.

My $.02

[Ben Grunow]

Scarf joint is the standard cut for this. Nail thru the overlap with pin nails and use glue for sure.

I think flush corners can look a little modern which is fine if you are in a modern house but for a more traditional look we usually install the side boards (on either side of the beam) and let them hang down 1" below the bottom of the rough (use level between the bottoms when doing this) and then install a 3/4" board between them to leave a 1/4" reveal which is please to the (my) eye. A rabbet makes this very strong and it can even be built in the shop and slid in place very easily.

Good luck

[Doug Shepard]

What about just using a half-lap joint? Either one is still going to show a vertical joint line. Just seems like a half-lap might be easier and stronger.

[mike wacker]

I vote for scarf joint. I was shown how to do this in a Wooden boat building class too many years ago to admit it. It's kinda hard to discribe but I'll give it a shot. Your scarf should be 8 to 12 times as long as your lumber is thick. So if you're using 3/4 inch stock, make your joint say 8 inches long. Lay the two pieces you are going to join together side by side with the ends that are going to meet together and the side to be joined facing up.

Make a mark at the 8 inch point from the end and then draw a square line across both faces at this point. Now rough remove the waste from each piece from that line to the bottom of each board at the end. Make sure not to remove more than the wood above the plane running from the 90 degree line you marked to the bottom of the end of the board.

After roughing take one of the boards and clamp it to a solid bench with the end of the board even with the end of the right side of the bench (assuming you're right handed) Now take a hand (or power, if you're brave) plane and remove the rest of the wood. Your goal is the last pass of the plane just nicking the 90 degree angle line and turning the end in to a "feather". Repeat with the other board, flip and check your fit.

As said in an earlier post, West system epoxy is your friend with this joint.

[Jim Holman]

Assuming this will be stain grade work and since strength is not an issue, I would use a router to cut finger joints and join the boards end to end. This will give an almost invisible joint, particularly from the floor looking up at a beam. Assuming you can get 16' stock it should be a snap to add a foot on to the end and trim to length. The CMT Professional Finger Joint bit is the one I use for work like this and it has served me well.

[Al Killian]

It will be a "U" shape. It is to cover where the two module halves where joined together. The wood will be 1/2" thick so it will sit level with the rest of the wall. It needes to be red oak:rolleyes: everything in there house is red oak w/ golden oak stain. It does not need to be strong as it will be nailed to the beam. I just trying to figure the best way to hide the joints. Where the vertical board meets the horizontal board I am planning to use a locking miter. The locking miter will make it hard to see that seam. But where the 10'or 12' peice meets the shorter peice, this is the spot where I want to try and hide the seam. I have to go to my lumber place tomrrow to see what I can come up with. We are going to do a three peice book-match. I will get over there to get some pic to show exactly what they want done.