Domino instead of Scarf Joints?

[John Stevens]

If the Domino can be used to join a handrail or "bar rail" seamlessly, then why not also use the Domino to join pieces of moulding instead of making a scarf joint?

Regards,

John

 

[Mirko]

John,
A scarf joint allows you to apply downward pressure, also the edge grain runs together making the joint less visable. Its tough somtimes to clamp somthing really long end to end, if you butt joint it. i guess it all depends on application.

Mirko

 

[Grasshopper]

I was also thinking about this.  I see the benefits of scarf joints, but I'm curious if anybody has done dominos instead, and how the outcome has been.

If there are any domino success stories for joining trim, I'd love to hear them.

If you prefer to scarf, do you like 45 degrees, or ???

 

[justinh]

I usually use biscuits but either will work.  With a biscuit you have a bit more wiggle room to snap fit on the wall.  You can also build the run on the floor and glue and nail/staple/screw a back gusset spanning the joint and install as one unit.  This works great for crown.  If you want to use the gusset on base board you cut out a section of drywall to make room for the backer.

 

[Grasshopper]

Thanks Justin!

I usually use biscuits but either will work.  With a biscuit you have a bit more wiggle room to snap fit on the wall.  You can also build the run on the floor and glue and nail/staple/screw a back gusset spanning the joint and install as one unit.  This works great for crown.  If you want to use the gusset on base board you cut out a section of drywall to make room for the backer.

 

[Kev]

I've always thought scarf joints were really cool, but I've never actually used them in anger!

Do many people use them these days?

 

[jools]

Never used them on trim just mitre but have joined ridge boards and barge boards with one. It's a joint that can be cut accurately with a HKC55 and a hand saw. Cut as a bevel scarfe  you get a locking joint with a large glue area. Useful when joining old work or the run is over 5metres
Regards
Jools

 

[cblanton42]

John,
    I was taught to do 45 degree cuts, glue the joint, and most importantly put the joint over a stud when you nail it.  I can honestly say I doubt I've had to do this more than 5-10 times in my entire life of about 1/2 a century.  It worked and the joint was close to invisible when compared to a butt joint.
    That being said using a domino would lock the two pieces together nicely and eliminate the need to find a stud, but would make installation harder since scarf joints slide over each other. You still would need to caulk or finish a butt joint more than likely, a scarf you don't.  I see no true benefit using them honestly and in materials used on houses these days, a domino may be too thick!! [scared]
CB

 

[toadjeep]

I just replaced all the facia boards on my house using 3/4" x 5 1/2" x 16' boards. I used butt joints reinforced with 2-6 mm dominos that also helped with alignment. I did this all without a second hand. The dominos helped in holding up one end while I tacked the other. Just as a precaution I landed the butt joints on a joist and nailed.  The joints were also glued. I picked this up from watching one of the this is carpentry video that Gary Katz made.

 

[justinh]

John,
    I was taught to do 45 degree cuts, glue the joint, and most importantly put the joint over a stud when you nail it.  I can honestly say I doubt I've had to do this more than 5-10 times in my entire life of about 1/2 a century.  It worked and the joint was close to invisible when compared to a butt joint.
    That being said using a domino would lock the two pieces together nicely and eliminate the need to find a stud, but would make installation harder since scarf joints slide over each other. You still would need to caulk or finish a butt joint more than likely, a scarf you don't.  I see no true benefit using them honestly and in materials used on houses these days, a domino may be too thick!! [scared]
CB

At true scarf joint is cut with an 8:1 to 10:1 ratio for glue surface  With a miter saw you aren't likely cut those ratios.  The way the joint slides actually makes it harder to install.  It requires that your pieces be exact lengths in order for the faces to line up.  A reinforced butt joint on an inside corner to inside corner run, like a cope, only gets tighter if cut a bit long and puts permanent pressure on the joint. The only runs that need to be perfect would be the ones ending in an outside corner. Insides are thankfully far more common.  To ease fitting these I use a biscuit because the shape allows for a lot more wiggle room when fitting.  You leave out the nails at the end of the runs and flex both pieces out and over the biscuit and "snap" them back at the wall.  The permanent pressure makes for a more durable joint as well.  A mitered scarf even when broken on a sud and nailed relies heavily on glue in held in tension on mostly end grain even with the nails.

With a biscuit in there for alignment there may be a bit of sanding but here usually is with a mitered scarf as well.  If the material is consistent and you've cut off the moulder snipe there is no filling required.

Most of the mouldings I deal with are at least 5/8" thick so there's almost always room for a biscuit.

 

[Cookannapurna]

Everything Justinh said