Lengthening boards (for moulding)

[Victor Robinson]

How do you all prefer to make long boards for [interior] moulding? This is prior to running the profile as opposed to during install.

I've seen a finger joint used most often. Is this the standard? Any other methods that are more suitable to a small shop?

I'll be running a Shopfox moulder. Seems to make sense to run the profile on long boards (~16') as opposed to make 8 footers and splice them during install?

Thanks!

[Mel Fulks]

I think the simplist way would be a scarf joint ,just diagonal glued lap before machining. It's not done often, but where client won't accept a joint it is a way to get them to accept a joint.

[Peter Kelly]

Butt joints with glue biscuts works well too. Trying to cleanly fingerjoint and run 16' lengths on a small moulder like that is asking for trouble.

[mreza Salav]

Butt joints with glue biscuts works well too. Trying to cleanly fingerjoint and run 16' lengths on a small moulder like that is asking for trouble.

I highly doubt that the joint will survive handling the long boards. Just the weight of the board when lifted up is enough to break the joint in a blink.
I did my house in solid maple trim all around (5000+ lnf of it). The length were mostly 10-16' for the crown and baseboards (shorter for casing) but I didn't mill myself (although I briefly considered doing it myself). If you can get up to 16' long boards then I wouldn't bother making them any longer.

[Peter Kelly]

To clarify - I meant a butt joint with glue and biscuits as opposed to a scarf for field installation. Helps aligh everything when nailing.

[John Lankers]

My first choice would be the famous board stretcher, but I misplaced mine a long time ago and can't find a replacement :D:D:D - I just couldn't resist, sorry.
Seriously, I would rig up an outrigger support for the router table and give the finger joint a try, it will still be week regardless - maybe with a biscuit as reinforcement.

[Bill Ryall]

1:12 scarf is very common in boat building to stretch boards for planking, etc. I see no reason it wouldn't work for this application, other than the difficulty running something of that length through smaller tools.

[Peter Quinn]

1:12 scarf is very common in boat building to stretch boards for planking, etc. I see no reason it wouldn't work for this application, other than the difficulty running something of that length through smaller tools.

Last time I really needed a board stretched for exterior use I did a boat scarf using a 1:10 jig I found on a boat building site, made with a router, took maybe 10 minutes to make the jig. I made 20' hand rails, brutally strong joint. I've done finger joints, decent for interior paint grade, ok for stain grade if done carefully, sort of a pia to set up. Usually I source 16' material for moldings and leave the board stretcher alone.

[Myk Rian]

To clarify - I meant a butt joint with glue and biscuits as opposed to a scarf for field installation. Helps aligh everything when nailing.
No matter. A butt joint will show as a butt joint.

[mreza Salav]

We had a few walls that were longer than 20' so the crown/baseboard had to be extended. We used the standard method of 45" miter, even though they were installed prefinished (stain/lacquer maple) it's hardly noticible.