Thread: How to glue scarf joints

Marco,
give us more info.

Is the scarf in two larger pieces of wood like a stringer, clamping with any normal sort of clamp should do.
Is it a joint in something thin like ply, if the joint is supported by structure underneath you can temporarily nail or staple with a tacking strip, if it's small normal clamps might work.

Regards
SWK

Thanks for the response, what I want to do is to join lengths of 22mm square timber together lengthwise to make a hiking staff. My plan is to make up the length of the staff using 3 lengths of timber, meranti at the bottom, pine in the middle and then meranti at the top again. Once joined, I'll plane the square cross section to almost round and use the angled joint as a feature. I hope that is enough info for more help.

Marco

You could try a bridal scarf joint and peg it.
bridledscarfjoint-300x225.jpg

Thanks for the suggestion, however, I'm going for an angled type joint with quite an acute angle.

Found some info on youtube:

https://www.youtube.com/watch?v=Dv-kKDyPkVw

How about something like this. Straight out of the green timber framing portfolio. Problem is as I understand it, that scarf joints are not particularly good at resisting bending pressure so not sure that it is suitable in this application.

Philip

To clamp the scarf joint you're thinking of, cut a pair of wedges with the same angle as the scarf. Glue a piece of sandpaper - something between 240 - 400 grit should be fine - to one side of each wedge. With the sandpaper against the pieces you are joining, and the outside faces of the wedges parallel to the join, clamp it up. The sandpaper stops the wedges slipping, and the clamping force is perpendicular to the join, so the pieces won't slip.

Originally Posted by AlexS

To clamp the scarf joint you're thinking of, cut a pair of wedges with the same angle as the scarf. Glue a piece of sandpaper - something between 240 - 400 grit should be fine - to one side of each wedge. With the sandpaper against the pieces you are joining, and the outside faces of the wedges parallel to the join, clamp it up. The sandpaper stops the wedges slipping, and the clamping force is perpendicular to the join, so the pieces won't slip.

Just done exactly that when gluing the top joint of an "A" frame. I used the offcuts as the wedges as they were the correct angle

Hello Marco. I'm with Chesand and AlexS.

The headstock of a guitar is often joined to the neck using a scarf joint, at about a 10-12 degree angle. A look in one of the guitar-making sites will show you how to clamp a scarf joint with wedges & clamps.

Marco,
I have used a Z splice when making archery bows and can attest to it being stronger than the wood. It is the point of the bow taking the most strain. It should do for your application and look good also.
For a walking stick I think 22mm is a bit small in pine and meranti as nither wood is all that strong. I would be starting with about 28mm at the top and taper to the foot at perhaps 18mm. If you had a good bendy wood like spooted gum or mulberry then go smaller. Here is a link to show the splice and for more info google Z splice and check out sone archery sites.
Regards
John
https://www.google.com.au/search?q=B...8%3B1024%3B525

Exciting stuff - thanks for all the suggestions. I also wondered about the thickness, so that sorts that out - I'll increase it. I like the Z joint idea too. Can't wait to get going.

Thank you!
Marco

Marco,
all the other suggestions given above are good, but if you don't go down the Z splice path the way to clamp the square wood is to first clamp the two pieces to a long flat board (or bench if you have one) at a few points away from the joint. That's to stop the joint slipping. Then you can lightly clamp the joint along its length with 2 or 3* clamps just to close up the joint a little. The geometry of the joint should be such that there isn't any real gap anyway and too much pressure will force the glue out.
Use cling film (Gladwrap etc) between the joint and the supporting surface to stop the joint sticking to the work surface.
Put your glue on both scarf faces and wait a short time before putting the glue faces together. That's to see if the glue gets sucked in by the end grain (some combinations of glue and timber might do this). Put more glue on if it does so you don't end up with a glue starved joint. If you orient the grain as shown in "C" below, this will be less of a problem and the joint will be slightly stronger too.

*If you use a scarf 8-10 times the wood thickness (I use more for what I normally do) of 22-28 mm, depending on what you end up choosing you will have a joint about 170-300 long, so you will want about 2-4 clamps over the length of the joint. Or you can use a top block about the length of the joint to distribute the clamping pressure more evenly. Use clingfilm here too.

scarf.jpg

Regards
SWK

Use a fast grip glue and do a rubbed joint. Works every tine


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Thanks for all the input everyone. I've just finished a sandboard for my daughter, so now I can start this project. I'll let you all know how it goes. Thanks also for the picture of the scarf joints, that's something I would not have taken into consideration.

Marco