Making the Strongest Joint

[McRabbet]

I am in the midst of an outdoor (commissioned) project for a branch of UNC-Asheville called the Kellogg Center for Craft, Creativity and Design -- two outdoor Bulletin Board Kiosks I designed for the entrances to their public Art Trails.

You'll notice the large doors that cover the bulletin boards (two per side, they measure 42-3/4'' by 39-3/4'' and have Lexan glazing). I wanted maximum window size, but they can't sag and need to be secure. I chose to make the doors from 2'' wide x 3/4'' thick white oak with half-lap corners -- getting 4 square inches of glueing surface (glazing sits in a centered saw kerf in this frame).

After inserting the Lexan and squaring the frame, each corner was secured with 5/8'' brads while the glue dried. A strong joint, but these needed to be stronger and a pegged joint is the answer.

I made a jig from a half-lap practice piece and drilled two 3/8'' holes with a Forstner bit. The jig assures consistent hole spacing -- it is oriented to avoid hitting the brads -- I precut 13/16'' long oak dowel pegs, glued them and hammered them home.
These joints aren't going anywhere! For consistency, the grain in each peg is oriented in line with the outside of the door frame; it will be cross-grain on the inside. A little sanding and the doors are ready to install in their two sided frames, also made of white oak.

More to follow...

 

[ptt49er]

Looking good! What kind of finish are you going to use on it?

 

[toolferone]

Yup, I rekin that will do. It looks like you drilled the pegs all the way through?

 

[Bas]

Two things will last forever. Cockroaches and doors built by McRabbet. Very impressive, and great tip on orienting the grain in the peg, I never would have thought of that.

 

[rbdoby]

Nice design. I have to build something similar for my wife's business. What did you use for the inside panel? I need to make one to hold plastic letters like those used on outdoor signs.

Rick Doby

 

[Mike Davis]

Uhhh, Yeah that's how i do it. :icon_thum And finish with marine spar varnish for lasting outdoor protection.

Nice job on the design and the usual excellent execution.

 

[PurpleThumb]

Good looking Rob, you always go the extra mile!!!

 

[McRabbet]

The oak pieces will all receive 2-3 coats of Spar Varnish. The doors will have continuous "piano" hinge and will be inset into a frame that is 3'' wide, with a sheet of 3/16'' tempered hardboard in a 1/4'' deep dado separating the frame into two sides. I bought 1/4'' sheet cork and will glue that onto the hardboard on each side to form the bulletin board surface. Here is one of the frames being screwed together -- it is hard to see the hardboard because this is being put together on my assembly table with the same surface.

Once I put a door into this frame, you'll get a better ideal of the assembly. More to come...

 

[Glennbear]

Very nice work and super sturdy joints Rob, I am just curious as to where one obtains 1/4 inch sheet cork ? A small bulletin board is on my short list of upcoming projects. :wsmile:

 

[DavidF]

Nice job Rob, very professional as always.

 

[TracyP]

Nice tutorial, it is gonna be a nice professional project. I appreciate the tips.

 

[McRabbet]

Very nice work and super sturdy joints Rob, I am just curious as to where one obtains 1/4 inch sheet cork ? A small bulletin board is on my short list of upcoming projects. :wsmile:

What I am using is 1/4" cork underlayment -- because of the size of the project, I bought a 50' roll that is four feet wide from a company in California called EcoPlanet -- with shipping, it was $202.70 and took nearly 3 weeks to have delivered. I found it using Google. I had check craft stores first and flooring stores -- you might have better luck than I did, but $1/square foot isn't all that bad.

 

[Jeff]

Very nice work & instructional as well. It's always good to learn something new each day and your presentation was clear and concise.

Just curious, but how did you land the commission? :icon_chee

 

[McRabbet]

Thanks for the nice compliments -- I try to share whenever I can... Almost all of my commission work comes from referrals by past customers or through friends that know I produce good quality work.

By the way -- I actually considered making the joint at these corners even stronger by using a pegged bridle joint which would have 8 square inches of glue area, but didn't think it was necessary.

 

[4yanks]

Who says they don't make them like they used to?!!! I hope the folks at UNC-A appreciate your conscientious efforts.

 

[Mike Callihan]

Thanks for the nice compliments -- I try to share whenever I can... Almost all of my commission work comes from referrals by past customers or through friends that know I produce good quality work.

By the way -- I actually considered making the joint at these corners even stronger by using a pegged bridle joint which would have 8 square inches of glue area, but didn't think it was necessary.

Rob

Nice job, I'm glad I read all the posts before asking you if you thought a bridle joint might have been even stronger. LOL

What type of glue did you use? I have found that even a type II PVA glue will sag with time on large pieces like these doors. Your pegs however should counteract that. When I built the front door for my home, a 2" thick 48" wide 84" high behemoth, I use epoxy. Messy but it won't creep over time.

Thanks for sharing.

Mike

 

[McRabbet]

Mike, since this is for an outdoor application for providing the public with information about the Kellogg Center and their trails, the eight doors needed to be shatterproof and have maximum clear area for the bulletin boards behind them. The glazing is UV-protected Lexan® that is set in a 1/4" deep saw kerf. It is much lighter than glass and should hold up well (but it is currently over $60 for a 36" x 48" sheet due to the increase in petroleum).

 

[Mike Callihan]

Rob

Back in days of yore I was a District Sales Manager for GE Plastics and trust me when I tell you they were never bashful when it came to raising prices. Lexan is a great product but they are proud of it.

Your right with Lexan as you're glazing material there isn't much of a load there, that and I'm sure they will spend most of their lives shut.

Mike