[im1dermike]

I'm planning to build a free-standing swing set. Here is my design:

The posts and beams are all 6x6x12 ground contact pressure-treated timber. The "major" gridlines are a square foot FWIW.

I have two questions:

• What is my best bet for joining/notching the posts and beams? Apologies for my ignorance in terminology, but I was thinking of either taking 50% off each piece of timber or working in thirds.
• What carriage bolts should I use to secure the posts and beams? Looking for size and material.

Lastly, an alternative I'm considering for the beam is two 2x12x12 pieces of timber instead of a 6x6x12. It would clearly be easier to work with, but I want this thing to be rock solid. Thoughts?

 

[de-nagorg]

The Lap joint, that you describe will be good.

Bolted with Stainless steel bolts, that PT eats the galvanized ones.

Or a double LAP joint with the 2 (2Xs), notched on opposite sides of the upright, will be good also.

Careful notching those, make sure that you don't leave any gouges or grooves that will cause a weaker area, to split the timber.


ED

 

[Nealtw]

I believe @chandler48 has built something similar.

 

[chandler48]

Thanks, Neal. Yes, I just posted it to another thread, but here it is again if you need a good design to go by. It is massive and rock solid.

 

[SeniorSitizen]

The last outdoor project i notched was 40 years ago using creosote bridge planks to build a corral. Since then i've determined i'd never waste my time notching again for a outdoor wood anything project because of wood dimensional change differences in - -with grain / cross grain - - dimensions. Since then i've considered notching a hellofah lot of work for 0.0 benefit.


Your mileage may vary but my mileage isn't getting a second chance.

 

[im1dermike]

Bolted with Stainless steel bolts, that PT eats the galvanized ones.

What diameter carriage bolts?

 

[chandler48]

For good holding power and stability use 1/2" bolts and washers and nuts. Length, of course, to go through the wood, but not too far as to cause injury.

 

[de-nagorg]

Yes 1/2" bolts with 2" diameter FLAT WASHERS, that have a 1/2" hole, this gives you strength holding the wood around the bolt.
And they make rubber caps to cover the bolt thread ends, to keep from ripping the skin of users.

Just don't use extra long bolts and you should be fine.


ED

 

[SeniorSitizen]

Consider searching for stainless Timber Bolts. T B's have a oversize head with a special wood holding feature. Also on this type DIY projects i prefer Nylock nuts and fine thread bolts if available. Go back in about a year and re-torque the nuts because things have changed. If stainless isn't available hot dipped galvanized will last longer than anyone is interested in swinging and the wood will be rotted long before the bolts have failed.

 

[Oso954]

The OPs design would be sturdier if he dug deeper holes. As it shown the post tops are 9 feet in the air. Without knowing the logic for the tall swing, I’d sink those posts further and reduce the chain lengths.

What is the local frost depth ?

 

[im1dermike]

The OPs design would be sturdier if he dug deeper holes. As it shown the post tops are 9 feet in the air. Without knowing the logic for the tall swing, I’d sink those posts further and reduce the chain lengths.

What is the local frost depth ?

I'm in the Philadelphia area which has, as I understand it, 36" frost depth.

 

[de-nagorg]

The OPs design would be sturdier if he dug deeper holes. As it shown the post tops are 9 feet in the air. Without knowing the logic for the tall swing, I’d sink those posts further and reduce the chain lengths.

What is the local frost depth ?

Correct, at least 1/3 the full length of the post should be securely buried in the ground.

Or they should use sono-tubes to be deeper, and still use the 12 foot posts, as designed.

Me I would use 16 ' posts and bury them 5' deep.

ED

 

[im1dermike]

Wow. I think I'll use the 12' posts and bury them 4'. That means the swings will hang from roughly 7.5' which I think is a good height for swings.

Thanks for sharing!