How do I secure posts to ridgepole

[Stephen1]

I have built 4  6''-x10''king posts to hold up my 26' x10'' round ridge pole. How do i accurately drill into the side of the round log to pin my tennons on the post? Do I drill just the ridge pole before i put it up and then use the holes as guids to drill thru the king posts?
Steve
Hopefully I will be able to download some pictures this week-end

[Jim_Rogers]

So, you have a king post with a top tenon going up into a round log shaped ridge beam.
And you want to peg it.
How long is the king post top tenon?
Usually the peg hole layout would be somewhere around 1 1/2" to 2" off the shoulder of the tenon at the king post.
If you mortise on the ridge beam has a housing then you can measure off the housing using a framing square to project a line up the side of the log to where the hole could enter.
Then at this location flatten out a small spot for the bit to enter the wood.

See this drawing:





If the ridge pole has a housing then move everything up so that the square rests on the flat surface of the housing. Again project the line off the framing square, flatten an area and bore the through hole.
If you can do a test fit, then insert the king post tenon after you have bored the hole and prick the hole center onto the king post tenon with the bit and then remove the king post and offset the hole a little closer to the shoulder (if you want to draw bore).

In the above drawing the ridge pole is 10" in diameter the king post is 6" wide in this view. The tenon is 6" tall, and the off set peg hole line is 2" off the shoulder of the king post.
You may need to off set it a little more depending on how long the tenon is and how big the peg is.
You should try and maintain a 4 to 6 peg diameters from the end of the tenon.....

Hope this helps...

Jim Rogers

[Stephen1]

Thanks Jim,
I mainly need to secure it for the raising as the 2x10,s or the roof will hold the structure together. The tennon is 4'' deep by 6'' long  Will 1\2'' hardwood dowels be enough or should I go with something thicker? The kingposts are spruce and the ridgepole is red pine.
regards,
Steve

[Jim_Rogers]

That's hard to say but we usually use 3/4" or larger for pegs.
But that makes it harder to maintain a 4 to 6 peg diameters from the end of the tenon with such a short tenon. And the offset off the shoulder should be at least 2" as you can see by my drawing that there won't be much wood in the ridge pole holding the peg, unless the bottom of the ridge is housed.
Is the bottom of the ridge housed where the king post comes in?

Jim Rogers

[Stephen1]

yes the ridge pole is housed. I do not how much. I should have made the tennon longer, but at the time I was worriered about taking to much wood out the ridge pole. I was designed in my head after reading about the ridgepole. I can still make new kingposts with longer tennons as I will not be ready to put the roof up till late july. I will look & measure the housing this week-end when i got to the cabin location.  I will also take some pictures of the housing & ridge pole. I am still trying to get my son the computer engineer to give me some software to shrink the photos.
Steve

[Stephen1]

I have 2 pictures of the Tennon's, they are 5" long by 6" or 10 " wide depending on which end of the post they are on. The 6" will be into the ridge pole, the 10" will be into  the walls or tie beam. 


The ridge pole has housings for the king posts. 2 king posts sit on top of the log wall's & tie beams which have been flattened. 2 posts will sit on 2 tie beams. This log building is only 174"x176" with the ridge pole covering a porch for 84"
The roof has a 12\12 pitch,with 6" sips,with steel going on top. our snow load is 50lbs. i did the calculations originally and the 10" log would hold the roof at 14' between king posts.

Should I recut and make new kingposts with longer tennons or can I use smaller pegs, say 1\2' but 3 instead of 3\4"? Would I be better to thru bolt with say, 1\2" or 5\8" threaded rod and put plugs in to make it look good?
Any thoughts would be greatly appreciated.

[Raphael]

5" tennons are just within the acceptable limits of a 3/4" peg with a 2" shoulder.  Unless you expect a lot of uplift from strong winds I think you should be fine.

[Stephen1]

Thanks Raphael.
          We do not experience super strong winds here.