Hi,

I have 40' round ridge beam with a diameter of 16''. I need to cut the top of the log as a triangle for the roof pitch of 10:12. How do I proceed to cut the desired angle? Any suggestions to make that angle for the ridge beam?

THanks

A sawmill such as a woodmizer with an extension bed would be the way I would do it. you would only have to lay it out on the ends.

Many options will work lacking a sawmill. You could rough hew with an axe and finish with an axe, adze or a heavy drawknife. Some might rip with chainsaw either jigged or free hand. You didn't offer anything on an approach, a skill level, a toolset or a comfort range. More input would invite more response.

Hi,

I have looked into a sawmill but there is nothing in my region.

Right now I am having difficulty marking the line on which I cut the 40 degree angle. I made a jig of a triangle with 40 degrees and put it to the end. But i noticed that you can't just use a snap line because it has gaps. How would I mark the 40 degree angle on both sides of the ridge?

I am a beginner with a chain saw. But I learn quickly and I have a large chainsaw that can do the job. But again, I am not sure what kind of guide to use and how to place it. Any suggestions?

A new tool a purchased a few months ago was a digital level, it can be set to degrees. Use it to mark the 40 degrees you are looking for.

But first snap a line down center length of the log, forming the peak. Then apply the 40 degrees.

I take it the gaps you are finding are because the round log is not perfect, hardly are they ever. If the bark is still on, leave it on(this is if you will be standing on it to score and juggle while hewing) or it will be slippery, and use a chalk which will show up well. If the bark is off, it should be dry. Even out any high spots such as knots of really rough bark with an axe and draw knife where the line will fall, it is not necessary to take it to the wood.

When snapping lines remember to always snap the line in the plumb direction, so when snapping the ridge line pull it straight up, it need not be forceful, a tight line with a light snap will do fine. You may not have to snap the bottoms of the 40 degree lines but I would rotate the log and dog it down so that the side you are hewing or chainsawing is in a plumb direction, check it as you progress down the log with what ever method you choose.

once that side is done rotate it so the flat side is up and the oppsite side is plumb, this will put the hewn side out of level but it is not necessary, the important aspect is the plumb/vertical line you are working on. Resnap the ridge line, as there may have been a bow up in the log and you will be able to lay the new ridge line within the timber where it really is. And proceed by surfacing the next side.

If you do want to snap the bottom of the 40 degree lines roll the log up side down so the angle of the side you are snapping is plumb and remember to snap the line in the plumb direction, if the line is snapped out of plumb it will cause a dip in the line.

Oh,
As a different approach you could, once all lines are snapped, saw kerfs across the timber connecting the lines, scoring with a saw, and pop them off with and axe. A method I recently saw on the Poland expedition.

Thanks for the opportunity to go over this, it is good practice, I probably left out some subtle details, such is life.

You can roll the log until one of the roof planes you are trying to define is level and nail or screw a 1x4 to both ends of the log with the top edge of the 1x aligned with the roof plane layout line. Make sure the 1x is is long enough to stick out on either side of the log a foot or more.

Then you can stretch a string along side the log nice and tight and use a level to locate points on both sides of the log that define the plane you are trying to create.

once you have marks every 10' or so (or more closely if there are irregularities in the log) you can snap the line on the surface of the log. Be sure to pull the string perfectly level as you snap it.

Once you have lines on both sides of the log it's a matter of removing everything above that line. Either freehand rip it or cut into the log every foot or so down to the line (stay 1/4" above it to avoid going to deep) and split the pieces in between off. Then rescore and hew as normal.

Alternatively, if you have a rotary laser level, you can use it instead of the 1x's and string method. You'll have to move the laser to the other side of the log and fiddle with the elevation of the laser until it's lined up. That's how I'd do it.

A 40' log can have a bit of flex to it. Make sure you support the log approximately where it will be supported in the final structure to avoid introducing sag or crown inadvertently.

Good luck and keep us updated. Photos would be great.

Thank you for the ideas Timbeal and Gabel. I'll have to try out your ideas and see which one works best for me.

After this I must make mortisers into the beams and tenon into the post. Any ideas on how to do this the best way without a chain mortiser?

Hello,

I once built a small house in the middle of a protected village and in order to make the roof line conform a bit to the existing, skyline, lets call it, I wanted it to look as if it were sagging a bit throughout its length so I snapped a line at a fairly steep angle to the side of the ridge beam rather than perpendicular and got about a 4 cm deflection on the 6 meter length which I then formed with an adze. Well, in the end it was hardly noticeable, but on the other hand maybe will speed up the entropy effect and sooner rather than later the new house will fit into the surrounding context. The point is that a perfectly straight ridge is a matter of choice and not a technical necessity.

Greetings,

Don Wagstaff

It sounds like you're asking how to cut a mortise? Are you a beginner? Or are you asking how to layout the mortise?
There are some video's on youtube. Timbeal has some good vids on his youtube page. Search "Moonhillfarm" on youtube and click to "see all" his videos.
If you are asking the basic question of how to cut a mortise, I always recommend beginners take a 2-6 day timberframe workshop. You learn a ton more from a workshop than anywhere else, and faster too. It's worth it. Cutting a mortise starts with hogging the majority of the material out with an auger bit using an antique boring machine, an antique hand auger, or a modern large drill and auger bit. Then you use your chisel to square up the mortise, and check it with your framing square and a machinist square. Though if working in the round, you probably won't be able to use the machinist square as you would with a square timber.