Cutting a curve in the underside of a knee brace

[bbjr]

Hey guys, I am putting the finishing touches on my home (conventional framing :'(, hey it's what's familiar to me  :D)), and I am trying to add some details to make it look like a timber frame. 

I just finished milling up about 3000bdft of salvaged oak barn timbers on my Woodmizer, and I am getting ready to start planing and sanding.  What I am wondering about, is what method you guys use to saw the curved underside of a knee brace?  I bashfully admit, I haven't read as many back posts in this subforum as I have in the milling subforum, but I read though the stickies and ran some searches using the terms curve, arch, and knee brace, and haven't found an answer.

I am hoping to accomplish this using conventional framing tools, but I can't see how using a circular saw would work without binding, and I don't think a jig saw would be powerful enough.  Any ideas?  Thanks.

[witterbound]

Band saw.

[northwoods1]

Band saw.

Yes, and another thing is a ....chainsaw. You can cut to a mark quite accurately and finish it up with hand tools. I did the same thing in my house.

[Rooster]

I found this link on the Guild forum.

http://www.tfguild.org/forums/ubbthreads.php?ubb=showflat&Number=15208&Searchpage=3&Main=2860&Words=curve&Search=true#Post15208

TF Guild forum member Joe Wood posted this on 4/22/08

I hope it helps.


Rooster

[Jim_Rogers]

We use curved stock to start with see post I just bumped to move it to the top....

[bbjr]

It looks like I may be adding a new tool to my arsenal, then  :D. 

Thanks for the link to the thread, Jim.  I do not have any curved stock to use, but your method makes sense as far as grain the grain coming out and creating a weak spot.  Although, since these braces are often used to prevent racking, and not to support the downward force of a tie or beam, is it critical to keep the grain from coming out the bottom side?

Rooster, I tried going to your link, but none of the pics were showing up for me and I did not see any mention of knee braces in the literature.  Not sure if my pc is redirecting me to a different page, or not?  Thanks anyways, though.

[Jim_Rogers]

Are you just accenting a normally straight brace? If so, I would axe close to the line and clean up with an adze and a spoke shave. For very curved pieces, you will want to use a naturally curved piece so that you don't have grain run-out.

If you are going to cut a curve into a piece of brace stock such as with a band saw, yes you may get some grain run-out where the curve is. However you usually start with a very large piece so that there is plenty of wood that is straight grained from the tenon to tenon and doesn't run-out. These long grain lines will hold the compression when the brace is working.

[bbjr]

Thanks, Rooster, the link is working now.  Looks like a clever way of getting it done with a bandsaw.

[jander3]

I use a small chainsaw (i.e) 35 cc.  If you use the backside of the bar it is a pretty easy cut.   I find the backside of the bar is a little easier to cut a curve with.

[Dave Shepard]

Jim, I think that post you quoted was supposed to be in this thread. :D I was thinking of really curved stuff, like the geometric design frame from last fall.

[Piston]

So THAT'S where you avatar came from Dave!

[Dave Shepard]

This is the building we built during the Geometry workshop in Oct./Nov. 2009. All of the members of the frame are located using the daisy wheel. We had a 1/12th scale drawing, and we had to use dividers and get the dimension from the plan, then step it off on the timbers to get the correct length. This is a combination hewn/sawn frame. The rafters, collars, posts, and anchorbeams I sawed on the mill. The braces, plates and joists we hewed under that tent. At one point there was something like 17 people all hewing and chopping at once. 8) This building was auctioned at the Timber Framers Guild 2009 Eastern Conference, is now in Texas.

[apratti]

Hi. Is there a special way to design the curve for knee braces? I look at them and wonder how they're so uniform and even. They look so cool, but I can't imagine it being easy. Do I start with extra-wide and stuff, like 4x8 and reduce it to what looks like 4x4 in the middle?

A lot of wasted wood from this design? Band saw too?
Anyone have a video?
Thank You, Amalio Pratti
 

[Chilterns]

The correct way to make curved braces is to select a section of tree trunk approx 9-10" diameter featuring the required profile (single curve or ogee). Half this along the centre line using a band saw then lay down the flat side on the bed and re saw to the required thickness - generally 3" for 1.5" bare faced tenons. This will leave 2 edges i.e. the inner and outer showing wane over the whole face. Lay this flat and score with an axe and then hew off the chips. It's worth running a draw knife over the finished edges to produce a nice flat face for scribing. This takes about 5 minutes.

We have just finished making and fitting 4 such braces from larch and this can be seen at :-

Oxfordshire Woodland Group on Twitter: "A change in atmospherics (dull day) has enabled the production of better pics of the cross braces & frame #1.? "

Regards

Chilterns

[Jim_Rogers]

How to do it with pictures here:
https://forestryforum.com/board/index.php?topic=102656.msg1595950#msg1595950

Jim Rogers