Timber Peg Size question

[shinnlinger]

H<brH>
 

 

[shinnlinger]

Hello,

My construction class is building an outdoor classroom at our school and we are getting to peg time.  Normally I would use a bed on my planer to make octagonal pegs but I happen to have a number of lathes and a number of students who are fairly proficient turners.  I also have a duplicator that was just donated so we are trying it out.  My question is do I want the peg to be a hair larger than the hole or pretty true?  Do I want an 1-1/16th peg for a 1 inch bore?  Red oak pegs and a white pine frame.

Thanks.

Dave

[Ljohnsaw]

I'm sure @jim_rodgers will be along shortly. 

When doing octoganol pegs, the flats would be 1" and the points will be larger and can conform a little.  Being 1/16" larger overall, I think that would get a little bit tight.  Are you making the pegs with a slight taper?  Maybe go from 1" up to 1-1/16".  Assuming you are through bored, you could drive until tight.

[flyingparks]

I like a 1" peg for a 1" hole. That's just me. Its always worked.

[TimFromNB]

I was just reading a few passages on this in Benson's book this morning. An octagonal peg that is over sized may work, because the pine is soft and can absorb some of it (on the points). However, for a round peg, where the entire surface is over sized, I would be scared to split the hole. He suggests shaving a bit off on two sides to create a slight oblong form. It is in the tips section near the end of the Timber Frame Workshop book.

Just my 5 cents.

[Heartwood]

Dave,
Are you going to drawbore the joints? If so, the pins should be tapered 1/8" under at the start with the nominal hole diameter reached at the point on the pin where the tenon will be, and straight from there on to the other end. If you can't do this taper on the lathe then drawknife or block plane the pins after. Then put a narrower point on the pin for a few inches to get it started in the drawbore. Drive the pin until the joint is tight or far enough so this point is outside the far end of the timber and cut it off (if wanted); include this excess when determining where the tenon will ultimately be on the pin.
If you're not drawboring, then make the pins 1" all the way, not any bigger.

[LeeB]

Just a question about drawboring, Would it be possible to drive the peg in further at a later date as the joints loosen up? Don't shoot me on this one. I know nothing about timber framing.

[Jim_Rogers]

Dave,
Are you going to drawbore the joints? If so, the pins should be tapered 1/8" under at the start with the nominal hole diameter reached at the point on the pin where the tenon will be, and straight from there on to the other end. If you can't do this taper on the lathe then drawknife or block plane the pins after. Then put a narrower point on the pin for a few inches to get it started in the drawbore. Drive the pin until the joint is tight or far enough so this point is outside the far end of the timber and cut it off (if wanted); include this excess when determining where the tenon will ultimately be on the pin.
If you're not drawboring, then make the pins 1" all the way, not any bigger.

x2
Jim Rogers

[Brad_bb]

For a line to line fit, you want a 1" peg for a 1" hole.  I like have a die on hand.  Drill a 1" hole in a heavy piece of steel.  You want to be able to clamp the steel to some timber drops that you can put on some timber saw horses.  You use the die to drive the peg through.  I did this on the last frame.  I had riven octagonal pegs (white oak) and I drove them through the die with a 3lb hammer.  The first time you drive them through they remove the bulk of material but they compress a little.  They weren't a good fit or the peg holes, so I drove them through a second time and it shaved a little more off and the fit was then good.  You can drive them a third time (they go through pretty easy by then) but it removes very little.

I like green riven peg blanks and as soon as I get them I put them in a rubbermaid tote of water to keep them wet.  This way they are easy to draw knife if you're draw boring, or if you're just putting a point on one you're going to do line to line fit.  Then I let them dry out for a couple months before driving them through a die.

[Heartwood]

Lee,
The beauty of drawboring is that the pin acts as a spring and the joint shouldn't get loose as the timbers dry. Assuming the pin is dry and the timbers are green.
By NOT drawboring, as the timbers dry, the joint will probably open up, unless you're really lucky or anal about pin location and grain direction (pins should be located closer to the shoulder of the joint where you don't want shrinkage to show up).

[LeeB]

Thanks Heartwood.

[PA_Walnut]

I am not a timber framing expert, but the dudes I've seen who specialize in timer framing rive the material, not turn it. When you turn, there's always the grain runout issue. Riving doesn't have this issue.

I discovered the joy of riving when I learned to make Windsor chairs. It was an adventure in drawknife and spokeshave work. Now, I use both ALL THE TIME...some of my favorite tools. Add a shave-horse for even more joy!

Good luck.