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Drawbore on splined joinery?

Started by S.Hyland, May 26, 2013, 01:36:41 PM

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S.Hyland

On the W.Oak frame that I posted about there are mostly splined connections. I did a small drawbore on the pegging, probably about 3/32 or so. My instinct on it was that drawboring a splined connection too aggressively would be likely to introduce excessive stress on the spline. So far I drawbore splines, but not as much as a similar tenon joint.
How do all of you handle this situation, and does anyone know of any engineering that has been done on this? 
"It may be that when we no longer know which way to go that we have come to our real journey. The mind that is not baffled is not employed. The impeded stream is the one that sings."
― Wendell Berry

Jim_Rogers

I traveled over to south western VT some years ago, to watch a spline jointed frame going up.
There are some pictures of it in my gallery

https://forestryforum.com/gallery/thumbnails.php?album=365

It was one of the first spline jointed frames I had seen being assembled. I watched the timber framer put the drill in the mortise hole and drill out the spline after the frame was standing. (Picture #8) Then he put a crow bar into the spline mortise and slid it over a little amount and then bored the other peg hole on the other side of the post through the spline. Then he slid the spline piece back, just a little bit. Then he drove in the two pegs, drawing the two tie beams together to the post.

As this was all done up in the air I didn't get to see exactly how much it was draw bored. And it was a white pine frame with oak splines.

I know this probably doesn't help you much, but that was an interesting method of draw boring a spline in place with the frame standing. After it was all done they released the truck strap going around the frame from outside post to outside post.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

S.Hyland

That is actually almost exactly how I did it too Jim. With this particular design it had to go up one piece at a time, so pegging happened in the air. It worked well in this case since nothing was more than 10' off the ground.
"It may be that when we no longer know which way to go that we have come to our real journey. The mind that is not baffled is not employed. The impeded stream is the one that sings."
― Wendell Berry

Satamax

Huh, daft idea, but what about using a realy green spline? When it dries, it would draw the joint together, no?
French CD4 sawmill. Latil TL 73. Self moving hydraulic crane. Iveco daily 4x4 lwb dead as of 06/2020. Replaced by a Brimont TL80 CSA.

beenthere

Quotebut what about using a realy green spline? When it dries, it would draw the joint together, no?

Are you thinking that when the spline dries, and shrinks....... that it will somehow fit tighter?

I'm thinking the spline will be a loose fit then.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Jay C. White Cloud

Hey Sean,

The frame looks great!!!! 8)  You got to give me a call so we can catch up on it and other things.  Loved the "drawing splines" they look as if they came out great.

Hi Satamax, 

You can use green splines but I try for dry ones whenever possible.  A green spline will get looser not tighter in most cases, and they don't shrink in length at all, no wood really does to any magnitude.

Regards,

jay
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

Satamax

Jay, i know wood doesn't shrink much when drying!

This was just a brain fart!

Beenthere, true, i didn't think about fit other than the pull.
French CD4 sawmill. Latil TL 73. Self moving hydraulic crane. Iveco daily 4x4 lwb dead as of 06/2020. Replaced by a Brimont TL80 CSA.

razor

Any splines I've used in the past has always been dry hardwood. Cherry, Walnut all work great and look even greater. Yes you are right in not being too aggressive in the drawbore offset, especially with dry hardwood splines. They simply do not give any. I have also made a sort of laminate spline by gluing two or more boards together. This really helps with the tension strength of the spline and pretty much rules out any relish failure

S.Hyland

Razor, I actually did laminate the 1 1/2" splines out of 2  3/4" pieces of Oak. Initially because I could not get any reasonably prices 7/4 Oak. But then I kind of figured that it would improve the strength as well, like you said. I used a Urethane glue in this case since a lot of these will subjected to freeze/ thaw cycles. I was unsure of how titebond would stand up to that.   
"It may be that when we no longer know which way to go that we have come to our real journey. The mind that is not baffled is not employed. The impeded stream is the one that sings."
― Wendell Berry

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