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stop splayed scarf with wedges

Started by addicted, October 06, 2014, 05:49:33 PM

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addicted

Hey Guys
I just started my first stop splayed undersquinted tabled with wedges scarf. Thanks to Jim for showing me how he does a bladed scarf. That was very helpful.
Now that both sides of the scarf have been cut, the one side has twisted on me. I assume from reaction wood in the timber.  Before I start to carve deeper into the twisted end of the the scarf I thought I'd ask how everyone else deals with this sort of thing.  My worry is that the more I try to correct for the twist, the more it will twist.
Thanks for your help
Rusty

beenthere

A pic or three would be very helpful.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Jim_Rogers

If the piece is twisting, you may need to make it into something else and get another more stable piece.

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

addicted

 

  

  

 

these photos show the alignment of the scarf which looked great til I started cutting and it started twisting. I can winch and clamp it somewhat tight but I'd rather have it fit right to start with.
thanks
Rusty
oh yeah... this is the bottom of a rafter plate. the top fits rather tight. the side that is twisting also will need a brace pocket= possible more movement.

Brad_bb

I wonder what would happen if you could clamp it in the correct position(force) and wait a couple months, would it dry enough to stay in that position?  Maybe you hose it down before you clamp it?  I don't know, just wonder.  Was the end grain sealed after you cut it?
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

Jim_Rogers

I would clamp it vertically and hold it clamped for a while as it is together.

If the top, which is the reference edge is flat along the cut line between the two then that's all that matters.
Measure down from the top to create your brace pocket. Once you have all your joints laid out, cut and ready put your wall together and then check your dimensions. If something is off a bit adjust your timbers then.
I would consider that bottom seam not bad enough to reject the timbers. If you site the pair end to end and then there is a visible twist that's a whole other thing.

For all:
In order to layout all the other joints on a pair of scarf joined timbers, you make the scarf first, join the two and then treat it as one long timber, for layout purposes.

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

addicted

Thanks Jim and Brad
I think I'll try both of your suggestions. If I slowly clamp and wedge at small intervals then I can get it to go together better than the pictures. once i reach the stopping point I'll leave it clamped and wet and finish the rest of the layout. As Jim suggested, the top is straight and level. When I sight down the bottom, the the twist starts right at the scarf. The next trick is how do you layout with clamps in the way.
In hind sight I can see my mistake. I cut the scarf out of the end of the timber with knots versus the end with out knots.
I guess it's ok as long as you learn from your mistakes
Rusty

addicted

As a side note I used the instructions given in Bensons book on making a template to layout the scarf. I did see a guy on youtube use a 2" or 1.5" wide straight edge for the tables instead of making a plywood template.  I guess carrying the exact angle from timber to timber is the key. 
I will try using 4 x depth for the scarf length on the next one as noted by Jim in another post.

Thanks
Rusty

Brad_bb

I have no idea if wetting it will help.  The water won't penetrate much.  I'm just thinking if it can wet and soften a little and then dry in the correct position(clamped) maybe you'd have a chance of improving the situation?  I think clamping it will force it back into shape a little bit, and should allow you to drive your wedge in better to help hold it in place.

In a critical joint area, I would definitely avoid knots if at all possible for just the reason you mentioned.
Anything someone can design, I can sure figure out how to fix!
If I say it\\\\\\\'s going to take so long, multiply that by at least 3!

D L Bahler

I agree that the twist you can see here is not enough to worry about. I've seen far more twisted examples of this joint in old barns.
If you are concerned about it it opening more or just don't like the look of it as is, you could consider tightening the joint with 4 through bolts. That would allow you to pull the joint tight, and also will make the joint significantly stronger

Southside

What does that joint allow one to do?  I guess I am asking where it is used and if it provides for a clear span. 
Franklin buncher and skidder
JD Processor
Woodmizer LT Super 70 and LT35 sawmill, KD250 kiln, BMS 250 sharpener and setter
Riehl Edger
Woodmaster 725 and 4000 planner and moulder
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Jim_Rogers

I have cut that scarf joint many times. Sometimes they come out perfect. Sometimes not.
After having one that was a real challenge I developed a method of laying them out that seemed to work good on the last one I did.
The key is to layout the scarf from the top down and from one end over. I drew the scarf in my cad program and dimensioned all the "points" of the scarf.
Once all the points are located you then draw the connecting lines.
It doesn't matter if you're drawing the bottom piece or the top piece of the scarf. If you use the same dimensions and do it the same way both halves come out the same and when you put them together they fit right.

Jim Rogers

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

addicted

Great idea Jim, that layout looks good.  Just curious, what's the dimensions of your slot for the wedges.
Rusty

Jim_Rogers

That drawing on the board was way to wide for the slot. It should be something a lot smaller. We had to make big wedges and that wasn't the best.

I'll research the correct size and get back to you.

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

addicted

Thanks Jim
I looked around a little for some guidance on wedges and the only thing I could find was the slope on wedges for a dovetailed through tennon

Jim_Rogers

I never heard back from one teacher I asked.
I'll ask another.
Maybe he's out of the area and doesn't have good email access.

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

Jim_Rogers

I heard back from one teacher that the gap should be 1 1/2" wide and the wedge slope should be 3/4" in 8".

I hope that helps you.

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

jamesamd

Bottom scarf is home,when You clamp them,there will be a gap on the top left.
Not cut squarely.Can correct with a hardwood shim.

I hate when this happens. ;)

Jim
All that is gold does not glitter,not all those that wander are lost.....

knowslittle

Jim- Would that wedge slope of 3/4" in 8" vary if hardwood vs. softwood?
Thanks.

addicted

Thanks for your help Jim
I'll apply that to the next one. I have three more to do
Rusty

Jim_Rogers

Quote from: knowslittle on October 19, 2014, 05:52:36 PM
Jim- Would that wedge slope of 3/4" in 8" vary if hardwood vs. softwood?
Thanks.

Normally the wedges are always hardwood. At least all the ones I've seen or made were.

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

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