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Ford: I think it looks good. It matches the rest of your bench, in style, color, and grain. Have you built your tailvise yet? Thank you guys for all your wonderful advice (how would I build this thing without Woodnet?)! I fiddled with the base some last night, and lag bolted the top down to it. That didn't help. I checked the stretcher / leg joints, and they all seem nice and tight with the bolts. I can't figure out why it's wracking only on that one side. My tenons must be just too loose either in the trestle or the stretchers, even with the bolts (or both).  The current lower stretchers are made of poplar, are 5.5" wide, with a 3.75" x .75" tenon. They are made from boards from the BORG, two 3/4" boards laminated together. I could get some more poplar from the BORG and make some upper stretchers also. And this time be much more careful about my mortising / tenoning. If I'm still not happy with it, I could go buy some 8/4 poplar, and remake the trestles. I could reuse the same stretchers. (Although I'd have to learn to cut mortises from tenons, instead of tenons from mortises, like I usually do.) As timgren suggests, I could probably finish it to look like maple. Or maybe I should skip the BORG altogether and just redo it out of poplar. It would also cost probably about half as much. I'll call the hardwood place today to get a price.
Turning impaired.
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Thanks, I am pretty happy with it. It's not elegant like many of the benches seen here at Woodnet, but it's heavy, and pretty solid. If you look closely you can see knot holes and other defects but I was more concerned with keeping the stretcher as thick and tall as possible. I think they are 7.5" x 2.75". If you do rebuild the trestles, cut through mortises and wedge the hell out of them. Wedges seemed able to cover my poor mortising technique  The tail vise is almost done. I need to install the guide rail and slap some finish on it. It is far enough along that I can use it to clamp a stick for use as a saw stop for my Ryoba (and, apparently, a skull gouger when I duck my head under to look at how to install the guide rail.) The only real complaint with my bench so far is that I should have put feet on it like Hank Knight did. I have one foot that needs a wedge under it to keep the whole thing solid. If you do decide to rebuild the trestles, that would be the perfect time to add decent, adjustable feet.
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Crooked Tail said:
I fiddled with the base some last night, and lag bolted the top down to it. That didn't help. I checked the stretcher / leg joints, and they all seem nice and tight with the bolts. I can't figure out why it's wracking only on that one side. My tenons must be just too loose either in the trestle or the stretchers, even with the bolts (or both).
CT, I think you've hit on it... you've got some loose tenons. Tight bolts and square shoulders will eliminate side to side or left to right racking in a straight line, but the tenons are what really help to hold things in place on a diagonal, along with your top to some extent. When you've got time, take the bolts out of your stretchers and check for some slop in the fit of their tenons. I'll just betcha you're going to find some there. You shouldn't have any at all. A nice, snug push / tap fit is what you're after. 
Crooked Tail said:
I checked the stretcher / leg joints, and they all seem nice and tight with the bolts. I can't figure out why it's wracking only on that one side. My tenons must be just too loose either in the trestle or the stretchers, even with the bolts (or both).
CT: I think you and Bob Z have figured it out. If you find that your tenons are indeed loose, there's no need to replace the whole stretcher. Just glue some shims to the tenons and resize them with a shoulder plane or a wide chisel so they fit snugly in the mortise. It's an easy fix. Sorry you're having a difficult time, but stick with it and you'll get it right. Good luck. Hank
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Well, I think I've come to a decision. I'm going to rebuild it, but out of poplar instead of maple. This is a compromise between cost and, well, getting to rebuild it. The local hardwood store sells 8/4 poplar for $2.24 a bdft, which seems pretty good to me and is less than half the cost of 8/4 maple. Even though much "softer" than maple, the poplar ought to be much harder than the doug fir. Also, I ought to be able to finish it to match or very nearly match the maple, whereas I don't think I'd get there with the doug fir. So yes, it is partly an aesthetic decision. Design changes: - Four stretchers instead two, upper and lower. Each stretcher will be at least 4" wide. I may reuse the current poplar stretchers, which are about 5.5" wide. - Set the legs further apart. The legs now are only 14" apart, measured from the outside of the legs. There is only 7" between them on the inside. I think setting them further apart will help with diagonal racking and stability in general. Don't ask me why I put them so close on the current base. I'm going to be super anal about the M&Ts this time. I have to admit that I went on a sort of chopping spree on the current base. I wanted to get it done quickly, and the doug fir was so much softer, that I just sort of went nuts.  A shoulder plane sure would be nice to have for this work... and the poplar is less than half the cost of the maple... and and and... 
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Crooked Tail said:
...Even though much "softer" than maple, the poplar ought to be much harder than the doug fir...
You might want to look into that. I built a trestle base for the dining room table I made for my little brother from poplar (primarily cost considerations plus it was being dyed black) but I found it to be quite soft and easy to ding. I never compared it directly to the construction lumber I had lying around but I don't think there is much difference. One might be stronger than the other though; I've never looked it up. It might be worth looking that up and decide that way. Also as far as finishing poplar to match maple, depending on the poplar it might be harder than you think. Some of it can have a pretty greenish cast and likely wouldn't match well. Other peices would likely match well. Bob
Sounds like a plan to me. Keep us posted. Hank
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On the strength of poplar vs Douglas Fir, poplar seems to be weaker. Here is a site with information about various woods. http://www.woodbin.com/ref/wood/strength_table.htmDouglas fir seems to win pretty much all around. The compressive strengths may be some of the more important values as far as the joints becoming looser.
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Interesting info, gjohn. I see "cottonwood balsam poplar" and "yellow poplar." I take it the yellow is poplar is that which is generally used in furniture? I'm surprised that it seems to indicate that doug fir is tougher. Maybe because the doug fir I was using was green, but it sure seemed much, much softer. It's hard to describe that feel, just that it was so much easier to work. It also seemed to want to "flake" off the way oak does, but with much less force than necessary to make oak slivers or flakes come off. 
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Locally, also in hardwood hell, red maples about the same price as poplar.. just about $3/bdft for 8/4. It's just about as hard as sugar maple and is almost indistinguishable. That being said, I made my base out of alder.. which is cheaper still here.. and not nearly as stout as doug fir even.. but it's been holding up fine and still as rigid as it was when I made it.
mike
I ain't a Communist, necessarily, but I've been in the red all my life
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