Thread: Tension logs with a Lucas

Thanks Sigidi thats clear as mud . But I think I get it. What caused so much scoring in the timber ?. Might have to come tail with ya for a bit, when ya get an other big job

Good pics Alan, being a bandsaw bandit i dont know but, have you ever with small logs like that when you are trying to get 5 by 3s out of it,ever turned the log over onto its flat side and cut back down again just to relieve some stress before you get in near the the heart? Also at 6m long in a log that big you are bound to get some movement bud

Good pics, Allan. Tension is something the Lucas does have trouble with and your method is one way of managing it to produce a consistent thickness. I have to say though, if the log has a lot of stress in it, then the boards will tie themselves in knots regardless and you'll be left with a consistently-thick boomerang.

I recently finished cutting an order for grey ironbark beams, 10 each of 200 x 100 @ 5.4 and 6.4. In order to get enough straight beams, I ended up cutting nearly 50 pieces and rejecting the bowed ones, which then got resawn into smaller stuff, mostly sleepers and posts.

I hate grey ironbark.

Thanks Alan, I have never tryed that before but I will certainly give it a whirl, basicly, perform an under cut on any logs that are showing tension, and then raise mill to go back over the top again then do the second vertical then back down again to finish the horizontal. Can't wait to try that. I do not get a lot of tension in my logs, as I've said before, I try to cut logs that have been down at least 6 months, that is my answer to reducing stress in logs and it does help, not all the time but. I realise this is no good for the type of comercial milling you do but suits me.
cheers

Originally Posted by itsposs

Thanks Sigidi thats clear as mud . But I think I get it. What caused so much scoring in the timber ?. Might have to come tail with ya for a bit, when ya get an other big job

Yeah clear as mud - even with pics it's sometimes difficult to understand what is going on without seeing it/being there.
As for tailing, I'm camped up at Maryborough (not far from Childers, around Bigenden way) most of next week if you wanna visit, spend half a day or more if you want.

Nifty, being a swinger, I never move the log once I start. Only time I've ever moved the log was to make very large posts, bigger than the blade could cut, it worked out well, but was very time consuming. On a bandsaw you have a level bed and can roll the log each board to equalise tension better hey? With the swinger it doesn't matter how level the ground is, or if it slopes etc. the next cut is always reference to the last cut, so if the log stays still all is good, but if the log moves cause it's too light or it's rolled out of supports, maybe the sawyer has driven into it too quick, then you have a lot of messing around to do to get back your levels. I don't like moving the log if I don't have to

Craig, I'm only accepting what falls under grading rules to begin with and then also looking at them from the point of view "would I want to use that stick?" if it passes both tests, then it's in, if it fails one or the other - it's out. I've found long spotty to be the most problematic of all the timber I've cut, some species have 'problem trees', but the majority of long spotty I've cut has been rough on tension.
Not been lucky enough to play with grey ironbark

Johnny, you've pretty much got the idea mate. Next big thing is to be able to judge/identify when you need to and when you don't, without going to the effort and time of raising the mill passing the blade over it to find nothing needed trimming off, then having to come back down to finish your board off. You could measure the board and confirm by way of the result from the tape, but again it takes a bit more time and I like to mill as quick as I can to get more timber done in a day. All these logs have been down and stacked in 2 piles since January this year, I just figure it's long spotty and also taking big layers - 1" feedstock doesn't seem to heave up as much, but taking 3" deep layers over 6-8m tends to allow huge amounts of tension to show up.

On that, I also had a fella once say he put is supports right at each end of the log to try and minimise any counterbalance effect the weight past the supports added to helping the log heave up in the middle, it makes sense theoretically and I do try to put my supports in the last 6" of the log ends, but sometimes this causes loading probs with logs turning and falling off the supports... which increases handling time and slows down timber output anyway that's another thread

Small, sappy logs are always going to be problematic.Maybe slicing them in half is a better option,rather than milling off the excess wood created by the spring.Might be more time consuming but at least the tension in the log will be released.

the idea behind putting the bolsters at the ends is so when the centerer humps up the ends don't go down. and you can run it off

if you have to bolsters 1m from the ends on a 4m log and the center went up 5mm then each end would go down 2.5mm. when you run back over to level teh top you take the 5mm from the center bu the ends are still 2.5mm lower. so u have to drop 2,5mm and run that off aswell.

if the bolsters are at the ends the center would just go up 7mm.

Alan, with the woodmizer we dont get this because the log is clamped in place, not allowing it to move up. We do however get it when resawing cants. I may want to flip the cant over to avoid a shake or whatever, when i release the clamp the cant will spring so i then have to take a trim cut. A customer of mine down south gets me to cut southern blue gum andspotted gum from his plantation. These trees are only about 20 years old so what he does is fall them and throw them into a shallow dam for about 3 months before i get there. We have found this a good way to release alot of tension, and its darn good fun watchin him charge into the dam on the old michigan loader to get em out

Great advice. Also should be followed by people producing feedstock. An occasional leveling cut to reduce the number of boards that are oversize in the centre. It may not be as noticeable in 1" boards but you sure notice it when you put it through a moulder.

My Bandsaw also clamps in the centre so it's not a problem.

I would also agree with shortening the log to reduce the magnitude of the tension but if the customer wants large section pieces in long lengths out of springy logs this is the best way to do it..

Cheers
Steve

i level off every layer as i go. normally its less than 1mm but there is always something to come off.

carl no matter where your supports are under the log the bow in the log is the same , u can also use the log as a bench cut over size ,trim L shape left in the log , reposition timber and trim one side filp and trim the otherside

yes tension is the same.

but if you have bolsters in a long way when u run the top off u have to drop a few mm then run it off or your ends are still low.

Originally Posted by Exador

Good pics, Allan. Tension is something the Lucas does have trouble with and your method is one way of managing it to produce a consistent thickness. I have to say though, if the log has a lot of stress in it, then the boards will tie themselves in knots regardless and you'll be left with a consistently-thick boomerang.

I recently finished cutting an order for grey ironbark beams, 10 each of 200 x 100 @ 5.4 and 6.4. In order to get enough straight beams, I ended up cutting nearly 50 pieces and rejecting the bowed ones, which then got resawn into smaller stuff, mostly sleepers and posts.

I hate grey ironbark.

How true! resawing oversize flitches is one way around the 1 in 5 success ratio.
regards inter

your saw still cuts a straight line from one end to the other no matter where the bolsters are