Question for you band millers.

[oakiemac]

While at the Logging conference in Escanaba I saw a band mill made by Serra that had an arm that could extend up and turn the whole log while it was on the mill. It also looked like the mill could cut going both ways. Are these options on most band mills? Or did Serra invent this? It seemed to me that if you had a band mill this is the way to go. Of course I'm sure the price is also a lot higher. Any opinions on these mills?
Oakie

[Bibbyman]

Most all the bandmills with hydraulics have some kind of log turner.  Some are like and arm with a claw and others have a chain that turns.



Wood-Mizer LT40 log turner



Wood-Mizer LT70 Log turner

Sawing both ways may have an advantage with longer logs but the time to rotate the head is offset by the time you could have just returned the head on nornal length logs.  

Some mills have blades with teeth on both sides,  I understand as I've not seen one in person,  that allow it to cut both ways.  But the cost of the blade and the maintenance may offset the benefits.

[Andre]

Sawing both directions?
https://forestryforum.com/cgi-bin/board/YaBB.pl?board=sawmill;action=display;num=1052964463;start=0
Not new.

[Bibbyman]

Forgot one turner for a manual mill.  It's also a claw on an arm similar to the ones on the hydraulic mills but is powered by a cable winch.



Wood-Mizer LT40 manual log turner

[Jeff]

Was the serra mill the german mill? When I was watching it it only had a one way band on it. I did not see the capabilities for bi-directional sawing. If we are talking about the same mill. It looked kinda like a big red baker had a big gen set on a trailer to power it. used about a 3 inch wide band. Sure seemed to take a lot of power to get it turning and I noticed a little later that the little cheap Hudson oscar was feeding almost as fast.

[oakiemac]

The mill I saw might not of cut both ways. I didn't actually see it do this but I thought it might be capable. By the comments, I gather this mill was nothing special. Did anyone see the little "toy" mills at the show. They had some that might cut a 9" log. Might be good for squaring up poles for log buildings and such.

[MemphisLogger]

I went and looked at Serra's website  :P

http://www.serra.de/eng/html/home.php

The most interesting/innovative thing I saw was their ability to skew cut. It seems to me that the ability to run the head at an angl;e to the direction of the cut might cut down on dives and waves on the hard-hardwoods.

http://www.serra.de/eng/html/alpin.php

Otherwise, Serra does look like a german version of the Baker.

    

[Tom]

I don't understand this "skew" cut thing.  It seems to be a gimmick to me though I've not seen it in operation.  

One of the concerning factors in sawing a log is its width.  The wider the log, the more difficult it is to expel the sawdust.  The gullets fill and you have to slow the feed to allow the blade to clean the kerf. The "skew" cut widens the cut.

What that angle of attack accomplishes by approaching the grain from an other-than-90⁰ angle hasn't been explained to my satisfaction yet.  Just the entry of the blade into the log, giving it a "soft" start, doesn't seem to justify the engineering.  My experience has been that grain other than straight, causes rip blades difficulty.  This looks like an effort to do just that.  While it is not creating a cross-cutting situation, it does seem to be creating a similarity to wide growth rings.  I know the problems I have with Loblolly Pine and attribute it to that phenomenon.

Carrying a generator set to operate an electric sawmill in the field appears to be complexity for complexities sake.  The only benefit would be eliminating having to carry so many hoses full of hydraulic oil back and forth all day. That is a difficult design to maintain where the carrying of electric wires back and forth all day may be less maintenance intensive.  That is, it would be if the the electric cables don't chafe.  Electricity getting all over the frame would hurt worse than a hydraulic leak.

At first blush, this looks like a mill that would be more at home in a stationary installation.

That wide blade would require a fairly extensive blade shop as well.

[Percy]

Neat lookin stuff. Always like to see what the "other" guys are up to ;D. Im thinkin the skew feature is so you can enter a cut faster. Entering a cut on my LT70 when cutting hardwood(Birch) isnt an issue as I just giver but on softwoods like Spruce and Cedar,specially the bigguns, you gotta enter the cut a little slower than your feed speed or theres a chance she'll do a wiggle :D.

Regardless, in my opinion, I think the fact that there are more and more small(portable?)mill manufacturerers springing up everywhere is a very positive thing for our industry. Keeps everyone on their toes and the more sawyers/millers there are in the world gives us a bigger voice with the politicians who only understand polls.

[EZ]

I dont understand the skew head either, Tom. I see they will be at the Paul Bunyan Fe. this yr. So I'll have to check it out when I get their.
As for for sawing EZer being the head is on an angle I think I'll just cut the logs on a 45 with the chainsaw.  ;D :D ;)
EZ

[chet]

I watched the serra mill at the Great Lakes Logging Congress for quite some time. It was big, it was pretty, it was quiet, but I wasn't impressed.

[C_Miller]

The Amish built mills around here run their blades on a skew.  The blade helps pull the sawhead thru the cut.  That way the stricter sects that don't allow electric drives have an easier push.

C

[Sven Christiansen]

Since Wood-Mizer is also prominent in Europe, we have had plenty of contact with Serra.  Here's the reason for the skew:

It keeps the machine street legal.  If they would set the head at 90 degrees, then it would be too wide for the road.  By setting it at an angle, they can get a bit more throat width out of the cut and still be legal for the road.

Other points on the skew:

1) They actually have more teeth in the cut because of the angle and need more horsepower to drive the blade.
2) A Serra engineer we've talked with admitted that in actual cutting it was disadvantageous because you are actually cutting more timber due to the skew.
3) The only advantage from a cutting point of view was that on entry to the cut there was less of a "shock", and that on exit from the cut, with a wide band mill, if there is tension in the log it can bind the blade.  The teeth are out and then the log clamps the body of the blade.  Skew helps to avoid this.

Hope this gives you some insight.

Sven Christiansen
Wood-Mizer

[Bibbyman]

I did a little report on a locally built mill I seen at an Ol' Thrasher's reunion early in July.  The sawhead set at an angle.  Claims were made that it made it easier to push and took the shock out of blade entry.  If it made it any easier to push,  I couldn't tell it by watching.

EZ Welding sawmill

I've seen bandmill operations were blade dive or dip upon log entry and/or exit was quite the norm.  Early on we'd have that problem too from time to time and still do on a rare occasion.  But I've come to keep my main drive belt tight and change the blade before it starts to get dull and, knock on wood,  about eliminated that dive/dip problem.  When sawing average size logs or cant,  we can bang right into the log without that annoying dip and dive.  We'll still ease into a log with a dry end.  

[Tom]

I ease into all of them.  It just makes me shiver to hit the end of the log hard, whether the machine can handle it or not.

[Bibbyman]

We eased into them all when we were running the LT40 with only an 18 hp gas engine.  I think the drop in RPMs (and therefore blade speed) before the governor kicked in may have contributed to dips and dive.  

Now that we've 25 hp 3ph available,  we don't see the drop in RPM (but those amps probably get eaten up pretty quick for that second.) so we can bang away and still produce good lumber.  If there is any adverse effect on the mill,  I've not seen it.  But it may be a good way to stress test blades to see if there are any cracks developing. ;D