Mighty Might edger saw diving.

[backwoods sawyer]

A mill down the road a ways from me came up short a sawyer due to medical issues, so I have been sawing with the night shift sawyer this week. The set up is a Mighty Might with a 40" main saw and a 32" edger saw. It can cut up to an 8' by 40' log. The problem I am seeing is the edger saw dives in a cut that is more then 8" deep making it tough to cut 12"x 17" FOHC beams. The edger saw just got back from the saw doc about a month ago, and had new teeth on Monday. It is diving as much as 1 ½" in Western red cedar, White cedar and Doug fir after about the first 8' feet or the first good knot that it hits. The main saw will take a full depth cut with no problem. 

[Ron Wenrich]

Is it just you or does it happen with other sawyers?  I've never even seen a Mighty Might, let alone run one.  But, I do run a vertical edger.

I had some issues with our vertical edger and I suggested to put a little lead on it.  That seemed to help it somewhat.  It doesn't eliminate all the problems, and the upper saw seems to want to deflect more than the bottom saw, and when in a deep cut. 

A few things come to mind.  One would be whether the saw is getting hot.  That's what my saw was doing.  Edger bearings are another thing that will cause heat.  Its easy to over grease them, and that will cause heat.  Its hard to convince people that a closed bearing system can't take that much grease.  You can get zerks that will limit the amount of grease that's put into your bearings.

Is the saw moving on the shaft?  Ours is run by hydraulics.  That holds the saw steady, but if your cylinder or valve is leaking, you can get drift in it.  I don't know if your system is run by hydraulics or not. 

How's the collars?  Collars go bad on vertical shaft mills just like on the horizontals.  You might not have a good fit all the way around.  Or, the saw could be a little lose on the collars or even too tight.  I know on the headsaws, you can make them too tight and that collapses the collar. 

Is it the same under different feed speeds?  Some guys think you can run a saw wide open no matter what the species or how deep the cut.  I've found that you can't, especially in knotty wood.  If its the same under different speeds, then its the equipment.

I don't know if any of the info helps, its just my experience from a vertical edger. 

[backwoods sawyer]

The mighty might is basically an over grown mobile dimension mill with the horizontal edger saw. The edger saw is mounted with tapered head Allen screws for flush cutting across the top of the log. The night shift sawyer was having problems with it diving on him as well and it seems to be an ongoing issue as he would avoid making a cut over 8" deep with the saw. This is an electric mill if that helps.
Lead and bearings could both be part of the problem or even end play in the shaft, they have plenty of water running on the top side of saw.
When the saw was run slow with both saws making full depth cuts, the main saw walked out, but the edger saw cut on track. I believe the saw was hammered for 1,100 or 1,200.

[Ron Wenrich]

It just doesn't sound like that thing is tuned up.  If you're cutting straight at a slower speed, but the main saw walks, there isn't a balance there.  I'm assuming that the main saw is an unguided system, just like the edger.

Electric motors shouldn't make much difference.  If you bog down your electrics, your saw will lay over.  I'm using a 60hp electric on my vertical and running 2 blades.  If you're doing an 8" cut, you should have 40hp per blade.  That's a rule of thumb number. 

Those high speeds are a lot harder to control.  If the electric bogs down, your 1100 RPM blade starts spinning at 1000 RPM. 

[sgschwend]

BW, you could ask the owner of the mill if you could call MM.  They have a small crew but all have many years of experience. (503) 266-3387

My 2 cents is that I visualize the horizontal shaft deflecting out which would tip the saw down.   A 5 degree deflection of that shaft would result in a 1" error!

[backwoods sawyer]

Thanks for the number.
I will run it by the millwright and the boss man on Monday and see what we can do to get it tuned up.  He wants the sawyers to do the maintenance on it, which is fine by me.

[backwoods sawyer]

I talked with the saw doc today and he is hammering the edger saws so they are as stiff as possible, and he says they are very brittle as well. There seems to be some variation in how the teeth are inserted in the saw, some are set flush, some a bit recessed and some are bit proud. The millwright uses a dermal tool sharpener made by mobile dimension, but it does not seem to be hitting the tooth square, the other sawyer used a heavier set up similar to the one I have for my Bell saw only powered by a drill witch leaves good square corners but takes more off some teeth then others. How critical is having all the teeth the same height? Bearing have not been ruled out as a problem either.

[sgschwend]

I did talk to John today at MM about a different machine.  He told me he was out of town the last two days so he didn't know if you called for him.

He did say it sounded like there is some sort of problem (from what I could remember to tell him).

I know on boat propellers after the pitch is set the tips are cut to the exact same height (as you know it is a curve, but you get my point).

I would expect a saw would need to have the exact same diameter and the grinder needs to control that face too. I am sure we could calculate the feed movement per tooth, if it was equal to the height difference then the shorter tooth wouldn't even be making a cut.

[Ron Wenrich]

A tooth that is too low doesn't present much of a problem.  The high ones will thump when they go through the wood.  Eventually, they'll pull out if they're not down in the socket the whole way. 

If the teeth are working their way out, then you have a problem with shanks.  They should be replaced if they don't hold. 

Tooth alignment is important.  If your teeth aren't setting in the shank like they should, they could make you cut off line.  Its like adding extra lead.

[backwoods sawyer]

The teeth do not seem to be moving, just being placed with inconsistency. The saw doc told me that by stiffening up the saw the shanks will be harder to pull out and put back in.

[backwoods sawyer]

Today I was sawing a 4'+, sixteen foot Doug fir log, The edger had been handling 8" cuts with out any problem, so I got gutsy and tried taking a 12" x 12" clear vertical grain cant out of the top of the log as that is the money cut. About 3' into the log the motor bogged down and the saw dove hard, I backed it up and eased into it again and again with it diving about every foot of the way down the cut. I am leaning towards it being a motor issue. The next cut it handled a 10" x 10" with out bogging down. The millwright is making some modifications to the heaver bell saw style sharpener so that it will sit square on the saw. I am sharpening the edger saw twice a day rather then once a day like they had been. An electrician will be checking out the pull on the motor under load as soon as they can have one come in. The motor has not been sent out for rewinding in the 15 years that they have had it.  New bearing for both arbors are on order as well. So hopefully this issue will get resolved in short order as this saw is ran 18 hours aday.  8)

[DanG]

I'll be interested to know how this plays out.  The edger on my MD is tiny compared to that, but it seems like I had more trouble with the edger diving when my engine went wimpy on me.  I haven't been able to saw enough since the rebuild to tell if that particular problem is solved, though.  It seems like the lead in the edger is more critical in the edger than it is in the main, even though my edger is only a 12" blade.  The lack of sufficient power to maintain RPM apparently exacerbates the problem, as it seems much more forgiving with adequate HP.

BWS, does that saw use separate motors for the edger and main, or is it a single motor?  Since the problem starts 3' into the log, that is about the point where the main would start loading it down.  If it has separate motors, you might have that electrician check out the power source as well as the motors.

32" seems like a pretty big blade to be laying down horizontally like that.  What guage is it?  What is the kerf on those bits?  Any chance of seeing some pics of that mill?  It must be a monster compared to mine. ;D

[sgschwend]

BW, I did talk to a MM electric mill owner the other day.  He told me that he monitors the motors amperage (acted like the amp meter was standard on the MM).  As long as the amps are within range the saw will cut straight.

He also said when he first purchased the mill the edger did not have lube, and he overheated the saw.  He now has edger lube.

[Ron Wenrich]

I think you have a power issue.  I just looked at the MM website, and they have a 75hp electric motor on their rig.  That's to run both the edger and main saw.  I run 60hp on just my edger with 2 22" blades.  If I go too fast with that set up and cutting a deep cut, it will go off line.  But, I'm not an engineer or designer. 

If you don't have enough power, your saw doesn't stand straight in the cut, and the gullets fill with dust. 

[backwoods sawyer]

Dang, good point on checking power source as well.
This mill has separate motors for the main saw and the edger. Sharpening every 3 hours today allowed for minimal diving in the 12" cuts. I will see about getting a picture of the mill soon.
There is no amp meter on this mill, just go by sound and feel, but that may be something that gets added. 

[backwoods sawyer]

 Here are a few pictures of the mill and a log that it is capable of handling even it dose take a few hours to whittle it down.

[Ron Wenrich]

They don't have the mills to handle any of the old growth out there anymore, do they?  There was the day when mills handled those big logs, but that must be a bygone era. 

The pictures gives a much better idea of the operations.  Here's what our operation looks like:



Our vertical edger is to the right.  Our saws move on a shaft and my maximum depth of cut is 7".  Its a little hard to see, but the edger saws do have top and bottom collars.  They're not the same as on the headsaw.  Those collars do the work of pulling the edger saws up and down.  There is a bearing inside those collars on the top and bottom and they add a lot of stability to those saws.  There's also a bearing at the top and bottom of the shaft. 

Feedrates for oak is about 240 fpm.  I can't feed at that rate if I'm taking a deep cut on the edger. 

Now that I see your setup I'm wondering if the vertical saw moves up and down.  With the way the shaft looks, it doesn't.  Then I get to wondering how in the world you don't get movement in the vertical shaft.  Its sitting out there in with very little support.  Unless there's something I can't see from my angle.

[backwoods sawyer]

Ron there is a mill in the area that has the same edger set up as what you have, but it is coupled with a bandsaw rather then a round saw for the main saw.

I have checked the setscrews on the bearings for the vertical shaft and they seem to be holding. They seem to be the only thing that is keeping the shaft from moving up and down. When the saw dives, the whole bridge is being pulled down into the cut. I was doing a walk around with the millwright and had a piece of metal just fall off into my hand, so there are other maintenance issues, after all it is a 15 year old mill. There have been improvements made to it as well, and there goal is to get it back in top shape as this mill is part of a larger operation where they square up the logs with a round saw and we both feed to the resaw which is a vertical bandsaw.

Most of the mills in this area that could handle the big logs went away back in the early 80's when the timber industry got hit hard and the large log supply dried up.

[Meadows Miller]

Gday

Looks like your getting ontop of things Backwoods She's a fair old settup i take it thats the largest MM model then  ;) and it would have sawn a power of wood in its time  ;) with the setup i like the tail out and greenchain and how large is that log in the pic and what sort of production are you getting even with the bit of mucking around you have to do Mate  ;)

Ron Shes a strait quatersaw with two saws at 90 deg to eachover Mate ;) i have acouple of Mates with Forestmills that will saw upto a 10 buy 12 inch and upto 25' cant and had 85hp iszus's on them they where a bloody good mill too  ;) ;D 8) pitty they dont make em anymore they built about 2000 of them since 1955  ;) ;D 8) 8)

on this note my uncle keiran just took uo a new horizontal saw for a MESM mill he reworked in PNG the other month it was a 6 gauge Simmonds B style and 27" dia i think  ;)

Regards Chris

[Ron Wenrich]

Boy, that sheds a different light on things.  Your saw could be cutting perfectly, but your supports are fatigued allowing it to dive.  Do you need a frame that is that long?  It looks to be about 30'.

[Meadows Miller]

Gday

Ron Backwoods said she'd take a log 40' long by 8' dia it would make the track about 50' thats a loooon bloddy span in anyones language and a bloody BIG LOG 54259bft Mate    ;) :D :D ;D ;D 8) 8)

Regards Chris

[backwoods sawyer]

 
The log that is 9' on the butt. Here is a 4' log on the removable stands. They use the full length of the mill quite often, but with smaller diameter logs. 14'- 28' are common sizes to cut. I have not put a tape on the length but it should be a 45'- 48' span to allow for the saws to enter and exit the cut. The first set of rolls on the out feed are scissor lift which help with handling the heavier pieces.




Note, the end wall is there to stop pieces that get thrown by the saws, the rack at the end is full of such pieces.

[DanG]

BWS, have you been keeping up with the thread on mismanufactured bits?  If you have a batch of those bits, you could change them until you're blue in the face and still be sent off on wild goose chases.  If I were you, I'd plunder the junk bucket for a usable set of old bits and give them a try before getting too drastic with other changes.

Ron, on the MD there is all kinds of bracing on the off-side of that edger, since it never comes in contact with the wood.  It has a rather stout setscrew to adjust the lead, with double nuts on it, plus it has two bolts in slip holes to tighten and help hold it.  The setscrew prevents it from getting too much lead, but it is possible to knock the lead out of it.  That usually happens when a board hits something while being dragged back, and the saw will start to climb after that.  One learns to monitor the boards closely when dragging them back.  When it happens, you have to shut down and loosen the two clamping bolts to allow belt tension to pull it back against the setscrew.

That edger should be flying through the wood without putting any downward force on the beam.  It is not designed to handle any downforce other than the weight of the head.  A poorly cutting edger will easily pull it down or push it up.