hot circle blades

lord_kenwolf · July 23, 2005, 10:18:37 PM

today while sawing with my brother and dad, we got our big 50 inch sawblade hot. i seen them get a little warm and get a very small wobble to them before, but today went way beyound that. it was going a good 4 inches off center and i thought it was gona fold up like a piece of paper.

that has been the scarryest thing i have seen in a sawmill yet. when you see a piece of hard steel act like a piece of paper in the wind its not good at all.
my dad has always told us that he has seen big circle sawblades fold right over when they get to hot. i thought he was just fooling but i sure do believe him now.
i was wondering has anyone had that happen to them before on here ?

J_T · July 23, 2005, 10:30:01 PM

Not that bad but when I first started I busted a few shanks :

Now I set my guids real good and at the first sign of sawing off more than one sixtenth I re work the teeth .

beenthere · July 23, 2005, 10:48:02 PM

lord_kenwolf
I don't doubt your tale one bit. I've seen (and heard about) saw blades goin' nuts, saw one once while in a log (layed over and dove into the cant, and came to an abrupt stop) and once when coming out of a log (set up a wierd sine wave that really was scary to watch). I think maybe that is what is meant by a saw blade 'standing up' versus 'laying down', but will leave that up to the experts here to clarify.

You think you are in for a 'hammering' job now at the saw doctor?

woodhaven · July 23, 2005, 10:59:14 PM

If my 52" ever gets that hot I think I will run for cover.

Buzz-sawyer · July 23, 2005, 11:23:07 PM

I am in no way directing this at you just my take on running blades.........and some thingds your post made me think of

I think there are 2 completly seperate camps on saw maintanance.some folks ,"Just run em " others watch pamper and pay meticulous attention to the blade , AS it runs, Cuts and the sounds, vibrations and temperature.
To my way of thinkin a blade needs to never feel ANY heat to the touch...and it never will..IF we keep everything right and keep vigilant.
The only time I ever got one warm was when a piece of rubber used for catching dust rugbbed it.....it wasnt to hard to tell when it was warm..... :D :D
Others do things like throw buckets of water on the blade....and running a hose on it...I DONT RECOMEND THAT ;)
Saws have a few dangers in em inherently...but we can do a lot to hammer em make em stand up straight and run cold...

Ernie_Edwards · July 24, 2005, 06:13:25 AM

Very interesting stuff.

Does anyone know of a site where I can read up on hammering blades, the whys and hows?

Thanks,

Ernie

Fla._Deadheader · July 24, 2005, 07:28:28 AM

Lindsay Publishing has a few small books on Saw care, from the old days. ;D

That "Sine Wave" I can relate to. In the beginning, I was sawin a Post Oak. Wasn't all that big, but, about ¾ of the way through, something went wrong ??? Never did figure out what, so, I pulled the stick hard, and sawed on out of the cut. 8'-6" never seemed so long. The cut had about 14" to go, and when that log cleared the saw, The blade looked like a Butterfly.

It's a wonder that I didn't ruin it . Shut down, went for lunch, came back, and turned the blade by hand. Looked just fine. Put the file to it and S L O W L Y brought it up to speed. Stood tall and proud, so, I sawed for 4 more years with it.

It don't take much heat to make them things so crazy. The blade was only extra warm to the touch, right at the rim.

lord_kenwolf · July 24, 2005, 08:20:16 AM

we might have to get it hammered again but once it cooled down it ran perfect and cut true. we let it cool down by just letting it spin, then dad used to oil can and put a few squirts of oil on the blade. it ran great the rest of the afternoon.
usualy our saw stays cold, we are really carefull with it cause it costs so much to replace. the reason it got hot this time was when we was sawing the log, we got to the last 12 inches and it wouldnt go no farther, just a small little piece was hitting on the saw guide. so dad backed it up a foot and got the chain saw and cut that little piece off. i bet it didnt take 30 seconds to get that little piece cut off but in that time with the blade in the log it got hot. live and learn i guess.

Ron Wenrich · July 24, 2005, 11:15:58 AM

I've gotten saws hot, but it is usually due to a piece of wood that falls down between the offbearer and the saw. Sometimes you just don't see it, sometimes it happens too quick to do much about it.

When a saw gets hot, 2 things happen. Hot steel doesn't have the same strength as cold steel, so it won't stand at straight. You also have expansion in the hot steel versus the cold parts of the saw. That distorts the blade.

I had one get hot when a piece of wood got stuck at the saw guides. The saw looked like a pretzel. Left it run and cool down and it worked fine.

I never let a log lie next to a running saw. The only time a log is supposed to be next to the saw is when you're cutting.

D._Frederick · July 24, 2005, 07:09:23 PM

The No. 2 American sawmill my folks had was built with babbit bearings, after sawing a couple hours on a warm day, the saw collars would get hot from the heat of the arbor bearing. The saw would start to push into the guide and wobble back and forth. We had a 5 gallon fire pump pail that we used to cool the saw collars, then add some more oil to the babbit bearing, and go back to sawing. My dad could tell by the sound of the saw when it was getting hot.

ARKANSAWYER · July 24, 2005, 10:30:14 PM

Sawed a log that had been pushed over by a dozer one time on a circle mill. The shattered wood rubbed on the blade and some fell down between the belt and blade. The blade got so wobbly that it was nicking the conveyor belt that was about 2 inches off to the side of the blade. We just shut down log enough to pull the carrage back and get the wood out and started back up to let the blade run cool. Glad I was behind bullet proof glass.

Arthur · July 25, 2005, 03:02:15 AM

seen an old blade get hot.

the tips got smashed off and the blade damaged so the mill operator took the blade off and used it as a hot plate on the open fire for the cooked meat that night.

took the blade to the saw doctor the next week, had it hammered and is still using it now.

Jeff · July 25, 2005, 01:43:58 PM

Buzz, when a saw gets that hot its rarely due to a maintenance issue, but due to as Ron said, a small, unseen stick of wood caught somewhere causing friction.

Yes, I have seen saws that hot and its a scary thing and surprisingly when you say "Hot" you may still be able to lay your hand on it after you get it stopped. Its not that its so hot, its that the plate temperature is so different from rim to collar.

Actually, if you can, you should cool a saw with it running. If its something causing friction, you will have to stop the saw and remove the offending stick or slab, but get the saw started again and turning to cool down. You don't always lose your tension when you get a saw that hot, but you don't help it one bit thats for sure. I don't recommend spraying ANY coolant on them if you can possibly avoid it. If its cooling down and straightening out, leave it alone. Accelerated cooling is what will dash the tension.

sawmillsi · July 27, 2005, 04:00:36 AM

Hey guys,

I watched a mill in PNG cutting and that blade (about 5' diameter) was wobbling like crazy until it stuck timber, then it straightened up like magic and cut beautiful.

A electrican friend of mine said that he worked on a real big electric motor on a breakdown saw (blade about 7' or 8' diameter). It had an old fashion 2 speed starter.

When he started it up to check the work he had just down, the blade was flapping like paper in the wind until it got to speed, then it straightened up. Scary stuff!!!!

Petersons scared me real good one day, gave me a 6" gearbox with a 10" collar (took a R&D box off the shelf by mistake). When the blade got to about 4000 rpm it sounded like a jet engine and the blade started looking fluid like, I shut it down real quick!!!

Si

artenvielfalt · July 31, 2005, 04:58:25 PM

hi there, i had that happen too. we went to cut for a job and ruined 4 blades that day, all went hot and lost their tension. i would not try to hammer or tension them myself after that scarry day. i like to have safe and secure blades,so i called a blade body manufactor here in germany and they did the job for me. and it was very low in cost, so no problem there. after that i ALWAYS cool the blade with lots of water. it is safe easy and even cuts better with the water running.
ulf
peterson wpf 10"
germany

Peach · August 01, 2005, 06:21:45 PM

just thought i would throw my two cent's in ! ;D i serviced nearly 23,000 saws in allmost 27 years and all these responses are right on . i mean, it is like those dear hunting stories we tell every november ! ;D however , one of the biggest facters is sharpening teeth that should have been changed instead or the usual , slabs/bark between the saw and the husk frame, shanks that should be changed or poor tooth sharpening ! i am allways willing to answer any questions . one thing i have allways done ,was to be honest with the customer because the more they are informed the more $$$$$$$$$$$$ in their pocket ,after all when the saw ain't turnin' ya ain't makin any $$$$$$$$$$$ ' peach'

woodhaven · August 01, 2005, 07:42:42 PM

Peach,
Is a 48"saw with a 12" crack in the rim worth repairing? Its old.

Shamus · August 03, 2005, 10:37:03 AM

Weebles wobble but they don't fall down. Wondered why my saw kept trying to make a left hand turn travelling south through my logs...

My first 'blue eye', part of the learning curve (lower slopes of Mt. Everest). Nothing a little hammering won't fix!

Jeff · August 03, 2005, 10:41:34 AM

Shamus, you got that picture posting thang down boy! :D Great photo.

Shamus · August 03, 2005, 11:02:09 AM

Thanks boss! Had to review the rules first, now they're on a post-it stuck to my forehead.

Peach · August 03, 2005, 03:27:07 PM

Quote from: woodhaven on August 01, 2005, 07:42:42 PM
Peach,
Is a 48"saw with a 12" crack in the rim worth repairing? Its old.

Peach · August 03, 2005, 03:36:38 PM

woodhaven , do not under any circumstances , use that saw ! >:( in the old day's some would have welded it and most of the time the weld would hold . but, the times have changed , in particular... ... osha . not sure what some states do , but in mich . it is a posted law on their websight . i did weld some cracked saws years ago , but it is not worth the risc today ! :( if you find someone that say's they will do it , you know the can't be to professional . use that baby for a sign ;) mi. saw doc. 'peach'

Frickman · August 07, 2005, 03:53:55 PM

I've had hot circle saws a number of times, more than I should admit. Like listed above, most of the time it is caused by an unnoticed piece of wood wedged between the saw and something else. Sometimes it's noticed but you can't shut the saw down fast enough. One time it happened because the mandrel bearings overheated after a hired hand overgreased them. The bearings on a Frick mill, if in good repair, only need a few shots of grease twice a year, at Christmas and Fourth of July. Well, this hired hand proceeded to pump in grease until it came out of the bearings. I had to run the saw, without using it, several hours to work all the grease out. Anyway, there are other causes of an overheated saw, but foreign objects are the number one.

Jeff B. had it right in that if the saw isn't hitting anything, let it run free so that it cools properly. You do this to let the saw cool evenly. If it was sitting still the portion above the husk, with more air circulation, will cool faster than that below the husk.

Woodhaven,

I'm not a trained hammerman, but there is no way I'm running a welded saw with that big of a crack.

sawmill_john · August 18, 2005, 02:17:10 AM

I'd agree with peach, dull teeth, wrong angle, & worn shanks, are the most common cause of heating. The guys I used to trouble shoot for would sware up and down that the teeth were sharp, as soon as the blades came in for repair it was clear they weren't, I even had a guy bring back a saw one day after hammering, saying we don't hammer it properly, he made two cuts and it heated, when he showed up, every tooth had a corner broken off, he swore that he didn't hit any thing but the saw told the true story. There is no way to guess how long a tooth will stay sharp, they need to sharpened before they get dull, a sharp saw cuts so much better than a dull saw.