How do you know when to get your blade rehammered???
You shouldn't have to have a saw hammered very often , unless you get it real hot , or make a set while in the cut . If your saw won't stand up straight at it's speed probly needs hammering.
Lyle when it gets snakey,wobbles at its hammered speed,and gives you fits.Its usally caused by heat.Most of the commercial mills I've talked to have it hammered at least once a year usally going into the winter season,unless something happens.Painfull leason,on my first mill with a freashly hammered saw a piece of bark got stuck unseen rubbing the plate heated it and the saw was all over the place had to have it rehammered. Frank C.
I think I heated my blade to many times, I made an appointment with the saw doc on saturday. I tried my other blade and it seems to have a wobble in it also, It hasnt been used since it was hammered and sharpened, maybe just from sitting???? I dont know????
Make sure the RPM you are operating is the same as the "hammered speed" stamped on the blade. If you turn it at
540rpm (normal PTO speed) and it's hammered for 900, it will never stand up straight.
I agree with the others, heat it the common culprit. Hope you get it figured out.
You wouldn't be getting any sunshine on your blade, would you?
Getting it hot just once can sometimes do a number on a blade.
Im back in production! I removed the 48 inch blade from the old mill I bought this winter and give it the on the ground test and it seemed allright. I then put it on my mill and made it rotate and it run true. I put a new set of teeth on and sawed a few logs and I think it should be OK. I didnt think that old blade would run true because it sat out in the sun for years. 8)
Sitting a spare in the sun isn't going to harm a blade. It wo't get hot enough to harm it by simple sunlight. The change in the way a blade saws in regards to the sun is for a saw in operation. Going from shade to sun or vice-versa can change the way it performs.
so a circle saw blade is concave or convex from the center point?
as it rotates it straightens out the blade to give it reinforcement during the cut?
a straight blade would wobble and move if kept straight and brought up to rpm?
A circle blade is concave on the lumber side. That is, the teeth are further from the log than the eye when stationary.
As the metal stretches as it spins, a concave blade can expand slightly, making the blade straighten so that it is essentially flat when at full rpms. If it were straight when stationary, then when spinning, the expanding metal would create waves along the saw.
Note the at the guides prevent catastrophic deviations for a large blade, but do not guide or steer the blade.
Ok?
thanks doc,
I have never been around a circular mill. I do find them interesting
That's where guys get into trouble. Trying to steer a saw with the guide pins. As Gene said, they are there only to stop catastrophic movement, to keep you from hitting the carriage in other words.
QuoteI have never been around a circular mill. I do find them interesting
Tom
For some reading that you might enjoy, here is a good basic circular sawmill read.
http://www.fpl.fs.fed.us/documnts/misc/circsaw.pdf
jeff, how long would a blade cut for you when just sawing logs,... meaning not hitting trash or other stuff that lessens the blade?
I've had the same saw on the arbor for as long as over a year at times. Then there are the times were its only been on for one day, or even part of one day. 8)
did you have to sharpen or change bits during that time? sorry if that sounds stupid but i know very little about circle mills, watched a nice one for about two hours one day, my total experience. ::)
Oh Yea, certainly. I'd probably sharpen every two hours. Bits might average 150,000-200,000 feet sawing debarked aspen. That would be a weeks production.
wow, more than i thought. the mill i seen was just sawing logs , bark and all, i do believe they pressure washed them though before sawing.
Sawing with bark on will really kill the life of the bits. Just like with a bandmill blade. That bark hides a lot of grit, even if it is power washed.
that is true, i like the logs peeled if i can do it. not dragged preferrably.
I'll start by saying that high production is not in my vocabulary but...
If everything goes along without any issues, when we shut down for lunch I will sit down and file the bits. I like to keep ahead of them and not let them get too dull, it saves time and wear.
A sharp saw is a happy saw.
Alan
Ok. back to the blade and hammering.
Just want to see if I understand.
A blade is hammered to put a concave into it.
The blade then stretches as it is turning to make it straight.
So a blade that is Hammered for a higher speed would have a deeper concave because it would stretch more with the higher cintrifigal force?
Are there known specs for the amount of concaveness for a given blade diameter? Metal type? Or is it more of an art form getting the concave right?
Quote from: Jeff on April 04, 2013, 04:13:04 PM
Just like with a bandmill blade. That bark hides a lot of grit, even if it is power washed.
smiley_thumbsup
Quote from: steamsawyer on April 04, 2013, 04:34:53 PM
I'll start by saying that high production is not in my vocabulary but...
If everything goes along without any issues, when we shut down for lunch I will sit down and file the bits. I like to keep ahead of them and not let them get too dull, it saves time and wear.
A sharp saw is a happy saw.
Alan
Steamsawyer... more true words have never been spoken. ;D ;D 8) 8)
moosehunter
A new saw from the factory will generally have little or no "concave" on the log side. It will however have some convex on the board side. Thats if it is a split gauge saw. Example 6-8 Ga. or 7-8 Ga. However most scragg saws are a straight gauge and are therefor flat on both sides of the saw. As far as more or less "concave" for a higher speed those are two different things when checked by your hammerman with the saw in two different positions. So there is no difference in the "concave" for diferent speeds
Smaller saw blades, like my 40 inch Belsaw blade, have no dish. They stand straight when not running. Larger blades are hammered to stand up straight when running.
Quote from: moosehunter on April 04, 2013, 04:36:41 PM
Ok. back to the blade and hammering.
Just want to see if I understand.
A blade is hammered to put a concave into it.
The blade then stretches as it is turning to make it straight.
So a blade that is Hammered for a higher speed would have a deeper concave because it would stretch more with the higher cintrifigal force?
Are there known specs for the amount of concaveness for a given blade diameter? Metal type? Or is it more of an art form getting the concave right?
I had posted some pics of a blade being hammered a while back.
Quote from: Jeff on April 04, 2013, 04:13:04 PM
Sawing with bark on will really kill the life of the bits. Just like with a bandmill blade. That bark hides a lot of grit, even if it is power washed.
Jeff, I have some stelite bits and new shanks coming tomorrow??? Im itchin to try them out. I have only run soft bits so far
I hate to tell you this, but anytime you are putting new shanks in a saw, it should be retentioned.
Quote from: Jeff on April 04, 2013, 11:32:17 PM
I hate to tell you this, but anytime you are putting new shanks in a saw, it should be retentioned.
Dang! LOL
Jeff,what would the odds be if Lyle replaced the bits and shanks and ran the saw.?Would changing every outher shank and running for a wile help.?? Frank C.
I would change them all and try it. You can always send it in if you can't make it saw. The reason for new shanks is to make the saw run efficiently if the old ones are causing problems. it makes no sense to me to change only half of them.
Jeff,perhaps its an old wives tail,many of which haunt our industry,that replacing every outher bit and shank then running the saw and later replacing the rest will somehow negate the need to rehammer.Personally I have doubts and never hesitate to have a saw retentioned,but some sawyers tend to be frugal to the point of cheap. Frank C.
Maybe it works, I don't know, but maybe you just end up with a saw that never ever reaches it's potential.