When a bandsaw blade breaks....where does it go?

[jrokusek]

Does it follow the sawdust......does it go the opposite direction of blade travel....does it break in a random spots and go wherever?   I'm just trying to mentally design some blade guards on my homemade mill.

I've noticed on some homemade mills that the back of the bandwheels are exposed and that doesn't seem safe to me.  Since I don't know....I thought I better ask.

Jim

[Bibbyman]

They can go about anywhere so guard all directions - including putting rods in the dust chute.

Another thing to watch for the blade jumping off.

Here is a link to an older post on the topic.

https://forestryforum.com/board/index.php?topic=3382.msg44207#msg44207

[Tom]

Broken bands will usually try to go out of the sawdust chute.  You will also find them bunched up inside of the shields where they hit the metal and bend. 

On mills with brakes on the band wheels the momentum of the band is stopped pretty quickly.  On mills with no brakes on the band wheels, and especially those with drive belts inside of the Shroud, The band can be broken in several pieces and become a projectile. this usually happens in the direction of sawdust flow and, unless you have an obstacle in place, can send the piece flying 50 feet or so away from the mill.   Broken bands on a machine that is still driving the wheel can cause the band to spiral out the front of the shroud and whip an area on the driven side, five or more square feet.

The side of the mill containing the Drive wheel is no place to work.  I have conniptions when someone gathers a handful of sawdust from the chute.

You will appreciate the value of Doors on the front of the Shrouds on the driven side if you examine an "old warhorse" mill that has a bit of experience.  The bottom edge of the door will probably have it's metal cut significantly and the sawdust chute will show signs of impact.

The area around the idle wheel is a war zone too, but seldom does anything come out of the shroud on that side.  The band either loses contact with the wheel or the wheel becomes jammed and stops.  The driven side, without brakes, is a different story.   The broken band is continually whipped, bent and macerated until the driven wheel can be stopped.

I wouldn't trust a mill that had open band wheels.  They should be covered front, sides and back.  As much as possible the part of the band that isn't in the log should be covered with solid metal.  Some mills have shrouds (guards) made from expanded metal.  I don't like that idea.  Don't give a piece of a blade any chance of getting out of there.

Watch your help!    Don't let anyone work  to the side of or in front of the head of the mill.  Some off-loaders will want to remove boards from the end of the cant where the blade exits.  I discourage this practice.    If that is the only way the mill can be off-loaded then the off-bearer should wait until the head of the mill has been returned to the front of the cant and the blade has stopped or is over 15 feet away.  Keep in mind that the average mill has a 13 foot long band, and many approach twenty feet in length. 

You may not get a second chance to be safe.

[SwampDonkey]

My father was terrible for not putting guards back in place when working on machinery. This machinery was used in potato handling and the belts and chains that run on them are moving quite fast. One day a young girl, under 12 years of age, was standing along side a conveyor belt with a chain drive and it caught a piece of her loose clothing and made of revolution around the cog. It didn't catch her arm, but gave her enough scare to stay away from the machinery. The chain was also unguarded as usual.  :

[jrokusek]

That's what I thought.  I never considered putting rods in the dust chute.  Looks like I'll be doing that now.  Good stuff to know.

If I am reading this correctly, the tops and sides of the guards probably take the greatest amount of abuse, where the front and back of the guards take a bit less.....but still take some beating.  So a bunch of flattened beer cans won't work after all.  Just kidding.

On another note I went to my favorite steel shop and found they were out of everything that I needed, but they started selling their cutoffs for 25 cents per pound.  They also have a pile of stuff like smaller pieces of sheet steel....just like I'll be needing.  2" solid round stock (shaft), round steel cutouts (good for target practice) and literally "tons" of other goodies.  I'm more of a woodworker but this place could be a lot of fun. 

Thanks again!

[Back40x2]

   Mine always seem to shoot out the shoot!  Just had one yesterday >:(

[Brucer]

When I started sawing for Louis last summer, he walked me around the mill '(96 WM LT40HD) and showed me all the safety features and where the danger points were. There were three fingers (1/4" diameter rods) pointing straight down across the sawdust chute to intercept broken blades. Of these, the middle one was broken off (from repeated impact) and the front one was bent flat along the top of the chute. There was also a big rip through the upper part of the chute where a blade went past the broken finger and punched right through the 1/4" thick reinforced neoprene chute. It gave you a pretty good idea of what would happen to your rib cage if you happened to be standing right there when the blade broke. On my 2005 WM, the "blade catchers" are made from 1/4" thick flat bar, mounted edgewise.

In one summer of sawing, I'd say about 1/4 of the blades broke and stopped in the cut. 3/4 of them tried to head out the chute, and bent up there as Tom described. Those seem to be the most common ways a blade breaks, but it's the uncommon ones that can be deadly 'cause you're not expecting them.

The one I didn't see (and it must have been pretty hairy) was when a blade broke just before reaching the idler wheel. It jumped forward off the wheel, bit into the bottom of the blade guard cover on the front side, ripped it right off, and threw it the full length of the mill. Think of a 2' diameter steel Frisbie. There was a 1" long cut right through the heavy guage cover where the blade cut into it.

One bit of advice -- make it easy to remove and replace the guards where you change the blades. If it's even a little bit difficult, it's tempting to leave them off "just today, 'cause I'm in a hurry."

[UNCLEBUCK]

I dont have a bandmill except for a 16 inch for woodworking in the woodshop but I have a 1 inch blade on it sometimes and slap a 8 foot long x 7 inch log on it and square it up and saw away . I learn alot reading others bandmill stuff. When I break a blade it just pops and stops pretty quickly after my heart stops pounding !

[Swede]

Doing my new guard I only left it open under the driven wheel and between the wheels. The best thing I did was; upper part of the blade is covered on all four sides. Have broken some blades but they all stayed inside the guard exept  maximum 3 ´.
I can start the blade with opened doors but not saw, so why should I leave them open?
I use 13´as "dangerous area".

One day I´ll put a circuit breaker to the doors so the engine can´t be started , that´s what the regulation says.........

Never check the temp. of the sawdust by taking it from the outlet with Your hand! [/b]I think no smoke  :D and straight boards tells me the blade is good.



Swede.

[Percy]

Another safety tip is to use your blade guide arm as it was intended. The "set and forget method" is not a good idea as I learned on my old LT40.  Had a blade break when the blade guide arm was wide open and there was alot of exposed blade before it entered the log. That particular blade broke and hit the log, possibly a knot, and turned around and went nuts on the idler wheel side of the machine. The whole freakin blade was in the log loader by the time it ran out of energy. I admit this probably wouldnt have happened if I had been using the blade guide arm properly but as said earlier, there is no real safe place near the blade when its doing 50-60 MPH.

[Kirk_Allen]

"where does it go"

It goes to blade heaven :D

[pigman]

"where does it go"

It goes to blade heaven :D

Unless it was a bad blade ;)

[Swede]

It goes to blade heaven

:

Unless it was a bad blade

:

Hmmmmmm, Seems to me that the right answer is: You´ll never know!  ;)

Swede.

[jrokusek]

Lots and lots of good info!  Thank you all.  I'll definitely beef up my guards.  I'll most likely wind up covering the entire bandwheel so you probably won't even notice it's a trailer tire unless you get up close!   :D 

[mike_van]

I had a wheel "blow up"   I built my most of my own mill, about 15 years ago, and one of the fabricated steel 24" wheels came out with a wobble in it -  enough that it made the machine vibrate.  In all the "stuff" I collected, I had an old cast wheel, just happened to be 24" dia.   I trued it up on a brake drum lathe, made a bushing for the bore, glued a belt to it for a tire, and started sawing.  On the second log, the wheel let loose.  My wife was home, 200 yards away, she heard it.   I heard it too, I was 8 feet away.  About 2/3 of the rim & those spokes were in a pile under the idler side, blade was wrecked, as was my confidence in choosing wheels. No injuries, thank God.  I've since bought Browning Poly V sheaves, 24", belt glued in the rim, rpm stamped on the wheel,  and have been "sawing smooth"  for quite a while.  Moral???   Don't even think of pushing the start button with the doors open!!!!!!!!

[Cedarman]

A big thanks for reminding me to have a safety meeting with the help Monday morning.  I have been guilty of catching a little sawdust out of the shoot. I know better, but not thinking better.

I would go absolutly balistic if I saw a mill operated with out the shields.
Our scragg breaks blades regularly. The blade speed is about twice the WM speed and when a blade goes it really goes.  We have had them shoot out the sawdust vent through heavy duty PVC elbows.

Thanks again for the safety reminder.