Gremlins in the shop

A

Andrew Holley

Well-known member
Anybody else ever get these?
I have a very large old metal band saw, that I use about once a month. It's a Johnson model J, made in 1963, probably my favorite tool in the shop. Every time I use it, I think about all the things it's made, and the different people that owned it, hoping my next project does it's legacy justice. Hopefully this summer, I will tear it apart, clean it up and repaint it. There is just a feeling I get using it, that I don't have with newer tools, similar to using old decoys.

Anyways, pulled it out yesterday and with the first cut, the blade pops off the wheel, put it back together, thinking that is odd, it's never done that before, heck in about 5 years I have never even had the blade off. Start again, off it come again, haven't even finished the first cut. Ok, maybe it's about time to change the blade, I run it dry. New blade, same thing continues to happens again and again.

I proceeded to spend the rest of my Saturday trying to figure out why it's doing this. Finally it stops and I can cut through some pieces, but now it won't cut straight, in a three inch cut it's off about 1/4", now I am wasting steel.
At about 7 PM I quit, it's been a bad day. I left open a beer and bag of chips, hoping if I feed the gremlins they will leave, if not, next step is to buy a gargoyle.

Hoping for more productive after church.
 
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Andrew
Check after church and see if the beer and chips are gone. If they are, there's your answer.:) :). Seriously, follow the Capt's advice.
wis boz
 
odd on an old reliable tool - maybe wear and tear has caught up with yours

but sounds exactly like the issue I had with the Grizzly I bought new several years ago

I bought it at a great sale price because I knew I was going to need one eventually- but it sat in the box well past its warranty date

When I put it together, I had the same issues as you are having - played with the tension until I finally gave up and let it sit for a long time while I used someone else's saw

then i really needed it when I decided to start cutting out decoy heads last year- searched the web and found a Grizzly video on you tube about how to check and fix an alignment problem

now- in the instruction manual - it says no alignment needed because its done at the factory - but here is a tech support video from them explaining how to do it on the model I have LOL

I did the measurements - got a bronze washer the right size for the lower wheel - and have never had an issue since- even after adding the riser block

https://www.youtube.com/watch?v=rxfZphxj2eM


hope it helps
 
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I agree with Capt. G. I had the same trouble years ago with my bandsaw. After many years of use every major and minor part becomes loose from vibrations, wear, etc. A through all day inspection, minor rebuild and adjustments cured the problems.
 
"Pulled it out" makes me think that it is the top pulley wheel alignment that slipped a bit... Mine is on a locking roller stand and will do the same thing when I move it a significant distance. I cut-up four sheets of tan cork this week. Had to spend a few minutes short of a half-hour realigning the guides and blade alignment settings after I put on the new blade. Forty-six bodies cut-out without a hitch.
 
Andrew, I have five bandsaws of various sizes in my boat shop. When we are busy, they are in almost constant use. Just like automobiles of the past, they need to be tuned up on a regular basis. There is an adjustment for the alignment of the upper wheel, which is the first place to look on your saw. The rubbing blocks and the blade rollers both above and below the table need regular attention. Most of my saws have a scale on the blade tension adjustment, so that you can put the proper tension for the width blade that you are using. The rubber tires, just like on a car wear out and lose their flatness, they get kind of a round cross section to the surface that the blade rides on, this makes the upper wheel angle adjustment much more critical, sometimes impossible. If this adjustment is just a hair off the blade will want to ride off the back or front of the wheel. While you are looking your saw over, blow it out with an air hose check it over for loose nuts, bolts etc, and a drop of lubricant of choice will not hurt. I have worked with big old ship band saws that were originally steam powered, they worked like new, I am sure maintenance was the key. I love my bandsaws, they are my favorite tool. Woodenboat magazine interviewed a famous old wooden boat builder some years back. In the interview they asked him if he was had to build a boat and could only have one powertool, what would it be? He replied " a bandsaw" Rich
 
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The rubber tires, just like on a car wear out and lose their flatness, they get kind of a round cross section to the surface that the blade rides on, this makes the upper wheel angle adjustment much more critical, sometimes impossible.
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Rich,

The statement you made is a common misconception and untrue as stated. Yes, the tires wear and thus the adjustment becomes less forgiving and hard to get set and keep in adjustment.

HOWEVER;

The wheel under the tire actually has, or should have, a crown to it. The tire itself is "flat" or in other words, it's cross section is the same thickness all the way across. Being thin and the same thickness, the tire will conform to the shape of the wheel underneath the tire. Thus the bandsaw wheel assembly WILL or SHOULD HAVE a crown to it.

ALL (with very few exceptions) machinery which employ a flat belt will have wheels, rollers, and pulleys that are crowned. Machinery which comes to mind includes; bands saws, belt sanders, belt conveyors and antique belt driven equipment. The crown is very beneficial and serves a critical function. Contrary to what one might think, any flat belt will tend to gravitate towards the highest point of the pulley or wheel. As machined, this crown will be in the center of the width, thus the belt or in this case the saw blade, will want to center itself on the wheel due to the presence of this crown.

Once the crown wears down or the rubber wears thin in the middle so there is no longer a working crown,,,,,, the tracking adjustment will, as you noted, be very difficult to achieve and maintain.
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Funny, reading the original post just reminded me that buried in the back of my shop is an old band saw that does the same thing. Maybe it's time to drag it out and see if I can't get it going again.
 
Dave. I guess you learn something every day. My modern day band saws have slightly crowned surfaces on the wheels, my antiques and metal saws are flat. I did some internet research on this, opinions vary among users kind of like ford vs, chevy. anyway when these tires get worn and ragged keeping the blades on is a problem and costs us a bunch in lost time! Rich
 
Boy o boy did you bring back a memory from a previous life as a young farm boy grinding cow food with a hammer mill belt driven off of a old John Deere A. The pulleys had a crown on them that kept the belt centered even if it got a bit loose or not perfectly aligned. It is amazing I can hear ANYTHING after that. Good call on the beer and chips.
 
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Well the beer and chips did work. Somehow everything is back to normal and cutting steel the way is was meant to. Now if I could just find some time to finish it up.
 
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