Question on releasing pressure on belt grinder

C Craft

C Craft

Well-Known Member
So I have this question on releasing the tension/pressure on belt grinder at the end of the day! So to speak.

The reason I ask this I saw something on another thread talking about releasing the tension off of the belt at the end of the day makes the belts last longer!!

I use to do it when I first started with my KMG clone but, now thinking back I don't do it very often anymore. I know it is supposed to make the belt last longer but,...........does it!

Most of my belts run until they quit cutting or I bust a belt. Most of my busted belts are do to operator error! Or you might say use/abuse!

That clone has became my go to machine most of the time. It is like, how did I not have 0ne of these years ago. My shop time is usually where I can steal it out of the day.

When metal fabricating I use it all the time as well!! I have begun to learn what (not to do) when using the machine and that keeps belts lasting longer. Grinding a weld, if you put too much pressure on when first starting, it is almost guaranteed to bust a belt. The hardness of the weld and the rough often pointed areas will cut a belt faster than you can say. $41t, I knew better than that!!! However nowdays I rarely release the pressure, unless I am pretty sure I am not going to be in the shop for a while!

So the question is do you release the pressure at the end of the day and do you feel it makes the belts last longer??
 
Cliff, I think all it does is to keep the belt from stretching. I take the tension off when I remember to, but that is not always. Over the years I have had 0ne 2x72 break, and 2 or 3 6x48's. All were older belts and very exposed to high humidity.
 
Good question, Cliff. I used to release the tension every time I was done grinding for the day. Then one day I asked myself why I was doing it. In all honesty, a j-weight belt is practically used up when I'm done with it. The belts that seem to last almost forever for general grinding (36, 60, 120 grit) are so thick that I don't think you can stretch them even if you wanted to.)

I don't see any harm in releasing the tension, but the more I thought about it the less I saw the benefit. It sure is nice to have a 120 on there all the time so that I can flip on the grinder and knock off a burr, etc whenever without having the belt go running off off the machine because I thought it was tensioned and wasn't.
 
In my experience releasing the tension isn't a matter of making a belt last any more or any less than it otherwise would.

The best reason I can offer to loosen belt tension is that if left under tension, the belt can cause flat spots on contact wheels, especially those 4" dia or less, and more so with rubber contact wheels versus urethane. I learned this the hard way when I was using rubber contact wheels. My flat platen setup has a 1 1/2" contact wheel at the top, and a 3" contact wheel at the bottom. I took off for a knife show, and left a 50 grit belt under tension on one of my grinders the whole time I was away (5 days). When I turned the machine on a day after getting back home, there was a distinct thumping as it ran, and when I started grinding on it, lots of "belt bang".

After investigating, I discover distinct flat spots on both the contact wheels. It was obvious that the belt tension had caused the flat spots. Long story short, I had to replace both contact wheels. (took them off and kept them, hoping the flat spots would "spring" back....but in never happened) I got myself in the habit of loosening the belt tension ANYTIME I shut the grinder off. A few of my knifemaking friends have experienced the same thing, and a couple have told me the situation can occur on their machines just by leaving the belt tension on overnight with rubber contact wheels....and the smaller the diameter the wheel, the worse it occurs.

I would suspect that urethane contact wheels would be less susceptible to the problem then rubber, but as I said, I make it a habit to loosen the belt tension anytime the machine isn't running.
 
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I generally do at the end of the day. I never heard about flat spots, but have found that belts tend to curl up if you leave them stretched.
 
I didn't know that it was a common practice to do so. (I'm relatively new to the 2x72 grinder). I always release the tension, every time, due to some small amount of OCD. I figured it would prevent the belt from stretching, but honestly couldn't tell you if a belt really stretched or not if left under tension. (May depend on the belt?) Sorta like the quench during tempering....I just do it. Doesn't hurt, and may be of some small benefit.
 
I never leave belts under tension on my grinder when I'm finished using it for a day or so. I think it may be related to the humidity where I live but I've had belts in the past that seemed to pick up wobble and not run true if I left them under tension.
 
Here in Fl. I find the humidy and heat to be the worst culprit in belt beakage. If you abuse a belt and it begins to look worn, it seems the humidty will get it faster after that. My shop is not cooled except by doors open and a fan to move the air. This summer had been higher heat and humidty than any in a long time. We have had rain here almost everyday since summer arrived way above normal and somedays it feels like you could ring the moisture out of the air. However I have only broke one belt and it was brand new . Only ran a time or two and the breakage of it was operator error! :eek: I let a piece get loose and it jambed between work rest and the platen. Before I could hit the kill switch it blew the belt!!!

Now Ed brought up a point I had not given too much thought and the is the flat tire effect on a rubber wheel. If I am using my 10" Grizzly wheel I had bearing pockets cut in. I always slack the belt if I am done for a while. I have too much invested there to ruin it!!

However I probablly do 90% of my grinding on the platen. Which mine has rubber tires. I hadn't noticed the flat spot effect but that could be do to the angle I have the platen at most of the time. My platen is probably set at about 30-40*.
Still the pull over the rubber wheels at the top and bottom edge of the platen should give the same effect.

Maybe it has more to do with pressure on the tensioner! My clone has a spring I picked up at the local hardware store and it has always held to belt tight enough for me!! I don't really have any idea on the pressure it holds. I just fully compress the spring and slide the work arm forward and lock it off!!

Hmm, it is food for thought. I am gonna keep an eye on the rubber wheels from now on!!

Ed. let me ask you a question when you flated the rubber tires was it cold?? Reason I ask is becuase I was born and raised the first 17 years of my life in middle of Nebraska. I still remember driving a cold tire first thing in the morning in dead of winter. Thump, thump, thump, thump, till they got warm and rounded out again!! Maybe it has more to do with region. Most of the time its hot, or at least not cold here even during the winter months!! Usually we have a cold spell of a few days, it warms up and rains. And repeat!! That is why Florida has such small deer. No need to bulk up for the heat!! :D Also that is why I freeze when the temps drop below 50* Time to ditch the shorts and find the long britches!! Not complaing just bragging!!! LOL
 
The time frame had to be in early spring, because it was the Oregon show that I went to..... but then again, April in Montana is often below freezing and snowy. :) For me the weather wouldn't have been the culprit....my finish shop (where the grinders reside) is heated and set on a programmable thermostat..... 45F at night, and 66F during the day (at least for the heating side), the finish shop has a swamp cooler for the "hot" month (yeah, that's singular) :)

The Blacksmith shop has in floor hot water heat, and the thermostat stays set on 55F year round.

I spent my first 5 years in Montana without heat in the Blacksmith shop....that's just miserable when it's well below zero and you gotta heat up EVERYTHING in the shop in order to use it. :)
 
EdCaffreyMS said:
The time frame had to be in early spring, because it was the Oregon show that I went to..... but then again, April in Montana is often below freezing and snowy. :) For me the weather wouldn't have been the culprit....my finish shop (where the grinders reside) is heated and set on a programmable thermostat..... 45F at night, and 66F during the day (at least for the heating side), the finish shop has a swamp cooler for the "hot" month (yeah, that's singular) :)

The Blacksmith shop has in floor hot water heat, and the thermostat stays set on 55F year round.

I spent my first 5 years in Montana without heat in the Blacksmith shop....that's just miserable when it's well below zero and you gotta heat up EVERYTHING in the shop in order to use it. :)
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Sheeez. talk about pampered!!!!! Not, that sounds like a set-up that works. I spent a lot of time in Montana, Idaho and Wyoming in the early to mid 70's. Had plans to go back out there before I married a Florida girl. Ain't life funny!!

Mine is not heated but that is not really a problem. IF it gets cold enough firing the forge for a few minutes will take care of that. So fall and winter is my busy time. The summer however well we have hit some triple digit temps and factor in the humidty and much of the summer is like 104-110* feels like temps!
Even with a fan you are blowing nothing but hot air. Now I still won't give up my fan and you would die without it. Little forging in the summer, except early in the morning and late at night. My neighbor asked me a while back WTH where you doing about midnight the other night. Not me, :eek: :rolleyes: you must have heard the other neighbors dogs barking!!!
 
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