Wear of contact wheel

Stacy E. Apelt - Bladesmith said:
First, contact Beaumont/KMG. Tell them what the issue is and show the photo.

Second:
Make sure the belt is tight enough. If the tension is too low the belt will move to the side as you apply pressure in grinding. That can expose the edge and you will be rubbing the blade on the rubber ... which will make those marks.
Check the tracking. It should be even on both sides or just a tad to the right ( for right handed people). If the belt is not tracking right, it can expose the edge and you will be rubbing the blade on the rubber ... which will make those marks.
If the belt wobbles (usually caused by a cheap belt or a bad seam) it can expose the edge and you will be rubbing the blade on the rubber ... which will make those marks.
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Thank you. I already show this image to Beaumont Metal works. They said it's normal. But I also wanted to hear the opinions of the users.

IMHO, my tracking was perfect. I don't think that scratch was caused by a blade.
 
logem said:
Vulcanized (cured) rubber has a limited shelf life. I managed rubber development for a high performance rubber company for 6 years. Rubber will em-brittle and harden over time and bonding agents which adhere the rubber to metal substrates will deteriorate too. Best case, is to store in a cool environment with low humidity for best storage life. In ideal situations, rubber should last 20 years. In moist or warm environments, it will perform much less. Of course, odds can have an effect too, in which one product may fail early. This is because of the many variables involved with mixing rubber compounds, molding them, etc.

Those of you who have 20-year old contact wheels probably have contact wheels which are much harder than they were when you purchased them.
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I hear you. But this rubber didn't get hard and brittle. It got sticky and actually fell apart just sitting there. You could sink your fingernail into it like butter. Stored inside, in a climate controlled work space. I'm sorry dude, but there's something wrong with that. I don't know as much about rubber as you do, but I'm thinking either substandard material or a problem with the manufacturing process, but there's no way that wheel should fall apart like that in 5-10 years. Perhaps some cheap chicom crap, but this was supposed to be a quality wheel.
 
Nathan the Machinist said:
I hear you. But this rubber didn't get hard and brittle. It got sticky and actually fell apart just sitting there. You could sink your fingernail into it like butter. Stored inside, in a climate controlled work space. I'm sorry dude, but there's something wrong with that. I don't know as much about rubber as you do, but I'm thinking either substandard material or a problem with the manufacturing process, but there's no way that wheel should fall apart like that in 5-10 years. Perhaps some cheap chicom crap, but this was supposed to be a quality wheel.
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Maybe polyurethane wheel ?
 
Nathan the Machinist said:
I hear you. But this rubber didn't get hard and brittle. It got sticky and actually fell apart just sitting there. You could sink your fingernail into it like butter. Stored inside, in a climate controlled work space. I'm sorry dude, but there's something wrong with that. I don't know as much about rubber as you do, but I'm thinking either substandard material or a problem with the manufacturing process, but there's no way that wheel should fall apart like that in 5-10 years. Perhaps some cheap chicom crap, but this was supposed to be a quality wheel.
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how old is your wheel Nathan? I have an 8” from them that I bought back in like 2005. Last time I used it it was running strong and I don’t store it any special way. I will pull it out and give it a look over to see how it looks.
 
JTknives said:
how old is your wheel Nathan? I have an 8” from them that I bought back in like 2005. Last time I used it it was running strong and I don’t store it any special way. I will pull it out and give it a look over to see how it looks.
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I think mine was bought new in 2007. The rest of the grinder is fine.
 
Should return that TX for a Northridge. Better grinder all around. George takes care of his customers as well.
 
I have Bader wheels that are 20 years old, and some from Ron Frazer that may be 40 years old. None have fallen apart, with one exception. Any nicks were caused by blades accidentally hitting the side or similar accidents.

The one exception was a 10" whee; that I was doing a hollow grind on. The edge was pretty sharp just from the grinding. I was cleaning the grind up post HT with a 400 grit wheel ... edge up ... and it grabbed the belt, cut it in half, and took a nice chunk out of the wheel. The knife rocketed to the floor between my feet. I had to check my pants to see if there were other chunks.
 
Stacy E. Apelt - Bladesmith said:
I have Bader wheels that are 20 years old, and some from Ron Frazer that may be 40 years old. None have fallen apart, with one exception. Any nicks were caused by blades accidentally hitting the side or similar accidents.

The one exception was a 10" whee; that I was doing a hollow grind on. The edge was pretty sharp just from the grinding. I was cleaning the grind up post HT with a 400 grit wheel ... edge up ... and it grabbed the belt, cut it in half, and took a nice chunk out of the wheel. The knife rocketed to the floor between my feet. I had to check my pants to see if there were other chunks.
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I recently had something like that happen, it sure makes you rethink everything that led up to that. Mine was a small pocket knife of my dads. He stopped by to get me to sharpen it which I did on the belt grinder and then headed over to the buffer. He was talking to me the whole time as I was working. While working the buffing wheel I went to switch to the other side of the edge and some how the very tip of the blade caught the buffing when. In a split second the blade was gone. Like gone from the rest of the folder. Snapped it clean off close to the pivot. I look down and it’s sticking in my pants. I lucked out as I was not hurt Besides a small cut on my support finger. it really drove home the fact to stay focused and give every machine the respect it deserves.
 
Recently, I bought a KMG 8-inch contact wheel and there was a similar scratches. I think the scratches on the 10-inch wheel was also made during manufacturing.
 
Sharpco said:
Recently, I bought a KMG 8-inch contact wheel and there was a similar scratches. I think the scratches on the 10-inch wheel was also made during manufacturing.
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I think to :) And I think that you are right .......that was not scratches but voids in rubber from molding process.........nothing bad I wouldn't worry about them :thumbsup:
If you think on this scratches

a2PC9eF.jpg
 
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Nathan the Machinist said:
I hear you. But this rubber didn't get hard and brittle. It got sticky and actually fell apart just sitting there. You could sink your fingernail into it like butter. Stored inside, in a climate controlled work space. I'm sorry dude, but there's something wrong with that. I don't know as much about rubber as you do, but I'm thinking either substandard material or a problem with the manufacturing process, but there's no way that wheel should fall apart like that in 5-10 years. Perhaps some cheap chicom crap, but this was supposed to be a quality wheel.
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One consideration in the deterioration of rubber is ozone. It is given off by electric motors. It affects latex rubber more rapidly than vulcanized rubber. We used to store our bicycle tires in the basement by the motors but moved them to a safer area when we uncovered the problem. The silk sew up tires were the worst. The side walls were latex with a vulcanized road strip. The latex construction was very flexible (in search of the perfectly elastic collision/deformation), but the stuff was adversely affected by salt, sweat, grease/oil, UV light, ozone, solvents, etc.
I am driving less than I used to. My car tires are wearing out before the tread does particularly on lower use items like trailers.
 
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