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Every picture tells a story . . .


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. . . don't it?

 

Just back to the Florida shop. Left a 120 grit belt on the KMG. Fired it up for a minor job and all of a sudden it was Iwo Jima. BAM!

 

Luckily, the shrapnel missed my head. Not sure what happened. I left the AC on at 75 degrees all Summer, but the rubber on the wheel is all "gooey" like it was left out in the sun.

 

Cheers!

 

Dave

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Glad there were no casualties Dave.

On the bright side, you now have a really nice steel wheel for the belt surface grinder.

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You could always skive the ends of some very heavy leather and with contact glue make a surface on the wheel with just a little give in it if you were wanting to use if as a contact wheel

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Glad you're okay Dave.  It's bad enough when a belt breaks, I can't imagine having a wheel blow up.  I'll admit, there would probably be something "gooey" in my shorts if that happened to me.:P

Edited by Alex Middleton
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I had a new pair of boots that was sitting in a box in the cupboard for 2 years. When i took them out the rubber just disintegrated. Rubber often perishes quickly here but it it a very hot humid climate. good you were not hurt. 

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contact kmg they might have an idea or two what happened and can make a suggestion of how to keep it from happening again it also might benefit to do a material change say a synthetic rubber vs a natural rubber or what have you

 

 

i bet a lot of us will be going out to the shops and checking for sticky wheels right about now  

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I also have a KMG and several rubber contact wheels. They all live in the shop full time and the shop is not conditioned space. In the summer here, the shop can easily hit 120+ degrees (without the forge running) and considerably higher temps with the forge going. I have never had such a failure happen (knocks repeatedly on head as he types). I'm thinking some sort of chemical reaction.

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The fumes from stuff like acetone or lacquer thinner can do that.  Did you leave an open can of something like that in the shop over the summer?  Or maybe have one that leaked?

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It remains a mystery. This 8" wheel was the one that was left on the KMG by default. I have a lot of other sized wheels but I only put them on for a particular job, then put the 8" back on. 

 

The other wheels were sitting in a drawer a few feet away all summer and none of them are sticky and melted looking like this. To the best of my knowledge, no liquid has ever touched that wheel. 

 

Oh well, it's 2020. If my kiln gets taken out by a meteor I'll probably shrug and just say: "What next?"

 

Dave

 

On 11/2/2020 at 3:15 PM, Alan Longmire said:

The fumes from stuff like acetone or lacquer thinner can do that.  Did you leave an open can of something like that in the shop over the summer?  Or maybe have one that leaked?

I don't think so. And if it was that, the contact wheels on the KMG horizontal grinder 2 feet away should also be "melty" but they're not.

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To me the picture tells the story, Dave. The rubber looks gooey as you said it was. Something in the environment of your shop caused that! I had some tools that I had put into a bucket while working on my truck! When I went to get them to put them up in their proper place. I was shocked. They were all rusting. 

 

 I was working on the brakes of my truck and although brake fluid is very caustic. They were rusting even the chrome parts. It finally dawned on me that the bucket I placed the tools in was an old pool chlorine bucket! I chose the bucket because it had a screw on lid!  Even though the bucket had been rinsed well, the smell of chlorine was there when I unscrewed the lid. The screw on lid kept the chlorine contained and each tool began to react to it! Being from Florida you understand about the constant humidity! 

 

I had a buddy that I was over at his house recently and he was complaining about how all his tools were rusting up! The way he talked it was a recent problem! Walking around his shop I caught the unmistakable smell of Muriatic acid! It wasn't strong but it was there. When I asked what was in that bottle up on the shelf. He replied Muriatic acid. How long has it been sitting there without the cap on it!! 

To make a long story short the Muriatic acid was what was causing his rust problem!!

 

Another quick story! I once had a shotgun that was laying on a shelf in a cardboard box it came in. A container of gun solvent on the same shelf got spilled. It had ran over to the box that the shotgun was in! The cardboard held the gun solvent to that area of the shotgun and it ate through the bluing and actually etched the metal! This was in an area I was in every day but I never smelled the gun solvent till I opened the cabinet door!  

 

Start looking for an open container of acetone or something like methyl ethyl, or some rags you used to clean with and you never disposed of them! I would almost put money on it that the rubber was deteriorated because of exposure to some strong chemical! 

Edited by C Craft
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Questions Dave.

1. Is the entire rubber surface affected or just a portion of it? My guess is just a portion. That portion is either what was under the belt, or what was left exposed by the belt. The edges of the rubber are likely all affected.

2. Was the belt damaged as well?

3. If your grinder setup is still the same as in this thread, I would wonder what you keep in that red cup, and what you store below the grinder.

Edited by Joshua States
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Some polymers do that on their own.  When I had a real job in high tech, I spent a lot of time in the engineering group and one of the engineers had received a sample set of of different polymers that were approximately 2" squares by about 3/16" thick all held together on a beaded chain.  They were all different colors and had an identifying name and durometer printed on them.  I ended up taking the samples home as I thought they might be useful for some craft project but years later I found them in a work bench drawer with about half of them melted and gooey between ones that remained intact.  They were never exposed to any solvents.  So the formulas for this kind of stuff may be the problem as well as the source of manufacture as quality control from some locations may be lacking.  Another instance of this is some castors that I had scavenged off obsolete equipment headed for the dumpster.  Really nice high quality castors with clean room approved tires.  I put them on my welding/plasma cart and on my c-clamp rack.  Now years later the tires are crumbling.  Makes wonder about the longevity of all the polymer firearms out there.

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I had a similar problem with the original wheel on my RadiusMaster; it didn't explode, but had extreme goo....the maker said that there were some bad batches of urethane that caused the issue. The replacement wheel has held up for the last 6 years or so in my hot humid environment.

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On 11/7/2020 at 11:11 PM, Joshua States said:

1. Is the entire rubber surface affected or just a portion of it?

I was wondering the same thing, but for the opposite reason.  Maybe the binder in the belt was outgassing, and effected the rubber?  This seems very unlikely, but as Sherlock Holmes said...

 

21 hours ago, Gazz said:

 I put them on my welding/plasma cart and on my c-clamp rack.  Now years later the tires are crumbling.  Makes wonder about the longevity of all the polymer firearms out there.

The ozone from the arc is very destructive to rubber.  However, polymers in general are not all that stable over long periods of time.

 

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On 11/7/2020 at 11:11 PM, Joshua States said:

Questions Dave.

1. Is the entire rubber surface affected or just a portion of it? My guess is just a portion. That portion is either what was under the belt, or what was left exposed by the belt. The edges of the rubber are likely all affected.

2. Was the belt damaged as well?

3. If your grinder setup is still the same as in this thread, I would wonder what you keep in that red cup, and what you store below the grinder.

 

The whole thing is gooey.

The belt seemed fine, but it was torn when the wheel exploded.

That cup (long gone) was just filled with water to dip the blade in while grinding a fuller.

Nothing is stored below the grinder.

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  • 2 weeks later...

I have had similar things happen with polymer idler wheels on large drive belts on farm equipment .Get sticky and then disintegrate. I think it is some hydrocarbons are not bound in the polymer chain correctly and they separate  or seep out. Once that happens the remaining material is brittle.

 

Similar thing happens on my grinder belt cleaning block. It gets gooey , gums up my belts, won't clean and crumbles up.

 

So my rule is any gummy polymer gets ripped out before the explosion.

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either trace amounts of ferric chloride or acetone...degraded the rubber and made it gooey....been there done that....also wrecked a pair of steel toed boots that way...spilled some ferric chloride on the concrete shop floor....didn't really pay much attention walked thru it...and about 2 weeks later the rubber soles of my boots disintegrated

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