Warning and Caution

D

Diggerdog

Joined
Aug 30, 2005
Messages
173
I am usually pretty vigilant when it comes to safety but I nearly blew my head off today in what would have been a completely preventable accident. I had on a 60 grit belt and was profiling a couple of blades so I was going at it pretty hard and with no warning my grinder seemed to just explode. I shut it down, got my heart rate back under 100, and then tried to figure out what happened. The long and the short of it was the 2 X 5 inch pyroceram glued on to the platen had come free and was shot around by the belt. I found pieces of glass all over my garage and the biggest piece I could find was a small shard maybe 1/8 X 1/2 inch. The pyroceram just disintegrated. The whole thing scared the !/^*% out of me.:( It's something that I hope to never experience again.
 
You could re-title this thread: "Fun with Belt Grinders" because of the stories that may be coming.

It really is a potentially dangerous tool (like most of the more useful tools ever invented).
Every now and then I have a belt go off, and that's always a loud production because I run 'em pretty fast sometimes. I had one (2x72 36-grit) break just under the work rest, go all the way around and clobber me in the face shield and chest. It's always surprising just how fast those things come off the machine when they totally let go. WHAMM!
No injuries, though.
 
The same thing happened to Ray Rogers on the knifenetwork site, and he told all of us that a good safety precaution with the pyroceram liners is to make a little "foot" at the bottom of the platen, like a little shelf for the glass to sit on.
 
Hey Diggerdog , Glad you came out in one piece ! What was the adhesive you used between the pyroceram and the steel platen ? I'm running one too on my KMG (2nd so far , & mounted with JB Weld)
 
Glad to hear you are OK my friend. This world has enough things trying to kill us without our helping out. :rolleyes:

Don't know if it helps, but I tend the use the contact wheel for power - and then pyroceram platen for finess.

Rob!
 
I think the problem was the adhesive that I was using was not up to the task and the temp has not been warm enough lately for the glue to set properly. The next time I will try using JB Weld or possibly gorilla glue and leave the garage heated for at least 24 hours. I like the idea of making a little "shelf" for the pyroceram to sit on. Stay safe everyone.
 
Dave, sure glad it wasn't worse for you ,
make sure all the glass is out of you also..infection won't be a good thing for you I'm sure..

make a little "foot" at the bottom of the platen, like a little shelf for the glass to sit on
Click to expand...

that's a very good tip from Ray ,,thanks for posting that psycho :thumbup:
 
I had my pulley loosen itself off the motor shaft a while back. When it finally wiggled off the end of the shaft, it shredded the belt and did a scary 1000 mph dance on my bench before landing across the room. I now look my machine over a few times a week to make sure nothing loosens up. A catastrophic failure like yours is toughter to avoid...
 
Diggerdog said:
I think the problem was the adhesive that I was using was not up to the task and the temp has not been warm enough lately for the glue to set properly. The next time I will try using JB Weld or possibly gorilla glue and leave the garage heated for at least 24 hours. I like the idea of making a little "shelf" for the pyroceram to sit on. Stay safe everyone.
Click to expand...


Please do not use gorilla glue, 5-minute epoxy, or the like. You will get the best and most-permanent bond by roughing up the surface of the platen, and the back side of the pyroceram (using ceramic belt) and then by using a very strong 2-part adhesive such as JB weld, PC7, or the Devcon metal-filled epoxy putties. It is my firm belief that any clear epoxy (and this includes acra-glass, for all you Brownells fans), does not have the strength under heat and pressure like the metal-filled epoxies.
 
That is one of a couple reasons I used a hardened plate of 1/4" 01 on my platten. It has four 10-24 countersunk machine bolts threaded into the original platten. The only way it is going to come off is if I want it off. When the 01 was annealed I was able to get it very flat using a granite slab.
 
Maybe it's just me, but I've never been too pleased with results from JB weld, though others speak of it like it's the toughest thing going. (????)

Frankly, I'm not too fond of trusting ANY adhesive (short of NASA stuff ... and even then ... ) in this situation. There are some extreme conditions (heat/cool cycles and vibration) and the potential for disaster is certainly there.
 
Glad youre OK, that could have been bad, really bad.

My old steel one is about worn out, Im going to make a new one from D2.
 
That's two fellas that are using hardened tool steel . What kind of life are you getting out of them.I realize that is a loaded question because of the # of variables. I know you're a fussy kind a guy Bruce B. , how long has yours been on.Just curious. I like the idea of using SHCS's to mount it and I also like the idea of being able to machine any given radii onto the edge prior to H.T.for a nice plunge.I never have been able to get a consistant radius on the edge of the pyroceram.I'm sure quite a few like the sharp corner too. All IMHO :)
 
Mine has been on for several months and alot (100+) of grinding hours and no wear except for the some of the HT oxides have been polished off. When it does show wear it will be easier to use it as a template and make a new one then to resurface it. I was able to grind the top leading edge to a nice bevel as well as the sides for the type of ricasso I want.

When it does wear out it can still be used for other projects like filing jigs etc.

I have never used a glass/ceramic platten so I cannot compare the two. The 01 was surplus from a previous project for a friend and I estimate the cost was $8 for that piece.
 
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