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Author Topic: Cupped Lapidary blade - home repair  (Read 1037 times)

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Cupped Lapidary blade - home repair
« on: December 11, 2017, 09:16:04 AM »

I have been testing a way to "fix" cupped blades that is so easy it is worth a try by more people to see if this thread should be pinned for the future.

The usual signs a blade is cupped or cupping is a slab that is tapered - thicker on one end than the other; excessive misting of the oil, seeing sparks coming from the side of the blade or a blade jamming in a cut.

I get all four at times but as soon as I see even one of these occurring:

1)  I stop cutting.
2)  I take the blade off and reverse the rotation (cutting) direction.
3) Use a hammer to sharpen the blade (tap, tap, tap not whack, whack, whack)
4) Cut a very wide but thin piece of very hard agate or jasper - at least 10 slabs.

So, far this has worked 100% of the time for me including "fixing" a 24 inch blade that was literally "tin canning" (bending out over 1/2 inch and staying there with an audible "thung" sound).

I told my partner about this and he tried it on a bent blade he was planning to toss as it was not worth paying to fix it and it totally worked for him too.

Between us we have used this on 24, 18 and 12 inch blades with 100% success.


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Re: Cupped Lapidary blade - home repair
« Reply #1 on: December 11, 2017, 04:19:05 PM »

Great post, I am going out to the garage this evening to switch blade around to see if misting and sparking observations are eliminated.


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Re: Cupped Lapidary blade - home repair
« Reply #2 on: December 11, 2017, 05:14:42 PM »

Excellent tip, Michael.  Thank you!


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Re: Cupped Lapidary blade - home repair
« Reply #3 on: December 11, 2017, 06:07:15 PM »

Thanks for the info. Really good to know, since I spend more time in the saw shop than anywhere. Just ask Robin... .


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Re: Cupped Lapidary blade - home repair
« Reply #4 on: February 11, 2018, 03:51:35 PM »

Sounds like very good advise.  I bought a very dirty "tile saw" at St. Vincents for $20.  It was a homemade 14" slab saw (gravity feed) that had been made out of a kit many years ago.  The blade had a lot of life left in it, but it was bent at about 30 degrees from something heavy being placed on top of it, since the top of the plywood box was missing.  I cleaned everything up and mentioned the blade to my brother-in-law.  He took it and slowly bent it back into shape.  Then he took it to his place and carefully restored it by hand until it was perfectly flat!  He is amazing.  I tried the blade and it cuts true.  It's astounding, what these blades will take and still be made useable. 
I like your method.  Thank you for the tip.
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