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Carbide knives chipping while grinding.6/9
The issue I'm having is, while sharpening carbide knives I'm getting chipping in the knives as it comes over the knife rest. It doesn't happen on all knives and it only happens in certain spots in the profile. I've tried everything I can think of from replacing the rest to even shimming it up so the knife lays flatter. Has anyone else ever had this problem, and if so how did you fix it? It gets so frustrating!!!
The grinder I'm using is a R960 with Powerlock heads.
What type of carbide are you grinding inlaid or double back? If your are grinding inlaid carbide there could be an issue with the type of filter your using, if debris is getting past the filter and into the coolant water then you spraying finely ground particles right into the carbide and it would cause chipping in the carbide. The first simple solution (cheap) is to start with fresh coolant water and see if the problem disappears. I think your problem lies there.
Thanks for the suggestion Russ! I will give it a try. It would make sense that it would be something like that because it doesn't happen all the time, but when it does, it's impossible to stop, makes you want to pull your hair out!! i usually just keep trying different things until I get at least one knife to clean up. The strange thing is, it will happen in exactly the same spots of the particular profile on both knives.
The knives I'm grinding are 2 piece, both Weinig and other styles. I'm using the large Weinig filter sheets as well, but it is definitely time for a change of water and filter right now.
That would make sense, I would tend to bet the spot you're talking about is a pinch area where the knife comes close to 60 - 90 degree, this does not allow the water and debris to move out of the way quick enough and it chips the carbide.
Something else to consider is the age of the carbide and how you may have cleaned it. Many tool cleaning solutions and coolants can leach the cobalt out of the carbide. This happens sometimes quickly and with other chemicals it can take several cleanings. The carbide will begin to chip some and will not hold a keen edge.
I agree with Russ as well and just wanted to add a little.
Dr. David Rankin
Dr David is correct. To add to that, I would check to see if the carbide was brazed in with shim stock. If not, this will help with SOME cracking, not all I may add. my2cents
It sounds as though your knives may have slight fractures. Especially if it occurs in the same spot all the time. This is very difficult if not impossible to see with the naked eye.
Just wanted to post that I figured out what the problem was. It ended up being that the knife rest pedestal was bent causing the edge of the knife to scrape the edge of the knife rest. It must've gotten hit with the motorized positioning at some point.