Keeping perfect edge on mulcher knives

[fishfactor]

If you run a mulcher with knives, you know how important it is to keep the correct angle and a flat surface from the cutting edge back at least 1-1.5 inches. New teeth cut like a razor. Trying to keep the correct angle and a flat surface with a grinder in the field isn't the easiest. It's hard for me not to sharpen the edge too much and develop a curved surface, especially on the fecon samurai teeth.

Found this 12" disc grinder(sander) at northern. It uses 12" sand paper discs. I was very skeptical at first concerning the life of the sand paper, but have been surprised. I took teeth that I had put in the scrap pile and got them back to good as new in 2-3 minutes each side. Actually faster than I could get them back to OK condition with an angle grinder. The table it comes with tilts both negative and positive, so you can get the angle you want.

I realize this will not be ideal for a majority of operators, but I found a solution that works for us. We run carbides most of the time, but put 10 knives in the middle of the drum when we are in large material. We have a large gas powered air compressor, so changing them only takes a few minutes with a 3/4 impact. If the teeth aren't bad, we touch them up with a grinder on the machine, but have found that we can actually save time when they get beat up to pull them off and get the angle and edge back to like new. We typically carry 30 knives with 2 sides. So if they are all sharp when we start, we can get 6 changes before we need to sharpen them all.

 

[ROWmulcher]

That's great, I'm gonna look into that

 

[fishfactor]

Don't be tempted by the 9" models. That's what I wanted to go with, but settled for this one. Turns out, 12" is perfect. 9" may be too small. These were on sale on their sight with free shipping. You'll need to order some more aggressive discs from MSC, ebay, etc. Northern only offers 80 grit. The 80 grit works, just doesn't last as long as the 24/36.

 

[yellowdogsvc]

Interesting. I've been recycling my used blades into the metal bin. I was concerned that as they wore down, my material would get stringy or chunky. I too run 10 blades in the middle of my mostly carbide drum.

 

[fishfactor]

Interesting. I've been recycling my used blades into the metal bin. I was concerned that as they wore down, my material would get stringy or chunky. I too run 10 blades in the middle of my mostly carbide drum.

It works. If you look at the bottom of the picture that shows a tooth being sharpened, you can see the end opposite the grinder that hasn't been sharpened. That's how bad they looked.

 

[ROWmulcher]

Ordered it up!!! Thanks for the tip. Gonna try both cimaf and samuris on it. Will update in a week or 2.

 

[fishfactor]

Just be sure to set your angle with a new tooth. Hope it works for you as good as it does for me.

 

[tmc_31]

Colby, that is a cool way to sharpen those carbide knives. As I was reading through the posts in this thread it occurred to me that their might be a better media to sharpen those knives with. I come from a machining background and many of my associates use diamond coated grinding wheels to sharpen carbide toolbits and end mills. Those of us who do machining as a hobby typically will use aluminum oxide grinding wheels to sharpen High Speed Steel toolbits. Those in the know say that the diamond wheels will sharpen a carbide bit 10-100 times faster than aluminum oxide wheels.

I am not sure if this will work for grinding mulcher knives or not but it may be worth a look as I am sure that the time spent in the field grinding knives is pretty expensive. I did a little web search and found a company that manufacturers 12" diamond sanding disks. I don't have a clue what they cost.

Give these a look when you have a spare minute:

Request Rejected

I know that this is slightly off topic but maybe it will be a help.

Tim

PS I don't know why the link is saying "Request Rejected" but click the link anyway, it works

 

[fishfactor]

These are not carbide, just steel. How would the performance of a diamond disc be in that application.

 

[tmc_31]

The way I understand it is if you use a diamond wheel to sharpen steel, under high temperatures during grinding, the steel will absorb carbon from the diamond wheel. This will shorten the life of the diamond wheel. If you are curious, it might be worth a call to UKAM Industrial to find out. Also they could probably tell you what the prices for the disks would be.

Tim