Trouble with #12 grinder knives. Standard square center hole size??

[cdherman]

Ok, bought an off brand #12 grinder. A nice heavy Vevor. Thing is clearly a pretty good chinese copy. Anyhow, looking to round out my selection of plates and knives. Thus far various #12 plates have all fit fine.

Today I got a very nice looking Pro-Cut carbide tipped #12 knife. Cost more, but I wanted to mate it to my 3mm (1/8") plate for faster final grind.

Anyhow, the center hole on this knife is not 1/2" like all the others, but only about 7/16". I am trying to find out if this is a one off problem with this knife, or are there some machines have a smaller square hole where the knife sits?

The square part of my auger measures precisely 12mm (1/2").

The knife is forged steel with carbide cutters brazed to the body. I touched the forged part with a file, and you can forget about filing out the center hole! Hard as heck!! And of course the carbide can only be sharpened with diamond. I actually own a set of diamond sharpeners for my wood working tools. Was really looking forward to this knife…

[processhead]

cdherman
There was a thread about this, or a similar problem a few months back. I will have to see if I can find it.

[processhead]

https://meatgistics.waltonsinc.com/topic/1855/12-knife-does-not-fit-my-grinder?_=1647120680446

[cdherman]

Thanks processhead. Looks like there is variation out there and others have experienced it in the #12 grinders as well. I don’t grind tons of meat. Perhaps I should just learn to sharpen the cheap (2 for $12.99 Amazon) knives and be happy.

I use a flat plate of glass with wet dry sandpaper to true various blades and mating surfaces for my other projects. I googled up grinder plate and blade sharpening and indeed there was a nice video on how to true up and resharpen grinder parts that way. Its really cool actually.

But the carbide tipped cutter looks like it would be a real performer. Afraid I should just send it back.

Too late to send the Chinese copy cat grinder back, and besides, it appears well built. Nothing against the stuff from Walton’s of course, but I was on a limited budget at the time.

[processhead]

cdherman

I’ve done plate and knife sharpening using the technique you described. It works pretty well, but is slow.

Recently I got the idea to put a silicon carbide belt on my benchtop belt sander.
It works fantastic for sharpening grinder plates and knives.

[cdherman]

I would worry that even a quality belt sander, while sufficiently true for woodworking might not be perfectly true to say 0.001" which is my language. I decked the heads of a subaru boxer block using plate glass, 320>400>600>800 grit sandpaper and WD-40 as lubricant (WD-40 was just what someone suggested on internet). Worked.

But conceptually, and for less than precise work, the belt sander might be the ticket for fast. I am really new to grinding meat, but not new to sharpening. I imagine that the better the plate and knife match, the better the grind. Makes me wonder if we should be smearing some valve lapping rouge on the plate and blade and running the grinder a bit first to mate the two surfaces. Just musing.

Looking at the various grinder knives I have in my possession thus far, they are really poorly ground and really not honed at all.

[Spidey]

cdherman I had the same issue and was able to file the corners and believe me it took a while to to do it to make it fit, after carefully clamping it in a vise to accomplish it. It can be done, although it was a slow process. It is a tight fit now, but it works.

[cdherman]

I don’t know. The geometry of the grinder/knife interface troubles me. If all four blades of the knife are not equally riding the disk, you end up with lots of poor cuts.

[Spidey]

In my situation it was cleaning up the rough edges of the casting, for the blade to slide down the stem.

[processhead]

cdherman said in Trouble with #12 grinder knives. Standard square center hole size??:

I don’t know. The geometry of the grinder/knife interface troubles me. If all four blades of the knife are not equally riding the disk, you end up with lots of poor cuts.

This is a legitimate concern. The fit between the knife hole and auger shank should be just a little loose, This allows the knife edges to self-align with the plate surface as the grinder nut is tightened.
If the fit is too tight, it prevent the knife from self-aligning and could cause one or more knife edges to ride high on the plate.

[processhead]

cdherman said in Trouble with #12 grinder knives. Standard square center hole size??:

I would worry that even a quality belt sander, while sufficiently true for woodworking might not be perfectly true to say 0.001" which is my language.

I was thinking this too. My belt sander is on a stand and has a milled cast iron deck that the belt travels over.
While far from perfect, I think the milled surface of the deck is reasonable flat.
My method was to put the plate up against the stationary fence, then with the sander running rotate the plate on its center hole axis so the material is removed evenly

[zbigjeff]

cdherman I did the glass and wet sandpaper process 2 weeks ago. Well worth the effort. The grind was like cutting through butter. Have a good rest of your day.