Optimal Grinder

K

Knifeman9000

New Member
Hey Guys,

I am a newbie wanting to get gear that I can keep for the long haul.

I am going through the process of designing/modifying/building a few grinders, and was hoping to get insight into belt length/width and grit approaches.

I am interested in making flat ground kitchen knives, in stainless.

The longer the belt, the cheaper it is per inch and the cooler it runs, so if the space is available, and the manufacturer can get you what you want, longer seems to be the way to go. Assuming you don’t need a narrow belt for contouring, etc., does the same hold true for wider – say 3” wide belts?

I know some makers use a 50 to 400 grit sequence – for a ”user”, is this okay?

TIA

John
 
The standard belt is 2x72

grinder info
Entry Level Grinders
Many makers start with the Sears Craftsman 2x42 belt grinder.
http://www.sears.com/shc/s/p_10153_12605_00921513000P?prdNo=3

Commercial Production 2 x 72” Belt Grinders
http://www.prometheanknives.com/shop-techniques-3/grinders

Mapp arm – Grinder Toolrest
http://www.bladeforums.com/forums/showthread.php?t=466024


DIY 2 x 72” Belt Grinders

KMG Clone
Free Plans
http://www.dfoggknives.com/PDF/GrinderPlans.pdf

NWG No Weld Grinder
http://www.usaknifemaker.com/plans-for-the-no-weld-grinder-sander-nearly-50-pages-p-723.html

EERF Grinder (EERF =“Free” backwards)
Free plans
http://wilmontgrinders.com/EERFGrinder.aspx
http://blindhogg.com/blueprints.html
http://www.atlasknife.com


Buy the kit
http://polarbearforge.com/grinder_kit.html
 
Personally I would stick with 2x72". It has the widest variety of belt types available. You can use a different size sander and you can probably find 50-400 grit aluminum oxide belts pretty easily but then you might have trouble finding blue zirconia belts, Blaze belts, felt belts, cork belts, etc...not to mention the different grades of flexible backing that come on belts.

My first sander was a 4x36", followed by a 6x48". I ended up using the 6x48" for quite a few years but when I finally got around to getting a 2x72" my 6x48" barely got used and I gave my 4x36" away.

The one benefit I found with the wider belts is, if you will be free hand grinding it makes it harder for you to accidentally rock the knife when grinding bevels and dig the edge of the belt into the blade causing a dip (referred to as the "dreaded 2" mark when using a 2" sander). The downsides I found were excess heat from the added friction of the wider belt against the platen, more power needed to overcome the friction of the belt against the platen/blade, less variety in belts, less blade shapes being easily able to grind, and the wider belts cut slower.

As for grit sequences that is a matter of opinion. I've seen some "users" left at 100 grit and some taken to 1000. If you are going for a fast finish that looks ok, but not superb, I like taking it to around 150-200 grit then using rough buffing compound, a cork belt, or a Scotchbright belt to give it a quick satin finish.
 
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