Grinder belt life span

L

lyuv

Joined
Oct 12, 2016
Messages
2
Hello all,
I"m looking for a general idea of how much work can I expect to get from a good belt.

Where I live, there are VERY few bladesmiths, and grinder belts (72X2) are VERY hard to get. So I can"t realy "check around". I want to determain if the brand I do get, is "good". Or do I need to make a (big) effort and risk a change.

I guess it's difficult to give such a measure. Say you need to thin a whole cheff knife (not hardened) by 1mm (1/16"), using rough belt. no polishing. How many belts do you need? (0.5 is a valid answer).
Any other measurment is welcome.
Thanks,
 
Well, what part of the world are you located? That would help with possible suggestions of where to find belts.

Since most all my bevel type grinding is done post HT, I can really talk about pre-HT grinding. I'd expect to get at least 2 knives from a belt. More likely with a decent ceramic belt in a large grit (36 to 60 or so) I'd expect to get perhaps 2 to 4 blades ground. This assumes the blade will be flat ground against the platen with some taper ground in. This also assumes the grinder is a 2X72 running a minimum of 4,000 SFPM belt speed. Belt speed is VERY important to belt life.

Looking forward to reading other responses and comments.

Fill out your profile to include age and location in world would be helpful.

edit: I see you've now filled out your profile with location and age. Thanks.
 
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Welcome to Shop Talk.
This is why we ask you to fill out your profile. Since we don't know where you live, or anything else about you, it is hard to give much advice. Please fill out the info in your profile.

A belt can make 100 blades ... or one - depending on your equipment and skill level. Most newer makers get five to ten knives from a belt.

It generally takes three different belts to shape a blade. Some people use many more grits, but this is a basic guide:
50-100 grit for rough profiling, tapering, and beveling
120-220 grit for getting a smooth surface pre-HT and re-sanding post-HT
400 grit for final finishing
 
I grind post HT as I'm using AEB'l and have been using Blaze recently. I can get 3-5 7" chef's out of my coarse belts. That being said, it does slow down significantly after the 2nd or so but I'm doing this as a hobby, not for production so I don't mind taking linger to grind and go slowly. If this was my job I'd be changing belts way more frequently as time is money. You do notice the heat a lot more after a few knives.

Another thing, I find the grinding goes way fast if I grind facets into the blade if I have a worn belt. If I have 1 steady bevel it takes way longer with a worn belt so I'll intentionally grind facets to "knock off the corners" then flaten out everything later with a fresh belt. More accurately, I start steep and keep grinding off the top corner to chase the grind up the blade. I'll use a new belt to clean everything up and I do multiple blades in a batch.

I don't have a contact wheel but hear that helps significantly with speed, heat and belt life.

BTW I'm a noob to take this with a grain of salt.
 
I'm also a noob. I find that I can get more life than expected out of a belt even when grinding full hard steel even on more wear resistant alloys. The thing to be very careful with is that it happens at the cost of accuracy and they build up a lot more heat. I find that I can take the bevels down about half way on a medium wear belt. If I used the same belt coming close to final thickness it would be very easy to burn a edge or bump a plunge. Because of this I find doing several knives in a row to be the most efficient use of belts.
 
There’s not going to be an answer that someone else can tell you.
It greatly depends on steel type, hardened or annealed, speed of your machine and most importantly your grinding style.
That’s why people will recommend trying different belts.
For instance, a lot of people like the vsm, so I tried them and for carbon steels I really like them, but for hardened AEB-L I prefer the cubitron 2. It took me a while to figure that out. Someone else may be completely opposite and both answers are right.
 
As with nearly all machine tools, feeds and speeds can actually make a dramatic impact on longevity/lifespan as well. Ceramic belts, for instance, cut much better and longer at higher SFPM. They're expensive, yes, but they'll last well more than double belt that costs half as much.
 
lyuv said:
I guess it's difficult to give such a measure. Say you need to thin a whole cheff knife (not hardened) by 1mm (1/16"), using rough belt. no polishing. How many belts do you need? (0.5 is a valid answer).
Any other measurment is welcome.
Thanks,
Click to expand...

Obviously you have zero experience with belt grinders :) I do not have either to much , but .......Probably different brand of belt have some differences in quality, but that is on you to find out in future .This is what I learn so far about grinding steel with belt grinders .
If you use ceramic belts they want speed and pressure and hardened steel .
That was technical part.What else you can do so the belts would last longer is this. USE ONE belt only for grinding bevel on clean steel .Only for that , don t even touch that belt with something else even that was piece of wood .For grinding shape of blade ,to clean steel from rust grinding after HT scale/decarburization use other belt , that can be cheap AO belt no need for ceramic there ........ Clean belt without contamination is key for longevity . And SPARKS no dust !! More sparks .. more will belt last :D
And look this video clip ... they would go bankrupt if they change belts after grinding 4 inch steel . . . . . or if they stop in the middle of grinding to change belt , you get the point , right ?
 
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When you are profiling with a ceramic belt you can get standard industrial results from a belt. You can use a lot of pressure on a small area and that allows the grit to fracture as it was designed. When we grind on the flats that force is distributed throughout the blade and the grit isn't fractured as easily. I do think grinding post heat treatment on high speed gives the most consistent feedback off the belts. For some task you want SHARP belts. You will notice after doing 1 blade the second the belt is no longer truly sharp. So it really comes down to how sharp you really want your belt to be and a lot of different options about how you get to your final grind and possibly finish sanding.
 
WOW - I never expected such a response. So much info! THANKS guys.
A little about me and my situation - I have a small hobby blacksmithing shop with a homemade belt grinder. Have made a few kitchen knives, all by forging, and now I want to try stock removal.
I live in Israel. All the bladesmiths in the country can share one cab. So, I have no one to learn from, other than youtube.
72X2 is unknown in Israel. I found a local factory with some nice guys, that are willing to custom MAKE me sanding belts. But I"m not sure if I get a reasonably good product (it's not free). My other option is to mail order from the USA, which is very expensive - shipping is about $100!. Tried cheap chinese belts, and these went to the trash.

So - I did learn some important things about saving belts. Having little/no experience with stock removal, I dont know how much work is 3-5 blades (I usualy start grinding with a banged lump). Any ideas on getting belts (or anything) will be appreciated.

Thanks.
 
On the topic of making belts last, you might try letting your forges work sit in a vinegar bath over night. The acid will remove the forge scale and your belts will last longer.

For a more immediate solution you can also use an angle grinder or something similar with a aggressive stone cup or disk to get rid of the scale.

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Most any belt supply ( not a retail store, but an abrasives focused supplier) should be able to make most any size you need. I'd ask around any metal fabrication shops near you to see who they use. Also, if you find a belt in a bit different length, and your grinder has sliding tool arms, you can use them. I bought a bunch of 80" cubitrons at an auction (12 for $5) and just slide out my platen arm to use them.
 
A lot depends on your process you can use less belts. It really depends on your personal time/cost ratio. I order from pops and my usual order is $400 to $800. If my cost of shipping was really high I would probably make less but larger orders. For myself I am switching to a lot of VSM since they seam to cut as precisely as high cost belts unlike some other lower cost belts. They don't last as long as high cost belts but seem too hit the best target for me. That may not be true for you. I have saw one you tuber who did a test on REX 121 and Norton blaze came out far ahead and that feels like what I have experienced. That's a lot of time in the mid wear section. Good but not great. 3M products are good but to a certain extent you are paying for surface quality/grinding feel (in my opinion) so other than maybe a scotchbrite belt they may not be the most steel removed for the dollar. N Natlek may have some similar problems as you do and he has a lot of work arounds that don't make as much sense for us in the USA(or he doesn't think our tooling choices make sense sometimes;)). For myself I am hoping to use high alloy tool steels and only really do stock removal. I am hoping to be make knives on the lower priced part of the market. For myself I am all about machine finishing and production. I have a friend that does really nice forged knives and is not looking for the bottom end and he from what I understand grinds primarily before hardening and only goes to 80-120 and hand sands. The belts he wants and the time/cost ratio is totally different from myself. The more specific you are about what you want to build the more specific answers you can get. You may find that very nice forged knives are what you since they don't have a high abrasive use. Also like Kevin said 2x72 is popular in the USA but you may have access to another size. From what I understand the longer the belt the better it cools so that's one thing to look for.
 
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