Recommendation? Belt Grinder Consumable Belt Cost Comparison

J

Jordan Erickson

Joined
Jan 12, 2022
Messages
2
Hello all,

Long time lurker, first-time poster.

As a process improvement engineer in the welding filler metal industry, I keep a close eye on consumables and the long-term costs associated with relatively low-cost items. This really got me thinking as I begin my knife making journey and before designing and fabricating my own belt grinder.


As I have done tons of research in different belt grinder sizes, styles, brands, etc, I decided to take an analytical approach to the consumable cost of the belts. With some simple math using Combat Abrasives Ceramic "Shredder" belt prices in common knife grinder sizes, I broke down the cost of the belts to a $/in^2 basis. Please note, I took out 36 grit, and 60 grit because some of the sizes were sold out at the making of this comparison. So I used 40, 80, and 120 as I think this is comparable to what can be used commonly used for belt progression. Whether you use 36/60/120, or 40/80/120 or any other combination, the numbers seem consistent with the 2x60 being the most economical. Again, this is with Combat Abrasives Shredder Belts.

SizeWidth (in)Length (in)Area (in2)40g $/belt$/in280g $/belt$/in2120g $/belt$/in2
1x3013030$ 3.25$ 0.1083$ 2.99$ 0.0997$ 2.99$ 0.0997
2x4224284$ 4.50$ 0.0536$ 4.09$ 0.0487$ 4.00$ 0.0476
2x4824896$ 5.25$ 0.0547$ 4.50$ 0.0469$ 4.19$ 0.0436
2x60260120$ 6.55$ 0.0546$ 5.48$ 0.0457$ 5.21$ 0.0434
2x72272144$ 9.29$ 0.0645$ 7.99$ 0.0555$ 6.99$ 0.0485

To break this down further -

Lets take qty. 5 2x72 40 grit belts. This would equate to 720 in^2 of grinding surface. This would cost (5 * $9.29) $46.45.
To use the same 720 in^2 of grinding surface in 2x60, you would need 6 belts (2 * 60 * 6 = 720). This would cost (6 * $6.55) $39.30.

Now we can apply this across the board to get a calculation for lets say 40 grit, 80 grit, and 120 grit, using 5 of each belt.

2x72 Cost per 5 belts2x60 Cost per 6 belts
40 Grit46.4539.30
80 Grit39.9532.88
120 Grit34.9531.26
Total121.35103.44

This equates to a $17.91 savings in only 3 different grits, at 5 belts of each.

Obviously, this is only an example as the amount of belt use on a weekly, monthly, and yearly basis can be drastically different from maker to maker.

I am truly not interested in pinching pennies, I was just surprised at the difference in cost I came up with through a little research and calculations. Over time, these costs can greatly add up which means additions to other areas of the shop.

I am just looking for thoughts and opinions on the above data and the justification over a 2x60 vs 2x72.

Thanks!

Jordan Erickson
 
Jordan,
You are comparing apples to oranges. A 72" belt is 120% the size of a 60 grit belt. $121.35 is also roughly 120% of $103.44. The cost per s2.in. is basically the same. A 72" belt will last about 1.2 times as long as a 60 grit belt because it has 120% the amount of abrasives.

What your chart shows is that for a 2" wide belt the cost per sq.in. is roughly te same regardless of length. The reason to use a longer or shorter belt is mainly based on the equipment size and motor used. In industry they use longer belts because they get more hours use per belt. Tne cost is the same per amount of abrasive on it.
 
I might be misinterpreting the response.

Jordan's calculation says the same amount of abrasive (720 square inches) is being set as equal in the bottom comparison. The number of belts and length of belt is irrelevant for the comparison.
So 720 square inches is cheaper at 2x60 ($103.44) than at 2x72 ($121.35).
Whether they are roughly the same cost is subjective. I imagine that a process improvement engineer could see 14% savings as a big deal, especially if this is a major cost center.

Why the cost difference? No idea. I expected the opposite, since there is more processing to do for a smaller belt (cutting, taping the splice, handling). Maybe someone knows why there is a difference outside of size.
I'm not sure if this same trend is true across other manufacturers.

Is 2x60 more economical?
Purely in this comparison, yes.
If other factors are considered, it becomes an argument, since they may not be quantifiable. Some considerations:

Time used to change belts.
Availability of belts to purchase.
Extra heat generated by shorter belts.
Better and more suitable equipment (grinder, tooling) that uses the belt sizes.
The impact of the belt splice on grinding - it can cause a 'bump' that shows up. You can take extra time to remove the grit at the splice, but that's more time and lost grit.

I stick with 2x72 because of the network effect it has; everybody uses it for knifemaking, so everything surrounding it gets better.
 
so based off his ideas /thoughts all he needs to do is build a belt grinder that can use a 2x48/2x60/2x72 and he can use any belt he can get a deal on..
i buy lots of belts and use them almost like they are free ..cutting is important to me ,not trying to get more cut out of the same belt.
better brands than "Combat Abrasives" are used by most "Professionals" because they work better..
"Combat Abrasives" loves to make big claims that their stuff is better , but strangely they have little/now proof about it..
 
I keep reading that heat (from friction) also dulls belts.
That is why longer belts stay sharp relatively longer.
I have no idea if it is actualy so and how it works
 
Hengelo_77 said:
I keep reading that heat (from friction) also dulls belts.
That is why longer belts stay sharp relatively longer.
I have no idea if it is actualy so and how it works
Click to expand...
It can t be true , ceramic grits can withstand temperature we can t not reach in HT oven
 
But backing, adhesives, and lubricant coatings come into play as well. Most certainly excessive heat causes belt deterioration.
 
Looks to me like the OP is comparing apples to apples. He's using the same Combat Abrasives Ceramic "Shredder" belt for prices and number of sq inches in each belt. By his numbers 5 of the 2X72 have the same 720 sq in that 6 of the 2X60 belts have. Sure looks like apples to apples to me.

The only possible consideration would be if the 2X72 belt would do more grinding per sq in than the 2X60 belt would due to possible extra cooling by the longer belt? I'm not at all sure that's a real factor for the Ceramic belts.

The OP's numbers confirm something I'd seen before. I tend to order 60 inch belts in 2.5" width for my SGA in the heavy grits due to price. It is also harder to find 2.5" wide belts in 72" lenght.

Good thread - I'll be following it.
 
You are just highlighting a phenomena i think is quite common, which is that the most in demand size is the most expensive. 2x72 is the most common size of belt grinder for home knifemakers, and so there is a lot of demand for that specific size. Its most likely to sell out, the furthest back ordered, and has the highest turnover rate for all the abrasives sellers we deal with, so of course its more expensive.

Its not exactly the same, but vegetable oil is significantly cheaper per calorie than gasoline or diesel, so if you just retool your car to run on vegetable oil you'd be swimming in savings.

Its the most in demand size and it sells out the fastest. Id be willing to be you can get more variety in 2 x 72 as well, along with more machines, tooling, and accessories for that most common size.
 
Greenberg Woods said:
You are just highlighting a phenomena i think is quite common, which is that the most in demand size is the most expensive. 2x72 is the most common size of belt grinder for home knifemakers, and so there is a lot of demand for that specific size. Its most likely to sell out, the furthest back ordered, and has the highest turnover rate for all the abrasives sellers we deal with, so of course its more expensive.

Its not exactly the same, but vegetable oil is significantly cheaper per calorie than gasoline or diesel, so if you just retool your car to run on vegetable oil you'd be swimming in savings.

Its the most in demand size and it sells out the fastest. Id be willing to be you can get more variety in 2 x 72 as well, along with more machines, tooling, and accessories for that most common size.
Click to expand...
So , if 2 x 60 is the most demand and common size , it will be cheaper then 2 x 72 or 2 x 90 ?
 
My error. I see where he added the 720sq.in. equivalency.

I will point out that it isn't a big savings - Just a tad under $1 per belt cheaper for the eighteen 60" belts. The improvement in grinding ability and belt life will more than compensate for that.
 
Natlek said:
So , if 2 x 60 is the most demand and common size , it will be cheaper then 2 x 72 or 2 x 90 ?
Click to expand...

I meant it more as, there is more demand for 2 x 72, people buy more of them more quickly, so the price goes up.

The cost to the manufacturer is identical per square inch, but because the 2 x 72 size is the most in demand it can be sold at a premium to meet the heightened demand.
 
I'm curious are knife makers the prime customer for 2x72 and 2x60 belts? It could be that the shorter belts are used in industry and made in much higher quantity making them cheaper.

From a manufacturing standpoint the longer belts should be cheaper to make. Longer length means less seams.
 
I appreciate everyones input! This is just something I have been dabbling with and had on my mind.

Definitely a good conversation with a lot of good points from everyone. I definitely see the supply and demand point possibly driving costs up slightly. I also appreciate the other considerations I wasn't taking into account, such as change over time, heat generation, and issues with the splice.

Again, Thank you. I look forward to getting more involved in the community!

Jordan
 
I doubt that increased demand rises prices.
I think that it will equily rise production/supply, evening out the price difference.
Belts are man made and it is just as easy to make size A as it is to make size B, C or D.

I chose 50x2000 mm for my machine because it is the most available belt size where I live and it is the easiest to order different kinds. I can order single belts for my machine. If I would have had a machine with strange size belts I would have had belts made to order, being more expensive, having to order per 10 and having a waiting time.
 
I think the 2x72 is a good size for a belt sander. If the belt was 12" shorter, the machines would be a bit smaller (especially a 3 wheel design!) and may not be as versatile (size of contact and drive wheels, platen attachment height size, etc). A 2 wheel machine, like the Grizzly, could be a 2x60, but a 3 wheel, like the KMG, Brodbeck, Ameribrade, Reeder, etc I think wouldn't work as well if the belt was 12" shorter? Plus 2x60 is less common, so there isn't the variety in belts in that price. If 2x60 was the standard knifemaking size, they would rise in price since they are in demand.

I used to use a 2x36" machine as a dedicated handle belt sander (slack belt and small rubber contact wheels, no platen). I had to order belts in multiples of 6 from Combat because it wasn't a normal size, or get 4x36 belts and split them down to use, but I still needed to order multiples. In use, with the same brand of belts and same grits, 2 belts lasted pretty well compared to 1 2x72, but the work was extremely slow (partly due to belt speed being lower with coarser grits). Shorter belts also clogged up quicker and needed to be cleaned much more often, too, or they didn't work as quickly and were much slower. Worse case, if I didn't keep up with the cleaning, they could burn the material at higher speeds when they got clogged. Plus I had to change belts more often as well. So with an oddball size, you have a harder time finding them, will often need to order since they are an off size and store more belts as well as take the time to clean belts more often. There is a bigger difference between 2x36 to 2x72 versus 2x60 to 2x72, but it was noticeable.
 
Greenberg Woods said:
Its not exactly the same, but vegetable oil is significantly cheaper per calorie than gasoline or diesel, so if you just retool your car to run on vegetable oil you'd be swimming in savings.
Click to expand...

I wish. I've never found vegetable oil that's cheaper per gallon than diesel, other than waste fryer oil, but then your savings end up being paid in a different way: spending time dealing with many gallons of stinky fryer oil! 😆
 
Jordan Erickson said:
Hello all,

Long time lurker, first-time poster.

As a process improvement engineer in the welding filler metal industry, I keep a close eye on consumables and the long-term costs associated with relatively low-cost items. This really got me thinking as I begin my knife making journey and before designing and fabricating my own belt grinder.


As I have done tons of research in different belt grinder sizes, styles, brands, etc, I decided to take an analytical approach to the consumable cost of the belts. With some simple math using Combat Abrasives Ceramic "Shredder" belt prices in common knife grinder sizes, I broke down the cost of the belts to a $/in^2 basis. Please note, I took out 36 grit, and 60 grit because some of the sizes were sold out at the making of this comparison. So I used 40, 80, and 120 as I think this is comparable to what can be used commonly used for belt progression. Whether you use 36/60/120, or 40/80/120 or any other combination, the numbers seem consistent with the 2x60 being the most economical. Again, this is with Combat Abrasives Shredder Belts.

SizeWidth (in)Length (in)Area (in2)40g $/belt$/in280g $/belt$/in2120g $/belt$/in2
1x3013030$ 3.25$ 0.1083$ 2.99$ 0.0997$ 2.99$ 0.0997
2x4224284$ 4.50$ 0.0536$ 4.09$ 0.0487$ 4.00$ 0.0476
2x4824896$ 5.25$ 0.0547$ 4.50$ 0.0469$ 4.19$ 0.0436
2x60260120$ 6.55$ 0.0546$ 5.48$ 0.0457$ 5.21$ 0.0434
2x72272144$ 9.29$ 0.0645$ 7.99$ 0.0555$ 6.99$ 0.0485

To break this down further -

Lets take qty. 5 2x72 40 grit belts. This would equate to 720 in^2 of grinding surface. This would cost (5 * $9.29) $46.45.
To use the same 720 in^2 of grinding surface in 2x60, you would need 6 belts (2 * 60 * 6 = 720). This would cost (6 * $6.55) $39.30.

Now we can apply this across the board to get a calculation for lets say 40 grit, 80 grit, and 120 grit, using 5 of each belt.

2x72 Cost per 5 belts2x60 Cost per 6 belts
40 Grit46.4539.30
80 Grit39.9532.88
120 Grit34.9531.26
Total121.35103.44

This equates to a $17.91 savings in only 3 different grits, at 5 belts of each.

Obviously, this is only an example as the amount of belt use on a weekly, monthly, and yearly basis can be drastically different from maker to maker.

I am truly not interested in pinching pennies, I was just surprised at the difference in cost I came up with through a little research and calculations. Over time, these costs can greatly add up which means additions to other areas of the shop.

I am just looking for thoughts and opinions on the above data and the justification over a 2x60 vs 2x72.

Thanks!

Jordan Erickson
Click to expand...
you should be congratulated for contributing something of substance here, and especially for your first post. I appreciate that you took some time to infuse the forum with a little something to think about, and especially that you are really challenging a pretty established bias with some actual objectivity. Very cool:thumbsup:
 
I think I'd be less interested in the cost per square inch, and more on the longevity (and quality of finish) of the cutting media per belt. Even if you just took the 2x60 belts, for instance, there are so many different brands of belts, and within each brand, so many "formulations" of each belt's abrasive, just the ceramic variations along will make your head spin. It seems like everyone always wants to compare their ceramics to the Norton Blaze belts though, so maybe they're already deemed to be the best, but then again, they're also some of the most expensive.

Then lets say you narrow it down to one make, model, and material... which grit should you start with, and which should you spend the most time using? I know there's a lot of variables, including steel type, belt speed, pressure, hardness of the steel, thickness of the steel, etc... but surely there are some common factors that say something like "grinding 56 HRC 1095 at 5000 SFPM is best done with "x" belt, and should be expected to efficiently remove "y" cubic inches of steel, or something to that effect....

After all, it's great if I can save $50 per 100 2x60 belts vs 100 2x72, but if I'm only getting 1 knife finished on a 2x60 "super slicey ceramalloy grindmaster" belt, vs 3 knives on a Norton Blaze, or whatever, then that's what I'm interested in knowing, and perhaps THAT is when I'm interested in a cost breakdown.
Yes, that belt grinds 3x as much material, but it's 4x the price of such and such, and so on....
 
I just buy from Pop's. I haven't found better prices or better service. I was worried when the new guys took over but the prices and service including the low shipping. The new items they have added to the inventory are nice too. Hell, they have the best prices on steel by far as well and even have MagnaCut. I do want to try their fancy new Actirox but the economy VSM are hard to beat. They are not as good as Norton Blaze but at 20% cheaper you can change them 20% more often and that has a way of making them the highest performance belt I have found. The quick check I did with them has 2X72 as the best prices by far.

As far as I know the reason knife makers use 2X72 is that it is the most common in industry and offers the best selection and prices. Unless there is a reason like the belts fitting into a roll with no waste or the stock not selling and having an older price it doesn't seem like things are right if the most common belts having a higher cost.
 
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