Below, you can find links to view additional data and discuss every test we have released:
How the machine was built, the tests were conducted & the data was collected
FLAP DISCS
Ovation Attacker Plus Flap Disc
Walter ALLSTEEL Turbo Flap Disc
Walter Enduroflex Turbo Flap Disc
FIBER DISCS
My favorite is Pearl 40 grit T-27
4.5" x 7/8"
Hight Density EXV Maxidisc zirconium
I didn’t see it on the list
LOVE what you are doing. Thanks
I’m curious if it might be considered to test discs from supply companies, the shop where I work is supplied by Kimball Midwest and their Crimson Fire wheels seem to be pretty good, but without objective data it is hard to be sure.
The 3M cubitron is basicly the only brand i recognize sold and used proffesianally in Sweden. I dont know about the rest of europe but the brands im familliar with is for example: Tyrolit, Flexovit, Klingspor and Rhodius. I can send you a package with discs from these brands if you want to continue testing. Just send me a message and tell me how many of each one you need!
Pferd is pretty commen over the border here in Finland, so I’m happy to finally see some tests with atleast few familiar names. And I’m guessing the cheapest ones should be pretty comparable regardless of the brand anyway.
I recently did a pretty unscientific comparison between 3M Cubitron III cutting disc, ~5 €/pc, against few generic hardaware store ones, 1 €/pc, and they lasted about 4 times longer and were about 20 % faster. So a pretty significant difference. I’d imagine there should be even bigger differences with flap discs, as the construction is more complex.
3M Cubitron 3 (and Cubitron II + also Norton Blaze) are ceramic grit , they last crazy long if used properly because for example ceramic dont like constant pressure etc and start to slow down rly bad then u need to push it to resharpen it.
In my case Cubitron II abrasives lasted in average 10-12x longer than corundum ones or 3-4x longer than cheap ceramic (long term test -4 maybe 5y of hundreds different discs)
but 3M Cubitron 3 is weird — it can last even longer and cut faster but its like designed for more powerful tools , when u push it u have crazy results but just meh with medium pressure compared to cubitron II
Then there is Norton Blaze …this thing is like 80% cubitron II “stock” performance but u can push it as hard as u want where cubitron II will fail
Biggest difference i see in case of all ceramic grit is that they like to go fast , like rly fast , belt sander in my case last way longer , grind faster and colder when uset with 6000 FPM (even better at 7000+ //around 35m/s but it feels bit dangerouse 
) than when used with my main ~4500fpm (around 23m/s) grinder (and need less torque for some reason)
but in case of cutting discs i go mostly with norton vulcan — cheap , you can brake it in half without crying about how expensive it was (like cubitron) , and on big flat surfaces 3M Cubitron II (beats Cubitron 3 in case of performance to price — half the price on facebook marketplace than online (around 2$ where cubitron 3 is like 5$ and only 30% better than Cubitron II )
Looking forward to these videos over the holiday. Finding a well performing disk at a cost priced point that makes sense to the hobbyist is essential. Thank you for publishing this data.
OK, it’s Christmas Eve and Test #8 of 31 is out (Black Hawk).
It seems to be pretty easy to predict which tests a disc will perform best on — even easier than I expected. Indeed, if anything, the surprise is the consistency between different discs.
That tends to suggest having a thread to compare the data between discs — rather than individual threads to discuss each disc — would be helpful. Are we going to see the data aggregated and comparable?
Relatedly, the videos have this screenshot, and I haven’t found a post with this presentation, did I miss it?:
Also, given that all the discs perform poorly with 4lbs and 8lbs is uniformly better, one wonders why those are good weights (forces) to use? It would be interesting to see 6lbs and 10lbs as well (or something?)
I realize it is probably too late to change the tests, but also, we’re definitely not learning a lot from the 4lbs test.
Thanks.
I was looking for the data as well, kinda confused if I’m just looking at the wrong places or are they not published yet?
I believe that the 4 lbs was chosen because it’s about the weight of a grinder, and we have heard a lot of people say things like “let the grinder(s weight) do the work”. From the tests this common saying doesn’t seem to apply to flaps discs.
same
I collected all the data from the videos into a spreadsheet:
The numbers are what Jason says if he gives a specific number or what I estimated from the hand drawn graphs otherwise.
So far all discs performed poorly in the 4lb tests, I think we can disregard those. I would also weight the cold tests higher then the hot ones as it seems more often you will not be grinding heated metal (certainly not red hot from an induction burner).
If you rank by material removed on the 8lb cold test you get
If you rank by cost per inch of material removed you get
You are a stud!
I’ve always gone with more expensive abrasives but these result clearly demonstrate the value in going cheap. An expensive disc would have to perform unreasonably effectively to beat the cost advantage of the cheap discs.
I’m going to use cheap discs for roughing out material then finishing with the pferd combiclick if the job needs it.
Thanks, @solomon, that’s the kind of thing I was thinking of. I’m sure Jason has this so I don’t know that we want to duplicate the work.
So far all discs performed poorly in the 4lb tests, I think we can disregard those
I was thinking similarly, but then the Norton Blaze results came out. It might be worth ordering your spreadsheet by the test numbers in the videos, or including them in a field, to help match them up (initially I confused the two Norton discs in your sheet because you ordered them differently).
I found it useful to transpose the sheet so I could use horizontal sparklines (mini graphs) to visualize the data. First cut here:
And sheet here: sparklines of Fireball Tool Flap Disc Results - Google Sheets
Ranking by 4lb cold cost per inch you get:
Ranking the discs only by the inches of material removed, I believe is a poor way to rank them. I don’t think that represents the true performance of the disc. Many other factors need to be evaluated. Like time taken to remove the material is important. For example 2 disks might remove 5in but one does it in 5 minutes and the other does it in 10min. What disk would be better? Also did it glaze or did it get totally destroyed in the process.
I agree, I think a more valuable metric is cost per inch of removal where the current top 3 are:
In my spreadsheet I also calculated Inches of grind per minute where the winners are
In your example the first would have twice the inches of grind per minute making it the more powerful disk. To figure out if it is cost effective to use the more powerful disk you need to look at the cost per inch to run the disk.
If the cost per inch is lower then it doesn’t matter that it was destroyed after only 5 inches, it will still be cheaper to use multiple of them to finish your project then it would be to use a higher cost per inch disk.
At the end of the day there are two questions that matter:
How quickly a disk fails doesn’t really matter, so long as its not failing instantly. It just takes a moment to swap out the disk.
Calculating cost per inch of grind allows us to factor out the lifespan of the disk and just think about how much it would cost to run a particular brand continuously.
Between cost per inch and inches of grind per minute you should be able to pick out your optimal disk. We can take those two rankings and weight them based on personal preference (grinding speed vs economy) then get an optimal ranking.
Wow the CGW disk performs so differently from all the others. Is there anything notably different in the physical construction of this disk? The manufacturers specs look consistent with the others.
@Fireball_Jason you described the 8lb cold test as a poor performance but it still took off 10 inches of material before failure. That puts it squarely in the middle of the pack for material removal but it did it insanely fast (3:30).
Wouldn’t that be a desirable property in a real world scenario? You would have roughly 10 inches of welds you can grind through and it only takes a few seconds per weld.
From a cost perspective it still can’t beat the cheap disks 
Sorry I keep posting more thoughts here, I’m really enjoying this video series and see it as tremendously valuable contribution.
Since the test ends at 20 minutes regardless of if the disk was destroyed we aren’t actually getting fair results for the high end disks (which tend to last longer). If a disk would have lasted 40 minutes but the test was ended at 20 minutes then its going to look way more expensive to run that disk.
@Fireball_Jason I know this experiment was really expensive to run but it would be really awesome if you could do another round with just the disks that maxed out the time limit where you let them go as long as it takes to reach failure.
I use Lehigh Valley Abrasives flap disks. Are they on the list to be tested?
