Belts Cubitron x984 > x784 > 947??? > 384???

[TdF]

Hello there,
We have a kitchen knife repair shop.
We have been using Cubitron II of #36, #60, #80 and #120 grit.
The Cubitron models used 784 and 984.

Application:
Flat grind of kitchen knive geometry.
At the spine 2mm, width of the blades aprox 50mm.
Flat grind to aprox. a 0.3mm thickness 0.6mm from the edge.

Steel:
high carbon which has high aloy and it is stainless steel (440c, VG10, 10Cr, S35V, S110v, Elmax, M390, K390)

784/984 issues
The belts work ok with up to 2 knives.
3rd knife starts take longer to work on.
4th knife is even slower and I have to use more pressure....using more pressure results in burind the very thin tip of the edge.


Does any one has please PRACTICAL experience and could recomend a suitable belt of #80-120 grit which can be used wet and wth low pressure?
Also could you please post a magnified pictures of the belt surface?
Under the microscope I could observe totally different structure as advertised on 3M website.

I look forward to hearing back from you.

 

[TdF]

This is 3M advertised Cubitron II structured abrasive.

 

[TdF]

Grain details of my belt.

 

[REK Knives]

For wet grinding at 120 you need to probably switch to Blaze belts, they are the only one I've found that doesn't cup outward at the edges when soaked with water. But for 36 grit I go with the 984f or the Actirox belts, I can get a lot of life out of them.

 

[Joshua Fisher]

I find the vsm actirox do really well with low pressure. The vsm 880 ceramics are also for low pressure grinding and are my go to for grinding kitchen knives (I make around 50 knives per month and most kitchen knives I shoot for that same edge thickness or less). At 120 they can warp if soaked but they grind really cool without water. Are you using a variable speed grinder?

 

[TdF]

d knife starts t

For wet grinding at 120 you need to probably switch to Blaze belts, they are the only one I've found that doesn't cup outward at the edges when soaked with water. But for 36 grit I go with the 984f or the Actirox belts, I can get a lot of life out of them.

Hi Josh,
Have also tried Norton Blaze (the orange ones).
I am not worried about the cupping upwards.
984 #36 - the Cubitron 984 has more grains per square inch...less bite....I found 784 with less grains per square inch work better for me.
Actirox bets - never heard of. Could you post the closeup of the grains? What technology they use?

As per the image 3M advertised if the grains are some kind of flat and oriented in a direction along with the lenght of the belt, this could work even the grains get worn out a bit.

The real pain is that the belts,
(no matter the brand)
seems to use the very similar technology,
which last too little.
In my case, I refurbish blades of used kitchen knives....removing at most 250µm from each side and only half width of the blade.
By lasting too little I mean, I can't use too much of a pressure. If I do, I overheat the very tip of the edge of the blades.

I am gringind edge in a direction of the running belt.

Abrasive grains are covered with some kind of porous material.
I guess it might be ceramic coating.
When this coating gets worn out a bit, the grinding starts require unvanterd more pressure!

Attaching microscopic images. Height of the image is aprox 2mm. Magnification 200x. Lengh of the belts runs horizontaly to the image.

A bit worn Cubitron II 984 grit #120. Magnification 200x

Worn out Norton Blaze R980P grit #120. Magnification 200x

Worn out VSM XK760x grit #80. Magnification 200x.

 

[TdF]

I find the vsm actirox do really well with low pressure. The vsm 880 ceramics are also for low pressure grinding and are my go to for grinding kitchen knives (I make around 50 knives per month and most kitchen knives I shoot for that same edge thickness or less). At 120 they can warp if soaked but they grind really cool without water. Are you using a variable speed grinder?

Hi Joshua,
Appreciate clarity that Actirox is VSM brand.
Having downloaded their catalogue in search of 880 ceramic
Attaching a link for a reference.
VSM complete line Catalogue vieved Nov-2022
Acording to their catalogue the only 880 is XK880Y and is for medium to high pressure.
They state Actronix AF890 only disc and #36 grit.

Having lookind deeply into their website I now found a borchure,
and the Actronix belt has a code AK890Y yes it should be for low pressure and it comes only in #36 girt.
I am sorry but got quite confused.....I would be more thankfull for aclaration.

Dry grinding I am trying to avoid due to a dust.
Yes I do use a variable speed grinder.

What direction is the edge against the running belt or with direction of running belt?

As per above mentiong about the coating...I am thinking it would be nice to have som kind of ceramic abrasive spray which would re-juvinate the belt...instead buying so many belts.

 

[Joshua Fisher]

Hi Joshua,
Appreciate clarity that Actirox is VSM brand.
Having downloaded their catalogue in search of 880 ceramic
Attaching a link for a reference.
VSM complete line Catalogue vieved Nov-2022
Acording to their catalogue the only 880 is XK880Y and is for medium to high pressure.
They state Actronix AF890 only disc and #36 grit.

Having lookind deeply into their website I now found a borchure,
and the Actronix belt has a code AK890Y yes it should be for low pressure and it comes only in #36 girt.
I am sorry but got quite confused.....I would be more thankfull for aclaration.

Dry grinding I am trying to avoid due to a dust.
Yes I do use a variable speed grinder.

What direction is the edge against the running belt or with direction of running belt?

As per above mentiong about the coating...I am thinking it would be nice to have som kind of ceramic abrasive spray which would re-juvinate the belt...instead buying so many belts.

https://www.vsmabrasives.com/en/XK880Y?file=files/inhalte/PDS/VSM-Product-Data-Sheet-XK880Y-EN.pdf

https://www.vsmabrasives.com/en/AK890Y?file=files/inhalte/PDS/VSM-Product-Data-Sheet-AK890Y-EN.pdf

Here are some data sheets for the belts I use in full time knife production, the 880 are technically listed as medium pressure belts, but I find they do well even with light pressure as far as not glazing over and continuing to break down in use. I think part of your issue is all of the 3m cubitron belts are high pressure and high speed belts so at first them may grind great but you are quickly losing their benefit, they are made for industrial use with automated machines that can apply far more pressure than what we can for this particular application. Both the vsm belts I use work better at slower speeds with low to medium pressure, I run them slower than the recommended 25m/s and find they grind very cool and quickly. I have a 5” drive wheel on my grinder and 3600 rpm motor so full speed runs at about 23.9 m/s or 4712 sfpm. For 36 grit(actirox) and 50 grit(880) I run at 50% speed, for 120 I drop down to 20% speed. At those speeds it’s nearly impossible for me to burn the edge or tip if I am wet grinding. If grinding dry I will dip the blade frequently and don’t have any issues overheating. With both belt lines my average cost for each belt per knife is under $1 meaning I’m typically able to grind 16+ knives on one actirox belt or 7+ knives on the 880s (all grinding done entirely post heat treating on hardened blades, higher alloy stuff obviously will wear belts faster regardless of brand). I can try to take photos of the belts today but only have a phone camera so I doubt it will really show what you want to see but personally I don’t really care what the belt looks like if it does what I need in a practical sense.

 

[Pinoy Knife]

as someone that has made knives for 25 plus years (all of them ground Hard) From M2/M4 to all the different stainless steels to my own forged Damascus from 57 Rc to 65rc
i have to remind you/Everyone else of the BEST ADVISE i was ever given USE BELTS LIKE THEY ARE FREE!!!!! this advise is priceless..
if you are worried about the cost of each belt you are doing something very wrong.. the Expense of what you use should be calculated into what you have to charge..
the Expense of what you use should be calculated into what you have to charge.. If too Little you loose money!!!
by trying to get "More " out of ANY belt means you are willing to RISK the heat treat that makes the knife good to begin with.. (not Acceptable in my shop) Always Quality not Quantity..
i have fixed many different types of knives from those by "Departed Makers" worth thousands to some worth 50 bucks..
Never cheap out on Abrasives ... find what works for your style of grinding and use them ... the price you pay simply has to be passed on (just how it is )
please understand im not trying to "Scold you" just passing on some honest thoughts /experience... Price/Quality/Service Pick 2 (there has to be a compromise if 1 is a concern....

 

[C_Claycomb]

Have you tried Norax U936 engineered ceramic for the 150grit equivalent? They also do an 80grit. I know their catalog says high pressure, but they work with lower pressure just fine and are less prone to glazing than the AlOx Norax. At worst, like other engineered abrasives, you might need to dress the belt, but they seem to need that much less if at all.

my understanding from discussion here, followed by my own use is that the Blaze and Cubitron need speed and pressure to re fracture the abrasive grains. If you don’t do this, you are not using belt as design intended and will not get expected life. Perhaps a quick blast every so often with some hard sacrificial steel to fracture grains would extend useable life on the regrinds?

the microscope pictures showing glue and grains. The stuff you say might be a ceramic coating is just the adhesive/grind aide used to bond the abrasive to the belt. It is not ceramic. Refreshing a belt with an abrasive spray is a lovely idea, but quite impractical. More coolant and higher pressure would be a better route.

 

[Stacy E. Apelt - Bladesmith]

Regardless of the pressure type, structured abrasive belts need to be refreshed when they slow down. Run them at full speed and grind against a diamond dresser bar. It will refresh the belt and grind like new again.

 

[TdF]

as someone that has made knives for 25 plus years (all of them ground Hard) From M2/M4 to all the different stainless steels to my own forged Damascus from 57 Rc to 65rc
i have to remind you/Everyone else of the BEST ADVISE i was ever given USE BELTS LIKE THEY ARE FREE!!!!! this advise is priceless..
if you are worried about the cost of each belt you are doing something very wrong.. the Expense of what you use should be calculated into what you have to charge..
the Expense of what you use should be calculated into what you have to charge.. If too Little you loose money!!!
by trying to get "More " out of ANY belt means you are willing to RISK the heat treat that makes the knife good to begin with.. (not Acceptable in my shop) Always Quality not Quantity..
i have fixed many different types of knives from those by "Departed Makers" worth thousands to some worth 50 bucks..
Never cheap out on Abrasives ... find what works for your style of grinding and use them ... the price you pay simply has to be passed on (just how it is )
please understand im not trying to "Scold you" just passing on some honest thoughts /experience... Price/Quality/Service Pick 2 (there has to be a compromise if 1 is a concern....

Hi Pinoy Knife,
I very much appreciate your advise "USE BELTS LIKE THEY ARE FREE".
It is vlaulable advice.
I followed this advice before I have create my account on BF.
I repair knifes for restaurants. So we are talking about removing 100-200µm on each side of the blade.
No burn 2 knives and acording to advice I need to replace the belt.
This does not make any economic sense.

This is my reason why I came to BF and asked.
I think the conversation needs to go different directions.
Will write.

 

[TdF]

https://www.vsmabrasives.com/en/XK880Y?file=files/inhalte/PDS/VSM-Product-Data-Sheet-XK880Y-EN.pdf

https://www.vsmabrasives.com/en/AK890Y?file=files/inhalte/PDS/VSM-Product-Data-Sheet-AK890Y-EN.pdf

Here are some data sheets for the belts I use in full time knife production, the 880 are technically listed as medium pressure belts, but I find they do well even with light pressure as far as not glazing over and continuing to break down in use. I think part of your issue is all of the 3m cubitron belts are high pressure and high speed belts so at first them may grind great but you are quickly losing their benefit, they are made for industrial use with automated machines that can apply far more pressure than what we can for this particular application. Both the vsm belts I use work better at slower speeds with low to medium pressure, I run them slower than the recommended 25m/s and find they grind very cool and quickly. I have a 5” drive wheel on my grinder and 3600 rpm motor so full speed runs at about 23.9 m/s or 4712 sfpm. For 36 grit(actirox) and 50 grit(880) I run at 50% speed, for 120 I drop down to 20% speed. At those speeds it’s nearly impossible for me to burn the edge or tip if I am wet grinding. If grinding dry I will dip the blade frequently and don’t have any issues overheating. With both belt lines my average cost for each belt per knife is under $1 meaning I’m typically able to grind 16+ knives on one actirox belt or 7+ knives on the 880s (all grinding done entirely post heat treating on hardened blades, higher alloy stuff obviously will wear belts faster regardless of brand). I can try to take photos of the belts today but only have a phone camera so I doubt it will really show what you want to see but personally I don’t really care what the belt looks like if it does what I need in a practical sense.

Hi Josh,
Thank you ever so much for a math challenge with m/s>RPM diameter of the disc and for the extremely valuable advice to make me step closer to be able to enjoy sharpening.
My 6.5" (16.5cm) drive did not provide sufficient torque with recomended speeds. I asked to have made 5" (12cm).

What was missing, but I have observed thank you to your instagram images, blade edge against the direction of the belt + support.
I was re-profiling blades freehand blade in a direction of a belt.
With support and edge agains the belt rotation betl bites against the steel and also against the suport, this way creates better contact and more even pressure.
It is real magic.
Thank you for an inspiration.
I hope that I can pay you back in some way.

 

[TdF]

FAKIR > pressure grains per sq. in.

Having tried to lay on the nails, I have learned more nails less punching. The weight of the body is distributed over number of the nails.
Folloing are 3 VSM belts. I am sorry not comparing equal grains the #80 vs #120 vs #120, but the FAKIR point is clear to me.
The #80 grits are visibly bigger.
The density of the gains within 2 mm cirle (0.0787" = 5/64") is higher thatn 880 or 870.

 

[Pinoy Knife]

Hi Pinoy Knife,
I very much appreciate your advise "USE BELTS LIKE THEY ARE FREE".
It is vlaulable advice.
I followed this advice before I have create my account on BF.
I repair knifes for restaurants. So we are talking about removing 100-200µm on each side of the blade.
No burn 2 knives and acording to advice I need to replace the belt.
This does not make any economic sense.

This is my reason why I came to BF and asked.
I think the conversation needs to go different directions.
Will write.

ok so "Sharpening" a "Chef knife" is 1 thing
if you or anyone else has to change the profile/ regrind the knife that simply has to cost more as
that requires much more work and abrasive belts to do..
i have a friend that sharpens knives for $5.00 each.. if anything more than sharpen he quotes MORE money for the extra work..
you did not build the knives !! you are simply trying to provide a "Service" for those that "Do Not Want" to sharpen the knives themselves..