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Consistency in the finish grind. Photo heavy.


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The Griz is direct drive, right? Your only options would be to get a face frame 3-phase motor to replace the stock one and add a VFD, or switch to a belt-drive system with step pulleys. I have a three-speed KMG with the step pulleys. Couldn't justify dropping another grand for variable speed at the time, but it's getting more and more tempting.

 

Oh, and I'm pinning this thread, there's just too much good info here!

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Haha, I actually sold a rifle to buy my grinder, so I totally feel your pain   So, I checked out around to see if I could find out where I had read that A45 belts were equivalent to 400 grit. A few

I love the Trizact Gator belts. I usually go to hand sanding at 220 right off the A45, and if I did my grinding properly it doesn't take long to get to 400 or 600.

In the quest for less hand finishing and more consistent finish grinds. Based on a conversation on another forum. I decided to do a study of grinds with the same weight belt with the same dimensions.

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im toying with the idea of saving up my pennies and getting a tw-90 or kmg. My grinder has already paid for itself 3 times. and seemingly i spend 75% of my time at the grinder it feels like.....

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I had the same exact system Wes.. and i would get to A65 and think.... this feels JUST LIKE A45 lol

 

I dunno what my fix is for the variable control deal. Im using a grizzly so she's just wide open all the time. Do i have to turn the machine off and use it while its slowing down? :(

 

The Griz is direct drive, right? Your only options would be to get a face frame 3-phase motor to replace the stock one and add a VFD, or switch to a belt-drive system with step pulleys. I have a three-speed KMG with the step pulleys. Couldn't justify dropping another grand for variable speed at the time, but it's getting more and more tempting.

 

Oh, and I'm pinning this thread, there's just too much good info here!

 

What I can say that is that having a VFD is a wonderful thing. I have never really used a grinder without one, and I shudder to think about using one without a VFD. Being about to run is slow is a very helpful thing. Like JJ does, I run it slow to polish the plunge. It is also great for making small changes to your plunges. Can't say enough good things about it.

Edited by Wes Detrick
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Wes, Care to cosign a loan for me? :P

 

Haha, I actually sold a rifle to buy my grinder, so I totally feel your pain

 

So, I checked out around to see if I could find out where I had read that A45 belts were equivalent to 400 grit. A few threads on here state that they are anywhere from 200 to 350(that was you Alan!). I found a Bladeforum thread repeated the ~400 grit for A45(and the same thread also says 360), and then Trugrit lists them as "2x72-400 A45CF", which I now believe is the FEPA measurement.

 

So I did some research, to try and find who is saying what and what things really are.

 

First, 3M has this PDF about Trizact abrasives where they have a conversion table that shows 3M A size to FEPA standards . FEPA grit measurements are European and CAMI grits are American , so I found a conversion guide on Wikipedia and one from Klingspor on FEPA to CAMI.

 

So, Trizact states that A45 is the same as P400, which according to both Wikipedia and Klingspor rates at a CAMI grit size of a little over 320 grit. Not 400 like I thought, but not 280 either. Now, if the A measurement really is the size of the abrasive particles in microns, then 45 microns equates to about 280 grit. But since 3M lists the A45 at P400 FEPA, either the micron size is inaccurate or not meant to be exact.

 

Anyhow, here is the complete conversion as near as I can make it.

 

3M Trizact Measurement : FEPA Measurement(European) : CAMI Measurement(US)

 

A5 : P3000 : ~1400

A6 : P2000 : ~1300

A16 : P1400 : ~750

A20 : P1200 : ~700

A30 : P800 : ~440

A40 : P600 : ~380

A45 : P400 : ~320

A60 : P360 : ~300

A65 : P280 : ~250

A80 : P240 : ~240

A90 : P220 : ~230

A100 : P200 : ~220

A110 : P180 : ~180

A160 : P120 : ~150

A300 : P80 : ~75

 

Primary Sources:

3M Trizact Chart on this PDF

Wikipedia

Klingspor

 

*Please note that the chart changed on 4/10/2016 to reflect a bit more accuracy and a better source for 3M "A" measurement to FEPA measurement.*

Edited by Wes Detrick
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Yea i was finding conflicting information as well. What I assumed was the grit was actually 280 - thats what i found on supergrit.com -- and that due to its design it performed like ~400 grit belts

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Thanks for that, Wes! I had forgotten the difference between the Euro grit and American grit as well. So that P400 paper I'm using is really only 320 mesh?

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Yea i was finding conflicting information as well. What I assumed was the grit was actually 280 - thats what i found on supergrit.com -- and that due to its design it performed like ~400 grit belts

 

Ya, I have seen the Supergrit one as well. I am really curious as to where they got their conversions from.

 

 

Thanks for that, Wes! I had forgotten the difference between the Euro grit and American grit as well. So that P400 paper I'm using is really only 320 mesh?

 

Sure thing Alan :)

I would imagine so. According to those tables I found(and others too) and they all agree that P400 is somewhere around 320 grit CAMI. I think P400 is exactly 330 grit(check the Klingspor link), but 330 grit sandpaper is not made...

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Really good feedback here.
Wes, thanks for the list of grit.
There is definitely some conflicting info out there.
In your list I am amazed I have never seen an A16 or anything like that.
Is that the gator or is it the finishing film?
The gist of this is the gator belt which I have only seen in A300, 100, 65,45,and 30 all have the same backing and grit mass not grit size.
So they all ride the platen the same.
Which is what gave me the ability to finish the way I did.

The next issue is time, pressure, speed and fracture.
Abrasives like this need to fracture and in order to do that there is a specific speed and pressure they have to be used at.
My conclusion is that the higher grits at high speed create so much heat that they glaze the abrasive.
Which is why I think I succeeded so well with the slow speed.
Minimal heat.

Thanks for pinning it Alan.
If I can find a gator in something higher than A30 I will add them to the process and document it.
Cheers gentlemen, happy grinding.

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I use A160 thru to A45, but after reading your thorough handing sanding lesson, I think that I will be substantially changing out how I do things. Getting the j-hooks and whorls out has always been a nightmare. I use a steel block, and then finish with a wood block with leather glued to it. What benefit do you feel the corian has? Also, I will go to 800, and then go over the blade with a ultrafine scotchbrite pad. Hmm. You have given me a lot to think on and try. Thanks!

The corian block is just a softness between the hardness of the steel and the softness of the leather.

So like using different durometer wheels when you go through grits.

But instead of grit jumping, I use the blocks for each grit.

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Haha, I actually sold a rifle to buy my grinder, so I totally feel your pain

 

So, I checked out around to see if I could find out where I had read that A45 belts were equivalent to 400 grit. A few threads on here state that they are anywhere from 200 to 350(that was you Alan!). I found a Bladeforum thread repeated the ~400 grit for A45(and the same thread also says 360), and then Trugrit lists them as "2x72-400 A45CF", which I now believe is the FEPA measurement.

 

So I did some research, to try and find who is saying what and what things really are.

 

First, 3M has this PDF about Trizact abrasives where they have a conversion table that shows 3M A size to FEPA standards . FEPA grit measurements are European and CAMI grits are American , so I found a conversion guide on Wikipedia and one from Klingspor on FEPA to CAMI.

 

So, Trizact states that A45 is the same as P400, which according to both Wikipedia and Klingspor rates at a CAMI grit size of a little over 320 grit. Not 400 like I thought, but not 280 either. Now, if the A measurement really is the size of the abrasive particles in microns, then 45 microns equates to about 280 grit. But since 3M lists the A45 at P400 FEPA, either the micron size is inaccurate or not meant to be exact.

 

Anyhow, here is the complete conversion as near as I can make it.

 

3M Trizact Measurement : FEPA Measurement(European) : CAMI Measurement(US)

 

A5 : P3000 : ~1400

A6 : P2500 : ~1300

A16 : P1200 : ~700

A20 : P800 : ~440

A35 : P600 : ~380

A45 : P400 : ~320

A65 : P240 : ~230

A100 : P220 : ~200

A160 : P120 : ~150

 

Primary Sources:

3M Trizact Chart on this PDF

Wikipedia

Klingspor

I am confused about these grits from the perspective of the gator belt.

As far as I can see the gator belt ends in grit at A30 and the A20 and A5 are just a cloth backed J weight belt.

This would cancel the progress made in flat grind with the same backing, height, and ride of belt over the platen.

Thoughts??

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I thought I had responded to this thread some time ago (like when it first appeared) but, I seem to have imagined that.

That's a really nice finish JJ and the information contained here is wonderful.

If I could turn your attention back to the knife for a moment, I do have a design question to ask.

It looks like the spine is square cut, but the bottom of the ricasso is rounded. Is that correct, and was it intentional?

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I thought I had responded to this thread some time ago (like when it first appeared) but, I seem to have imagined that.

That's a really nice finish JJ and the information contained here is wonderful.

If I could turn your attention back to the knife for a moment, I do have a design question to ask.

It looks like the spine is square cut, but the bottom of the ricasso is rounded. Is that correct, and was it intentional?

Hey Joshua, thanks for the compliment and the question.

The answer is yes the ricasso is rounded and the spine is flat.

And yes it was intentional.

I have both technical and philosophical issues with ricasso.

The first is that it is a square block in what is other wise a set of distal tapers.

It seems to me that the knife should taper from the shoulders back to the end of the tang and the shoulders forward to the tip of the blade.

But since I'm working towards my stamp and the rules seem to be that the ricasso is to be square on all four corners to a few thousandths.

So not only is this a PITA to accomplish it also looks, to me, blocky and out of sorts, breaking the lines of the tapers.

Past that, having read a conversation on another forum about the bottom of ricasso never being truly square.

That they are to some extent crowned.

I decided to embrace it and crown it totally.

Where as keeping the spine square is a lot easier.

I also do some pieces with fully crowned spines.

Especially kitchen knives.

 

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It just looks off to me.

If I round the bottom of the ricasso, I also round the spine of the blade.

If I leave the spine square, I leave the bottom of the ricasso square.

Just my personal compulsiveness......... :wacko:

 

"Past that, having read a conversation on another forum about the bottom of ricasso never being truly square.
That they are to some extent crowned."

 

Balderdash I say.

If you want it square, make it square. Why would it be possible to make the spine square, but not the bottom of the ricasso?

Edited by Joshua States
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I am confused about these grits from the perspective of the gator belt.

As far as I can see the gator belt ends in grit at A30 and the A20 and A5 are just a cloth backed J weight belt.

This would cancel the progress made in flat grind with the same backing, height, and ride of belt over the platen.

Thoughts??

 

Correct, I just added all of the stuff above A35 in grit for reference, so that we could see what the grit compares to.

Considering that I have been stopping at A45(but plan on using the A35 belts going forward) I don't think that it has a direct consequence to how your process works.

I figured that it would be useful since 3M is a fairly common maker of abrasives. Also helpful to have the FEPA to CAMI table as well.

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It just looks off to me.

If I round the bottom of the ricasso, I also round the spine of the blade.

If I leave the spine square, I leave the bottom of the ricasso square.

Just my personal compulsiveness......... :wacko:

 

"Past that, having read a conversation on another forum about the bottom of ricasso never being truly square.

That they are to some extent crowned."

 

Balderdash I say.

If you want it square, make it square. Why would it be possible to make the spine square, but not the bottom of the ricasso?

.

 

To some extent I'm still playing with looks and styles.

I also am not overly attached to anything I make so I'm willing to jump into crazy ideas all the time.

May look good or not.

I tend to feel it out and look at other people's responses.

The conversation about ricasso was on the ABS forum and the general response from those giving feedback was that to some extent ricasso bottoms are crowned.

For me. Since I've never made a fully square ricasso in any dimension, all I can say is that it's one more detail that will have to be addressed.

But again I don't like how square ricasso look

Edited by JJ Simon
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.

 

To some extent I'm still playing with looks and styles.

I also am not overly attached to anything I make so I'm willing to jump into crazy ideas all the time.

May look good or not.

 

J.J. You just keep doing what you feel like doing! It's all part of the journey and your knives are looking great.

 

 

.The conversation about ricasso was on the ABS forum and the general response from those giving feedback was that to some extent ricasso bottoms are crowned.

 

Hmmm, the ABS forum.........Probably because they "shoe shine" the final finish so they end up with a crown, or at least rolled edges. I'm not opposed to breaking the edge a little and calling it square. Maybe that's what they meant, but it doesn't have to be crowned.

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The definitely discussed breaking the edges.

I think the edges on all parts of the knife should be broken.

This is one of the main harping points of my friend and favorite critic Sam Salvati.

Along with a good handle should feel like a firm hand shake.

I appreciate the compliment.

I tend to be a little design schitzofrenic.

Would help if I drew things before I started.

And I can draw.

But hell what's the fun in that?

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I've seen pictures of your arms, so I know you can draw...... :)

I also used to work very organically, designing at the anvil, figuring out the handle design after the blade was forged and finished, experimenting along the way, etc. Things were going well, I thought. Then one day someone suggested I do the opposite and completely design the knife down to the last detail before I even put the steel in the forge. Being a fan of "not-doing" I decided to give it a shot. So I built three knives. Two were by the new technique and the third was by my normal methods. I finished all three knives and was pretty happy with the way they all turned out, so I took them to work to show the guys in the shop. These guys are not knife makers, only one of them (the welder guy) was a metal worker of any kind. These guys were building maintenance workers. Carpenters, plumbers, HVAC mechanics, etc. Skilled tradesmen all, but not knife aficionados by any stretch. All three knives were of the same quality (or so I thought) in terms of fit & finish, materials, etc. Everyone had the same opinion.

The two knives I had designed from the beginning were much "higher quality" than the organic one.

Nobody could tell me why they felt that way, they just did.

Now I have a new method of making knives and it's just as much fun as the old method.

The truth be told, it's much more challenging. So it's really more fun.

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JJ ive got a compliment of belts coming in (i was due a new batch) and i had a procedure question for you. I just ordered a grinding magnet as well, do you use one? At what point to you know when to stop hogging? Lately ive been grinding 36 until around 80-85% (made up assumed number) of the finish i want then stepping up a grit. For some reason it seems to take an eternity to wash out all the previous grit marks. I get all that i can see then etch for 30 seconds and a few rows of marks show their face. Is there a trick that you use that will improve my results? I find myself jumping back a grit sometimes to try and get a bit of material out for a deep scratch here or there. Originally i was using 36-80 blazes, then A160 A65 A45. But in all honesty i probably skilled the A65 almost every time.

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JJ ive got a compliment of belts coming in (i was due a new batch) and i had a procedure question for you. I just ordered a grinding magnet as well, do you use one? At what point to you know when to stop hogging? Lately ive been grinding 36 until around 80-85% (made up assumed number) of the finish i want then stepping up a grit. For some reason it seems to take an eternity to wash out all the previous grit marks. I get all that i can see then etch for 30 seconds and a few rows of marks show their face. Is there a trick that you use that will improve my results? I find myself jumping back a grit sometimes to try and get a bit of material out for a deep scratch here or there. Originally i was using 36-80 blazes, then A160 A65 A45. But in all honesty i probably skilled the A65 almost every time.

I use a 36 then an 80 to get the grit marks out

Etching is a good idea

I grind to maybe 90% finished with the 36 then got to the 80 and then use the first Trizac at full speed.

My machine runs somewhere around 6000 SFPM it really hogs material.

Then I heat treat.

Go back to the Trizac and get out any decade and then finish.

Again to use the high grit belts you have to be able to really slow the machine down or they will just glaze over.

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maybe thats what i do wrong. I pre HT grind like you. But after HT i tend to go back to the hogger belts to get the blade closer to final dimensions. I have no options at the moment about my belt speeds without checking my grizzly will be stuck at 1800? Grinding post HT with a A160 gator to get the final dimensions is super slow for me.

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maybe thats what i do wrong. I pre HT grind like you. But after HT i tend to go back to the hogger belts to get the blade closer to final dimensions. I have no options at the moment about my belt speeds without checking my grizzly will be stuck at 1800? Grinding post HT with a A160 gator to get the final dimensions is super slow for me.

 

I wouldn't go all the way back to a hogging belt to do post heat treat grinding. I typically go back to an 80 grit belt, and take the bevels down to their final dimensions. Mind you, this isn't a lot. I leave the edge about as thick as a dime, and then take it down to about .5 mm. Then I start moving into the gator belts. I would never use gator belts to make substantial dimensional changes. They just don't seem good at it.

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I have to test if a 300 belt makes a significant dimensional change but I agree going back to hogging is a bad idea.

One because hardened steel with a 36 grit scratch in it is a bitch to get out by hand

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