What belt are you surface grinding with?

Josh Rider

Josh Rider

Stuff maker
Joined
Sep 2, 2014
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I usually use a ceramic like a vsm if I’m trying to take off material fast.

If I’m wanting a better finish then I go with a gator a160 or higher.

I’ve tried the ceramic norzac (the expensive ones) but find I get a lot of heat.

I’m curious what others are using are using on their belt converted surface grinder.
 
On my attachment, I'm using vsm up to 120. I haven't gone higher since I'm likely to have to clean it up during bevel grinding. Then I just use a magnet on my flat platen
 
I've got a Wuertz SGA and use ceramics up to 120 for pre heat treating surface grinding and then Norton U254 Norax Engineered Aluminum Oxide up to X22 for finishing. At that stage I'm taking very superficial passes so heat doesn't build up.
 
100 grit VSM followed by a 220 ceramic belt . I finish by using a magnet on a flat platen at 320 or 400 grit and then grind my bevels. Everything else after heat treat. Larry

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Josh Rider said:
I usually use a ceramic like a vsm if I’m trying to take off material fast.

If I’m wanting a better finish then I go with a gator a160 or higher.

I’ve tried the ceramic norzac (the expensive ones) but find I get a lot of heat.

I’m curious what others are using are using on their belt converted surface grinder.
Click to expand...

I go up to an A65 gator for all my stuff and customer knives. If it just needs a kiss to remove the heat treat scale/coloring then a65 is all I use.
 
I'm roughing with a 50 grit Blaze and finishing with Gator belts. I found I can almost get a good finish with the blaze belt, but they tend to glaze up during the spark out. I've tried doing the whole grind with the Gators but they wear too fast.

I'm loading up a 10 x 20 magnet on an automatic grinder and removing about .025" per side in steps. I can remove about 10 lb of steel with one 50 grit Blaze
 
I guess while I’m on it, what speed are you guys grinding at? Since my surface grinder is on my vfd I’ve been keeping it at the max speed that’s on the motor. Being that it’s a surface grinder motor, I didn’t want to push it and kill the motor earlier than I normally would.
Maybe I’m being over cautious.
 
I rough with the 3M 984 in 60 grit.
Clean with Gator A100 while I'm working on the piece and then final clean with A30.
And I switched to a 1" wheel five years ago from the 2" I originally put on. Because we convert these things to belts does not change how the machine is designed to work.
If 2" stone wheels were more efficient then that's what would be on them.
 
for tapered tangs i use 3m 984 belts. 36, 60 and 120 grit. i have a tw-90 with the small 120v motor i run the vfd speed control at around 11 oclock.
 
I mean for the dedicated surface grinders. They have motors that you can’t easily just swap out with another motor if it goes paws up, so I haven’t been doubling the speed.
Not sure if this is a necessary precaution.
 
I think you want about 5000-6000 SFM for grinding. If your spindle is 3600 RPM you'll want a 6" wheel. If your spindle 1750 you need a 12". I wouldn't change the motor speed, I'd use the right wheel size.
 
I use a 2" wide belt because a 1" belt will have excessive wear decking a 10X20 table load. If you have a smaller table or run smaller loads you might want a 1" belt so you can get on and off your parts quicker.

My wheel is 2 1/8" wide to fully support a 2" belt without risk of some of it hanging off the side. If you have belt hang over it won't wear at the same rate as the rest of the belt and it can create stripes if it wanders back onto the wheel.
 
Nathan the Machinist said:
If you have a smaller table or run smaller loads you might want a 1" belt so you can get on and off your parts quicker.

My wheel is 2 1/8" wide to fully support a 2" belt without risk of some of it hanging off the side. If you have belt hang over it won't wear at the same rate as the rest of the belt and it can create stripes if it wanders back onto the wheel.
Click to expand...

I do have a smaller table, so the one inch is perfect for me. My wheel is .040" over for that very reason.
I've seen so many guys think that because they have converted their surface grinder over to a belt that it is now somehow no longer a surface grinder, but rather a new configuration of a belt grinder.
It's still a surface grinder meant to function like a surface grinder - just that now it's using a belt and not a "stone" wheel.
Even these rubber wheels need to be dressed from time to time and I do that with an end mill in a holder I made.
Belts are not "true", which is one of the reasons to use the machine as a surface grinder moving across the work piece in small passes. With a 2" inch wheel that can take forever and is a poor use of the belt's working surface. Very inefficient.
Maybe someday I'll have a larger machine but for my uses and folder parts, etc., the one inch works great.
Thanks for your clarification. It may help others.
 
I'm using a belt rather than a stone because I need to peal off upwards of .025 per side in a production setting which is outside the scope of most stone wheel surface grinders. The belt runs much cooler and can take much deeper cuts. However, being a regular automatic grinder it is limited to .002" down feed per pass even though the belt could take much more. So, I'm feeding it over much more per pass than a stone would. I'm roughing a 10X20 table load pealing .002 at about 100 IPM and feeding over 1/4" per pass. It only takes a few minutes to rough in the full table load. I reduce my depth of cut to .001 and the step over to 1/8" for finishing and have it set to three spark out passes on the finish belt.

Something that's surprising to me is I appear to get very little heat this way. Very little sparking. The swarf is shiny and bronze colored. I figured I'd need to run coolant but we're just running it dry. The chips from the roughing cycle are pretty heavy, it almost looks like coffee grounds piling up. The finishing cycle generates regular dust, though it still doesn't spark much.

Something I struggle with is belt wear which can erode faster than the work. If I need .005" I need to dial in at least .010" on the finish belt. The work piece thickness is consistent across the table, in part because I'm going across the table so quickly and because the belt is pretty wide. The belt erodes a little more on the edges and the center of the belt is doing the finish work on the spark out passes.

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I have been able to avoid striping and choppiness and can dial-in whatever surface finish I want simply by changing belts. Part thickness is very consistent within a batch, but can vary from one load to the next depending on how well I dial it in. Right now if I get the part thickness I'm aiming for to within . 001 I call it good so a run might vary from .187 to .189.
 
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Nathan the Machinist said:
I'm using a belt rather than a stone because I need to peal off upwards of .025 per side in a production setting which is outside the scope of most stone wheel surface grinders. The belt runs much cooler and can take much deeper cuts. However, being a regular automatic grinder it is limited to .002" down feed per pass even though the belt could take much more. So, I'm feeding it over much more per pass than a stone would. I'm roughing a 10X20 table load pealing .002 at about 100 IPM and feeding over 1/4" per pass. It only takes a few minutes to rough in the full table load. I reduce my depth of cut to .001 and the step over to 1/8" for finishing and have it set to three spark out passes on the finish belt.

Something that's surprising to me is I appear to get very little heat this way. Very little sparking. The swarf is shiny and bronze colored. I figured I'd need to run coolant but we're just running it dry. The chips from the roughing cycle are pretty heavy, it almost looks like coffee grounds piling up. The finishing cycle generates regular dust, though it still doesn't spark much.

Something I struggle with is belt wear which can erode faster than the work. If I need .005" I need to dial in at least .010" on the finish belt. The work piece thickness is consistent across the table, in part because I'm going across the table so quickly and because the belt is pretty wide. The belt erodes a little more on the edges and the center of the belt is doing the finish work on the spark out passes.

View attachment 1031584

I have been able to avoid striping and choppiness and can dial-in whatever surface finish I want simply by changing belts. Part thickness is very consistent within a batch, but can vary from one load to the next depending on how well I dial it in. Right now if I get the part thickness I'm aiming for to within . 001 I call it good so a run might vary from .187 to .189.
Click to expand...

I do .003" reduction per pass at a .200" feed with 60 grit. Surely doesn't take long to reduce anything I need.
I think some folks don't get the concept of only moving a little at a time. They use these surface grinders like knife grinders.
In your situation working with large pieces it makes sense.
For the average knife maker, or even a folder maker, a 2" wheel is greatly overkill and is more detrimental than helpful.
I couldn't make a knife without mine anymore.
 
Contrary to how I use belts for grinding by hand, I actually found the high end ceramics to be a waste of money for roughing billets of damascus, and general hogging application on my hydraulic feed SG. This isn't a huge grinder by SG standards, by any means, but it's big for most knifemakers. Unfortunately I made the mistake of putting a 6" contact wheel on it, so I don't get the SFPM to be optimal for ceramics, and at 2" full engagement (which is ideal for my use on typically 2" wide bars), don't really have the HP (3HP spindle) even if I did have a larger wheel, on this grinder.

I was using the same high end ceramic belts I buy for grinding bevels for a while, but when I was out, in a pinch, I used some of the cheap blue Zirc/AO belts I get from Pop for handle material, and amazingly, they're every bit as effective, or more, with this machine, and it's variables.

That being said, I utilize the "crank the Z down 30 thou till it's starting to bog, with the auto traverse engaged, and walk away, until it stops making a lot of noise, come back, and repeat. This machine doesn't have a working auto on Z, so HP is a limiting factor here, for this method.


I use a stone entirely for knife work, the contact wheel is strictly for hogging damascus billets or other heavy stock reduction, and I'm not using flood for this. The Ceramics seem to load up much easier on soft billets, and maybe flood would help here, but without more SFPM and HP to increase DOC, I don't see me getting gains from 4x as expensive belts (the ones I'm using run like $2.something each), and I say that, as someone who you couldn't pay enough to make use cheap belts when hand grinding blades.

One thing to note, maybe unrelated, but while I'm on the subject; any material with heavy scale on it, will greatly reduce the life of any belt, no matter how expensive, from what I've seen, so pickle first, or use a worn shit belt and get that crap off before you start really going at it, otherwise you're just pissing money down the drain.

For reference, this SG typically runs 12" diameter stones, 1-2" wide, weighs maybe 2-3k lbs.
 
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