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Green teeth Carbide

Bart

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Anybody have any insights into the carbide type of Greenteeth, particularly the red vs green versions of the 700 series? All I've found thus far is the red is a harder type than the green. thanks. Also if its in your wheelhouse do you figure diamond wheel is indeed superior to silicon carbide for sharpening? Wet vs dry sharpen, high vs low wheel rpm? I've seen the Greenteeth drill press jig up video. thanks
 

lumberjack

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Reds are more concave and thus more aggressive. The flip side is the cutting edge is thinner and thus more susceptible to damage/chipping from rocks.


Greens are less concave, have a thicker cutting edge, are less aggressive, and do better contacting hard things.

Wet diamond sounds like a win to me, less/no airborne particulates and it should last a while. RPM of the wheel is dependent on what you're cutting with and what you're cutting, cutting edges have a target surface foot per minute speed. Lower RPM would imply a larger diameter wheel which all things being equal will last longer since it's larger and has more material doing the work/wearing.
 

Tree09

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I don't know much about grinder teeth, but i know a bit about steel. The harder steel is, the more brittle it is, and the more carbon it has. The less carbon, the tougher it is, but is more malleable so it will dull quicker. Exactly what Carl said. When dealing with hardened steel, it is almost always best to wet grind, because you are trying to preserve the hardening process. When steel is hardened, it is heated quite hot and then quenched, forming certain grain structures. It is usually then carefully heat treated (tempered) to relax some of the hardening and make it tough enough to be useful. You can technically do this yourself with a forge, but if you don't know exactly what you are doing you will have mixed results. The particular steel used might be an alloy with other elements, so preserving the heat treatment is best. You need to be able to touch it bare handed at all times, very little heat input.
 

Tree09

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Oh nice. They are still heat treated if I'm not mistaken, so just about everything stands, including carbon content. It's just tungsten rather than iron. In fact white cast iron is called iron carbide, and is used for its hardness as well. The wear part on train wheels for example.
 

Bart

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Lumberjack, would that be a picture of a new cutter? I don't have access to one yet. If you happen to be a machine shop type guy, would you say the new edge is pretty sharp like a cutting tool for a lathe etc or does it have a tiny blunt radius right at the cutting edge? We're talking tiny radius like you're not sure it's there except that the edge feels like it could be sharper based on "shaving' your fingertip. Or bigger if it is. ? thanks

Would you have a picture of a 700? The 900 looks like it changes curve right at the cutting face to a tiny flat maybe 1/2mm wide. ?

edit - sorry for being internet dense, I've since found multiple pictures of the 700 red showing the tiny flat at the edge. But the shaving question still stands. And I think the carbide is probably the same composition just different geometry green vs red.
 
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flushcut

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Diamond wheels will not produce silica dust like green wheels but will produce carbide dust which can be equally nasty if not more so depending on the exact composition of the carbide. But still bad for your health.
High speed. Wet, is best for cooling and dust control but the machines are expensive, and cooling really isn't a concern with carbide as it can take a massive amount of heat before it will soften. You will melt the silver solder/braze joint long before any damage comes to the carbide.
Also if dry grinding be outside with a powerful fan or vacuum going to control the dust.
There are other types of wheels such as ABN and CBN that can be used but I don't know much about those types other than they can grind both carbide and steel without loading up. They will not last as long as diamond tho.
The edge is sharp but not shaving sharp like fine wood working blades. It's stump grinding not fine furniture making.
 

treesmith

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The pic Carl posted is of a 900 series Wear Sharp tooth, which I run on my machine. They claim (and somehow it is true), that as the edge wears, it wears back to a new edge. I think that's the ledge you're referring to. They are not "sharp" like a knife, but have a good cutting edge. And they stay sharp longer than regular Greenteeth.
 

lumberjack

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The edges are sharp enough to cut the edge of a finger nail on, or at least make a divot, but they're not sharp enough to cut skin.

I just pulled that picture from Green's website.

The non wear sharp teeth are a simple concave as best I recall. The wear sharps have some extra geometry like treemith says, which allows them to wear the edge sharp vs rounding.


If you're looking to duplicate an original tooth, why not spend the few bucks and buy one? That'll give you plenty of reference to improve your process.
 

Bart

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Thanks. With the Covid, boogying around getting stuff is a bit of a no no, but I'd love to get one to mimic. I have to look into it, and the local outlet is probably shut down due to Covid. Turns out machinists regularly put near shaving edges on but that would be pointless in the dirt. It looks like the cup is shaped during the sintering, my 700 is a 1" radius bang on, then the top edge is probably honed lightly and then the side with the clearance angle is ground to form a more supported cutting edge (because its carbide) and to form an actual ground cutting edge. The next conundrum is that machinists say to never grind the top face because it promotes fracturing, grinding up the side faces is bueno, but the green teeth video showed grinding the top concave face to sharpen. I was planning on the drill press top grind, probably still will.

Anyone have experience with what to use to dress a resin bond diamond wheel to deal with any plugging?
 

flushcut

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The diamond wheel I bought was from Eagle Super Abrasives and it came with a cleaning stick. It looked like aluminum oxide in stick form.
 

Marc-Antoine

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Grinding the side would remove less carbide than the face and easier to do, but I see two downsides : you would quickly bite the steel indexing form and with a reduced diameter, the carbide head wouldn't protect enough the holder on the wheel, so it will wear faster with the dirt.
 

Bart

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Update. State of emergency declared, all non essential businesses closed by tomorrow night. Today I scooped a new tooth from a distributor 10 minutes from me who has remained unknown to me for at least 7 years. He said "Maybe I need more advertising." I heard the emergency announcement on the drive home.

There's enough cutting edge to easily scrape high spots off the back of your fingernail. The flat on the front is about 0.040 wide, the small grind on the vertical is about 0.050 long and the clearance angle measures out about 7 or 8 degrees. With old man eyes and all the tricks I can muster I say the cutting edge is a 90 degree form. That makes sense because non-support equals broken carbide. So the upshot of this is that I think I need to recreate the 90 degree form to balance support, friction and efficiency of the cutting edge. The drill press method may be stage 1 with a 90 degree form chase stage.

I'm not quite convinced the vertical is ground, it might just be during sintering. But the top face looks ground as it seems at this point.

Now knowing this I can see side by side how the original tooth just kind of went away, even the overall height of the carbide.

I think I read somewhere else about white aluminum oxide as a dressing stick. Flushcut, was your wheel metal with a thin skin of diamond or has about 1/4" ring of diamond stuff i.e. thick diamond material?
 

Bart

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You got the good one. I got same but small diameter. Different company but resin bond. I'm currently running slow with plain water bath. I'll get into my rig later. Norton mentions white aluminum oxide dressing stick for us. I'm going to try to dodge dressing by using lots of clean water.

How much material do you feel comfortable with removing? Keep 95% O.D. or keep 80 or 90% front face to rear braze thickness etc? I'm going to squeeze my brain with some math for nut clearance on my wheel. Other than that if it's got proper support geometry I figure you can hit them pretty hard. My 150 grit is not leaving a nice finish. It did successfully create the 90 degree cutting edge after forming the face curved dip. There's hope.
 

flushcut

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Right on. I suggest sharpening once and then tossing them. You should have made enough money to justify buying new teeth after two grindings.
 

Bart

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Well, the only highlights of my rig is drill-press-like, but I sacrificed a cheap cordless drill and put the cutter horizontal spin, grinding stone in mill spindle - this is so I can see the grind progress on the cutter face and see the outer edge too. Couple hundred rpm stone, slower on cutter. Just dribble water on it, surface tension keeps it on, re-dribble rinses out grit, drops in small plastic tray, no dust or spray at all. Drill mounted on bar at battery spot and pivots so pivoting moves the cutter face into the wheel. At first I did it by hand, then I noticed a table clamping T slot nut/bolt/nut was an adjustable tensioner. Plastic drill has enough give to allow wobble for off center carbides or bit bent bolts (accidental feature). Use mill table to align face grind or either 90 degree tiny grind. Use a power supply direct to drill motor to pick steady speed I like. I mix between by hand and setting/forgetting/check back,

Bit slow but I kept the red cutter angle and didn't turn it into a green cutter angle. I also noticed that the face is only lost after the O.D edge has been seriously beaten back. Lots of nut clearance left starts out as 01 to 0.2" and only 0.010's are being cut off the cutter dia.
 
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