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Post by holajonathan on Feb 1, 2021 13:35:13 GMT -5
I bought the 7" tuckpoint blade that jamesp linked to in this thread.I have used many different types / brands / sizes of diamond wheels and blades, and James is right -- this is the fastest cutter/grinder I have used. I tested it on a Makita 7" angle grinder which is way too fast. But it just ripped through a very gnarly 4" diameter prairie agate, leaving it pretty well rounded off in 2 or 3 minutes. And that was with me awkwardly holding the angle grinder against a table with one hand, while working the agate against the wheel, spinning at 8,000 RPM, with the other hand. By-the-book OSHA stuff. I just sent the Ebay seller an offer for 11 more of these wheels with plans to make a basic 3" wide (12 blades stacked) pre-tumble grinder using pillow block bearings, steel rod, a pulley / belt, and a 1750 RPM 1.0 hp motor. My plan is to mount it all to a small stainless steel table and cut a slot in the table below the blades, allowing the blades to pass through the slot as they spin. That will get me the clearance I need since the pillow block bearings will only bring the shaft about an inch off the table. And it will allow me to hang a garden hose under the table to spray the blade with water as it passes under the table. This will be an outdoor / summer grinder. The blade has some beefy sintered segments, which should bode well for longevity. But I am wondering if part of the reason it cuts so aggressively is because it has a very soft bond. A soft bond wears fast, quickly exposing new diamonds. This is what you want for hard materials like agates. But if the bond is too soft and wears down too fast, you get large pieces of diamond exposed which tend to fracture and break off long before the diamond actually wears down. The reason I am concerned about this is that after just a few minutes of grinding with the blade, the surface seems even more aggressive than when it was new. This is based on a visual inspection and running my finger across it. Question 1: Has jamesp or anyone else worn one of the Advanti tuck point blades out using it as a grinder? Or a different brand of tuck point blade? If so, did it last about as long as you expected? Question 2: What RPM should I run? Faster tends to be smoother when grinding with segmented blades, but faster also wears out the blade quicker, make it harder to keep the dust down, and usually makes balancing more of an issue. I am thinking that the motor's 1750 RPM output might be a good start. Or maybe even down around 1200-1500 with a little added torque. I have other more powerful motors available, including a 2.0 hp Baldor, but I think 1.0 hp is plenty. Unless someone wants to convince me otherwise. Thank you!
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Post by rmf on Feb 1, 2021 14:57:25 GMT -5
I would think a 1/3 hp motor is fine for a 7" blade. Unless I did not understand something.
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jamesp
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Post by jamesp on Feb 1, 2021 18:24:56 GMT -5
holajonathan I must have purchased a dozen different diamond wheels and I have to say nothing cuts like that Advanta 7" tuck. It is one of the longest lasting and fastest cutting diamond wheels. Must be good diamonds because they don't shed like a soft bond wheel. Yes the bond seems to wear back and expose longer teeth. I bought a 5 pack to get a discount and have ground many many tumbles with it. Add a 5 gallon bucket of 1.5 to 2 pound hard agates and pet woods. Removing 25% of their weight, heavy grinding and I have yet to reduce the 1/2 inch thick band down to 1/4 inch. The diamonds are not roundish whole crystals but crushed diamonds of some form that makes for the super sharp cutting surface. I mounted mine on a $99 tile saw. It bolted straight to the motor. The slot in my saw was barely big enough to fit it's width. This motor turns at 4000 rpm, another reason why it removes material so fast. Because it can be lowered down so low in the table I feel safe grinding at such high speeds. Like only a 1/4 inch can be left protruding up thru the table or less for less than 1 inch tumbles. I use the original water pan in the tile saw but add a drip hose to keep the level up. Because the diameter at 7 inches is the same as a 7 inch tile blade. Darn thing is cheap at $25. Lots of sintered diamond for the buck. Overflow drips into a larger pan below. I like grinding with it's 1/4 inch width. It is easy to get more point pressure. Once the pressure reaches a certain amount it steps into another level and cuts rapidly. Like sawing with a chain saw with a poor angle filed on the blade, it has a sweet spot where it saws rapidly when a certain pressure is reached.
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pizzano
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Post by pizzano on Feb 2, 2021 2:29:40 GMT -5
I too use Avanti Diamond blades, but never their tuck point, only segmented and turbo rim type. The tuck point is to aggressive to manage safely due to the overhanging blade being stationary and exposed with no height or depth adjustment available (7" MK 170 1/2hp, 5500rpm wet tile saw). Both the segmented and turbo blades "grind" everything I've thrown at them fast and without serious kick back or chipping. But, they will not grind wide swaths due to the rim surfaces being smaller than a tuck blade. I like them because they work great as cutters as well......and remind myself to rotate/switch to both sides of the blade when grinding......lol
If I remember correctly, it was jamesp who suggested to me to use the segmented diamond for grinding. I found/find the Avanti's at Home Depot between $15.00 and $18.00 each. They evidently are not "soft bond" material because, like James, mine have worn tremendously well. Evan as I abused the first one learning the proper skills, it still cuts a very nice track and doesn't leave very deep scars. Just a little slower.
I've only been at this cutting/grinding stuff for about 2-1/2 yrs, and only cut about 6 to 8 pounds (2 to 3 hours worth at a time) of hard tumbling size material, every couple of months......so far, have only needed to purchase 1 segmented and 2 turbo Avanti blades.......I can't say that for the other dozen or so "off the shelf" inexpensive brands I've throw out or use for field target practice.....lol
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jamesp
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Post by jamesp on Feb 2, 2021 6:42:22 GMT -5
Not sure why they perform so well pizzano. It is a fact that synthetic diamonds are not created equally. There are many variations designed for specific tasks. Under magnification Advanta diamonds are appear crushed to expose super sharp edges and then sintered. This flickr link has photos and a couple of videos showing them mounted on an old tile saw that has an adjustable table. Sure comes in handy for lowering the blade so only a small portion is exposed for increased safety. SAFETY FIRST. You'd think the notches would cause bumping but at 4000 rpm it is if they are non-existant. Old saw has 3/4hp and my hands are not strong enough to slow the blade down when bearing down very hard when grinding large rocks. photos and videos www.flickr.com/photos/67205364@N06/albums/72157683648790962Blade height at 1.5 inch, for small tumbles I run 1/8 to 1/4 inch height. 2.5 pound Rio agate with bleach patina removed totally. After what must be 50 hours of heavy pressure use. Looks 40% worn. Note diamonds appear to be crushed particle. Segment 1/4" wide. Advanta diamonds seem tuned for the Mohs 7 stuff. Guessing the sintering is hard(Mohs hard) so the long life on Mohs 7 rock.
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pizzano
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Post by pizzano on Feb 2, 2021 12:08:24 GMT -5
Outside of blade material type, function, application and quality, I gotta believe many manufactures have simply "tuned" their blades to specific RPM tolerances which they all have some type of "sweet-spot" meant to be either throw-away or longevity.......? They all have some type of Max RPM disclaimer (generally around the 8000rpm) limit........it's finding that sweet spot for your application that makes a lot of difference as well..
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jamesp
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Post by jamesp on Feb 2, 2021 16:51:04 GMT -5
Outside of blade material type, function, application and quality, I gotta believe many manufactures have simply "tuned" their blades to specific RPM tolerances which they all have some type of "sweet-spot" meant to be either throw-away or longevity.......? They all have some type of Max RPM disclaimer (generally around the 8000rpm) limit........it's finding that sweet spot for your application that makes a lot of difference as well.. The use of these diamond cutters on many different materials this day and age from brittle to hard and soft to tough should warrant a whole book on feed speeds/rpm/diamond type/sintering hardness/grinding pressure/etc. Most are used in industrial applications. Lapidary is a small segment. It would seem Mohs 7 rock is an animal all to itself when compared to most industrial materials. A tuck blade is used for removing mortar from between brick and rock. Guessing they are designed for up to granite hardness since the wheel may hit granite when working a rock wall.
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Post by holajonathan on Feb 3, 2021 1:49:23 GMT -5
jamesp Although it is only a part of my business, I sell diamond blades / cup wheels / abrasives -- mostly Husqvarna, Diamond Products (Core Cut), Lackmond, MK Diamond, and 3M brands. I deal in the construction related products, not lapidary lines. I claim no special expertise, but I've sold a lot of these products to contractors, including a few guys who do nothing but cut and drill concrete and stone all day every day. I always ask their opinions and try to learn as much as I can from them about the products. I'll gather my potentially relevant insights and post them here sometime in the next few days. Advanta on Ebay agreed to sell me 11 of the 7" tuck point blades for $18 each shipped. When I bought just 1 they shipped it in a USPS flat rate envelope which costs them $7.50 to ship. I explained to them that they can ship me all 11 in a USPS medium flat rate box for around $13.50 vs $82.50 shipping cost if sold individually. They understood and agreed to pass all of the savings on to me. Hard to beat at $24 each; even more so at $18 They said that after selling me the 11 blades they have 10 left in stock at the current price. After those 10, they are going to raise the price since the Trump-era China tariffs have increased their cost to import these blades. (I thought China paid the tariffs?) This may be just a sales pitch. Who knows. I noticed that Advanta lists a diamond grit size in some of their Ebay listings, but not for the tuck point blades. I just wrote them asking 1) the grit size for tuck point blades; and 2) which other Advanta products use the same bond and diamond size as the tuck point blades. As you point out, the reason these work so well is that the diamond and the bond are a good match for Mohs 7-ish rocks. I would have expected a harder bond in a product designed for grinding mortar joints. I think mortar is lower than Mohs 7 and more abrasive than mohs 7 agates / jaspers. Those factors would suggest the use of a hard bond. If they tell me this uses the same diamonds and bond as the tuck point blades, I may end up being the owner of an absurdly large rock grinder. I might buy one or two if you and others are willing to give me a few pointers when trying to figure out how to power it. At 18" and with the weight being concentrated on the rim, it would produce a substantial fly-wheel effect, giving it an enormous amount of grinding power in short bursts. I am getting excited just thinking about it.
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Post by holajonathan on Feb 3, 2021 2:25:45 GMT -5
Outside of blade material type, function, application and quality, I gotta believe many manufactures have simply "tuned" their blades to specific RPM tolerances which they all have some type of "sweet-spot" meant to be either throw-away or longevity.......? They all have some type of Max RPM disclaimer (generally around the 8000rpm) limit........it's finding that sweet spot for your application that makes a lot of difference as well.. The use of these diamond cutters on many different materials this day and age from brittle to hard and soft to tough should warrant a whole book on feed speeds/rpm/diamond type/sintering hardness/grinding pressure/etc. Most are used in industrial applications. Lapidary is a small segment. It would seem Mohs 7 rock is an animal all to itself when compared to most industrial materials. A tuck blade is used for removing mortar from between brick and rock. Guessing they are designed for up to granite hardness since the wheel may hit granite when working a rock wall. "The use of these diamond cutters on many different materials this day and age from brittle to hard and soft to tough should warrant a whole book on feed speeds/rpm/diamond type/sintering hardness/grinding pressure/etc." Under diamond type, there is the natural vs synthetic issue, the issue of grit size and shape, but also the issue of how the diamonds are placed in the segment. Some of the more advanced manufacturers like 3M and Diamond Products have developed ways to bond the diamonds within the segments (or in the case of 3M, to bond them to things like hand laps and wheels) at a certain angle or orientation to the cutting surface. By aligning the diamonds this way, they can minimize fracturing and increase cutting speed and longevity. I sell some 3M diamond abrasives and Core Cut blades that use this technology, but I do not have personal experience using them. I try to understand all of these factors by thinking about how a diamond blade is supposed to grind through material. The diamond does the grinding, and the bond holds the diamond in place. As diamonds wear down or fracture / break, the bond must wear to expose more diamonds. If the bond wears too fast, you lose a lot of diamonds to fracturing, since large piece of exposed diamond are fracture prone, especially with increased pressure. (Diamonds are very hard but fairly brittle.) If the bond wears too slowly, you end up with not enough exposed diamond, which means slow cutting. And if the user response to slow cutting by increasing pressure, the pressure makes a lot of extra heat because the bond directly against the rock/concrete does not cut and instead just generates heat. The increased heat and pressure causes even more diamond fracturing, which is a downward spiral of poor performance when using too hard of a bond. The most advanced manufacturers like Husqvarna have extremely specialized lines of blades designed for a specific density of concrete, with a specific type of aggregate, run at a specific speed of feet per minute (when used on a walk behind concrete saw). From the customers I talk to, if they perfectly match the blade to the material, they really do get great results in terms of performance and longevity. The challenge is that the up front cost of these blades is so high, they are only a good investment if they can cut a lot of the same material. If they go from one small job to the next, and don't feel like constantly swapping out blades (some of these blades are 36" to 48" x 0.25" and weight 100+ pounds), then they have to make a compromise. At least one guy a talk to a lot always wants a hard bond and high diamond concentration, and he adjusts his forward speed or cut rate depending on what he is cutting. He thinks this offers a better compromise than a soft bond, which will cut everything fast, but wear out quickly in harder materials. At this point I'm rambling, but as you point out, there are a lot of factors at play here, and the consequences in terms of performance and longevity are huge.
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Post by parfive on Feb 3, 2021 2:37:25 GMT -5
(I thought China paid the tariffs?)
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jamesp
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Post by jamesp on Feb 3, 2021 5:28:59 GMT -5
Never underestimate China made holajonathan. Other country's valuable technology mysteriously ends up in their hands. Then their products are manufactured and sold inexpensively due to government subsidization, brutal labor practices and without concern for the environment.
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jamesp
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Post by jamesp on Feb 3, 2021 5:46:11 GMT -5
A basic cutting performance test to perform on any diamond cutter is to rub a Mohs 7 rock against it. If it cuts scratches deep in the rock with low rubbing pressure then it likely has sharp diamonds. If you must bear down hard to scratch the diamonds are likely duller whole roundish(octahedron ?) crystals. This is not a guarantee of longevity but it is a good sign that you have aggressively shaped diamonds. Of course the next test is grinding Mohs 7 on it to see if it holds up. I believe this is another brand of tuck wheel sintered with whole diamond crystals. It cut poorly. diamonds appear to be roundish whole crystals I believe these were comparitive scartch tests in a Mohs 7 pebble. One the Advanta and the other the red tuck blade
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jamesp
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Post by jamesp on Feb 3, 2021 5:57:34 GMT -5
The Advanta tuck blades I received are real slashers. They can grind with a safer lower pressures. Having to push a rock hard against a grinding wheel increases chances for accidents. Another reason I don't like stacked blade grinders Using a smaller single blade contact point requires less hand pressure to remove a lot of material. Beware, due to their sharpness they will also remove epidermis quickly
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jamesp
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Post by jamesp on Feb 3, 2021 6:10:53 GMT -5
This was the worst diamond wheel I ever used. Great shape but only lasted a few hours. Rated for reaming drain holes in kitchen table top granite. About 3 inches in diameter. Loaded with sintering. It cut fast but wore faster. Expensive.
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jamesp
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Post by jamesp on Feb 3, 2021 6:18:13 GMT -5
And the dangerous finger abuser back in 2013. No thanks. Fast, cheap, dangerous and dusty. Often used to shape and remove the bleached patina from petrified coral as shown on the example in the link. Removing the patina from this locally collected coral was always my favorite tumble. The valley worn in the Harbor Freight 4 inch cup wheel was real nice for small tumbles. www.flickr.com/photos/67205364@N06/albums/72157632945074217
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pizzano
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Post by pizzano on Feb 3, 2021 11:50:08 GMT -5
And the dangerous finger abuser back in 2013. No thanks. Fast, cheap, dangerous and dusty. Often used to shape and remove the bleached patina from petrified coral as shown on the example in the link. Removing the patina from this locally collected coral was always my favorite tumble. The valley worn in the Harbor Freight 4 inch cup wheel was real nice for small tumbles. www.flickr.com/photos/67205364@N06/albums/72157632945074217And you still managed to keep all 8 fingers and 2 thumbs intact......and no shrapnel in your chest or arms........?..........lol
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Post by holajonathan on Feb 3, 2021 12:39:43 GMT -5
Never underestimate China made holajonathan . Other country's valuable technology mysteriously ends up in their hands. Then their products are manufactured and sold inexpensively due to government subsidization, brutal labor practices and without concern for the environment. I do not underestimate China made. Many diamond blades are made in the U.S.A. (or more accurately, assembled in the USA). But 99% of them use sintered segments imported from China. This is due to an old law (pre-Trump) that applies import tarrifs to diamond blades but not to the segments or cores individually. The good companies cut the blanks here in the USA and use robots to laser weld the segments. Other companies import the cores from China as well, and only do the welding here. I spoke to a technical guy at Diamond Products (Core Cut brand) who works at their factory near Cleveland, Ohio, and he said they import all sintered segments from China except for the ones that have the diamonds systematically arranged in the segments. Those come from a USA supplier. Diamond Products also makes core bits for Ridgid, and those use segments imported from Germany. Everything else they make uses Chinese segments. All Husqvarna and Bosch sintered segments seem to come from China as well from what I have been able to find out. My guess is that most MK Diamond lapidary blades are also using Chinese segments / rims, although I don't have any specific information about that brand.
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Post by holajonathan on Feb 3, 2021 12:48:51 GMT -5
jamesp"Beware, due to their sharpness they will also remove epidermis quickly" Your warning comes 4 days too late. First time I have ever drawn blood with a diamond blade / wheel. It felt like scraping a knuckle across 36 grit sandpaper.
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