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Post by Admin on Jun 12, 2022 10:16:01 GMT -7
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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Post by Admin on Jun 12, 2022 10:17:25 GMT -7
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 Admin on Jun 12, 2022 10:19:34 GMT -7
@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 Admin on Jun 12, 2022 10:22:01 GMT -7
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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Post by Admin on Jun 12, 2022 10:24:22 GMT -7
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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Post by Admin on Jun 12, 2022 10:26:42 GMT -7
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.  |
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Post by Admin on Jun 12, 2022 10:39:22 GMT -7
I am tired of having pits,hollows,fracture areas,spots that are not smooth.Pre-grinding all that goes in to the tumbler seems like a good practice.It takes so long to tumble off so many types of imperfections.Those new coarse grit dry diamond wheels at Home Depot will remove material quick and last a real long time.They fit on hand grinders,better on a bench grinder.I think they are 50 grit. www.toolocity.com/4-adt-vacuum-brazed-diamond-cup-wheel-coarse.aspx?gclid=CJrNgsXn2bMCFQ2znQod52gAnwI have a similar to this 'diamond cup wheel' on a 4.5 inch hand grinder.It reduces agate quickly-very quickly.I use it to grind a flat glueable bottom on specimen agates.I clamp the hand grinder and hold the rock against it.It is threaded 5/8" for shaft of a 4.5 inch hand grinder.Notice that it is 30-40 grit diamond.Home depot has them.Next tumble load i am going to do what Carlos does-preshape.Avail. in 4,5,6,7 inch dia.My 4 incher is very effective in dry mode. This is over kill.The I-beam is also an anvil.A wood frame would do fine.Just do not tighten the steel clamps too much or you will bind the bearings in the grinder.I prefer giant tie wraps.    |
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Post by Admin on Jun 12, 2022 10:43:00 GMT -7
SiC 30 grit, clay, 55 RPM. Finer diamonds on grinding wheel leaves shallow scratches. 2 days of SiC 30 and they are gone. But it still cuts super fast considering finer diamonds. Before grind, finger on subject. Rio moss:  After 15 minutes pre-grinding two days ago Monday:  After 2 days in 3/4 cup SiC 30, clay, 55 RPM, 6 pound 6" PVC rotary barrel. Dry. Nary a scratch left. 2 days in AO 80 in vibe and 18 hours in AO 14,000 all w/Borax and she'll be shinning. 5 day tumble.  and not to bad wet:  This stone was ground on another diamond wheel. Has bigger diamonds but they are dull and cut one tenth as fast as the finer sharp diamond wheel. Tumbled exactly the same as the red moss above. Note serious scratches still left. Bigger diamonds, deeper scratches, but slow cutting due to dull diamonds and much more pressure required. Much more. But only 30 RPM which may have a bearing.  The other barrel turning 55 RPM had this palm in it. Best palm I found on the Rio. ~15 minutes pre-grinding also Monday: Dry, darn cracks though:  Not too bad, wet:   This is the five big rocks, each in a 6 pound barrel with average size tumbles. The top 3 at 30 RPM, the lower 2 at 55 RPM. Four of them were ready to go to vibe in AO 80, the polish. The small tumbles a long ways from being shaped. All 5 dry, the big one at upper right still has some scratches in the red area. 2 days SiC 30:  wet:  Rubber guide wheel ground to mate better to edge of tumbler. the edge of the wheel was cutting into the PVC a bit:  When 3 barrels are running on this set of shafts and gas makes the rubber caps swell it pushes the end barrel into the Zerk fitting lol.   strange moth on the spare v-belt simulating a broken limb, attached sorta at a right angle like a broken limb:    Going to run them another 2 days. I thickened the slurry. This will reduce the bumping and remove the tiny white impact marks. Letting them dry tells a lot about their condition.  the glue is missing in some ares. Can not grind or tumble away. Runs throughout rock. Typical of these chalcedony filled shocked rocks.  Thanks for looking in. |
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Post by Admin on Jun 12, 2022 10:52:12 GMT -7
Speed of grind is less important than alignment. My home made has some vibration in it. Rattles rock against blade a reaps havoc at times. Rock bouncing against the hard wheel is a real game changer. Messes with karma in a bad way, slows cut, messy, more dangerous. Motors are precision aligned. The ole tile motor is super smooth. Eye opener. And that blade fits perfect on the funky threaded motor shaft. Clamped well and perfect roundness. Butcher the tile saw cabinet to you likening. the box that holds the motor is pretty much a separate structure from the table on my tile saw. |
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