Gem'n I
freely admits to licking rocks
Member since March 2008
Posts: 980
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Post by Gem'n I on Jul 29, 2008 12:37:46 GMT -5
Although I have been doing this for a while there are several questions which come to mind and certainly many opinions on what is right or wrong in saw blade maintainence...so here goes: How often does a blade need to be dressed? Is it relative to the material being cut or does it just slow down when it is ready? What is the best type of dressing material?...I have heard old brick, obsidian, old grinding wheels...etc. What is really not good to use and why?  How long do you dress the blade? Several cuts? 10 Minutes? or what??? When is a blade gone? Other than it will no longer cut.... Do you dress wet or dry? Would like to hear your comments along with any other tips ;D ;D  |
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darrad
fully equipped rock polisher
Member since September 2006
Posts: 1,636
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Post by darrad on Jul 29, 2008 19:07:47 GMT -5
I would say if what you are using and doing works continue. If it aint broke don't fix it.
Myself, I have only had my 16" saw since March so do not take me as a guide. As my blade slows(weight feed) on hard stuff I switch to soft (Obsidian, Sodalite, Calcite etc) and it brings it back a bit. When I need to I use a fire brick and make one cut through it and I am back in business for the hard stuff. Again take this with a grain of salt as I am a newbie with a slab saw.
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Post by bobby1 on Jul 29, 2008 22:32:00 GMT -5
When you cut Agate it dulls the blade rather quickly. If the cutting slows noticably, make a cut through an old grinding wheel. Usually a 5" or 6" cut (wet) will do. If you hear the saw struggling any, its time to sharpen it up. Obsidian works well, too but it takes a couple of passes to equal the grinding stone.
Bob
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Post by johnjsgems on Jul 30, 2008 0:50:42 GMT -5
Anything abrasive will work. You are wearing away the softer matrix material to expose new diamonds. Always cut wet. The best choice would be a dressing stick or block (60 grit aluminum carbide works with one cut. I use broken cinder blocks but they don't clamp down as easily as a nice square block. Old grinding wheels work ok but not as abrasive (usually 100 or 220 grit) so may need a couple of cuts. If you are hand feeding you should notice when the blade dulls. If cutting agate you may need to dress the blade as often as every 6-8 cuts. Of course everytime you dress the blade you lose a little blade so like someone else said don't do it if you don't need to. Depending on blade type it should cut until the notches or sintered ring is completely worn down to the core. Don't dress a plated blade as it can strip the diamonds off.
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Gem'n I
freely admits to licking rocks
Member since March 2008
Posts: 980
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Post by Gem'n I on Jul 31, 2008 19:30:50 GMT -5
Thanks guys...I thought we would get more opinions...especially from the super slabbers..not that you guys are chopped liver...far from it...but like I said ...I have been doing this for a while and these are questions I had no answers for???
John, why does 60 grit AL/C work better than 100 S/C? I have a 10" & 18" that are both auto feed so it is really hard to tell a slow down...I guess I get about 40 or so slabs before dressing...I use an old 100 grit SC wheel but its usually one pass through. Are plated blades the ones that are directional ( follow the arrow cutting )?? Or am I wrong in typing them??
Why does obsidian work...isn't that just natures glass...would an old bottle work as well??
Thanks again!!
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Post by Jack, lapidaryrough on Jul 31, 2008 23:04:34 GMT -5
Damit, the new kid would rather hang back in the Petrified wood work and keep to him self.
After reading the tread and the commits. Here`s my 2-bit`s worth.
Never use a brick on a saw blade, Cerf, is the side of the saw blade where it was rolled with the hot diamond in slot.
Bricks well grind this thickness off real fast, then you`l have a blade that well not dress or sharpen the face of the diamonds.
Never use a grinding wheel course then 220 grit and only cut about 15 Sq inch`s of the wheel.........
the very best material to dress a blade is OBSIDIAN only or 220 grit wheel>...........
BLADE`S must be ran in both direction !!!! un-less your using non-lapidary blade`s such as Concert / Asphalt, Green cement Blade`s.
As a diamond blade cuts a diamond well ware down, And the matrix well expose more of the diamond face.
if you only cut in one direction the blade well glaze and then you`l be thinking ...I need to dress the blade ..NO NO ..you need to re move the blade and run in the other direction !!!
and dress the blade with a piece Davis Creek Rainbow obsidian Or Lassen Creek.
Gold Sheen works fine to.
the cutting face and edge of blade is where the cut is made, On the sides do more cutting of the rock then the face edge.
The cutting face of the Blade MUST BE Square and a right angle to the blade Flat at the point it contacts rock.....
If the blade is rounded .....that's saw Blade abuse.
time to mark the blade, with a felt pen,
Lesson and feel what i saying, Take a large file using the edge of file strike each and every 1/8 inch of blade to Sq. face,
Do not hit hard......just enough to flaten the face. each and every hit must be the same !!!
Then repeat Dressing with OBSIDIAN.
Do Not run File across blade, only used to flatten with a striking hit !!!
Oh ya some diamonds well be wasted and the matrix of the blade well be fine.
Dressing well clean it up,
Dressing needs to follow with a max size Brazilian Agate for the saw blade.
Make two cuts, if you can with rock in vise remove blade and reverse blade and cut twice more,
I did this to blades 40 years age and i do it the same today.
Dad`s DAD did it and Son.
And many others i have spoke to about the condition of there blades,
MK-Blades are the best in by Lapidary BOOK.
And this well extend the life.
I have done it to rounded blades that had 40% ware lift.
Cut fine tell i ran it down to the bottom of the diamond slots.
Jack In Oregon.
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idabound
off to a rocking start
Member since March 2022
Posts: 2
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Post by idabound on Mar 11, 2022 15:24:19 GMT -5
I had been having trouble with my 14 inch saw blade deflecting away from the vice, so initially tried dressing the blade by cutting a couple chunks of obsidian, and although it seemed to sharpen the blade it didn't solve the problem. I could tell the blade was rounded over some on the vice side which could be expected seeing that side usually does more cutting. I tried reversing the blade and it just started deflecting toward the vise then. My next idea was to drain the oil, and then run the saw, and tried dressing the blade with my 4 inch disk grinder. That squared up the edge of the blade again and sharpened it at the same time so it's running good again. Now i think I'll try that on an 18 inch saw blade that I had replaced that was doing the same thing.
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Post by Peruano on Mar 11, 2022 16:46:48 GMT -5
If a blade is being deflected, it is possibly vice alignment relative to the saw blade Pushing too fast relative to the cut rate could cause a slight shift in the rock but this would not be a constant or subtle effect, but would cause the saw to slow, bind, or shriek. Is your blade securely bushed on the arbor and does it have the proper sized flange bushings on each side?
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Post by stardiamond on Mar 11, 2022 17:03:58 GMT -5
I had been having trouble with my 14 inch saw blade deflecting away from the vice, so initially tried dressing the blade by cutting a couple chunks of obsidian, and although it seemed to sharpen the blade it didn't solve the problem. I could tell the blade was rounded over some on the vice side which could be expected seeing that side usually does more cutting. I tried reversing the blade and it just started deflecting toward the vise then. My next idea was to drain the oil, and then run the saw, and tried dressing the blade with my 4 inch disk grinder. That squared up the edge of the blade again and sharpened it at the same time so it's running good again. Now i think I'll try that on an 18 inch saw blade that I had replaced that was doing the same thing. What kind of saw do you have? I have/had a 16 inch Covington combo saw and the carriage drifts away from the blade. This causes un even slabs and the blade binding. Dressing and replacing the blade helps. Fortunately, I don't need a larger saw now and at some point will shit can the Covington. |
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idabound
off to a rocking start
Member since March 2022
Posts: 2
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Post by idabound on Mar 12, 2022 20:28:36 GMT -5
The 14" I have is a new Highland Park, and the 18" and is an older Highland Park. I did check the blade for being true to the carrage on both saws. The problem of deflecting was solved after dressing the blades enough to get rid of the rounded over corner on the vise side of the blades. I also have a 14" Covington that apparently someone bought as a kit, and built a plywood case for it which needless to say leaked oil pretty bad at the seams. I decided to cut about 2 1/2 inches off the base to turn it into a 10" saw., I had a 3 in. deep steel tray made to set it in so any leakage was caught by the tray. It doesn't have a power feed and still trying to decide if I want to order a power feed attachment from Covington.
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Post by Rockoonz on Mar 12, 2022 23:03:04 GMT -5
Have you used a straightedge to check the blade for flatness? It sounds like it may be dished a little.
John Rowland made a good video about swedging the blade with a file, calls it sharpening. I do it with the blade off the saw and use a hammer, the thing you're doing when swedging is slightly mushrooming the edge of the kerf to make it flat and wider again so it doesn't wedge in while cutting.
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Fossilman
Cave Dweller 
Member since January 2009
Posts: 20,715 
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Post by Fossilman on Mar 15, 2022 12:16:22 GMT -5
I cut Obsidian every five cuts on my blades... Cleans them up pretty good..
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Post by victor1941 on Mar 17, 2022 14:56:45 GMT -5
Gem'n I, I sharpen like Rockoonz and then make several cuts in an old firebrick or grinder blade. My blades are Mk 14" and I sharpen when the top edge starts to round.
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