View Full Version : Sharpening a diamond blade
12-09-2006, 08:10 PM
I'm using a diamond blade to cut bluestone for a patio. The blade was fairly new when I started. I've cut through about 30' of 1.5 to 2" stone and it went pretty easy but now it is taking a lot more time and effort to cut through. The blade and saw starts to bog down and the blade gets very hot. There is still plenty of blade left (cutting mason brick I've taken a 7 1/4" blade down to a nub before I had to replace it) and you can see and feel diamond bits in the blade still.
I remember hearing about (I believe it was a This Old House segment) a stone company that was making soapstone sinks and counters and they used a granite table top on their cutting machines because it kept the blades sharp on account that the soapstone was a soft material. Would bluestone fall into this situation as well and what exactly is it that "dulls" the blade and how to I sharpen it? Can I run it through a granite boulder?
12-09-2006, 09:56 PM
Here is the scoop on diamond blades. The diamond blade is actually diamond grit which is bonded to segements, these segments are then laser welded to a steel core. The bonding agent in the segments is made to release the diamond grit as it gets dull. If you use a diamond blade that is designed to cut hard material for cutting soft material the diamonds never break free of the bonding material. Therefore the fresh "sharp" diamond is never exposed. Taking your blade and running it into a brick or piece of concrete should wear away the dull diamond and expose the fresh sharp diamonds.
This will be a temporary fix, if you keep cutting soft stone it will do the same thing. If you need to cut alot of this material, go to your diamond blade supplier and get a blade specked to cut that specific material.
If you use a diamond blade meant for soft material on hard material you have the opposite problem, the blade exposes fresh diamond to quickly resulting in a shortened blade life.
Allowing a blade to overheat also shortens its life, the bonding agent breaks down and the diamonds "fall off", or the blade will warp causing more heat etc.
There a multipurpose blades which can be used in multiple applications, but if you have a large quantity of cuts to make in a specific material it pays to get a blade that is made for that one task.
I hope this helps.
12-09-2006, 10:54 PM
I have never heard of sharpening them. We build a lot of walls and of course cut caps. I just bought a new blade this year that was 5 years old. I did buy a good one and complained that cost 165.00. I just figure on buying new.
12-10-2006, 12:40 PM
run water to cool the blade.
12-10-2006, 12:50 PM
Another important factor to keep in mind is the rpm in which the machine operates. A table saw is designed to run at a slower rpm than a quick cut saw. Putting a blade on a quick cut that is meant for another application will overheat in no time and start warping. We spend on average 450 dollars per blade and use about 5 per year. The ones we buy for 150 -200 dollars are garbage. So also keep in mind you get what you pay for.
12-10-2006, 07:59 PM
Well, I finished up the patio today with a new blade and I can tell you two things. One, the old blade was definitely dull, but not worn out. I'll try exposing new diamonds by running it through some granite chunks I have at the shop. Two, my saw was not up to the task anymore! I've been using an older B&D circular saw (from back when they were made of metal!) The saw has served me well cutting brick and pavers over the past few years but today it when to circular saw heaven!
I finished the last few cuts with a saw one of the carpenters on site let me borrow. I was so used to that old B&D, I had forgotten how much more efficient a new, more powerful saw could be. I went from tedious grinding through the stone, to cutting buttah.
I'm definitely going to stay with a circular saw as opposed to one of the larger 12" or 14" cutoffs. I like the portability and light weight of the circular. Any thoughts on what saw might work well. I worry about spending too much cash since they tend to get gummed up a bit with all that dust. I was thinking about a worm drive saw, but mostly cause the look cool, not necessarily because it would be effective/efficient.
But, back to the blades...the two blades I've been using are a Brick/Block blade from dewalt, the only diamond blade at the local hardware store, and an MK General purpose blade that my paver supplier gives me when I ask for a blade while picking up pavers. The dewalt was a desperation purchase, but the MK works great on bricks and pavers, but is obviously not adequate for bluestone. What type of blade should I be using on this (I have several more bluestone projects next year for the same house so I'll definitely need one)? As I said earlier, it will be a 7" circular saw and dry cutting. I'm assuming that my paver dealer can get or has other MK blades in stock other than the General purpose ones by the counter. I checked out MK's website and they list all of their blades on there but they don't give very good descriptions or specs for blade hardness or best usage.
Any guidance would be greatly appreciated.
12-10-2006, 08:13 PM
Are you cutting irregular or dimensional bluestone????
Oh...and where you from in maine? I lived in Bangor for almost 7 years and graduated from UMO
12-10-2006, 08:26 PM
It is pre-squared stone. All 12x12, 12x18 and 18x18. Stones vary in thickness but are generally 1.5 to 2" thick. This is my first patio using this stone. In fact you really don't see it much in this area, but I love it. It has an awesome look to it. The stones are dry laid as opposed to mortared in which gives it a sort of a refined but not pretentious look.
I am down in the Farmington area. We had our first snow last Friday, but temps have warmed nicely so I had a chance to finish the last of the patio this afternoon. The weatherman said temps in the upper 30's to low 40's next week but I wasn't taking any chances. I want to get paid for the job this year!payup
12-10-2006, 08:57 PM
Oops, just reread you post and see that you LIVED in bangor, so I am UP in the Farmington area!
12-11-2006, 09:16 AM
Buy the worm drive Ridgid or similar (around $175)...3 year warranty and buy the HD warranty also. You will burn out the normal circular saw. Invest in a 10 or 12 gauge extension cord for the saw.
Buy 7" T-segs from an online dealer (I've used Garden State Diamonds) for around $40 each and they last 2-3 times longer than the Hitachi or DeWalt you can get at retail.
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