This article takes looks at some of the most common issues sawyers experience, the reasons for them and presents solutions, helping to avoid risks to your production.
If you need further specialist advice that was not covered by this article please contact us here.
The ability of a segmented diamond blade to cut is a result of the interaction between the blade and the material being cut. This interaction is very important. As the blade wears down new diamond crystals are exposed. It is the exposed diamond crystals sticking out of the segment which does the cutting. Two important parameters to understand when using bridge saw blades are tip speed and feed rate.
A blade on a bridge saw needs to be rotating at the right speed for the blade diameter. Or rather the right blade diameter needs to be selected for the rotation speed of the saw. The diamonds need to be scraping the material at the optimum tip speed for the material being cut. There are other articles on this site to help you select the right blade diameter and most factories have many years experience in this and have got it right. If you have doubts then we are happy to advise.
The parameter which seems to cause the most issues, however, is advance speed or feed rate. This is the speed at which the blade is moved through the material.
A sawyer cannot routinely have an feed rate which is too high because the motor will overload, draw too much current and trip out. If this does happen the sawyer will learn quickly to slow down.
Blades are often moved through the material too slowly. In some operations, it is inevitable (such as dropping the blade down into the material for a cut out) but for normal straight cutting it is important to advance the blade through the material at the optimum rate.
With angle grinders everyone naturally does this because they can feel how much the blade is working. However, on a bridge saw there is nothing to show you the optimum rate. Experienced sawyers will listen to the motor noise changing as it loads. You can also observe the load to the motor if there is an ammeter showing the current drawn. These are good guides but they don’t necessarily tell you that you could be going a bit faster.
All our blades are fast cutting and some new technology blades cut faster than your sawyer may be used to or may expect. Feed rates of about 2 meters per minute when cutting a 30mm granite slab in one pass are standard now (this depends on the motor power of the saw) and some of the blades can achieve more than 3 meters per minute when everything is working properly and the saw is powerful. We provide the feed rate for 20mm and 30mm granite and quartz for the blades we sell. These are, however, guidelines, and we suggest using the highest possible feed rate achievable for the material being processed.
In order to acheive this highest posisble feed rate, is important that the blades are “pushed” or “worked”. The motor of the saw should be doing some extra work when compared to just the free running work. You can tell this by watching the ammeter of the saw go up or by listening to the noise the motor is making. Tickling the stone is not a good plan. Going slowly does not avoid problems, it creates them. If the feed rate is too slow then the diamond blade will “glaze”. This means that the diamonds sticking out, wear away but the metal doesn’t so the blade becomes blunt and struggles to cut. In this state, it can easily veer off course. Once a blade is glazed it is impossible to increase the feed rate (on a full depth cut) without unglazing it.
A well known way of unglazing a blade is to run it through something abrasive like sandstone. Another way which can be faster is to cut a depth of just 2 milimeters but with a very high feed rate to skim the surface and erode the diamond segment.
A well selected blade, right for the material, with the right diameter for the saw, with good water supply and a high feed rate should not glaze. A blade that is regularly glazing is often a symptom that the feed rate is too slow. Try increasing the feed rate. It may keep the blade cutting well, straight and true. It also gets the work cut more quickly and this can increase the output of the factory!
The main cause of segment loss is an accidental collision with the workpiece whilst moving the bridge to a new cutting position. Also if the material moves while it is being cut there is a risk that the segment may impact the side of the cut or jam with enough force to break the segment or bend the blade.
Maintenance of the saw bed can sometimes help if this is a problem.
Failure | Cause | Recommendation | |
 | Excessive wear of the segment |
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 | Uneven wear of the segments |
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 | Uneven wear of the blade body |
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 | Cracks/breaks of the blade body |
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 | Damaged or distorted bore |
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 | Overheating of the outer blade body |
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 | Uneven rotation/ loss of tension |
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 | The blade does not cut |
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 | Cracked segments |
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 | Segments break off |
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 | Segment is no longer straight |
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 | Glazed Segments |
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Magnum Blade for Quartz & Granite 
Diatex Blade for Quartz & Granite 
M1 Blade for Marble