Top Tip for Finishing: Use a finishing chip breaker with a small enough radius to get the chip breaker working. This is a common mistake engineers make: trying to finish with an 0.8mm rad with a medium chip breaker taking a 0.1mm cut. This is just going to rub on the work piece and cause poor surface finish. Furthermore, on stainless steel you will just put heat into the job and make it unmachinable.

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Top tip - Lever Lock or double clamp style tool holders give higher clamping strength and stability compared to screw clamp holders.

Once are able to install it, clamp a scrap 2x4 over the top of it and then turn your table saw on. Now very slowly raise the blade to the maximum height.

Use a jigsaw to cut out the radii on the ends and cut around any mounting tabs. Leave about a blades width of extra material to be sanded later to the exact size.

I’ll explain why you need a zero clearance insert (safer, better cuts, better dust collection) and then show you how to make it. I’ll cover cutting out the basic shape, zero clearance insert layout, cutting out the tabs, finger hole and adjustment screws so you can level the insert when done. I’ll also show you the safe way to run the blade through your insert.

Diameter of workpiece.Material.Shape (e.g. rough, hexagon).Machine capability.From this, they can make a quick assessment of the most suitable grade of carbide for your job.

In this video I’m going to show you how to make a zero clearance insert for your Dewalt DWE7491 table saw! Even though this is specifically for the DWE7491, it can be used for many other table saws. Especially other DeWalt table saws.

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A roughing grade is very tough and will run at slower surface speed but withstands intermittent cuts well. However, your roughing may be very different to someone else’s roughing.  For example, a turner on a VTL turning large stainless steel castings will be taking 5mm+ depth of cut, whereas a turner on a smaller lathe will be roughing with much smaller depths of cut.

Are you roughing, finishing or just doing some general turning? Negative inserts are strongest and the best option for roughing and general turning applications, as these will allow deeper depths of cut and higher feed rates due to strong insert shapes and thickness.

Use a fostner bit to drill about a 3/4" finger hole. Drill part way through on one side and finish the hole on the other side to reduce the risk of tear out.

If you are roughing, it is important to go with a roughing chip breaker (such as Korloy’s RM, HR, B25, GS & VP4 chipbreakers) to deal with the chip load and the depth of cut.

Remove the hardware from an old factory throat plate and clamp it to your work piece. Now mark out the profile, mounting tabs, adjustment screw location and the finger hole location.

Now, observe the location of the riving knife when the blade is all the way up. Mark out extension lines on your insert to allow the riving knife to clear in the max height position.

Now, very carefully, cut out the area for the riving knife with your jigsaw. If your insert is very thin after cutting the blade relief groove, you should reinforce the ends of the relief groove before doing this. I cut some pieces of wood on my table saw and glued and clamped them in place.

Using the marks you made during layout, drill and countersink holes for the adjustment screws. Be sure the holes are slightly smaller than the threads of the screws you plan to use.

A chipbreaker can make a huge difference to cutting load, chip control, vibration and even prevent work hardening in materials like stainless steel or inconel.

A) Grades beginning with N (e.g. NC3225) are CVD coated.  These grades cope with higher cutting speeds than PVD grades and can withstand longer contact periods with the workpiece.  They are most suited to medium to large diameter workpieces.

Each member brings with them their own experience and know-how to add to our growing pool of technical knowledge. That’s why our services are known for being the best in the business!

CNMG (rhomboid 80 degree), DNMG (diamond 55 degree) and WNMG (trigon 80 degree) are the most popular roughing inserts.  For heavier roughing operations, SNMGs are an excellent choice with a 45-degree approach angle allowing for larger depths of cut and reduced cutting loads.

D) The final part represents the toughness according to the ISO scale.  NC3225 ends with 25, as it is for steel it has a toughness of P25.

Reinstall the blade but leave the riving knife off and attempt to install the insert. If you can not install the insert because it's hitting the blade, put your old insert in and cut a blade relief groove in the slot just deep enough to allow you to install it.

They can help you work out the best chipbreaker for your material and applications, whilst also recommending the minimum and maximum depth of cut you should take.

B) Grades beginning with P (e.g. PC8115) are PVD coated.  These grades work at lower cutting speeds than CVD grades and are more suited to shorter contact periods with the workpiece.  They are most suited for small to medium diameter workpieces and also make excellent multipurpose grades.

CCMT (rhomboid 80 degree), DCMT (diamond 55 degree), VCMT or VBMT (diamond 35 degree) are the most popular finishing inserts.

Now, test fit the part in the slot on the saw and note any areas that need to be sanded. Then carefully sand and test fit until you have the perfect fit.

A finishing grade will be the hardest grade run at higher surface speed. This will not work well under vibration or heavy intermittent cuts.

For roughing applications, you would usually opt for a 0.8mm or 1.2mm radius depending on your machine’s horsepower and the depth of cut you plan on taking.

With the table saw unplugged and the blade removed, raise the blade adjustment all the way up. Try to install the the new insert and note any areas of interference. If there is interference, cut clearance using a router or whatever other tool you have or makes the most sense.

If you are finishing, positive inserts are always the best option as these create less cutting forces and can therefore get away with lower depths of cut, eliminating vibration.

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Turn the saw on and raise the blade to the max height to make sure there are no clearance issues. Then lower it back to a normal level and cut a thin strip of wood to make sure it works as it should.

For finishing operations, 0.4mm or 0.2mm rad would be the best option. This allows you to take the smallest depth of cut without causing vibration.

All chip breakers have a minimum depth required to get the chip breaker working.  However, instead of struggling to figure out the right chip breaker for your job, please ask our Technical Team to advise.