Hi all hope ur having a great day

1-When nesting melamine boards should i plung cut? Knowing that i use pcd bit

2-I am having a problem when nesting some time a corner of a part will break knowing that i am cuting chipboard laminated panels

Since you are using a pod and rail machine, I suggest you add a lead-in and don't start or finish on a corner. Ramps will leave flaws in melamine when the up cut portion of the compression bit enters the top face.

Thank you for the tip
But i am using a flat table

Small screen on my phone! I read PCD for pod. I always ramp in usually with a lead in. My software isn't very sophisticated as to the location of the start point so when it is critical I manually move the start point to midway on a straight vector and where I can get lead in room in the nest. Leads and ramps need not be very big .5" or so.

Tom - what is the difference between a lead in and a ramp? I usually ramp in with melamine and other sheet goods to avoid stress on the bits and haven't had any edge quality issues.

A lead in is a small vector added at an angle to the part's perimeter so the bit's entry is done off the edge of the part. It is automatically added when the option is selected. You can get a small defect on parts at the start/stop point due to machine deflection. Bigger machines are less affected.

Ok, that makes sense. Thanks for the clarification Tom.

We cut lots of Melamine sheet and I use a 3/8 compression bit for all the outlines. I plunge the cut to start, but only insofar as to get past the up-cut part of the compression bit. Then I ramp the rest of the cut. The plunge doesn't seem to leave any undesirable finish on the part, and seems to have no effect on the bit life. The ramp is there to allow the rest of the bit to enter the work without plunging the whole bit at once, and to save a bit of wear at the cutting height of the board thickness. If you try to plunge the whole depth, you will get some burning, which is bad news. Your PCD bit may need a lead in depending on the geometry of the bit. Most PCD bits look like the rake angle is not that far off from 90 degrees, and the upcut portion looks significantly longer than a typical carbide compression bit. We are using the Vortex 3130 and 3184, and the cost per bit, when bought in quantities of 20 or more, make this more economical than any of the PCD bits for our situation. I get about 60 to 80 sheets of nested base and upper cabinet parts, + misc plywood and PLam panels, per bit, per sharpening. I send them back to vortex and they come back like a brand new bit. Our local service didn't do so hot with the sharpening. Hope this helps.

I would always recommend ramping in where possible. Also remember a PCD bit will usually not run as high of feed rate as a spiral just due to it usually being on a shear vs the spiral. But in the right application will out last the spiral hands down. I would try the new coated bits that most of us have out.

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thank u all for ur great tips
i start ramping when nesting and my starting point not from any corner

i wish i could get coated bit but no one sell them in my country are they that good ??
i use to get carbide compression bit 2 fluts from here but they are made in china and and priced 30 usd and i get 5 to10 laminated chipboard per bit
and all my work is with chipboard boards

Coated bits are easily getting 30 to 40% more life than standard bits, some are getting a lot higher in certain applications.

We tried PCD and it wasn't worth it. I suspect the corner chipping is due to the use of the PCD. How many flutes? We now use the coated (Marathon) Leuco 2 flute compression, Get much better life when cutting HPL laminated board than with the non-coated bits. On melamine we get about 25% more life out of the coated bits. Well worth their minor increase in price. We are picky about the quality of cut so we can get good banding results. Our old bander doesn't have pre-mill.

Chuck said "Coated bits are easily getting 30 to 40% more life than standard bits, some are getting a lot higher in certain applications. "

Am I correct in assuming that this benefit would be lost once the bit is sharpened?

Gerry,

Not completely, When we sharpen a coated bit, we only sharpen inside the flute, not on the Diameter, You do loose some benefit, but not all.

I made a mistake on my post about which bits we use. It should have said Onsrud Marathon. We use Leuco saw blades on our beam saw.