3-knife versus 2-knife jointer

[newood2]

For example, does the Delta JT360(3-knife) cuts better than the Ridgid JP0610(2-knife)?
Or, is the difference negligible?

[LCHIEN]

I think the smoothness of the cut is determined by the number of cuts per second and how fast you feed it. (which with the RPM speed determines the number of cuts per inch.).

So the design options for the jointer are, 2 blades or three and how fast does the head turn?

If they use three blades, RPM and feed rates being the same, it will cut smoother than 2 blades for modest feed rate.
If the speed up a two blade machine by 1.5X, it will cut as well as the 3-blader but the blades will wear faster.
If you take the two blade machine at the same speed as the three blade machine but feed slower then it could cut as well as the 3-blade machine at a cost of your time and also the blades will wear out faster (each one does more work).

So it depends on the RPM of the 2-blade machine relative to the 3-blade machine for the performance. But in any case 2 blade will wear faster than three..

By the specs JT360 4800 RPM cutter, 14,400 CPM.
JP0610 has a three blade head as well, 15,000 CPM (so it makes the above theoretical discussion moot)
basically a wash there.
JP0610 does have a 1 HP motor, JT360 has a 3/4 HP motor.

[newood2]

[QUOTE=LCHIEN;347307]
JP0610 has a three blade head as well, 15,000 CPM (so it makes the above theoretical discussion moot)
basically a wash there.
QUOTE]
Yea Loring, the specs. at HD site say dual blades, but I just check the Ridgid site and it is 3-blade. So much for HD accuracy.

[ksum]

As already mentioned, the resulting cuts per inch could be the same regardless of the number of blades.

A third blade theoretically gets you longer blade life, and, if the machine is capable, the ability to offset the nicked blades. Of course, longer blade life is with blades of equal quality. 3 blades also means that their 1 time replacement price will be higher. Of course, if they last longer, that could equal out or become a savings. Offsetting 3 nicked blades as opposed to 2 would result in a smoother yet more spread out nicked blade surface.

I do not know if either of the example machines have the ability to offset the blades.