Why Parallelogram Jointers

[Art Travers]

Can anyone tell me the advantages over regular jointers??
Why do they sell both?

[glenn bradley]

Do a Google search here and you'll find plenty. In a nutshell,

- beds stay the same distance from the cutterhead regardless of height.
- easier to adjust the beds if ever required.
- beds are better supported.

[Peter Quinn]

The tables on parallelogram jointers can be precisely adjusted to compensate for wear or misallignment via set screws below the table bed which insures countless years of service. The only way to realign jointers with dovetail ways once worn is a sort of hit and miss approach with shim stock. Parrallelogram tables are probably more neccessary in a comercial or heavy use environment.

Many woodworkers use the jointer only to flatten and straighten boards but it is capable of much more. It is capable of producing accurate rabits, tapers (legs) and half laps and tennons. If the jointer is used for these things regularly causing the infeed table table to be moved often over its entire range the ways will wear relatively more quickly, and in this case the adjustablity of the parrallelogram design is an advantage.

A further advantage of the parallelogram design is that the gap between the infeed table and the cutterhead remains constant as the infeed table is lowered because the tables move on excentric bearings. The infeed table on a jointer with dovetail ways moves both down and away from the cutterhead increasing the gap and reducing stability during advanced jointer applications.