Jointer Ways: Parallelogram Versus Dovetail

A discussion of jointer table mounting methods and the maintenance characteristics of different types. May 23, 2007

I am looking to get some opinions on Parallelogram and Dovetail jointers. Is one better than another as far as stability or ease of adjustment?

Forum Responses
(Solid Wood Machining Forum)
From contributor R:
A parallelogram jointer offers four point adjustability for each table. Dovetailed ways units can only be shimmed to account for sag. Also p-tables can be removed and ground and reinstalled if it's warped. D-table jointers must be ground as an entire unit. There really is no real adjustment on d-tables except shimming.

P-table has a slightly tighter throat because of the table movement but it's an insignificant reason. P-tables are much more complicated to take off compared to d-tables. My personal favorite table design is the inclines on old Olivers, and Crescents. They are the simplest and best to remove and adjust.

The odds of a table warping are low but it does happen. I've had a dozen jointers resurfaced over the years but I was professionally repairing them so I worked on more than most people even see in a lifetime. The ones with warped tables were from the 50's and 60's.

From contributor S:
I recently rebuilt a 12 inch American and a 16 inch Northfield jointer. Both of these have dovetailed ways but the tabletop is removable from the top and can be easily ground and shimmed along its length. The Northfield jointer was from 1946 and the table was dead flat only requiring grinding to remove rust. The American infeed table had a hollow in the center before the cutter head. Tables rarely warp. If they do it is a manufacturing defect from improper seasoning of the casting. Old tables are not "warped" but worn. Cast iron wears from excessive contact.

From contributor R:

They certainly can warp. Wear is a factor but I've had to regrind tables that were barely used. When you spend years working on other folks machines you see a lot more stuff than the average person.