Monday, April 8, 2013

V4.14 - And finally, leveling the tables

Our friend, the jointer is still on our hot list this week, but I think we’ll be finishing it up. So far, we’ve talked about what the jointer is used for. Then we checked the tables for flatness and being level with each other. Then we talked about setting the knives. Last week we talked about the importance of a good fence. The last thing on our list was how to level the tables. Leveling the tables always requires a good machined steel straight edge and a sent of feeler gauges. Don’t try this with a carpenter’s level or an aluminum straight edge…the tolerance of those items is nowhere near the accuracy that is needed.

So, let’s get after it and discuss leveling the tables. There are three main jointer designs: 1: Parallelogram, 2: Wedgebed & 3: non-movable outfeed.

The Parallelogram design jointer originated outside the USA, but many industrial jointers use this design. This design has the table pivoting on 2 rods that have eccentric bushings on each end. The secret to adjusting the tables on this design is found in the 4 eccentric upper bushings of each table. (that’s a total of 8) These bushings allow you to raise or lower the tables, front & rear or side to side. You cannot raise or lower them by the corners, tho. All that does is create a binding that stops movement of the table.

The wedgebed design was the most common design for many, many years when jointers were first invented. It’s still in use. This design has the tabkles sliding up and down on machined ‘ways’ and they are held in place with gibs and lockbars. The secret to adjusting the table of a wedgebed jointer is found in the gibs and lockbars of the bed ‘ways’. Loosening the gib screws and lifting the tables above where you want them is the key. You lock the gibs screws back down to hold the table there and then slowly loosen them and just at the point that the table gets where you want it…you stop and re-tighten them. This design does have one inherent problem. As the jointer is used, dust can lodge inside the ways. Over time, the dust will pack in and create a wedging effect that will cause the tables (usually only the infeed table) to go out of alignment. At times it is necessary to disassemble the gibs and clean the ways before adjusting.

The non-moveable outfeed jointer is usually reserved for the most basic jointer (if you want to read that as ‘the cheapest’ - that’s OK). I’m sure this design came about because it is the least expensive to make. Most jointer operations do not need a moving outfeed table, but there are times it might need adjusting. This design secret is that the outfeed table usually has 3 mounting points and they are mounted with rubber bushings that can expand or contract- depending on how tight the mounting bolt is.

Send your questions or comments to: and we’ll see what we can do to help you.

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