How to Handle Jointer Fence Twist?

[Chris Schumann]

I finally got my jointer together, again, after buying new knives. It's a used Jet JJ-6OS, but seems very capable.

However, I got a new combination square that's showing me that the fence has a twist. At the center of the table, it's very close to perfect. At the outfeed end of the fence, the top tips back, and at the infeed end, it tips toward me... just enough to be annoying, maybe 1 to 1.5mm at the top.

I noticed that tightening the fence down, both the angle and the position, seem to put some stress on the fence, so I'll keep that as low as I can manage too.

To get by, where should I adjust it for square?

[Greg Carr]

Perhaps it's an alignment issue. Have you checked the fence against a known flat surface?

Just a thought.

Greg

[glenn bradley]

Greg is on to something. Another member went through all kinds of grief because he thought one thing was out of whack on his jointer and it was something else. The something else was discovered after he had tried to true up dovetail-way tables and gotten in a bind.

I would check the fence with a high quality straight edge to make sure you are not referencing off of non-co-planer (is that enough hyphens?) tables. If you have no straight edge, get one (sorry, just kidding ;)); you could lay the fence on a known flat surface and check it with feeler gauges.

If the fence checks out then go after your tables. If the fence is goofy then a machine shop could resurface it or you could shop for a replacement. If the tables are goofy, they are adjustable to some degree. The type of issue you describe would play heck with edge jointing in particular but any operation would be suspect in my mind without achieving a proper setup.

The jointer sets the flat surface off which other milling operations are done. It really help you out going forward if you can get your setup as close as you can ;-)

[Chip Lindley]

The infeed and outfeed tables should be checked to insure they are both in the same plane. Simple winding sticks placed across the end of each will allow you to view any difference in their parallelism. If the tables check out parallel, take the fence off and lay it face up, using the same winding sticks to check for twist from end to end. There is no adjustment to compensate for "twist" in cast iron. Regrinding is the only option and usually expensive. Good Luck!

[Chris Schumann]

Excellent ideas, all. I'll get or make some winding sticks first. Those can show twist in the table or fence. Feeler gauges will also be handy. I'll get that on my wishlist immediately. I have a 4 ft level that is extremely straight, checked against my brand new table saw, at least, but a calibrated straightedge is also going on the list.

Thanks guys.