Replies

1. 
   RickL | Dec 01, 2008 03:43pm | #1

   I assume it's a dovetailed ways machine as opposed to a parallelgram type.  My first way to test this problem is with a machined straight edge and feeler gauge to determine if the tables are sagging.  This coplanar condition is often confused with dull knives, outfeed table set a few thousandths higher than the top dead center of the knives or technique. Having the table set a few thousandths above the knives will casue the cut to taper to zero at the end of the board and it's often confused with coplanar issues.

   You need to give more info on the jointer and how you came to the conclusion you feel tables are coplanar. There's a very specific methodology to follow through on this and it's logical and specific. Start with the blades and outfeed table height. Jointers don't typically just unadjust. Was it fine at first?  How old is the machine? How many times have you changed the knives?

1. 
   pwaldc | Dec 01, 2008 05:35pm | #2

   Yep, the ways are dovetailed. I first noticed it because I was edge jointing boards and the edges weren't coming out 90 degrees. Sure enough, when I set the fence at 90 degrees to the infeed table, it's off by about .005" on the outfeed table.

1. 
   RickL | Dec 01, 2008 05:44pm | #3

   Did you use a straight edge and feeler gauge across the tables? That's how you check tables for Coplanar.

   Did you try setting the fence to the outfeed table and edge jointing?

   .005" off from what??? The edge of the  outfeed table to the infeed table?  What if you move the fence forward?  

   Sorry for all the questions but I have been adjusting machines for 25 years in commercial, custom shops, and schools.

2. 
   PeteBradley | Dec 02, 2008 05:31am | #4

   .005 over a 6" jointer is more than ideal but nearly insignificant in use. Not sure what problem you're trying to solve but if it's taper, the issue may well be technique or expectations rather than coplanar.

   Assuming your measurements are correct (always worth rechecking), the most likely cause for a dovetailed jointer out of plane is loose gib screws or unevenly tightened screws. These screws are on the back of the machine along the ways. You can loosen them a bit, then evenly tighten them just snug while applying a bit of upward pressure on the end of the table. Don't overtighten.

   If the jointer's been run for a few years or run a lot, you get gunk in the ways that has to be cleaned out, which requires disassembly. Usually you'd have sagging tables also though.

   Pete

1. 
   pwaldc | Dec 02, 2008 05:49pm | #5

   After rechecking, here's what I've got:- With the fence squared to the infeed table, I can slip a .005 feeler between the fence and a square placed on the outfeed table- Placing a straightedge across the tables and next to the fence, I can slip a .005 feeler under the end near the end of the outfeed table and slide it under toward the cutterhead. It stops about two-thirds of the way. If I do the same thing with the straightedge moved to the side away from the fence, it stops about half way.Together, this tells me that the outfeed table is both sagged at the end and tilted out of coplanar. So you're saying that if I loosen all the gib screws and then tighten them while pushing up on the table in the direction I want it to go, it'll go back into place? That seems too easy - I was expecting something that involved more screaming and yelling.

1. 
   PeteBradley | Dec 03, 2008 03:40am | #6

   What you're describing really isn't too bad, but you can probably make it better. What you're measuring could be from either or both tables. It really is that simple unless the ways are dirty. At the factory, the machine was ground flat as a unit. The ways keep the tables aligned. It takes a *lot* of use to wear them down, more than most jointers will ever see. I don't know what the original tolerance of the machine was, but you can probably get it closer than it is now. I wouldn't expect perfection. Honestly, you're close enough now that you might not notice it in use.Pete