MIMF

I'm having a problem with my jointer tapering boards. The end fed into the cutter first gets more taken off than the other end. After a few passes the board gets a noticeable taper from one end to the other. I have a book on machine set up but no mention of this in the book or the owners manual. I did a complete set up on it when I bought it about eight years ago. Today I went through the whole thing again with a 4' machinist's straight edge and shimmed the out feed table so it's within .001 of an inch of the out feed table. I've ruined several neck blanks and I'm getting pretty tired of this whole thing. Any ideas would be greatly welcome.

Your outfeed table is not coplanar with your infeed table and a straightedge is only one of the tools needed to align the tables, etc. Suggest you make up a bed-length master bar using some 3/4" MFD and drywall screws (these bars will have 3 points of contact, so avoid the issues which a long straightedge creates when attempting to set tables in the same plane). Three pieces of bed-length 3/4" MDF shelf stock or half sheet of MDF (ripped into 8" wide pieces) works. John White's book on setting up and maintaining shop machines covers making, calibrating, and using a master bar (Care and Repair of Shop Machines, Taunton). Your 4' straightedge or an outfeed table length master bar will work for setting twist on the outfeed table and setting the table level with the cutters.

I correct outfeed table twist first, followed by outfeed table droop, then set the outfeed table level with the top of the cutters, and then set the fence both square and parallel. All of this assumes the infeed table, outfeed table, and fence are flat and free of twist.

I've fought with a lot of jointers over the years and nothing can replace an accurately manufactured unit. Once I figured that out I just kept looking for the right used machine until I found the one I have today. If your jointer was working correctly before now then I'd check the outfield table height first. If the blades aren't sharp or the wood you are milling has some runout and has a tendency to fuzz up or spring back at all then you will have a really tough time. I used to set the outfield table with a straight edge but now I do it to minimize snipe at the very end of the board. if the cutter head is too high you'll get a lot of snipe, if it's exactly right you won't get any but I find it safer to to lower the outfield until I get just a trace of snipe especially if I'm working with fuzzy woods like khaya or alder or western maple. Extremely hard woods like snakewood and African blackwood can also pose problems as they tend to chatter if you can't hold them down firmly enough. Going to a spiral cutterhead like the Byrd head solved a lot of my problems and has saved me hundreds of hours in blade changes and setups over the years. Well worth the hassle of installing it and setting it up. I really like Todd's idea for a master bar but I'd simply go and buy a section of aluminum H beam and have it precision milled on all sides and edges at a place that does metal planing, i.e. an automotive machine shop.

Lastly never go shopping for a jointer without a straight edge, preferably the 4' cast iron machinist's kind that's stored in a wooden box. Short of that then a machinist's 12" or 18" level can tell you a lot about coplanarity. A Starrett #199 Master Precision Machinists level is what you want along with some wedges you can tap under the machine to get it level on the sales floor. If no one will lend you their 199 then try for a 98-12 or 98-18. I broke down and bought a 98-12 on eBay for $30 and then sent it back to Starrett for new vials and calibration. I couldn't live without it now.

Thanks for the tips guys. I have White's book and was hoping I could get by with my 4' straight edge and not have to build his master bar. I guess I need to re think that. David, I already have a spiral cutter and am not having trouble getting clean cuts. Just having problems with a length wise taper. Thanks again.

You can do this with a straight edge or master bar - either should get outfeed and indeed table squared away. If you have a long bed jointer, the extra length of the master bar may provide a longer baseline, but it there's a big hump in the casting, you've got a bigger problem to deal with, so spend some time on surveying the beds and fence. Agree with David - I don't have an issue with minor hollows that very localized, but a twisted or warped table is going to cost you more to correct than dumping it on Craigslist and buying another tool...the guy that bought my PM came in with a full kit of tools to measure and evaluate...good idea.