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Thread: Northfield Jointer Knives Installation?

  1. #1

    Northfield Jointer Knives Installation?

    I'm having some problems adjusting the knives on my 12" Northfield MD jointer. Unlike other jointers I've owned this jointer doesn't have any adjustment for the tables other than up or down. In other words there is no adjust that I know to make the tables coplanar. On my jointer the outfeed table is about .003" askew of the cutter head (TDC) top dead center. The Northfield knife setting gauge uses the cutter head TDC as a basis for adjustment, which if used would put the knives .003" different on one end of the outfeed table. I also have a Oneway height gauge that would use the table surface as a basis for setting the knives. Should I use the Oneway gauge or find some way to shim the cutter head so it's in line with the outfeed table?

  2. #2
    Join Date
    Feb 2014
    Location
    Lake Gaston, Henrico, NC
    Posts
    8,973
    On any jointer, I use a small strip of thin, very hard wood (Boxwood currently), on edge on the outfeed table. I bought different gauges decades ago, but find it quicker to set straight knives by feel. The trick is being able to tighten the end blade gib screws just enough to hold the knives, but still allow them to be pushed into place. If the tail end of the wood never lifts off the outfeed table, it's not possible to push the knife down too low. A wrench, on one of the center gib screws swings the cutterhead back and forth, while you push each end of the knife down, and feel for it just brushing the wood, but not raising it. When both ends are just right, tighten the gib that the wrench is on, and then the others.

    Using that method, that three thou probably won't matter, since this is keying off the outfeed table.

    Takes about 20 seconds per knife, and works with any length straight jointer knife. I posted pictures, and a how-to on another woodworking forums, a while back, but can't find the pictures in my computer now. We're not allowed to link another forums from this one. I also included a picture showing a reflection of light from a window off a board just run across the just set knives.

    edited to add found pictures:

    I wouldn't mind having one of those Byrd heads, but the time required to change the cutters would drive me batty.

    Look closely, and you can see the machine marks. Light is from an early morning North window. The Boxwood strip has both edges resurfaced by the jointer, at the end of the install. I use a tiny cut depth, and the eraser ends of a couple of pencils for push sticks. No micrometer suffers wear, and no spot on any knife touches metal. I checked the first few times I did this with a micrometer, but that's been so long ago that I forget how close they were. The surface of the wood run is a good enough test for me.

    Last edited by Tom M King; 11-18-2019 at 7:22 PM.

  3. #3
    Join Date
    Mar 2013
    Location
    North Alabama
    Posts
    548
    On mine, probably the oldest variation of the Northfield 12" MD/LD design there is, there are several square-headed screws on the underside of both tables. These can be adjusted to level the tables to the cutterhead and to one another. Does something like that exist on yours?
    Chuck Taylor

  4. #4
    Join Date
    Nov 2009
    Location
    Peoria, IL
    Posts
    4,444
    .003 makes a big difference? Keep the shop a little colder, the cast iron will shrink that much! LOL

  5. #5
    Quote Originally Posted by Charles Taylor View Post
    On mine, probably the oldest variation of the Northfield 12" MD/LD design there is, there are several square-headed screws on the underside of both tables. These can be adjusted to level the tables to the cutterhead and to one another. Does something like that exist on yours?
    No, there is only one hold down bolt for each table. Although I could shim the tables to make them coplanar and then shim the cutter head mount accordingly.

  6. #6
    Join Date
    Jun 2008
    Location
    So Cal
    Posts
    3,739
    I recommend you don’t mess with the tables.
    If they are coplaner to each other use your Oneway.
    I use a dial indicator thats held in a fixture to set knives in my 12 inch Oliver. My head is also not perfectly in line with the tables. If you don’t have lifters for the knifes it’s a bit more challenging but doable.
    Just takes some practice and knifes ground straight.
    Good Luck
    Aj

  7. #7
    Quote Originally Posted by Steve Mathews View Post
    I'm having some problems adjusting the knives on my 12" Northfield MD jointer. Unlike other jointers I've owned this jointer doesn't have any adjustment for the tables other than up or down. In other words there is no adjust that I know to make the tables coplanar. On my jointer the outfeed table is about .003" askew of the cutter head (TDC) top dead center. The Northfield knife setting gauge uses the cutter head TDC as a basis for adjustment, which if used would put the knives .003" different on one end of the outfeed table. I also have a Oneway height gauge that would use the table surface as a basis for setting the knives. Should I use the Oneway gauge or find some way to shim the cutter head so it's in line with the outfeed table?
    You are right, the tops on a Northfield jointer are dovetailed into the brackets that adjust the height. They are not adjustable but the head is. It could be loosened and shimmed. Now, is the two tables coplanar with each other?

  8. #8
    The 3 thou matters . 1and 1/2 too high makes the work "climb". But for now you can improve by having ONE end right .
    And the the smallest knife nicks make cuts inaccurate, so if you think you must run dirty wood ...do it first on the "bad
    side" 'till you're ready to put in time to adjust all deficiencies.

  9. #9
    Join Date
    Dec 2005
    Location
    West Lafayette, IN
    Posts
    6,529
    My NF is dead nuts basically with no shims. When I called to inquire about the tables being off when I first assembled it, their recommendation was to remove the tables and clean the mating surfaces and that did the trick for me. Especially if your machine has been painted.

  10. #10
    I would pull outfeed table and clean those surfaces, however I wouldn't fight try it too much.

    Rarely do I use a setting gauge on a jointer, just a small board with two pencil Mark's. That matches knives to outfeed table.

  11. #11
    You can probably get them dead on by just removing the outfeed side and doing a deep cleaning and degreasing on the bottom of the outfeed platform and the dovetailed ways. I would guess that you could fix .003 just by doing that. If you try that first and find you are still off .003 then you can order some metal shims off Amazon for a few dollars and shim the outfeed side under the dovetailed ways that the entire outfeed side rises up and down on. Should take a few hours but not an entire day. I would also highly recommend you consider adding a spiral cutter head so that you can set your tables coplaner and never have to worry about setting knives or adjusting the tables ever again. I love those big old cast iron freaks from Northfield, Oliver, ect. They just take a bit of time and money to make them pretty much superior to any thing on the market today. If you can’t spring for a spiral cutterhead then invest in a good dial indicator or a oneway gauge.

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