Issues with JT160 jointer


Brandon Williams

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Hey guys. I seem to be haveing a problem with my jointer creating a twist in my project pieces. Im still pretty green when it comes to using a jointer.  I have adjusted the blades to be as flush with the outfeed table as best as i can, and the fence is 90 degrees to the table. Im not sure what i am doing wrong, ive tried slowing down my feed rate only to see the twist get worse. Any and all advice is greatly appreciated. 

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Correct.  I owned that jointer and the tables were not coplaner.  The result was the twist you describe.  Although there are no adjustments for this, it can be easily fixed.

First set your expectations that you will probably be able to greatly improve your results but, do not kill yourself trying to make the jointer something it is not.  You will want a decent straight edge of a length close to the full length of the table surfaces combined and a set of feeler gauges. 

A dial indicator on a base would be very helpful if you want to get one.  A $10 Harbor Freight and a $15 1-2-3 block could be used like so to your advantage on this and other machine setups.

Rotocator-poor-mans.jpg

Now, determine which table is in closest alignment with the cutterhead.  In my case the outfeed table was fine.  There are articles on setting knives, TDC, table alignment and so forth online.  Here is one by Marc S.  This will familiarize you with what you are trying to do although the methods will be a bit different on your little benchtop machine.

Hopefully one table or the other is already in good alignment with the cutterhead.  If one is even really close I would call that our reference and move on for now.  Based on how much success you have you can decide how much effort to put in before the reward just won't equal the cost in effort.

As you noticed, the coplaner deviation increases with table position so pick something like 1/32" of cut and adjust for that spot.  If you are lucky you will be able to adjust for more stock removal and return to this 1/32" (or whatever) spot and still be coplaner.  If not I would just consider it a limitation of the machine and pick a spot and leave it; better good slow results than poor results at any speed.

Even if you get the machine perfect it is very lightweight.  This means that too much force by the operator can actually flex the machine body during operation and foul your cut.  Here again I am trying to encourage you to improve your result but not to drive yourself nuts trying to fix something that is inherent in the machine.

The tables are each held on with four Allen head cap screws.  You will be using the surface area where the casting that surrounds these cap screws meet the base.  Using the straight edge and your feeler gauges, determine what area of the table that is to be adjusted is lowest. That is, find the area that needs to be elevated the most in order to meet the plane of the reference table/straightedge.

Remove the table and make a shim from foil tape, cut up soda can or actual shim stock.  A piece shaped like a washer about the diameter of a quarter will do.  Add enough shim to compensate for about how low the spot was at that cap screw location and put the top back on.  Using a consistent (or as close as you can do by feel) amount of torque on each cap screw during reassembly will make things easier.

Recheck using our chosen "reference" table, straight edge and feeler gauges and see if you have solved the low spot, gone too far or caused another low spot somewhere else.  Now you just rinse and repeat at the required cap screw positions until you get as close to coplaner as you can.

Take your time, take coffee breaks and expect to commit a reasonable amount of time to this.  Do not try to do it in spurts or between other tasks; this method leads to madness :D.  I was able to get mine to the point where it did quite acceptable work as long as I did not exceed the machine's design parameters.  By that I mean I did not try to mill material too heavy nor did I press down on the machine enough to flex the housing. 

Once you get aligned and develop a "touch" the machine will turn out consistent work for you.  Please keep us in the loop as to your progress.

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Ok, so not heavy in and of itself.  Remember I owned this jointer so I am speaking from actual experience here and not just offering an opinion ;)

You need to be careful with your feed pressure. Supply only enough pressure to keep the material firmly against the fence and table. Any pressure in excess will cause the actual frame to flex and misalign your feed path.

 The tool is really made for very lightweight hobby use. You have to bear in mind that the entire jointer weighs less than the motor in my current jointer.  I do not say this to be derogatory, you just need to make sure you don't expect more from the tool than is able to supply. 

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