how to adjust for perpendicular?

I’m using the perp testing tool and I can see that its a bit off the surface consistently on one side. It seems like the z-axis needs to rotate about the axis shown coming out of this view. There are 4 bolts labeled in this pic (2 you can’t see). Are these bolts useful in adjusting the z-axis w.r.t the middle assembly? If so, in this case, to rotate as shown about the axis coming out of this view, how should I adjust these? 1 tighter, 2 loosen?

Or what is a better way to make this adjustment?


Thank you.


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Ooohhhh don’t hate me, there isn’t an easy answer.

Try to see if you can loosen the mount and just move it a bit and lock it back down correctly.

Make sure all 4 corners are at equal heights.

Make sure the spot you are testing on is relatively flat, I spent a while tweaking my last cut to find out the board I was sitting on had saw dust under it…

For the most part the center gantry should not be touched unless it is actually the problem like are your Z rails at an angle? If they are by all means fix it at the gantry. If the rails are straight just shim the dewalt with tape or something.

Perpendicularity is one of the hardest adjustments because it takes a lot of weird tweaking. I spent about a day doing this and I still couldn’t get it perfect, just better.

Those tension bolts can help, but don’t do all that much. Take off the dw660 and verify the z axis itself is perpendicular with your work first before shimming. If you shim first, it could be possible that your z is not perpendicular, but your dw660 is!
That will mess up your cuts just as much as not doing anything at all because the tool won’t feed at the same angle as it’s pointed.

My z was at an awkward angle for whatever reason, ended up just shimming with tape I folded which helped.

If you haven’t already, make sure you leveled your bed by surfacing it. Otherwise, your test isn’t really accurate anymore.


so remove the 660, lower the axis and check it with a speed square?

can you post a pic of how you shimmed the z-axis?

shimming the mount or the tool i can imagine, but I’m not sure how I would shim the z-axis