Completing the Alignment Procedure
I talked about completing the alignment procedure for the right side of the blade last time. Now it’s time for the left side.
Moving the positioner base unit towards that side showed an immediate problem: it gradually got harder to do it. I figured out that the rails must not be parallel, and confirmed it with my tape measure. Note to Incra: add to the instructions that you push the rail all the way into the bracket as you tighten the bolt. Reseting all four rail bolts, pushing firmly on each as I tightened, solved the problem.
Also, since the brackets that slide on the rails were exposed, I decided to make a minor improvement:
To allow them to slide a little better, I applied some UHMW tape I had to the sides (it shows as translucent in the picture). I had to trim the tape to avoid blocking the holes. There is already a plastic pad for the main point of contact, the weight-bearing part, but on the sides, it is aluminum to aluminum, and it has to bes a reasonably snug fit if you don’t want the mount to wobble. And you don’t.
I noticed a problem when zeroing the fence to the blade. You’re supposed to use the micro-adjuster to make a fine adjustment, but it seemed to lag – like I had to turn it many times to get it to start to move, and then turn it many times before it would move in the opposite direction. Hmmm. Sounds like a problem? I wish I had done a test cut at this point, but I saved it for later.
Replacing the Extension Table
As I mentioned earlier, I had to remove my extension table to tighten screws on the underside of the base mount. I took some time to attach it again. It is much closer to being level with the metal top than the first time I installed it, years ago, because I used a clamping rig to put it and keep it at the correct height while tightening the bolts.
Finally, The First Cut! But…
Because of the problem with zeroing the blade, I thought I would try cutting a scrap to exactly 1 inch by the fence guide, then measure it with calipers. They suggest this as an alternate way of zeroing the fence. If it is off, you simply dial in the amount it is off, and reset the scale to make THAT zero.
Yow! Even after a careful blade-zeroing, my calipers said the cut was 1 3/64”! I could do MUCH better than that with my Delta Unifence and eyeballing it! What gives?
This is where I was certain there was a problem, because the microadjust did not change the fence position for a more accurate cut.
Diagnosing the problem
I put the SuperBar gauge into the miter slot, and brought the fence close enough to contact the gauge’s rod.
Then I rotated the microadjust to watch the scale change. IT DIDN’T MOVE, not at all. Yikes. I kept turning the microadjust. Eventually, it started moving, and moved about 1 mil (thousandths of an inch) for each click, like it’s supposed to. Tried the opposite direction. No movement until after about 50 clicks, then consistent movement.
Then it hit me… 50 mils… well, 3/64” was the error in the test scrap, and 3/64” is 47 mils. Perhaps this is not a coincidence.
Next, I locked down the fence, grasped it, and tried to move it. Nope, it’s solidly locked. I partly unlocked to microadjust mode and did it again. It moves. Measuring, I find it can be moved 50-55 mils back and forth. But why? The fence system is impressive, even intimidating, at first glance. But I’m an engineer, so let’s keep going.
I removed the fence carriage from the LS positioner, allowing me to examine the latter closely. The problem is with the microadjusting mechanism, and the red lever must be set to middle position to be in microadjusting mode, so…
I put my finger inside, and touched the silver part (red arrow points to it). It moved! This seems to be the clamp that controls microadjusting.
I removed the screws that hold the windows in place for better access. It was clear that this part wobbles because the two screws that hold it in place have not been tightened. The red arrow above points to the back of one of the screw holes. I the loose screws also explain why sometimes it was hard to insert the carriage into the positioner: this threaded clamp may have been in the way sometimes, and not others, depending on how it wobbles.
Conclusions and Next Steps
I would call this a manufacturing flaw. Obviously these fences are built by hand, and someone just did not tighten it. But it also got by whatever quality control they have.
The screws to tighten it are inaccessible without disassembling the critical LS Positioner. There are four screws holding a bracket that holds the microadjust clamp into place, but they are tightened VERY firmly, and since there are four, I assume that this part is adjusted critically, probably using a jig that I don’t have.
So I’m not going to mess with it. If this was an old tool from a company that is out of business, I’d fix it myself as best as I could. But given that I paid a lot of money for a brand-new tool, I’ll ask them to send me a replacement, or to walk me through the fix if that can be done by me.
This is extremely disappointing. I was really looking forward to using it this weekend. I even had a bad dream about it not working last night, and spent some insomniac time wondering what was wrong. Well, at least now I know what’s wrong. And I’ll spend the weekend doing other tasks that I have been putting off in my excitement to get this fence going.
-- Mark, hack amateur woodworker, Medford (greater Boston) MA