Still trying to get to the bottom of the mysterious lower counter on my Martin shaper's display. Where we last left off I had found a section in the maintenance manual where it stated that if the spindle was raised to the top position, the lower display would reset to 0.0. I tried that, and it did not reset.
I talked to Ed at Simantech in Mew York some more and he said he would visit another customer nearby who had a T-26 shaper of the same vintage who also had a calibration device. The T-26 was the tilting version of the T-20 shaper that I have.
Ed got back to me and said that you have to raise the spindle ALL THE WAY to the top, and that when I did the lower counter would reset to 5.00".
Hmm, okay. Well, I gave that a try today. When you raise the spindle by pushing the '↑' button, it begins rising at slow speed. If you keep the button held down, it starts then to rise at higher speed, until it gets near to the top of it's travel, whereupon it begins rising at slow speed once again. I guess last time I hadn't kept on with the slow raise portion until the very last gasp. This time I kept that button pushed down until the cutter came to a dead stop and would raise no further. I looked over at the readout, expecting the same result as before, and was pleasantly surprised to see that the lower readout had actually reset - to 6.000"(!):
So, that's interesting. The manual says it will reset to 0.0, Ed said it will reset to 5.000", and mine resets to 6.000" for some reason. But at least it resets, which means the digital readout isn't pooched and in need of replacement. That's good news.
Still, I remain puzzled at the discrepancy between the 0.0 that the manual says, 5.000" that Ed obtained on the machine he looked at, and the 6.000" reset obtained on mine.
Here's the cutter in the very top position, with a combo square placed nearby so you can readily see the position relative to the tabletop:
A closer look:
You can see that the bottom of the ruler (top of the tabletop) is about 1cm down on the collar of the main spindle housing. Above that you can see a slight space, then the bottom of the 1.25" spindle itself, and above that the first of the spacing rings. This is the position that has been reset on the lower counter as 6.000". It doesn't really make sense to me. Shouldn't the reset be to a value such that when the bottom support surface of the spindle (immediately below the bottommost spacer) is exactly in plane with the top of the table, the readout would be 0.000"? If not that, then what exactly is being referenced by this lower counter and how is it supposed to be employed? If I put a taller cutter on the spindle, and have it sit right on the bottom of the spindle, the readout would be saying 6.000" and yet the bottom of the cutter would be something like 1.25" or so off the top of the table. I'm not quite getting it, but perhaps that is because it is really obvious and sometimes I don't see things right in front of my face. Any readers have any idea?
I've asked the tech guy at Martin, who also thinks the counter should reset to 0.0" at the top, to ask the people at Martin in Germany. Hopefully I'll get to the bottom of this soon enough. I like to know how things work and why, that's all.