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The DoAll 16" LHF Bandsaw, Part 10:
Yep, the lower belt was too thin, and the upper belt was worn. I replaced 'em both, and now the speed control
works very well. Smoothly and accurately, and with a nice solid, precise feel. The saw is now 100% usable and
ready to go, although perhaps not quite 100% "finished".
The only remaining sticky point is the speed indicator,
which as I noted earlier, was badly buggered when I got the machine. I have no photos of what the linkage is
supposed to look like, so I had to make a "best guess" given what was there.
It does work, but as I said, it's
pretty crude. And, as I've found out, it's not really... in calibration, to borrow a phrase.
I have a non-contact phototachometer which I can use to get the exact blade speed, but if I set the pointer
to be correct for that given speed, it's not correct for any other speed- and the error gets worse the
further away fromthe set point you get. I'll probably have to do something like make a new faceplate,
or fiddle with the linkage ratios to see if I can fix it.
Or, I bought an actual DoAll gauge-type tachometer from another PM'er, which I could rebuild and try to install.
The problems there are the fact I have no cable, no drive box, and the gauge has a dial for a three-speed machine
(with a max of over 10K sfm.) I suspect getting the drive ratios right would be tricky and probably expensive
(having to buy multiple gear sets to trial-and-error) and I'd probably have to make/etch/print a new gauge face.
Or I could just buy a cheap Chinese digital machine tachometer off eBay and use that.
For the time being,
I've got the temporary tags shown, for various ranges, and that seems to do for now. The saw cuts extremely
well, straight and smooth, and sails right through aluminum bar stock (one of the main reasons for which I got it.)
So while there's still a few minor things to tweak on it, it's up and running, and ready for use.
I already have a couple of blades and guide sets, and have more of both on the way. I picked
up an older Craftsman miter gauge off eBay, which fits perfectly, and despite my having removed
the table at least three times, it still cuts dead square.
So here's a closing (slightly photoshopped ) photo of it set up and ready to run.
Now here's something interesting. I ran it through the full range with
the new adjuster
and new belts, in both high and low ranges:
The minimum possible speed in low range is approximately 45 SFPM.
The maximum possible speed in low range is approximately 240 SFPM.
The minimum possible speed in high range is approximately 700 SFPM.
The maximum possible speed in high range is approximately 4,300 SFPM.
Now, that's not too far off what the faceplate says- 50 to 250 in low, 850 to 4750 in high.
But what's with that relatively huge 460 SFM gap in between? That seems odd.
And factory, since the stock faceplate goes from 250 to
850- a 600 sfm gap. More oddly,
there's plenty of entries on the factory
"Job Selector" dial that show speeds right in the middle
of that gap- brass, for instance, and aluminum bronze, that need (according to the
around 400 to 700 sfm. I wonder why they did it that way?
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