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Sat 1 Oct, 2011 09:31 pm
I've got a 10-year old Craftsman tablesaw, which has seen very light use over the years. Just recently I noticed that when turned on, and when reaching its maximum RPM, the tablesaw sounds to be out-of-balance, and is simply not running correctly. The big giveaway of the problem is the lack of the typical high pitched whine, that is characteristic of most tablesaws when running at their maximum RPMs.
I'm not sure why this is happening. Thinking the blade I was using had somehow gotten bent or out-of-round or had some sort of warp was causing the grind/wobble noise. So, I removed the blade and tried running up the motor to speed, with nothing mounted on the arbor. Doing that seemed to eliminate the grinding/wobble noise, but a visual inspection of the blade didn't indicate any kind of defect or other problem.
I still suspect there's some sort of problem either with the motor, the bearings, or simply the driveshaft itself - although I've got nothing to prove (or disprove) this. Any suggestions on further isolating this problem to either the blade or some other part of the motor/driveshaft. I know I can buy a new blade easily enough, and I feel comfortable disassembling the motor, but I'm not sure what I'm looking for that got a problem, so that I know what to replace. Anything?
@CDobyns,
Is that a direct/shaft drive saw, CD?
@CDobyns,
I'd certainly try it with a new blade before I started taking stuff apart...
@JTT,
Yes, I believe this is a direct shaft-drive model, which makes me want to think that the shaft isn't the problem (since it's pretty thick). Can't discount the possibility though, and would assume (from the schematic diagram) that the replacement of any of the motor/drive components wouldn't be terribly difficult (I'm good at taking things apart - a little less-good at putting them back together right though . . .
).
@CDobyns,
How'd it run after you remounted the blade? Since it sounded good without the blade, I wonder if it might have somehow become loose. Not likely as the nut would be threaded so it tightens during use, but other than balance and bearings, I can't think of another thing. Oh, for some reason, some machines vibrate when out of level. I've seen this with washing machines and refrigerators. Never saw it with a table saw, but it's an easy thing to check.
@CDobyns,
There's lots of talk at,
http://www.woodworkingtalk.com/f12/sears-craftsman-10-flex-drive-table-saw-3363/
about these direct drive saws. One guy mentioned that the arbor always wobbled. That doesn't sound great when you're trying to get a fine cut. Check it out.
More here,
https://advice.thisoldhouse.com/showthread.php?t=241
@roger,
First, I'm not sure it necessarily sounded "good" without the blade. I would say it sounded "different". But since I've
never run the saw without a blade mounted, I wouldn't have clue as what that should sound like, and if it would sound the same or different with (or without) the blade - so nothing to compare it to. But I would say that I didn't hear anything that sounded like the saw was out of balance without the blade, and visually, I couldn't detect anything that suggested the shaft/arbor were not "true" - and spinning in anything other than perfectly straight alignment. Talking this through with you (and myself), I'm now drifting to the idea of investing in a new blade first. Will follow-up with what I find.
@CDobyns,
Okay, went out today and invested in a reasonably good quality replacement 10-inch Skil blade from Lowe's. Installed the blade and fired up the motor and I'm pretty sure there's still a problem. The whole tablesaw is stable enough, but missing is the characteristic "hiss" of the saw blade when it reaches its maximum RPM. I've always been surprised at this sound, since with the blade spinning and other than when you're actually engaged in cutting operations, the tablesaw is typically nearly silent - except for the slight sound of the motor and the "hiss" noise the blade emits.
Okay, well enough of this reminiscing, since we've now ascertained that there's something amiss with some component of either the motor or the driveshaft. I've already looked at exploded schematics of the motor/driveshaft assembly, and clearly that's designed with the idea of purchasing replacement parts and making repairs - and as the son of a mechanical engineer, I'm actually remarkably good at making repairs (something about the "nut doesn't fall far from the tree" I'll assume . . .). Any suggestions about a diagnostic course of action, since I'm not sure where to begin, nor what I'm even looking for that might represent something that's been damaged for that matter? I can assume those things will look like parts that are not "true" or damaged bearings - and fun stuff like that?
@CDobyns,
Quote:The whole tablesaw is stable enough, but missing is the characteristic "hiss" of the saw blade when it reaches its maximum RPM.
Every blade is different and many blades have designs specifically pointed at reducing blade noise.
@CDobyns,
you might check with Sears before you start, but my experience has been that they don't service much from the diagram, and it will be chunks.
a motor for instance, but no bearings...
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