Wondering if anyone can shed some light on a problem I’ve been having with my 10″ Jet cabinet saw. Had it for about 13 years and it’s been chewing up my zero clearance plates. At times I think I can almost see the blade jerk when it powers up! It does this with any blade I put on it so that rules out a warped blade. I’ve recently replaced all 3 of the drive belts (how do you know proper tension on those?) and all seems okay.
From what I’ve read if it were a bearing issue I should be able to hear them and/or wiggle the blade by hand but that’s not the case. Almost as if there is a power surge as it powers up but, like I said, it’s not consistent. I’ve noticed too that the kerf in my jigs and sleds is widening as well.
Any and all help and advice is greatly appreciated — Thanks
Replies
Dont be afraid to yank it around.
Well as you know I am not much of a table saw person. I have one and I went through it and made it all precise and stuff but then I don't use it much. I am how ever a mechanic and understand the V - belt issue as well so here goes.
As far as belt tension just enough but no more. I know, I know . . . what the hell does that mean ?
The belt should not be saggy. There should be some tension on it but you should still be able to push in the middle between the pulleys and get some indentation fairly easily . If the belt tension is much tighter it puts unnecessary load on your bearings and heats the belts without improving the performance of your saw.
Now
when you put on new belts you will need to keep an eye on them and when they wear in to fit the pulleys you will need to take up some slack.
One way to passively keep an eye on them is wait and listen for the day when you start the saw and you here a squeal. That's the pulleys slipping on the belts
Probably best to keep a closer eye on them than that though. Turn off your power and use the push in the middle of the belt test described above. Waiting for the squeal probably means the belts are slipping for a while in use and that is not good wear wise.
As far as the wear on your plates and other accessories :
Is there any chance the top is moving around on the saw cabinet ? Maybe it is not bolted down ?
TO CHECK THE BEARING PLAY :
Be aware it will probably take more than a friendly wiggle. Turn off the power and get in there and really heave the shafts/arbor back and forth and up and down like you really mean it. You might even want to put an indicator on it incase the bearing seals ( or sawdust and gunk build up) are dampening the clunk or movement.
There could be considerable slop before you ever hear bearing noise while it is running.
As a last thing to check; are the threads on the blade arbor nut in good shape ? There is a chance something has caused a gouge to form on the thread and it seems to tighten against the blade but may be just jamming on the thread anomaly and the blade isn't being fully clamped down an so it has a slight looseness on the arbor..
Belts
Thanks for taking the time to reply. Here's a weird one, I replaced all three belts a few weeks ago and the two on the outside are tighter than the one in the middle --- how in the world would I compensate for that?
That sounds lucky
Thanks for keeping me posted as to how it is going.
Any luck finding the kerf movement problem?
Well i mean what would a person do if the middle one was tight and the outer two the loose ones?
Asuming you bought high quality belts (what ever that means these days. Did i tell you about my recent Snapon purchase ? The only time i have been disapointed by Snapon.) . . .
. . . any way belts . . . and a matched set from the same batch just for this particular application. You did that right ?
if you did your best in this way on your end then i wouldn't worry about the middle belt. If you are cutting normal lighter stock at home for hobby work at a relaxed pace then it does not matter and two belts will handle it fine. If you are in a production shop taking advantage of the full capabilities of the saw and feedIng wood at it like your life and your fortunes depend on it . . .
. . . then . . . the outer belts will wear, you will take up the slack and the middle belt will at that time take up a greater share of the load. In any case i am sure it is handling some of the power transfer now.
Tell me more about the kerf prob when you find time.
I hope the weather is as nice on your end as it is here. Warm, cloudy, no terrible wind, might rain soon. Beats the hellout of hot, dry, high wind and fire danger.
PS: I supose you could change the order of the belts and put your slacker on the out side. That is assuming you can get some yaw adjustment in the set up. Mark it with chalk before you take every thing all apart. I am not sure it is worth it (see my thoughts above).
Belts/Kerf
Well, since I have your attention and anyone else is free to chime in, thought I'd take a picture to illustrate. Hard to focus but it's a zero clearance plate made of UHMW poly. You can see at the ends where the initial cut is, then it widens quite a bit. That's what I'm trying to figure out. Everything seems snug, no discernable play in arbor, 3 belts were purchased directly from Powermatic so assume they're as good as it gets.
I really am stumped!
You always have my attention.
If you put in a new plate how long would you estimate it would take to look like this again ?
You used dial indicators during arbor slop check ?
The threads on the nut and arbor are clean ?
The face of the arbor where the blade seats is true checked by indicator with the blade removed ? Maybe the blade slipped and you got some galling of the face of the arbor. Long shot I know.
Oh you know what ? It wasn't long ago I was reading about a similar case here. The saw teeth seemed sharp but the side facets were dull on one side or some on both sides and so the blade was being deflected side to side by the dull teeth.
Or something like that. Maybe your saw sharpener has had a set back in help or hardware.
Maybe you are getting some extra fresh electrons from the power company instead of all those old tired ones they keep putting out.
: )
Any change in your power supply ? Gone from phase inverter to three phase power ?
I originally wrote the following but then thought what an inconvenience it would be but am posting it anyway. Maybe until the problem is solved you may have to start the saw with the blade down and then raise it every time. Yah . . . that was stupid . . . right ?
Brings up the question though :
Have the mechanisms that move and tilt the blade worn and are no longer moving in a flat plane ?
PS: Oh Jet saw Powermatic belts. Could it be host rejection ?
I don't know. Is the pulley geometry from a pretty much Japanese/Taiwanese saw the same angle, depth etc as a pretty much American saw belt ? Or is everything melted into one pot ? I don't know.
My mind is going. Anyway here is the thread I was thinking of.
Weekend is almost over and I think I've used up the allotted amount of brain cells for this predicement! Checked it once again with a dial indicator and the blade is true when rotated by hand. Could be the sharpening although it's a firm in SLC recommended by the blade manufacturer, Tenryu. Both blades have been sharpened half a dozen times. Maybe it's a blade problem and I should consider a Woodworker II which I understand is the best out there. You mentioned the power and honestly, it does seem as if there's a surge at times but ............
Thanks for your input, have a great week
Far fetched, but....
This sounds a little far fetched, and admittedly it is, but it almost sounds like your blade could be hitting an interminant harmonic, shaking, and then dissipating. That would kind of sound like a power surge. Trying a different blade would possilbly shed light. It doesn't necessarily need to be a good one, just as different as possible. Everyone needs a cheap blade for crummy wood anyways:) The idea is to see if it behaves/sounds differently.
Can you describe the circumstances when it vibrates or surges? Is it constant, on start up, random, sort of random? Does it always do it under load, never under load, sometimes? What kind blade is the current one, brand, tooth number, pattern, etc? This would help diagnose.
Roc, what say you? I know I have seen stranger things.
Well, the blade is a Tenryu, gold medal series, 10", 40 teeth. You may have something about the blade and some kind of harmonic heebie jeebies! Was using a dado set today and didn't notice any jerk on start up as I did with the Tenryu. I'm wondering if maybe the blade is the culprit so will try another tomorrow if I get the chance. I live in Las Vegas and have plans to go to the AWFS show so maybe I can get a good price on replacing the blade. I remember buying one of these 2 years ago at the same show. Everything I've ever heard mentions a Forrestor Woodworker II -- should I lean towards that one?
As far as power surge and all, I have one 220 line in my shop and notice that at times my planer seems to have an extra kick on start up. Not much of an expert on electrical but is it possible to have power surges like that? I'm in a residential garage/shop but I guess anythings possible. I plan to make some more zero clearance plates and will see how they react. Another thought I had is that possibly there is enough slop in the plate to cause what I'm experiencing.
Thanks
Blades, inserts, and surges
It is possible that for whatever reason your saw just doesn't like the blade and causes it to vibrate. I have occasionally had tooling that should work perfectly on a machine, but just doesn't for whatever reason.
I must admit, I do like my Forrest blades. That said, I would probably test the saw with a $20-$30 blade to see if it runs better or different before I bought a $120 one.
Insert slop is a possible culprit, and you do normally get a little chewing at the ends, although your pictures did look a little excesive. Best to check that first though as it is easy and cheap.
An electrical power surge on start up isn't likely, typically the opposite happens where the big inital amp draw from start up causes a voltage drop, the lights to dim, the motor to chug a little, etc. However, machines like table saws and planers do tend to "jump" a little, due to the surge of mechanical energy going into the power train, something about moment interia I think. If you had a little slack in your belts or a loose pulley, this jump would be larger still; this can also be intermintant, depending on how and where the belts and pulleys stop.
Thanks for the insight Hackmeister, I'm going to try a different blade and see how things react. Interesting about the belts, I just replaced all three of them with OEM from Powermatic/Jet so have been keeping my eye on them. The outer one is fairly tight, maybe 1/4" deflection in the middle but the other two seem to be slack --- 'tis a puzzle!
Maybe the Answer!!
Don't know if you're still interested in this older post of mine but since I may have the solution today thouhgt I'd pass it along to you. After tightening everything, changing belts, checking bearings, and doing all I could think of I had a repair guy come out to my shop. It drove him crazy too!! Decided to replace all of the bearings but still a harmonic vibration and you can see the blade move ever so slightly on start up. So, just have to live with it as we'd done every possible thing we could think of.
As I'm replaceing the blade I look at the flange washer for the umpteenth time and notice kind of a wierd wear pattern on it which made me think that it's not making full contact on the blade. The repair guy said it didn't look right so I ordered a replacement washer which I installed today. Guess what? When I put the throat plate on I noticed it was tight on the left hand side of the kerf so after lowering it completely, turned it on and raised the blade. It probably removed 1/32" from throat plate (zero clearance) and now my splitter is a little snug. Only thing I can figure is that the old flange washer had gotten deformed after 10-12 years that I've owned the saw and was no longer keeping the blade secure on the arbor. Attached a couple of pictures for you.
Hello Landmade, I tried with different blades as well. After deciding whatever was wrong was beyond my capabilities to diagnose and/or repair had the only authorized repair company in Las Vegas come out. Guess what --- they couldn't figure it out either!! He decided that even though physical testing of the bearing didn't indicate any problem he replaced them. Put meters on the electrical to check wattage and all checked out okay. Same with motor bearings. The only saving grace is that he didn't charge for any of the parts, just a service call charge so that's good. The problem seems to persist so I'm just going to live with it. I'm more of a hybrid woodworker anyway so everthing is followed up with hand tools but it really has become an aggravation to say the least!
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