what did the machine shop check? – – have you used a dial indicator on the arbor – could the arbor be bent or a bearing not concentric? – is the cut rough and/or binding against the fence? –
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well... - you see both entry and exit teeth marks on both sides of the cut? - - suggests the blade is 'chattering', I think - I'm not familiar with the machine, and do not at this point have any blinding flashes of insight to offer - I think I would look toward the bearings - altho I'd think that bearing problems would onset gradually rather than exhibit dramatic sudden deterioration - I'll think about it - DOUD
I remember the original conversation, but not the details back and forth. Please forgive any redundancy.
My first guess would be that the blades are not seating firmly. Have you tried putting the washer and nut on without a blade to see if it will run smoothly up to the flange? I also would look for a burr near or on the flange.
Dave
You've checked the runout - it's ok. That should also eliminate bearing problems. Offhand, I'd follow Occam's Razor here - the simplest solution is the best. Your problem sounds very much like "heeling." Heeling occurs when the blade is not parallel to the line of cut - leaving pronounced marks on the face of the cut. Blade chatter is a long shot here and since you've tried various blades that have workied well in the past - that would rule out blade warpage.
Is the blade parallel to the miter guide slot. If it's not, perhaps the table became misaligned during the move - this would affect crosscuts.
How about blade alignment to the fence. The fence should be slightly out of parrel with the blade - just a few thousandths to the rear of the blade - the outfeed side. This relieves pressure against the workpiece as it exits the blade.
Bernie Maas
I agree with Bernie it would seem that in the move the table moved out of alignment- check it as mentioned earlier with a dial indicator and your best sawblade as reference. good luck Joe
Check the table is flat and not rocking, try a free hand cut and check results. Are both sides of the cut the same? or one side smooth and the other rough?
Sounds to me like the trunion is tweaked from the move. You can verify it if you tilt the blade over to a 45 and check to see if it remains square to the mitre slots. If its not square at a 45 but is at 0 then the trunion is tweaked and needs to be completely realigned. Another tell tail sign is a slight curve the lenght of the board when ripping.
One other thing that can cause the same problem is a misaligned splitter. Take the splitter off if you're using one and try ripping.
Steve - in Northern California
If the doctor says you have Attention Deficit Disorder, do you pay attention to him?
Sounds like you have checked and tuned the usual suspects. If you're getting arced scratches, the blade flutter has to come from somewhere. As said above, the trunion is a possible source of the problem which would be worth another inspection. Check trunion bolt tightness. In an old FWW mag Robert Vaughan did a table saw tune up article in which he stabilized a trunion by installing a bolt which held the two parts of the trunion tightly together, which reduced the gap to zero and reduced blade vibration. When he switched to a tilt cut, he removed the bolt so that one of the trunion parts could move in its arc. You could try this just to see if it makes any difference. Also the trunion could have a crack in the cast iron at a point where it would cause vibration and blade flutter. Vaugh's article also pointed out that, on some saws (and specifically the one he was using for the article), if trunion bolts loosen, part of the trunion (the part with the groove) can move away from the part that fits in the groove, causing too much slop, which results in vibration.
"...part of the trunion (the part with the groove) can move away from the part that fits in the groove, causing too much slop, which results in vibration." I discovered, the hard way, that the 'part that fits in the groove' can even fall out! Fortunately, this happened while I was underneath the saw, foolin' with it, not while it was running. Any time one adjusts the trunions, I'd suggest, after tightening the bolts back up, that one check for slop between the cradle assembly and the trunions, both at 0- and 45-degrees. Otherwise the vibration may be the most pleasant thing to experience.
f_g... we finally found a post that we don't have to hijack.. How's it goin with your saw.... BTW the trick I've found is to never loosen those back stretcher nuts more than a turn or so. That way, the trunion won't have enough slop to fall apart on you. Just loosen them until you feel a little play then shake the *^@^#@^ out of the rack to get it to come back to its natural positon. Once it does your in like flint.
Steve - in Northern California
If the doctor says you have Attention Deficit Disorder, do you pay attention to him?
Hi Steve! Thanks for checkin' in!
Well, my saw is better, but not nearly close enough to perfect for any serious panel cutting, which I assume is the operation most affected by the "parallel" issue. I'll go through what I did here:
I had already tried the stretcher-shake method, and I thought I'd better follow your recommendation on inspecting for cracks, etc. So, my sweetie helped me put it upside down again (it was much easier with him helping). I took the cradle assembly out tried to check it for overall squareness. A little difficult to do, but I didn't see anything frightfully out of square. I double-checked the front trunion and set it smack-dab in the middle of it's left-to-right range, and lined the casting of the trunion up carefully on both sides with the casting from the table.
Then I installed the cradle assembly, and fastened down the rear trunion. Just looking down into the cradle assembly and the underneath of the table, they didn't look lined up, and sighting along a stretcher bar and a long casting line underneath the table, it was obvious they weren't parallel -- way off. And, going to the max adjustment on the rear trunion didn't come close to lining things up.
I took the cradle assembly out again, and removed the stretchers completely. I did a cursory check for straightness, didn't see anything obvious. Then I looked carefully at the casting of the holes/brackets they go through. The only thing I noticed was that the inside face of the front bracket on the left-hand side (the face that the stretcher body fits up to) did not appear to be perfectly flat. This part of the iron bracket is a semi-circular affair, looking somewhat like a Mickey Mouse ear set real low. The outside face (which faces the trunion, and butts up against the stretcher nut) is flat and square, but the inside face looks like it is minutely angled (so, the "ear" would be thicker on the outside than on the inside where it branches off the bracket).
If this is an accurate perception on my part, it would mean that when that stretcher is tightened, it would angle inward slightly over its whole length , which might push the entire assembly in that direction, which happens to be the same direction the assembly was canting.
As I said, it was the only hint of a problem I could find, but I wasn't able to "document" it with any kind of a measurement. What I ended up doing was to angle the front trunion to compensate for the incorrect angle the cradle assembly was taking, and of course I had to angle the rear trunion accordingly to keep the cradle assembly brackets tightly gripped between the trunions. I mounted the cradle assembly, then loosened the possibly-bad stretcher, leaving the other stretcher tight. I shook things up a little, and then re-tightened the stretcher.
I'd say it's off by about 1/16th" now. Not too great, but believe it or not, way better than when I started! I'm going to try and work around it for a little while -- I've got a few projects that I can make a little money off of, and probably fork out for a new saw in a couple of months. I know you don't approve of enlarging the holes in the cradle-brackets, but do ya think in this case it might be ok? In the meantime, I guess if I'm needing a square panel I'll rough-cut it and grab the router to square it up. Any tips would be welcome, as usual!
Hi f_g, it sounds to me like you've got about the best you can get out of it. If I read it correctly, it almost sounds as if it may have been run for a while with a loose streacher or maybe the motor mount got smacked really hard. This would explain the odd shape of hole. You may be able to take the piece into a shop and have them build it back up and remachine it or may just order another from Jet. I think you have definitely found the problem.
I'll again suggest that you not elongate the mounting holes but only because I think your can fix the real problem. However, if you are planning to buy a new saw and just want a temp fix, then elongating the holes might work just fine.
I am a little bothered by the fact that the whole assemble is obviously tweaked and I'm not sure if this is a safe situation or not. You'll have to be the judge of that. I might also suggest that if you need to cut miters using the blade tilt, do it only with the fence to the left of the blade and only if the blade is kicked out to the right at the rear. If the blade is kicked out to the left, don't even attempt them.
Good Luck
Steve - in Northern California
If the doctor says you have Attention Deficit Disorder, do you pay attention to him?
Hi Steve. Thanks for the safety tips (I plan to be very careful).
The stretchers were very tight when I first took a look at them, but I do believe the rear trunion might have been a bit loose. Actually, the hole itself is round, it's the face that looks a bit wierd (see pic below -- and keep in mind I cannot draw!) This is what the "ear" part of the bracket would look like when looking down from the top:
<img src="http://www.islandpastimes.com/Knots/Stretcher.jpg">
Well, off to work. Hopefully some woodwork later tonight or tomorrow! Thanks again.
I'm trying to get image to work. Be patient.
Well, I can't get it to show up, but the address will work if pasted into your browser.
Edited 4/2/2002 5:35:48 PM ET by forest_girl
Edited 4/2/2002 5:37:56 PM ET by forest_girl
Edited 4/2/2002 5:48:48 PM ET by forest_girl
Yep, its definitely damaged...... Are you thinking of replacing it ?
Steve - in Northern California
If the doctor says you have Attention Deficit Disorder, do you pay attention to him?
I'm thinking it was mis-cast, rather than damaged -- seems like that face (on the left side in my crude drawing) should have been flat. May have put a bend in the stretcher though.
Yeah, I think I'll call Jet and see how much a new cast piece and a new stretcher would be.
In the meantime, I'll do what I can.
cp,
Something you might try is to raise the blade through a piece of pvc sheet or some other sheet stock and measure the width of the slot along it's length. If the blade is wobbling, this would confirm it as the slot would be wider at the front and back than in the center. From your description that the saw is leaving both leading and trailing arcs I suspect this is what is happening. It may only happen when cutting due to feed pressure and variations in density as you run through the wood. It may not show in a runout test where you are simply spinning the blade by hand.
If you find this is the case, I would first check the arbor for lateral play. In other words measure the lateral movement of the blade by grabbing it and moving it side to side. Looseness in the trunion should be visible if the blade moves excessively side to side while you are raising it.
Also, the condition you describe of leading and trailing edge arcs would be caused by pinching the workpiece at the trailing edge, as someone mentioned above. Make sure your fence is dead parallel to a bit open at the back of the blade.
Again as someone mentioned above, ensure that the table is correctly aligned by measuring the distance from the miter slot to the blade at both the front and back of the blade. This is very possible on the PM66 as the table mounting bolts are slotted for the purpose of alignment.
I have a PM66 so I will look at it closer and chew on the problem. Let you know if I think of anything else.
Good Luck
TDF
Seems to be a few of these bad FII blades floating around. I just bought one and it is a dream but I'll be hessitant next time and likely switch to another brand.
Thanks for relaying the final root cause of your problem ?
Steve - in Northern California
If the doctor says you have Attention Deficit Disorder, do you pay attention to him?
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