Sorry in advance for the long post – but I think I need to preface a couple of points leading up to my problem and questions for all of you.
About two months ago I checked the alignment on my Delta Contractor’s TS (saw is about four years old when it was still Proudly Made in the USA). Needed some adjustment – mainly realigning the top/miter slots to the blade. When I was finished there was less than 0.001″ deviation – acceptable for me.
About a month ago I heard the link belt make some rather odd noises. Checked it out – didn’t find anything wrong – removed one link and replaced. Saw ran fine; almost no vibration.
Yesterday – wanted to rip some 4/4 Birch. Put in a home made zero clearance insert that I’ve used before with my Forrest WWII blade. Coincendentally, the blade has been in the saw for a few months now, but I’ve been using the insert that came with the saw, as I’ve been doing a lot of compound miter cuts.
Powered up the saw, raised the blade, everything started to shake – and shake bad. Cut power, removed the insert and went back to the insert provided by Delta. Saw was not making any unusual noises so I started ripping. About four feet into the first board, the blade stopped and the motor started shaking violently. I thought the motor tripped but that wasn’t the case, the blade was stuck. Managed to free everything and without the insert in I fired up the saw again to see what was happening. The shaking resumed so I powered down and checked the belt.
There were three or four belts that had melted slightly. Having extra links handy, I replaced those and reinstalled the belt. Turned on the saw – same result violent shaking.
Next checked the pulley alignment. The pulley on the motor was approximately 1/4 ” to the left of the arbor pulley when viewing the saw from the rear. Adjusted this so they were parallel. Reconnected the belt and fired it up. Violent shaking gone, vibration present.
I fiddled around with the alignment a little more and got it to where the vibration was barely noticeable, but then of course I did my usual move thinking I could get it better and actually made it worse. Damn. Okay so there is still some vibration but no violent shaking. Ripped the 4/4 Birch-everything came out okay. No burn marks on the wood.
Today – took out the blade to clean it; I hadn’t done this in about a month and during this time I’ve ran a ton of MDF, Poplar and last night’s Birch through it. Right away I noticed two blue burn marks in the blade. One is about a half dollar size but more elliptical in shape. The other is much smaller. Both are about an inch or so lower than the teeth.
I probably don’t have to ask since the comments should jump out – BUT WHAT HAPPENED? I had used the saw four or five weekends in a row doing baseboards, casing, etc without one problem. I have a DC system that gets most of the dust out of the saw but I had not cleaned out the residual since I had checked out all the alignment a couple of months back.
Questions:
1) What happened? Has this type of thing happened to anyone else? I searched the forum but could not find anything too similar.
2) Is my saw blade through or still useable? Is there a good chance that it is weakened to the point it will crack where it has become blue? I find it curious that the blade burned, turning blue, but the wood was fine – no burn marks.
3) How long do link belts last? Mine has been on the saw three years.
Couple of other things – saw is wired for 220V (neither the motor nor the circuit tripped yesterday). Just before this post – I ordered the Contractor Saw Upgrade that includes the machined pulleys and link belt and the PALS Alignment system.
Any comments/suggestions/help is greatly appreciated.
Thanks, Kosta
Replies
Kosta,
I can think of two issues you might be having:
1. After you "realigned" the blade did you drop the blade all the way below your zero clearance insert, turn on the saw, and raise it back through the insert? If not the blade could be rubbing on the sides of the insert.
2. Since your description of the blue marks on the blade indicates that they are not continuous bands around the blade but are isolated areas - could it be that the blade is not flat? A blade that wobbles (especially in conjunction with an insert that is rubbing) could cause these isolated hot spots.
You might also check the arbor bearings to see if all is well. I can guess at what is causing your melted belt links and violent shaking.
Good luck.
Dean
Thanks for suggestions Dean. I cannot remember if I did that with the zero clearance insert after the blade was realigned. Given that it made the first horrible sound when I used that insert and fired up the saw that very well could be what started the problem.How this led to the shaking has me baffled unless this caused something to come loose, which then led to the violent shaking and vibration.I e-mailed Forrest regarding the blue marks. I'm curious to hear what they'll say regarding further use.
This is a long shot, and for your sake I hope it's totally off base! There's a slim chance you might have tweaked the connector bars that run front to back. Hard to imagine that the force on the ZC insert would do that, but who knows. Assuming you've checked the blade and it is parallel to the miter slot still, tilt it to 45* and see if it's still parallel to the miter slot. If it isn't, one of the trunnions might have moved a bit. If the connector bars are out of whack, it'll really show up when you tilt the blade.
It really sounds like you ran into something -- those melted links might be the biggest tip.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
Thanks Forestgirl! I had used the 45* tilt a lot in the past two months. When I did the intial alignment it was only to the miter slots when the blade was at 90*. I'll check it versus 45* as well.I too had a feeling one of the trunnions may have moved slightly. When I made the adjustment I didn't touch the front two (closest the saw operator) as they were difficult to reach. I did loosen them and retighten them but who knows. I may not have tightened them well enough.I did order that PALS alignment system - I had seen it recommended on Knots before and I'm hoping its a whole lot easier than using a mallet and 2X4 to get the saw right. For only $20 it has way more potential than not.
On the contractor saw, if you raise the blade to it's maximum, the pulley can hit under the table. With a link belt, that clearance is reduced. Larger pulleys, the balanced type, can also add to the problem. Unplug the saw, raise the blade to where you had it and see if you can rotate the belt by hand. I suspect you have already checked for debris in the cabinet.
I have no guess on the blade. Rubbing of any type would put a circular mark around the blade.
Beat it to fit / Paint it to match
Hammer - I have a blade dampner/stiffner that I use which limits how high I can raise the blade. Since it lowered the maximum height, I never thought the pulley or belt could be hitting the table. I'll check into that as I sometimes go overboard with raising the blade; especially since Forrest recommends raising the blade higher than you normally would.Thanks, Kosta
Kosta,
I can tell you what happened to the blade, but I'm not sure why it happened.
The blade was overheated to the point that it buckled. Once this happened you observed the effects, severe vibration from the now out of flat blade and burn marks where the high spots on each blade face were rubbing inside the kerf and the insert. Once the blade cooled off it probably went back to being close to flat. It's hard to say for sure if the blade is ruined.
My guess is that the insert was rubbing on the side of the blade causing enough friction to lead to the overheating. The link belt was damaged when the blade jammed in the cut and the motor kept spinning, burning the links that were on the drive pulley.
John W.
Thanks John W. I want to understand what happened so I can eliminate or lessen the chance of this happening again. I put in an e-mail to Forrest explaining what happened and what they think of the blade. I'll post their response as soon as I hear back from them.
Before this incident the saw ran like a dream. I think in the end I was careless with the insert (others have also suggested this in their responses to my original post). Now I need to check the arbor, the pulleys, countless screws, etc to make sure everything is all right. Hopefully the only damage was to the link belt and the blade. I'm replacing the link belt and possibly the blade (depending on what Forrest says).
Kosta
John's opinion is probably correct. I can't think of another scenario that gives an adequate explantion.
The only times I have ever stalled a blade on a table saw were when the kerf closed and pinched the blade. Even with a splitter in place, it's possible for this to happen, and it's pretty common even if you don't use a splitter.
The other possibility I can think of is trying to tilt the blade while the saw is running, and having the blade bind in a slot that isn't relieved for an angle cut.
It's possible that Forest can re-tension the saw. One of the commercial sharpening services I used to use retensioned baldes as part of their normal service.
Michael R
Just saw JohnW's post. He's usually right-on with these tool problems!
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Another proud member of the "I Rocked With ToolDoc Club" .... :>)
Wanted to say thanks again to everyone that responded - a lot of good information runs through this forum. Also wanted to give everyone an update on my conversation with Forrest regarding the blue marks on the WWII.
Spoke with Forrest this morning. Very friendly individual named Dan spoke to me about the blue burn marks in the steel. Long story short - Forrest uses a mild steel (as opposed to hard steel) so the blue marks are no big deal. The blade has not been compromised and is not brittle. He went on to tell me some stories of blades sent in by cabinet shops using power feeders. He said those blades are practically blue from just below the teeth to the center; using power feeders on wood that sometimes has defects or is green is not forgiving on the blade - power feeder will just push it through regardless.
One other interesting note - we talked about how I did this and I shared some of the comments on this board about the zc insert and the alignment I had done previously and he too suggested getting the PALS alignment system.
Kosta
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