Getting sparks under bandsaw table off blade/thrust bearing!

[Randall J Cox]

I was trimming the corners off some turning squares today on the bandsaw and noticed little sparks down below the table. I immediately turned off the bandsaw (MiniMax 18") as I had my dust collection system running pulling sawdust out - sparks and sawdust together are not good as we all know!! With the DC off, I turned bandsaw back on and tried it again this time looking very closely to see what was going on. It was sparking where the back of the blade (fairly new Lenox Diemaster Two 1/2") was rubbing against the thrust bearing when I was cutting. If not cutting, it was not contacting the thrust bearing (and not sparking) and they were a hair apart as they should be. The side blocks (ceramic) were set like they should be with the blade tensioned (flutter test). Why would I be getting sparks?? Most blades rub against a steel bearing when cutting. Mine was also turning as it should - bearing turns easily by hand. The back of the blade is nice and smooth as you would expect it to be. The Lenox Diemaster2 blades are primarily metal cutting blades and are bimetal but, very popular with the woodworking crowd. Anybody heard of this and/or have any ideas whats going on? Randy

[Sam Blasco]

Ceramics can cause sparks. Or, if your thrust bearing is too far past the blade, more toward the center of the bearing than the edge, then it won't turn and you'll get sparks too, and possibly wear a groove in the bearing. You want the blade right at the edge of the thrust bearing's edge, enough so that it contacts the bearing in such a way that it's downward movement will start the bearing turning as it is touched by the back of the blade, but not enough so that the back of the blade wants to slip off and past the edge of the bearing - the Goldilock's zone.

[John K Jordan]

Did you "stone" the back of the blade to knock off the sharp corners and round them a bit? I'm wondering if the thin sliver of metal on the corners would otherwise be heated quicker and make sparks. One of my bandsaw books recommends putting a nice radius on the back of each new blade. Helps with cutting a tighter radius too.

JKJ

[Van Huskey]

Are you positive the sparks aren't coming from the ceramic block/blade interaction? They are well known to spark.

[Randall J Cox]

Ok, thrust bearing is not adjustable other than in and out (how close to the blade it sits). Ceramic is known to spark??? So how can they be used with dust collection without starting a fire? Also, after I took everything apart to double check all settings I now remember / seeing that I added two very small tin strips in with the ceramic guides (little square ones, not round euro ones) to take up some space as one of the ceramic guides was a little loose in its holder. I will back those off away from the blade or change them out to something non sparking. And no I did not stone the back of the blade but, I will do that tomorrow. I got so spooked with the sparks I just emptied my sawdust barrel just in case something started to smoulder during the night. (My son is a fireman.) Back to the drawing board tomorrow to start fixing, hopefully. Thanks for ideas. So I just bought $48 worth of ceramic guides that create sparks - great! Randy

[Patrick Walsh]

My ceramic guides throw sparks also from time to time.

Drives me nuts. I cant wait to upgrade to a saw with just bearings...

[Tom Ewell]

Can check out Carter for upgrade bearing guides unless a new saw is the real motivation

[John K Jordan]

Ok, thrust bearing is not adjustable other than in and out (how close to the blade it sits). Ceramic is known to spark??? So how can they be used with dust collection without starting a fire? Also, after I took everything apart to double check all settings I now remember / seeing that I added two very small tin strips in with the ceramic guides (little square ones, not round euro ones) to take up some space as one of the ceramic guides was a little loose in its holder. I will back those off away from the blade or change them out to something non sparking. And no I did not stone the back of the blade but, I will do that tomorrow. I got so spooked with the sparks I just emptied my sawdust barrel just in case something started to smoulder during the night. (My son is a fireman.) Back to the drawing board tomorrow to start fixing, hopefully. Thanks for ideas. So I just bought $48 worth of ceramic guides that create sparks - great! Randy

Wait, earlier you said you saw the sparks coming from where the back of the blade was rubbing on the thrust bearing. I don't understand - is the thrust bearing also made of ceramic? Or do you now see sparks from the ceramic side guides?

Are they persistent hot, bright sparks or tiny short-lived sparks?

I had ceramic guides on one of my bandsaws and never saw a spark or heard of sparks from ceramic guides. I did replace them later with some I made from lignum vitae which I can recommend.

Here is a thread about Laguna ceramic guides and sparks and whether to worry about them: http://www.sawmillcreek.org/showthre...-making-sparks

JKJ

[Jeff Duncan]

I get sparks off my lower thrust bearing frequently too, figure it's probably due for replacement but just haven't gotten around to it yet. So I'd say don't worry about the ceramic guides just yet and focus on where the sparks are coming from. If they're coming from the thrust bearing as you say, then inspect the thrust bearing, it's probably time for a replacement

good luck,
JeffD

[Van Huskey]

Ok, thrust bearing is not adjustable other than in and out (how close to the blade it sits). Ceramic is known to spark??? So how can they be used with dust collection without starting a fire? Also, after I took everything apart to double check all settings I now remember / seeing that I added two very small tin strips in with the ceramic guides (little square ones, not round euro ones) to take up some space as one of the ceramic guides was a little loose in its holder. I will back those off away from the blade or change them out to something non sparking. And no I did not stone the back of the blade but, I will do that tomorrow. I got so spooked with the sparks I just emptied my sawdust barrel just in case something started to smoulder during the night. (My son is a fireman.) Back to the drawing board tomorrow to start fixing, hopefully. Thanks for ideas. So I just bought $48 worth of ceramic guides that create sparks - great! Randy

Fast moving steel on ceramic will indeed cause occasional sparks, so will steel on steel but it is more rare. Kepp in mind all sparks are not created equal and these don;t cause an issue. Laguna have been using ceramic guides for years, Felder has for a couple of years (and EU company, let that sink in for a second) and Space Age Ceramics have been selling them for years, no issues ever reported.

You certainly can replace the guides if you like but solid block guides are better than moving guides (IMO) and ceramic is by far the best suited material used for anything except narrow blades where phenolic or wood guides are a better choice. I use Space Age guides (Euro style) on my MM20 and love them, but honestly it is dedicated to resawing so with the blade and tension on it the guides don't come into play often.

[Van Huskey]

Can check out Carter for upgrade bearing guides unless a new saw is the real motivation

Not sure what if any guides Carter makes for the S45 but if they only make their 2000 series "skateboard" bearing guides for it then it would be a downgrade now if they make Guidall or Micro-Precision guides for it then it would be at least a lateral move on the side guides but an upgrade on the thrust bearing. I am guessing he has an older S45 since he appears to have had solid side guides and the current S45N has bearing side guides.

[Randall J Cox]

Ok, to clarify, only the side square guides under the table are ceramic. The thrust bearing is metal and turns freely. I have adjusted the thrust bearing as far as it will go so the blade back rides close to the edge of the bearing, probably only moved it 1/16", not very adjustable. Blade looks like it is riding on thrust bearing where it should, right close to the outer edge. Sparks are very tiny and short lived. Back of blade is nice and smooth and if I remember right, someone in authority on one of these woodworking sites said that bandsaw blades no longer need stoning, that they are good from factory. Mine is Lenox and sure feels smooth on back edges. I just bought this saw (used, built in 1995) and have no desire to buy another new one. Nor do I want to spend more hundreds of $ to move to carter guides under the table (I have euro guides above the table). I took table off to fine tune lower guides with blade tensioned, will put all back together tomorrow and try it again. Guess seeing sparks just totally spooked me thinking something was wrong. Maybe not........... Randy

[lee cox]

Did you buy your ceramic guides from Minimax? I think I have the same S45 bandsaw. My guides are more like a hard graphite than ceramic. But I bought my S45 bandsaw used so I don't know what the originals look like. I don't see any sparks with my S45. I am also only using original Lenox bandsaw blades.

[Van Huskey]

Did you buy your ceramic guides from Minimax?

My bet is they came from Space Age Ceramics.

As for stoning a Lenox tech told me there is no need for this to prevent fatigue cracks with today's BS blades. It still can be useful to clean up the weld if it was poorly deslagged but still straight or when the back of the blade gets nicked etc. That said there is still a magnet back stone stuck on one of my bandsaws at any given time. I often stone a new just because it is my process and I have been doing it my whole woodworking life. Be aware it produces lots of sparks and they "appear" hotter than the ceramic/blade sparks so it might be a good idea to clean out the saw first...

[Randall J Cox]

Did you buy your ceramic guides from Minimax? I think I have the same S45 bandsaw. My guides are more like a hard graphite than ceramic. But I bought my S45 bandsaw used so I don't know what the originals look like. I don't see any sparks with my S45. I am also only using original Lenox bandsaw blades.

Lee - One of the existing guides, not ceramic, was broken when I bought the saw, hence the new ceramic guides. Bought
the ceramic guides from Space Age Ceramics recently.