band saw booboo. What happened?

[James Baker SD]

I know the answer is on this forum with all the knowledge on band saws I see. Well, I was cutting some useless scraps of wood down to fireplace size using a 1", 1.3 tpi old rusty blade on an LT-18. Stupid me, I forgot to tension it, so the scale read around 5mm (scale is in mm of blade width). Cutting small pieces went so well that I didn't even notice the problem. But when I tried to cut off a glued on 3/4 ply from 8/4 maple (a table sled I had given up on) the problem announced itself. About 2/3 of the way on the piece (12" into the cut), the blade started to spark like I had hit a screw buried in the wood. From there on the blade fluttered horribly and made the worse cut I have ever seen. When that piece was done, I checked the guides and noticed that the blade wasn't tensioned. I checked the blade and saw 2 teeth were missing, but I didn't think it would make a big deal on the cut and I was wearing my bullet proof full face PAPR helmet. So I tensioned the blade and tried to cut the other side of the sled maple/plywood to salvage the maple. Almost the same thing; less flutter, but absolutely terrible quality of cut, lots of sparks. I carefully examined the cut wood and I did not cut any metal buried in the wood.

So the questions. What happened? What broke off the two teeth? What created the sparks? Why does two missing teeth result in a terrible cut? What else probably happened that I am not thinking of?

James

[Jamie Buxton]

So you're still seeing sparks? Where are they coming from? The upper guides, presumably. The rear edge of the blade against the thrust bearing? The front edge of the blade against the side guides?

[James Baker SD]

So you're still seeing sparks? Where are they coming from? The upper guides, presumably. The rear edge of the blade against the thrust bearing? The front edge of the blade against the side guides?

Not seeing any more sparks because the blade is in the trash now. Figured I had ruined it. When I finally got around to tensioning the blade, I checked the guides (Laguna ceramics) and they seemed fine. The sparks, if I remember, were coming from near the cut, what made me think I had hit a buried screw. The kerf of the cut, after things went bad, was 3 or 4 times the thickness of the blade. I attributed that to the lack of tension, but even after tensioning, the cut was still much wider than the blade and the wood surface was almost fuzzy like a course wool sweater.

Now of course I am beginning to worry I may have damaged the saw as well as the blade? Any thoughts on that? Thanks.

[Damon Stathatos]

I start getting sparks from within the cut when my blade is getting real dull. It is usually accompanied with a banana or barreling cut. Also a burning smell and burnished wood through the cut.

[John Coloccia]

I might suggest you empty your dust collector to remove the danger of a smoldering fire.

[Brian Weick]

I know you said there was no metal embedded in the wood but it sure does sound like your teeth hit something, and it wasn't wood....did you check it with a metal detector before you ran the board through? Teeth just don't fall off, sounds like they were ripped off.....


Just a thought,


B,

[Gary Max]

Sounds like you chewed up the ceramic guides------DAMHIKT----- if so, get a major CC ready----they are proud ot them.

[Myk Rian]

Make some guides out of hard wood for free. Soak them in mineral oil.

[James Baker SD]

Sounds like you chewed up the ceramic guides------DAMHIKT----- if so, get a major CC ready----they are proud ot them.

ouch, you're right. The top top left ceramic is cracked in two, front half ready to fall out.

[James Baker SD]

Make some guides out of hard wood for free. Soak them in mineral oil.

any particular hardwood to recommend?

[Gary Max]

I have been saving up for a set of Carter replacments------- they don't give them away either------Ouch

[James Baker SD]

I've rechecked the wood and there is no metal in it, so I am still curious what broke the teeth, and why 2 broken teeth made such a difference in the quality of the cut.

James

[Stephen Cherry]

Since I got my shapers, I've started to do a "walkaround check" before I run them. Just looking at, wiggling and checking everything. Maybe this would be a good idea a bandsaw also.

[Gary Max]

Don't throw anything at me but------- the teeth on the blade ate the ceramic------ being out of adjustment let it drift. Kills the band and guides at the same time.

[Jamie Buxton]

I've rechecked the wood and there is no metal in it, so I am still curious what broke the teeth, and why 2 broken teeth made such a difference in the quality of the cut.

James

The blade is moving quite quickly. It is unlikely that something can get to just two teeth, and leave all the others untouched. More likely it is that something hit and damaged lots of teeth, and two of the most-extremely damaged came off. Lots of damaged teeth make the bad cut, not the two missing ones.

[Mike Wilkins]

From what you describe, your lack of tension may have let the teeth of the blade come in contact with the ceramic guides. The hardness of the guide material distorted/broke the teeth, which in turm caused the sparks and extra-rough cut. In addition to junking the blade, you may have to replace some pieces of ceramic. Sorry about the harsh lesson.