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Sparks on bandsaw

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Forum topic by richgreer posted 1226 days ago 2060 views 0 times favorited 12 replies Add to Favorites Watch
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richgreer

4522 posts in 1706 days


1226 days ago

I’m using a 1/4” blade on my bandsaw and trying to cut a curve with a radius of 3.75”. I’m cutting through 6” of white oak. I’m getting some sparks from the blade. I’ve never seen this before.

Is this normal? If not, what could be the cause?

In advance of your responses let me say that I believe I have the right tension on the blade (20,000 lbs./square inch) based on my tension gauge (not the indicator on the side of my bandsaw).

All advice is appreciated.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.


12 replies so far

View blackcherry's profile

blackcherry

3156 posts in 2455 days


#1 posted 1226 days ago

The blade teeth were hitting the guide bearing, to tight a turn in such a thick piece. You may need to set the guide bearing back a bit more…BC

View BigTiny's profile

BigTiny

1664 posts in 1520 days


#2 posted 1226 days ago

Might also be mineral deposits in the wood.

-- The nicer the nice, the higher the price!

View TimKane2's profile

TimKane2

9 posts in 1305 days


#3 posted 1225 days ago

Having no experience, and essentially no knowledge of band saws except they cut stuff, 20,000lb/square inch sounds like an insane amount of force. That is a normal tension?

View wchips's profile

wchips

314 posts in 1720 days


#4 posted 1225 days ago

could be sand on the wood or embedded in it

-- wchips

View William's profile

William

8976 posts in 1474 days


#5 posted 1225 days ago

My old Craftsman 12” has guide blocks on each side of the blade. If I cut too tight a radius in wood, according to the thickness, the blade teeth sometimes will contact the guide blocks in a way to throw sparks.

-- http://wddsrfinewoodworks.blogspot.com/

View richgreer's profile

richgreer

4522 posts in 1706 days


#6 posted 1225 days ago

In response to TimKane2 – - I’ve read from several sources that 20,000 per square inch is right. You need to realize that a 1/4” blade has a cross section that is a very small percentage of a square inch. My calculations say that it is about .55% of a square inch. That implies a total pull on the blade of 110 lbs. That sounds reasonable to me.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View bubinga's profile

bubinga

861 posts in 1299 days


#7 posted 1225 days ago

Where exactly are the sparks originating from?

I saw sparks one time, when the blade broke and flew off, not fun
Actually had that happen with mineral deposits.

-- E J ------- Always Keep a Firm Grip on Your Tool

View gfadvm's profile

gfadvm

10736 posts in 1322 days


#8 posted 1225 days ago

I had sparks when my lower thrust bearing siezed.They obviously were below the table but the upper thrust bearing siezing would generate sparks above the table.I studied all the blade tensioning advice and use the 1/4” deflection and or the flutter technique.These have both been effective and simple to perform.You should be able to cut a much tighter radius with a 1/4” blade so I dont think that is the problem.I routinely cut 1” diameter circles with my 1/4” blade.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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Popsnsons

327 posts in 1613 days


#9 posted 1225 days ago

Rich,

I had sparks come from the guide blocks. But when I run a Carter Stabilizer with my 1/4” blade the standard guides and bearings, both top and botttom, are not used and the operation is much smoother.

-- Pops ~ In So Cal...

View Dusty56's profile

Dusty56

11644 posts in 2320 days


#10 posted 1225 days ago

Hi Rich ,My first thoughts were mineral content or foreign objects , but you don’t mention if the sparks are before entering or when exiting the wood , but I’ll assume they’re up top because it would be impossible to see below the table while slicing. That would leave blade contact with the guides or bearings and not much else that I can think of.
Sorry.

-- I'm absolutely positive that I couldn't be more uncertain!

View Maddhatter's profile

Maddhatter

126 posts in 2209 days


#11 posted 1225 days ago

Rich, have to agree with Dusty 56, with out knowing where the sparks came from it is hard to provide a recommendaton. most likely I would check the lower guide blocks as they can come out of adjustment and because they are below the table, you may not have noticed.

Hope all goes well. good luck and safe sawdust.

-- Norm (AKA - The Maddhatter), Middletown DE

View SteveMI's profile

SteveMI

849 posts in 1926 days


#12 posted 1224 days ago

My band saw started making sparks at times and I found that one of the bearings had siezed. When cutting straight it was fine, but when trying to cut any kind of curve the blade contacted the bearing and caused the sparks. I changed the bearing and sparks went away.

Steve.

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