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Sparks on bandsaw

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Forum topic by richgreer posted 04-20-2011 12:48 AM 2303 views 0 times favorited 12 replies Add to Favorites Watch
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richgreer

4525 posts in 1827 days


04-20-2011 12:48 AM

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

3209 posts in 2576 days


#1 posted 04-20-2011 12:58 AM

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 1641 days


#2 posted 04-20-2011 01:12 AM

Might also be mineral deposits in the wood.

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

View TimKane2's profile

TimKane2

9 posts in 1426 days


#3 posted 04-20-2011 03:57 AM

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 1841 days


#4 posted 04-20-2011 04:05 AM

could be sand on the wood or embedded in it

-- wchips

View William's profile

William

9287 posts in 1595 days


#5 posted 04-20-2011 04:13 AM

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/

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richgreer

4525 posts in 1827 days


#6 posted 04-20-2011 04:16 AM

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 1420 days


#7 posted 04-20-2011 04:17 AM

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

11549 posts in 1443 days


#8 posted 04-20-2011 04:43 AM

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

329 posts in 1734 days


#9 posted 04-20-2011 04:51 AM

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

11688 posts in 2441 days


#10 posted 04-21-2011 01:03 AM

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 2330 days


#11 posted 04-21-2011 02:17 AM

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

870 posts in 2047 days


#12 posted 04-21-2011 04:05 AM

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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