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Can't cut straight on bandsaw

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Forum topic by Derakon posted 599 days ago 1307 views 1 time favorited 23 replies Add to Favorites Watch
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Derakon

83 posts in 762 days


599 days ago

Topic tags/keywords: bandsaw

I have a Grizzly 14” bandsaw that I’ve used happily in the past for a number of projects. Now Christmas is rolling around and I’d like to make some building blocks for my niece and nephew. I want these to be as square as possible, since unsteady building blocks are just no fun at all! So imagine my dismay when I find that I can’t seem to cut straight! I went through the full calibration of the machine, checked that everything was square; it all looks good as best I can tell (it’s really hard to check squareness on some of the bearings), but I keep getting cuts like this one:

That piece of wood is lined up like I’d send it through the saw (as if the ruler was the saw’s fence). The cut consistently slants to the left at the start of the cut, and then straightens out. It’s a pretty subtle effect but it’s definitely noticeable and the cut’s simply not straight!

I’m using a 3/8” Wood Slicer blade; I wouldn’t think I’ve pushed it past its limits. Any ideas what’s going on here?


23 replies so far

View cstrang's profile

cstrang

1769 posts in 1763 days


#1 posted 599 days ago

I had that problem with my Delta band saw a few years ago, all the bearings and blocks were adjusted nicely on the bandsaw but it would taper just like the pic, a new blade solved my issue. Quick and easy fix… hopefully it is that simple for you, good luck!

-- A hammer dangling from a wall will bang and sound like work when the wind blows the right way.

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patron

12952 posts in 1936 days


#2 posted 599 days ago

i’m with cstrang

sounds like one side of the teeth are dull

-- david - only thru kindness can this world be whole . If we don't succeed we run the risk of failure. Dan Quayle

View JAAune's profile

JAAune

750 posts in 912 days


#3 posted 599 days ago

If it’s a new blade there may be burrs on one side that cause it to favor the cut in one direction. If that is the case then the cut will probably improve with use as the burrs fall off. If the blade is old then it’s probably just dulled in an uneven manner. There’s also the possibility of one or more teeth having the improper amount of set.

If the blade is just slightly dull it still shouldn’t pull itself noticeably to one side like that unless you’re feeding too fast. The upper blade guides should prevent that from happening. They might be set too far from the blade.

If you are getting a new blade I recommend a 1/2” 3tpi skip tooth blade for the replacement.

Also, make sure the blade is tracking on the center of the upper wheel.

-- See my work at http://remmertstudios.com and http://altaredesign.com

View Derakon's profile

Derakon

83 posts in 762 days


#4 posted 599 days ago

Hm, I wouldn’t have thought that the blade would be worn, but I grant I don’t really have a feel for how quickly blades go bad. I’ve owned the saw for almost a year now, but I’ve not been doing all that much carpentry for most of it.

I’ll take a look for burrs, but in the meantime I’ve gone ahead and ordered a couple more woodslicer blades. I also have a cheapo 1/4” blade lying around that’s never been taken out of the packaging; I suppose now’s as good a time as any to see if it’s any good!

Tracking is definitely not a problem; I checked that as part of the overall calibration.

Thanks for the advice, all. I just hope the new blades arrive quickly. And once I have those and the holidays are over, I guess I can start looking into how hard it is to resharpen the old blade—seems little sense in just throwing it out!

View David Craig's profile

David Craig

2130 posts in 1704 days


#5 posted 599 days ago

Just for clarification, are you using the saw fence when doing a crosscut? I only ask because you stated “That piece of wood is lined up like I’d send it through the saw (as if the ruler was the saw’s fence).” This could potentially be your problem as the fence might be catching your piece when you first start out, slanting it to the left, and then straightening as you push forward. Crosscuts should not be done with the fence in place. You may not be doing this, but your comment led me to question.

David

-- There is little that is simple when it comes to making a simple box.

View Straightbowed's profile

Straightbowed

717 posts in 893 days


#6 posted 599 days ago

yes are you using the miter I have a little sled I use on my bandsaw its on one side kinda like a miter gauge its really handy

-- Stevo, work in tha city woodshop in the country

View pintodeluxe's profile

pintodeluxe

3256 posts in 1408 days


#7 posted 599 days ago

replace the blade with a 3tpi hook blade

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View Derakon's profile

Derakon

83 posts in 762 days


#8 posted 599 days ago

I’m using the miter guide, not the fence. I should have been more clear; I was just trying to describe how the wood is oriented with respect to the blade.

View David Craig's profile

David Craig

2130 posts in 1704 days


#9 posted 599 days ago

One other question Derakon. When you state that the board straightens after it veers, are you basing this on observation during the cut? or on the combo square? What is the tightness of the blade? If it is happening only at the start, there is an event that is occurring right when the blade makes contact. Maybe the blade has flex and the forward pressure causes the flex to dissipate after it starts cutting. It is not uncommon for a bandsaw to have some blade drift. This is usually rectified by marking lines along the wood, free hand cutting the line, and noting the angle you are holding the board after a few inches in the cut. You can then adjust the miter to be even with that angle and you should get a straight board. Even if the blade is unbalanced, that cutting angle shouldn’t waver. But if you are getting flex at the start, this would explain the behavior of that strange starting cut.

-- There is little that is simple when it comes to making a simple box.

View Rick  Dennington's profile

Rick Dennington

3272 posts in 1789 days


#10 posted 599 days ago

You’re getting what’s called “bandsaw drift”.....

-- " I started with nothing, and I've still got most of it left".......

View tomd's profile

tomd

1724 posts in 2365 days


#11 posted 599 days ago

Maybe check the clearance between the back of the blade and you rear guide, the guide may not be close enough. If there is too much clearance the blade will flex untill it is pushed back enough to hit the guide then will straighten up.

-- Tom D

View Surfside's profile

Surfside

3030 posts in 769 days


#12 posted 599 days ago

That must be a blade issue.

-- "someone has to be wounded for others to be saved, someone has to sacrifice for others to feel happiness, someone has to die so others could live"

View Derakon's profile

Derakon

83 posts in 762 days


#13 posted 599 days ago

David: I’m basing my statements on the combo square, not any observations during the cut. I haven’t tried making any longer cuts since I noticed the issue, so it may well be this is only happening at the start of the cut.

The manual calls for a .016” (approx. 1/64”) clearance between the back of the blade and the rear guide, so I basically set it up so that there’s the tiniest of visible gaps between them.

I’ve checked the blade tension as well; it’s accurate.

View hairy's profile

hairy

1988 posts in 2127 days


#14 posted 599 days ago

Maybe slow down the rate of feed? I second using using a miter gauge or sled.

-- what a long, strange trip it's been...

View Mark Smith's profile

Mark Smith

491 posts in 635 days


#15 posted 599 days ago

Isn’t this cut sort of normal for a bandsaw? I’ve never tried to use my bandsaw for an exact square cut because I just didn’t think it could be done. I use mine mostly for resawing, and I fully expect that I’m going to have to send the two halves through the planer or drum sander after the cut.

-- Mark Smith, Tracy, CA., http://www.markscustomwoodcrafts.com

showing 1 through 15 of 23 replies

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