Hi all running into a problem where I am milling up some lumber from logs"  12" high max.

When cutting the logs the bandsaw deflects toward the inside.  As I travel down the log it appears to get worse.

What causes such an issue.  Across the face I am probably out of flat by 3/4" in the middle.

The tension on the saw is at or above the 3/4" mark which is what the blade is.

Why is it doing this?

Hi Mike!

For resawing the blade should be wide. Depending on you saw use the widest possible. Also very low tpi 2-3 is good. The tension gauge on my saw isn’t very accurate. 
Are you using a fence or a single point contact post?  
Have you watched the Alex Snodgrass setup videos? 

 

I am using a sled with are hardwood slip fit in the mitre gage of the saw table.

I like his set up tips and will follow his example and get back to you.

However this wood is not dry it is has more moisture in the middle of the log than the outside.

 

Moisture content is not the problem, it is your setup. Probably blade tension so try the Snodgrass method and see what you get. Also let the saw do the work , you are probably feeding too fast also.

My guess is blade tension as well, and that problem is fairly common. Those blade tension scales on most band saws just aren't that good an indicator of how tight the blade should be.

And, each bandsaw is different, not all bandsaws are nor can be perfectly aligned. Sounds like your blade is drifting, so you'll need to calibrate your fence for the drift, if that is the case, does this Snodgrass video talk about adjusting drift out of the machine?

One of the biggest troubles is a dulled blade.  If one side of the blade hits something the teeth dull and then the sharp teeth on the other side of the blade cut well and draw the blade to that side.  I am talking about the alternating teeth of course.

1 hour ago, John Morris said:

And, each bandsaw is different, not all bandsaws are nor can be perfectly aligned. Sounds like your blade is drifting, so you'll need to calibrate your fence for the drift, if that is the case, does this Snodgrass video talk about adjusting drift out of the machine?

Yes he covers drift, but with sharp blade and proper adjustment there should be no drift. Drift will not cause this bow effect.

Edited July 21, 20241 yr by Gerald

1 hour ago, Gerald said:

Drift will not cause this bow effect.

I didn't see where that was his problem. So he's getting a curve, or a bow affect in his cut?

Band saw tension is an issue for many woodworkers, me included.  That is why I purchased the EZTension bandsaw tension gauge.  It help me eliminate one variable.   Danl

https://www.eztension.com/buy-one-now/eztension-bandsaw-tension-gauge

 

1 hour ago, Danl said:

Band saw tension is an issue for many woodworkers, me included.  That is why I purchased the EZTension bandsaw tension gauge.  It help me eliminate one variable.   Danl

https://www.eztension.com/buy-one-now/eztension-bandsaw-tension-gauge

 

Thanks, @Danl!

That’s a cool devise . I don’t wootoo much about the curve dinfee we most of my BS work is for turning blanks do curve not really a problem.

5 hours ago, Gerald said:

I don’t wootoo much about the curve dinfee we

40 minutes ago, HARO50 said:

I wasn't going to go there, I was just going to let Gerald have his moment, but I'm glad someone did!

2 hours ago, John Morris said:

I wasn't going to go there, I was just going to let Gerald have his moment, but I'm glad someone did!

Someone has to be the poop disturber!

Hey I was getting ready for procedure. But OK now, I Think? Someone please define OK.

 

I don't do much work on BS that needs straight line . Most of my cutting is for turning blanks.

15 minutes ago, Gerald said:

Someone please define OK.

It's you Gerald, you are A O K! Glad you made it through and you are feeling lucid again

I am now working with a 1/2" x 2 AS series from timberwolf.  They say in there videos to remove all tension set up the blade by hand and then tension up to 1/2" but slowly remove tension until I see wobble then turn it back 1/2 to 3/4" turn.  That said my blade is set for a 1/4" blade and then you follow the video to set up the fence.

It seems that has resolved this issue but i have one more log to process.  Some time the blade does drift but as this is a rough cut of 12" T Pin oak.  The AS series has really helped AS for alternate set where each tooth is canted in opposite direction.  It cuts a curf of about 1/8" which is fine before all my blades were PC series.  That series has no set and the blade would get too hot and aneal the blade.  Then the curve starts.  Setting up this blade is tricky because of the very deep gullets.  But I have it working and will report back first log processed just fine.  Second log will tell me if this one works  the PC series would go thru one long then fail.

Timber wolf warns of 3/4 or 1" wide blades because that extra metal is extra friction. The wides blade in AS is 1/2"

Edited July 28, 20241 yr by Michael Thuman
Updating content.

Sounds like classic blade deflection. A few things to check: Blade tension—even if it’s set right, try increasing it slightly. Blade sharpness—a dull blade or too few TPI can cause wandering. Feed rate—pushing too fast makes the blade flex. Guide setup—make sure the blade is well-supported. Also, log stability—if it shifts, the blade will too. Try these adjustments and see if it improves! 

What size blade are you using btw?