Operator error. How do I fix it?

[brizylad]

G’day All,

Like a lot of people, I have purchased the Laguna 14SUV.

Today, I was trying to cut a 300 long piece of 35 x 88 kwila into 2 x 44mm lengths, but when I made the cut, there was a significant bow in the length.

I realised that the top guide was too high (about 75mm above the piece), so I dropped it down and tried to shave the piece down.

That took out most, but not all of the bow.

Do I need to increase the blade tension?

Any other suggestions?

Almost forgot to mention that I have a Resaw King blade fitted.
Stuart

[Treecycle]

Is the bow top to bottom or along the length?

[brizylad]

It is along the length. When I turned them over on the table, with cut side up, one length was concave, the other convex.

[joez]

Have you adjusted the fence to account for the blades drift?

I am not familiar with your particular model bandsaw but the attached youtube clip gives you a basic understanding of whats involved, I would start with that.


http://www.youtube.com/watch?v=IZThUPOr_Ug

[brizylad]

I have (to the best of my ability) adjusted for drift.

If it were not a "curve", I might has expected drift....could be wrong.

Here are two pics of the concave piece. It was the piece on the outside of the blade.

When I lie the piece flat, I can slide the steel rule under without a problem.

[joez]

It could be internal stresses in the timber that have been released during the ripping process, try another cut on some scrap and see how it looks.

Personally I only use my bandsaw for rough cutting, I never go from the bandsaw to the project I am working on. If it were me I would sticker it and leave it for as long as possible before flattening it with handplane/jointer and putting the piece to use.


I was resawing some pine on the weekend, one of my boards ended up looking like a bannana after the cut, would say it was bowed by about 15mm on a 1m board.

[pjt]

I have (to the best of my ability) adjusted for drift.

If it were not a "curve", I might has expected drift....could be wrong.

Here are two pics of the concave piece. It was the piece on the outside of the blade.

When I lie the piece flat, I can slide the steel rule under without a problem.

Doesn't look like a drift problem, and the pieces you have there don't look that bad, but it is a curve and has me thinking one side of the blade is just a bit more blunt than the other or a set issue, if you were to cut a longer piece and the curve went from concave to convex (wobble) I say that is more a low blade tension issue, Is the blade sharp?



Pete

[brizylad]

The blade has only been used to cut about 10m of Qld maple and some other sundry stuff, so I would hope it would still be sharp.

I have some more of the kwila, so I might see if I can duplicate the problem. Bit busy at the moment though.


Stuart

[Master Splinter]

Make sure your fence is square and do not adjust it for drift.

Band Saw Clinic with Alex Snodgrass - YouTube (http://www.youtube.com/watch?v=wGbZqWac0jU)

[Dengue]

What size blade and number of teeth per inch are you using?

is this one of the blades with carbide teeth that are supposed to be the bees knees for resawing?

[Chris Parks]

Ignore the first video and look at the second one. BS's do not have a drift angle if set up correctly.

[Dengue]

:iagree:

[Dengue]

One of the reasons for curvature out of the vertical plane is that you are pushing the timber too hard for the optimal blade cutting rate, the blade is pushed back against the thrust bearing, it is fixed in position by the upper and lower guides, and the only thing left for the blade to do is to bow out to relieve the excess pressures it is experiencing. There needs to be a reasonable number of teeth in contact with the timber, and there needs to be a decent gap between the teeth to allow the sawdust to clear, hence the question about the blade teeth above

[Chris Parks]

Mods, is it possible for the link to the Snodgrass video to be made a sticky, it is the single most important tutorial on the net especially when it comes to fixing drift problems.

[brizylad]

I agree about the second video. Very informative.

The Resaw King blade is the 1 inch version, and I'm pretty sure it has carbide tips.

As I put in the title, I believe this is operator error/setup problem. I am not blaming the saw/blade just yet.

Stuart

[Canoath]

Disclaimer first, I've spent more time reading tips and watching videos than time spent on my bandsaw which I've used over the past week or so.:rolleyes: However, I can't help but think you're blade might need sharpening despite being new.

I say this due to my recent experience with ripping an old ironbark railway sleeper and 1metre long 20cm diam green eucalyptus log with a new 16mm 3tpi carbon blade. For both, the new blade wandered and seemed to follow the grain. I dispensed with the fence and tried freehand and couldn't adjust the angle enough to make straight cuts. I was so annoyed, thinking I was wasting my time and the idea I could rip my own wood and veneer was beyond me. I revisited a video I saw a while back and that's been posted before about sharpening new blades which I'll post below. I touched up the top of each tooth and to my surprise the blade didn't wander anymore. I could freehand cut the rest of the log and sleeper following a straight line drawn on their surface and tried some approx 3mm veneers on scraps. Three cuts were done prior to sharpening, yet much more was done after sharpening and the blade does not seem to have dulled.

I set my bs up as per the Snodgrass video and I was convinced about his thoughts on drift. My blade wandered and sharpening set it straight. It's worth a thought if your issues continue.

http://youtu.be/UygEQ-079Ws

[Hermit]

Mods, is it possible for the link to the Snodgrass video to be made a sticky, it is the single most important tutorial on the net especially when it comes to fixing drift problems.

That video is in the forums' 'Videos' section, under 'Instructional / Demonstrations'.

And I agree, I set my bandsaw up this way over a year ago and haven't had a single problem since.

[Chris Parks]

That video is in the forums' 'Videos' section, under 'Instructional / Demonstrations'.

And I agree, I set my bandsaw up this way over a year ago and haven't had a single problem since.

Yes, I know that but I think it is such a useful tutorial a link should be stickied to this forum. The new BS users will not know to go the video section unless the link is there. I am continually surprised that those who have issues with WW problems don't use YouTube videos more as it is a great resource for information.

[Hermit]

Yes, I know that but I think it is such a useful tutorial a link should be stickied to this forum. The new BS users will not know to go the video section unless the link is there. I am continually surprised that those who have issues with WW problems don't use YouTube videos more as it is a great resource for information.

I agree Chris. A sticky thread titled 'Bandsaw Clinic video', 'Cure all of your Bandsaw Drift Problems' or similar, with a link to the vid, would be much easier to find.

[brizylad]

Thanks to all that are contributing to this thread.

This is my first purchase of a bandsaw, and it is a steep learning curve.

From the Snodgrass video, I have gleaned a lot. Not real keen on throwing the table around like does, because mine weighs a lot more. But I will probably get some help for that.

I have a question though about the gullet placement at the "crown".

The problem blade at the moment is 1", does it matter that the back of the blade may be unsupported by the wheel, or is the gullet placement more critical?

Stuart

[Hermit]

The problem blade at the moment is 1", does it matter that the back of the blade may be unsupported by the wheel, or is the gullet placement more critical?
Stuart

That's a good question, Stuart. My blade is narrow, so the back doesn't overhang the wheel edge even when the bottom of the gullets are centred.

Thinking about it, though, with a 'crowned' wheel even when the blade is centred over the wheel, only the centre would be fully supported, so if it were me I'd (probably) try it and see, as long as it wasn't going to rub on anything. I'd give it a good few spins by hand before powering up, just to make sure.

* This may not be good advice, it's just what I'd possibly do. Others might know better.

Otherwise, all you can really do is to rotate the table to align the mitre slot with the cut direction.
If you rule a line up the centre of a short scrap with parallel sides, then freehand cut halfway along that line and, without moving the timber, turn off the saw, the angle that the scrap is on will indicate the error. (Hope that makes sense. It does to me. :D )