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I was trying to resaw some blood wood today and experienced weird scary sounds. Could feel it too. Looks like what happens about one minute into this video. Pine did not cause it. Anybody know?

[youtube]YqkpxKWKkME[/youtube]


http://youtu.be/YqkpxKWKkME

Mike

In the vid he locked up the saw on the cocobolo. If you have a decent saw, enough motor and a good blade resawing is 99% set up and adjusting your fence for drift. Optimally your blade will stay clear of your cut/kerf. If your not getting that stop till you do. A well tuned and set up saw really makes some nice back and sides

I own a Driftmaster Fence, and I spend a lot of time working out the drift etc. I have cut endless boards. Never had this happen before. And, it did not happen with a pine board that I tested. What I'm looking for is someone here who had experienced this and knows what the root cause is.

Thanks,

Mike

Could it be as simple as a dull blade?

Don't think so. But if I don't hear any better, I'm ordering another and sending it off for sharpening. I know pine is not near as challenging.

Mike

In the video it looked like the blade bound and jumped off the wheels. I have had that happen in the past and it is usually due to having not enough blade tension and/or too fast of a feed rate. A binding blade can also happen if it is dull or not clearing the dust well enough.

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I was rather surprised by the amount of dust cutting blood wood created. It was everywhere. I don't normally hook the vacuum up to the bandsaw. I saw a video by the wood gears guy that makes me feel I was filling the gullets too fast. Ill try higher tension. I'm reading up on tensioning Resaw King blades. This blade does not have a lot of run time on it

When I saw the video Mike, this is exactly what I thought "he is filling the gullets and the blade is not clearing". In my mind tension is KING. My experience is a little limited. I have sawn nearly 10,000 spruce and cedar sets but probably only a few hundred hardwood sets but they have included Mahogany, Mun Ebony, Bubinga, Acacia, Rosewood Maple and a few others. If the tension is not right or the gullets clog then this issue will happen. Different woods seem to reduce to shavings differently and the oily woods do tend to crumble more and clog as a result. Anyway, a sharper blade will help to create a different shaving that will clear better.

Hope this helps with your thought process!

Shane

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Thanks Shane. Appreciate the insight. Had this ever happened to you?

I'm guessing the last quote was from the YouTube video. For some reason, I couldn't see the comments on my phone. I think I'm going to upgrade to a larger resaw blade. And crank up the tension. I swear, this is one effect u won't ever want to experience. To me, it seemed like I was hitting hidden nails.

Mike

Btw Shane, I would not use the phrase "limited experience" with anything you have done but I do get ur point! Thanks!

Hi Mike, Yes I have had this happen before when my blade on my small resaw (older 16" Hitachi with a 3" stellite tipped band) when the blade became a bit dull. It is indeed something to keep your heart going. As the gullets fill the saw no longer cuts as the teeth are no longer exposed to the wood. Once a few gullets finally clear it appears that the band then "grabs" the wood causing the loud bang and tug but then the gullets fill again. So, you need lots of tension, sharp blades and appropriate feed rates that allow the gullets to clear.

Good luck!

Shane

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Mike its the bloodwood. I find it one of the most difficult woods to resaw. In all likelihood your blade is caput. Dont order another resaw king. I t will do the same thing. Does the dust look burnt? Get aLenox woodmaster ct blade and feed slow

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Aren't these two aims fighting each other? (tell me if I'm wrong). I resaw with a 3/8" Lenox Trimaster on my 14" Delta with riser, as it's the widest blade I can get up to anything like the desired tension. (Remember, your saw frame is exerting a total force. Tension is force/cross-sectional area, so a bigger blade on a maxed-out frame or spring = lower tension.) Or maybe I'm misinterpreting and you haven't cranked up the "tension" as far as you can go yet. (Your blade tensioning spring is measuring force, not tension - it doesn't know what blade is on the saw and can't tell you anything about tension unless you have calibrated it for each blade you use.)

In the video, I don't like the resaw fence face extending past the blade. Mine ends there. Not quite the same as a short post, but it does give the wood more room to move after the cut.

My setup has been good for stuff up to 9" Ovangkol, but I've never tried cutting a piece of oily wood like cocobola the size of the one in the video.

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Jim Kirby
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As Bob C. was saying, the wood itself can be part of the problem. Boodwood is one of several woods with
a very high silica content that will dull blades quickly. Even Koa will dull edges rather quickly because of silica
content.
Brent

Looks and sounds like the kerf closed and the blade bound up -- a sharper blade may have prevented it but it was moving along nicely, so if the blade/cut had the slightest cup, the board and the cut off became a wonderful, effective "clamp/brake."

One of the most effective changes I made in our re-saw operation was to take the slices off the outside of the billet which eliminates the binding problem --- here's what we did:

http://www.acousticguitarconstructionfo ... f=7&t=1819

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Ken Cierp

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Double check your set up while your at it.
#1 where are your push blocks for safety
#2 if the lower bearing is too far back your blade will force feed itself.

I agree get the lennox blade. 1 2/3 tooth. Too many teeth may not be good . I also like the European guides or ceramics

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That quote is from youtube, but that's my video from a few years ago and the solution was more tension on the blade. Actually the solution was a bigger saw that could put more tension on the blade... the saw in the video was pretty well maxed out tension-wise.

And bloodwood is as difficult a wood as you're likely to come across... if you can resaw that you can resaw just about anything.

What makes blood wood so difficult? Before I buy a new blade and attempt another cut, I want to understand what might ruin that blade. I have a Jet 18". What kind of saw is sufficient to cut blood wood?

James, nice to meet you. We're u already experiencing the problem (the reason for the video)? You looked pretty tentative when feeding the block, like you were expecting it.

I inspected my blade and I cannot say for sure it was not there before. But there is a grayish cast around each tooth. And whatever it is, it will scrape off.

It sounds like everyone is recommending the Lenox Trimaster. I went to their website and got a bit confused. For my 18" Jet, which would you recommend? To include blade width, TPI, tooth set, varitooth?

I'm pretty sure I want at least 1" if not bigger.

Mike, the blade will probably make no difference, at least it will not eliminate the problem. This is just a thing that happens when resawing bloodwood, as Bob C. mentioned. I have a BEAST of a resaw setup with the best blades available, and my saw is tuned up as precisely as any saw could be, and this still happens sometimes when cutting bloodwood.. I have cut at least 1000 sets of bloodwood. Just the nature of some woods, cutting katalox does the same thing. Although the jerky, slamming effect is much less with my setup, it is still noticeable sometimes with certain woods. This can be very dangerous, so be super careful.

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Where I work, our bandsaw has has an air nozzle hooked up an inch or so below the upper blade guide that blows the material out from between the teeth before they reenter the material. We cut aluminum pretty much exclusively but maybe something like that added to your resaw setup may help?

I have had this problem resawing Osage Orange with the Woodmaster CT blade on my Rikon 18" bandsaw. Someone explained to me that the angle of the teeth on the Woodmaster blade was too aggressive for the hardness of the wood and the strength and power of my saw. When I changed the blade to the Trimaster (which has a less aggressive angle) the problem was solved. If I were to buy a saw again, I would buy one with a stiffer frame and a more powerful motor. Who knew that 2.5 horses would be inadequate?

I'm not sure blowing out the gullets will work, will it? Will dust make it all away around the blade path?

Aaron, Bob C, others... I am still looking for the explanation. And thanks for making me feel better...

I can't help myself (engineer). I want to understand why it is happening, not just that it happens a whole lot with bloodwood. I reviewed a really interesting video by the Woodgears guy on YouTube (Mathias). His use of blade models and sand makes a lot of stuff clear. But not everything. Something weird happens with bloodwood... perhaps the blade/wood combination creates so much dust so fast that the gullets fill up faster than normal. Full gullets explain the effect (binding, blade twist and slap), all of which more power, more tension, and a bigger blade (gullets) could help solve.

Here is the engineering aspect of it (to me). I have a number of constraints. My blade can be only so big, I can apply only so much tension, I can vary feed rate (but I have read that it is not very effective), my power & speed are constants. Blade TPI is a variable. I have noticed that the problem gets worse (using bloodwood) as the height of resaw increases. This suggests to me that a lower TPI is in order (like John/Bob suggested). That way, if a gullet fills (or several of them) I will apply all of the saw's power to fewer filled gullets (which are now not cutting efficiently at all).

I just spoke with someone who said he had the exact same problem and it went away when he tightened his drive belt. Claimed the bottom wheel will slip and catch back up.