Problems resawing cocobolo on bandsaw

[Jim Ringo]

I am having some issues trying to resaw some 8" cocobolo with a 1" woodmaster blade. I have no problems going through 10" mahogany, maple, and other softer hardwoods, but the really dense woods are really quite frightening to resaw as the blade seems to want to pull the wood in and violently grab it. I believe my saw is set up well... bearings are all very close to the blade, table is 90 degrees, blade is tensioned at very nearly the maximum for this saw (Rikon 10-340 with 18" wheels). This video shows feeding some 3" macassar ebony through very slowly before the coco... if you listen very carefully you can hear a little 'thok thok thok' as the ebony is being resawn, then the coco is put into the blade with violent results:


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

Is this probably a bad weld or do I need to look at something with my saw's setup?

[Ted Calver]

The upper guides need to be as close to the top of the piece being sawed as possible to minimize wander. I take a coarse stone to the back of the blade as it is revolving to round over the back edge. Also look for the weld and try and smooth it out with a grinder...that's likely the source of the thoc thoc.

[Harvey Pascoe]

Would that be a carbide blade? If so, cocobolo and other resinous woods can be a real problem with carbide blades. I have no clue as to why other than probably being too aggressive. When I resaw coco ( or rather should say, used to resaw with carbide) my Trimaster blade blew huge chunks of wood out the bottom of the cut. Nothing I could do would stop this other than stop using the Trimaster.

[Paul Symchych]

Purely anecdotal but I had similar thumping with a Timberwolf blade but it cut OK until I tried to resaw some lacewood. A very similar result to your video. It also began to drift and after I got the blade off it looked to me like the teeth had acquired a set at a slight angle.
The quickest replacement blade available locally was an Olson and it has no thumps and cuts lovely veneer in very hard woods. So well in fact that I began having fun and cut a small stack of veneer that I have no use for -yet.

In lieu of making a diagnosis maybe trying a different brand of blade would fix things.

[Phil Thien]

Have you tried for the other end of the board? Is it possible there is something embedded in that end of the board?

How sharp (old) is your blade? If the blade is dull perhaps it is catching the taller board, but unable to saw it?

Do you have any other blades you could try?

[Andrew Hughes]

Hi Jim,I had the same problem with a laguna resaw king blade.The Throat plate was flexing and the wood was being pulled down wasnt as bad as your video but seems like the same thing.Resawing a piece of cocobolo that high is a tall order nasty stuff.also check the front of the blade is square to the table or close.Hope this helps.Great idea with the video. Andrew

[Jim Matthews]

The feed rate is related to the number of teeth. If you have too many teeth in contact with the workpiece, the chips cannot be ejected fast enough to keep the blade cool.

This waste heat will result in both an expanded blade and release of the Cocobolo's natural resin. The heat, extra sawdust and resin appear to make a fast-setting epoxy to stop your motor.

My real reason for chiming in is that this stuff has natural insect repellants that can have a cumulative effect on your health. Tropical species like these should be handled with a mask, at a minimum.
It's a beautiful poison (http://www.sawmillcreek.org/showthread.php?18571-cutting-cocobolo-w-o-dust-protection-%28scary%29)...

[John Coloccia]

I have enough trouble resawing Cocobolo for fingerboard blanks, never mind an 8" piece (are you building a guitar, by the way?). It's got to be one of the least friendly woods to use in every respect. It's difficult to work by hand and machine, it will grind your cutting edges down to nothing in no time flat, and it requires special treatment in order to reliably glue it (at a minimum it requires a good wipe down with alcohol to clean it before gluing). A lot of it isn't even that pretty, leaving me to wonder why I even bother with it at all.

Does it actually stop the motor? I'm noticing a lot of dust being kicked out in front of the cut. It's almost like it's not cutting as much as abrading it's way through. I've never seen a bandsaw get it's butt kicked like that before. When it gets stuck, what's the mechanism. Is the wood pinching on it?

[Brian Kent]

I'm learning from your thread. The only other time I have seen that is at a woodworking show, where a guy was demo-ing a huge Laguna bandsaw, cutting through a log section. Several times he started the cut and Bam!

[Mike Hollingsworth]

I think you'll have better luck if you bolt the saw to the floor.

[Jim Ringo]

Thanks for all the replies. I was hoping there was something I overlooked in setting up my saw, but the more I think about it the more I think that this blade is just too aggressive for a 2.5 HP saw and 8" of cocobolo. Which stinks because I bought this blade (1" Lenox Woodmaster CT w/ 2/3 TPI) specifically for cutting these billets after reading glowing reviews of it's smoothness and durability. I've used woodslicers before with OK results but they dull so quickly in this type of wood that they end up being a pretty expensive option. I guess I'll have to wait until I can buy a bunch of woodslicers or a bigger saw before I can process these boards.

What also stinks is that, besides spending $150 on it, now I'm scared to death to put any kind of wide board into this blade. Having all 2.5 HP come to an immediate stop like that was quite the attention-getter.

[David Kumm]

Jim, The lenox blade needs more tension than I believe the saw can manage. It probably cuts fine with softer woods but needs all of 25000lbs tension for that wood. Any deflection causes all kinds of problems assuming the teeth are ground correctly. Sometimes you get poorly sharpened teeth that only become apparent in your type of situation. I haven't looked up the band thickness but you need a stout resaw to handle the lenox blades. Trimaster more so than woodmaster. Does the motor seem to slow at all? Dave

[Richard Wolf]

You get that bang from your band saw because your blade is building up slack between the wood and the top wheel, when enough slack builds up, your blade will slip around the wheel and cause that bang. The question is why are your building up slack? Not enough tension? Blade bogging down in the cut? Wood pinching?
Too many teeth per inch? It could be any one or a combination.

[Jim Ringo]

Jim, The lenox blade needs more tension than I believe the saw can manage. It probably cuts fine with softer woods but needs all of 25000lbs tension for that wood. Any deflection causes all kinds of problems assuming the teeth are ground correctly. Sometimes you get poorly sharpened teeth that only become apparent in your type of situation. I haven't looked up the band thickness but you need a stout resaw to handle the lenox blades. Trimaster more so than woodmaster. Does the motor seem to slow at all? Dave

This could very well be. Tension is just about maxed out on the saw so if it needs more that's an end to it. I don't have a tension meter but I can deflect the blade about 1/8" max to the side with the guides 9" above the table. It is a 1" wide blade. The motor did not bog down or anything before the blade grabbed and came to a sudden halt.

[Damon Stathatos]

I resaw a LOT of cocobolo and 8" gives me pause even with my 36" Tannewitz. I've never had my motor seize on me like that but at 15 horse, other stuff (loud wailing sounds, smoke, heavy vibrations, and the primal-instinct-of-survival voice screaming inside my head) usually get me to back off before I can get to the 'bottom of the motor.'

Even with the 2/3 tpi, you're still pushing too many teeth through for that width. One problem is that it's hard to get less tpi until you get up into 2" or 2+" blades. You can get away with the 2/3 tpi in some cases such as with the softer woods like mahogany or even manageable widths of harder woods like your mac ebony, but you're taking that blade and consequently motor to the extreme with the 8" of cocobolo.

You can see that the wood had closed behind the blade when you tried to pull the board back out. My guess is that the wood is compressing onto the blade and that coupled with the buildup of dust that your blade is not able to clear out is overloading your ponies. If you had been able to complete the cut you would have seen a sheet-like mass of ultra-fine (and hot) sawdust caked on one side or the other or both sides of the cut. You're basically encasing your blade in a quick-set mixture and your motor was the first in this equation to 'flinch.'

If I had my mind set on it and wanted to cut this thing no matter what, I'd try a regular steel blade with a very aggressive set to it. You'll lose some in a much larger kerf but that aggressive set may clear enough way for the sawdust to cake up and still have enough room for the balance of your blade to clear. You don't necessarily need a wide blade either so if you have a 3/4 or even 1/2" blade already, you can give that a try. Lastly on the blades and if you want to give this a try, it doesn't have to cost you a fortune to do so. Stay away from the local retailer or 'name brands' because there's just too much marketing money in that equation. I buy 1.5" x 220" regular steel blades directly from Tannewitz for under $40 each. They make them to order so you can specify any length (width, tpi, etc) with a presumably lower corresponding cost. Or, if you rather, source out your local industrial saw blade companies (the guys who service full-time shops) and give them a try.

A lot of cocobolo is very resinous. If you get a buildup on your blade tips, acetone works well at cleaning it off. I also periodically 'prime' my blades with regular candle wax usually after every few cuts. I do that by sticking the end of a taper candle into the sides of each blade, especially the teeth, while the blade is still running. That seems to lengthen the interims between the acetone treatments.

A couple of final notes in that there were two things that scared the heck out of me watching your video. First thing is you need to do your best at resisting pulling a piece back out during a cut. If you're going to give up on a cut, turn the machine off and wait for the blade to stop before trying to get your piece free. It's possible to pull your blade completely off of the wheels when you pull back like that. The second thing is I'm guessing that your band saw is on a mobile base? It doesn't look as if it takes much effort at all to get your saw to 'rock and roll.' I'd reconsider either the mobile base itself or at least maybe a different version. It's not that the saw itself is so heavy but with a blade moving at some measure of feet per second, the last thing I'd want to do is to get into a wrestling match with one.

Best to you and good luck with your coco. It's a beautiful wood and well worth the efforts.

[David Kumm]

Damon, Have you tried the CT 1.3 on your saw. I use that on my 116 that runs at 6700 fpm. Have not sawed cocololo so can't relate to that. The DD tanny's ran at 8400. Is yours belt drive or slowed down at all? I'm not sure Jim can do that cut with any consistency on his saw. Dave

[Damon Stathatos]

David, are you speaking of a carbide tooth with a 1.3 set or one of the Lenox (trimester) blades? The only carbide I've used is when fellow creeker (Tim) put up some of his 'surplus' blade material on the classifieds here and he made me a couple of them. They work great but I'm afraid that I'm only going to get a couple of sharpenings out of them so I use them sparingly. If it is the Trimaster you're referring to, they're just to darned rich for my blood ($300 - $500 depending upon specs).

My Tannewitz is direct drive and runs at the full 8400 fps (no bi metal blades allowed).

I think that you're correct that Jim would have a hard time with his saw with wide coco on a regular basis but if he's just trying to get through one slab or something such as that, he may be able to do it with a wide set. Also, there were a few posts made while I was composing my first reply and the blade slippage on the wheel probably makes more sense. He could have an inch or so removed from his current blade (and then re-welded) to allow him to crank up his tension a bit and that may help as well.

[David Kumm]

Damon, Lenox makes a carbide blade that sells in the 150-175 range with a little thinner band, a little narrower tooth at 1.3 tpi. Your tanny takes a little longer blade than my oliver so price it at industrialblades.com. Shortening the blade won't help with tensioning unless the blade is at the top of the range and bottoms out. Putting in a stronger spring could theoretically help but once the frame structure starts to deflect a million problems occur. Even a slight deflection causes the blade tracking to go out of whack as the blade spins. Check out the lenox- not the trimaster. Dave

[Jim Ringo]

Thanks Damon, that's excellent info. I would like to point out that the first thing I did when the blade caught was turn off the saw; you just can't see it because the wood's in the way. The point to bolt down the base is well taken.

[Kent Chasson]

Hey Ringo, I had that exact thing happen with cocobolo with a Laguna 1" 3tpi Re-saw King blade and that was with 5" stock. Mine bucked before I was even a blade width in so it wasn't blade binding in the kerf. I think the response about slack building up and the wheel skipping is right on and it makes sense that more tension is needed. I think I tried some mahogany just to see how that would cut and it did fine but I wanted to return the blades so I didn't cut much else with them.

I switched to a 3/4" Timberwolf A.S.S. and it cut OK but the whole thing made me nervous enough that I put the wider stuff away for awhile.

I would add that I've sawn plenty of 9" wenge and sapele with no problems so it has something to do with that combo of cocobolo and that blade.

[Rick Fisher]

I had a similar thing happen with a piece of 1x6 Teak that I was resawing.. Sure Teak is an easier cut than coco.. no question.. I cranked up the tension on the saw and tried again, It cut through with ease afterwards.

For that reason, I think its the tension on the blade. I run a 1" Tri-Master right now and never paid much attention to the tension prior to that cut.. I had resawn a bunch of Oak and Wenge with it .. I think the problem with the teak was it is so oily, it built up in the kerf. My motor did not stall, it was just a thwacking / banging and was during feeding.. which was way too fast..

[Jim Ringo]

Hey Kent, small world! I'm glad to hear I'm not the only one who has had these problems with coco and carbide... too low tension does make sense. I think a call to Rikon is probably in order to see if this saw's frame will handle the tension needed on this blade and if so what I can do to get there.

I hope all is well with you and yours.

[Phil Thien]

After reading this thread I'm removing cocobolo from the list of woods I'd like to try one day.

[Joe Angrisani]

After reading this thread I'm re-convinced the biggest blade a 17"-18" saw should run is 3/4".....

[David Kumm]

Most 3/4 blades are the same thickness as the 1" ones so you actually need to step down to the 1/2 to 5/8. Dave

[Kent Chasson]

David, given the same force, wouldn't you get more psi on a 3/4" blade than you would on a 1" blade of the same thickness?

Ringo, Steve wanted to talk to you about gilding. I gave him the email I had but am not sure it was correct. Please send me a pm or email.

[Damon Stathatos]

After reading this thread I'm removing cocobolo from the list of woods I'd like to try one day.

Funny thing is...I work almost exclusively with coco, probably about 80% of the time. If it's not coco, then it's ziricote or jatoba around 15% of the time. No question about it that I have commercial-type equipment but people walk into my shop and often times ask about the difficulty in working with such hard woods (by the way, if you think coco is hard, try working ziricote some time, it makes coco seem like butter, no pun intended). My only response is that it cuts fine and since I have such a limited frame of reference, I can't give a comparison other than on the rare occasions that I do cut more normal woods, it does seem pretty effortless. The only other thing that I have been able to identify is that it does seem as if band saw blades do need sharpening often and is the reason that I have two or three of each configured blade on hand at any given time. I'm going to take David's advice and give the Lenox blades a try the next time I go to get a blade. The tip about industrialblades.com looks to be a good one and goes into the archives as well. I don't have that same impression with table saw blades as much though, possibly because they are all pretty heavy carbide blades. And so, once you either get used to it or 'geared-up' for it, it becomes wood, just like any other wood you need to cut.

The point of my post is that after you get used to working with it, the rewards are fairly high because it is a spectacular wood once it evolves into a finished product. The tell-tale sign is when woodworkers and non-woodworkers alike are immediately drawn over to a finished piece, drawn to it presumably exclusively because of the characteristics of the wood rather than a particular design. And in my case, that's a big and much needed advantage.

Again, my advice to Jim is to stick with it and get through the intended project. I think you'll realize that the reward was worth the effort. That looks as if it's a pretty nice piece of coco with a really good figure and I'm betting that it is going to finish-up really well. By the way, coco is a prime candidate for MicroMesh sanding (the oily content and high wood density) and usually results in a very polished surface with great depth, so consider that as you near the end.

[george wilson]

Are the teeth hook shaped? If so,I'd switch to a flat faced tooth,that is,a tooth shape whose cutting edge is a 90 degree angle to the blade. Since your wood is getting sucked into the wood,it makes me think you are using too aggressive a style of tooth on your saw.

Do be very careful to not breathe cocobolo. It is very harmful indeed. I heard about a guy turning it on a lathe,and he went blind for 2 weeks.

[David Kumm]

The thickness of the band affects the strength needed to tension it rather than the width. Don't know the science but if you can't tension a 1" blade you won't tension the 3/4. When purchasing blades you need to look at the thickness as not all are the same. The lenox CT is less than the trimaster. Dave

[John Coloccia]

It's thickness and width. A 1/8" blade will require far less force to tension than the identical blade in 1" width....or 100' width, for example. The distance you must stretch the blade is the same for the same thickness. That's why you can measure the tension by measuring the stretch, given the properties of the blade (i.e. the way that dial indicator tension meters work).

Personally, I don't use anything bigger than a 3/4" blade on my G0514X2, mostly because 1" blades are incredibly unwieldy and inconvenient. I also don't really see any improvement in performance. Honestly, I haven't seen any improvement in performance past 1/2" wide, so I doubt any new blade coming into my shop will be greater than 1/2".

[David Kumm]

John, You are correct. It is width x thickness in the calculation. I should have boned up on the science before I spoke. I also agree that a 1/2" blade is a good choice for a saw 18" or under except for the beefed up saws by MM or others. I would prefer a narrower blade at higher tension. I keep a 1/4 bimetal blade in my Yates Y20 and tension it to 30000 psi. It resaws most stuff to 6-8" easily. Not like my big saw with the 1" blade but great for tenons, etc. Dave

[Joe Angrisani]

1/2". Even better. Thanks for your insight, John.

[Jim Ringo]

So just to follow up I spoke with Rikon's excellent customer service today and after assuring me that this saw coupled with this blade is certainly capable of consistently resawing this sized billet of cocobolo, they pointed me to a few tweaks I could make and a few things to consider. First off was the possibility that the tires were not properly anchored or glued to the wheels which could cause them to slip (I investigated and my tires were fine). Second was a trick engineered into this saw to move the tensioning mechanism up a bit to effectively reduce the size of the blade and thus allow me put more tension on it. Backing out a simple set screw (rather than cutting out 1/2" of the blade and re-welding) let me effectively reduce about 1/2" of blade's length and gain that much tension. Finally I was reminded that this is a dual-speed saw and that for this job I needed to run it at the faster speed.

I made the adjustments, and whether it was the added tension I put on the blade, the faster blade speed, or a combination of the two I was able to turn the billet into 8 neat slices without incident. I wouldn't say it cut the cocobolo like butter but it got the job done and frankly I've never understood the desire to cut butter on a bandsaw in the first place. As an aside I was able to track the 'thok thok thok' sound to the blade's weld... it was not perfect and the back of the blade rides about 1/64th out of true over about a foot of blade length right at the weld. While not ideal it didn't seem to hinder performance in any meaningful way, but I must say after experiencing the blade slipping the constant pulsing rhythm from the weld is a bit unnerving.

Anyway thanks for all the replies and hopefully this thread will be useful for future folks having similar issues!

[Damon Stathatos]

Hey Jim - Hoo Rah

[Paul Symchych]

I got a similar response from Timberwolf about the 'thonk' noise. The weld looked and felt fine but they said the blade must have acquired a set from how it was coiled. I did cut just fine, thumping noise and all, until resawing the lacewood finished it off. That was a 3/4" which I replaced with a 5/8" x3tpi that has been great. I can't imagine a need to get another 3/4".

[Gary Kman]

1. Lubrication is vastly underused in many applications. Pulling electrical wire, making hoses, hand planing. Often it is simply the difference between success and failure.

2. Bandsaws are built with a comprimise between rigidity and throat size. I have added a temporary "jack" between the table and the upper bearing to reduce flex.

3. I've never used expensive blades but I have never used one that liked to have a fence parallel to the cut like a table saw. They always have more set on one side and pull accordingly. I've fed with the work skewed at 10* or more.

4. Instead of a long fence, I use a point (for the lack of a better word) fence. A plywood assembly with a vertical dowel beside the cutting edge. I steer the work-piece through the blade pivoting on this dowel.

5. Your wide board is certainly pretty but one half as wide would be pretty too.

Good luck.

[Jim Sears]

Just call these guys and tell 'em what you want to do. They can fix you up.http://www.woodcraftbands.com/Pricing page.htm (http://www.woodcraftbands.com/Pricing%20page.htm)

[John Coloccia]

You know, I THOUGHT I noticed that the blade seemed to be running slower than normal on the video, but I convinced myself that it was just the video. Shoot, I always run my wood bandsaws as fast as they'll go. The only time I would consider going slower would be to cut metal, which I never do on my wood BS anyhow. Just that will probably make a big difference.