Carbide bands, my experience

[JoshNZ]

I wanted to ask the group here their thoughts on whether carbide bands are worth their cost when used exclusively, assuming no metal strikes. Based on my experience alone I'm seeing maybe 2-3 days of reasonable use where their performance diminishes from say 100% sharp, to 70% sharp, then snap. As compared to a carbon steel band that does 100% sharp to 20% sharp in perhaps 1-2 hours of use (at which point you might do another log or two, if they're small and free of knots, or might swap it out), then can be sharpened 10-20 times. My theory is the carbide bands would go a lot longer if the gullets were polished every couple of hours like the carbon steel bands are, but there doesn't seem to be any carbide sharpening solution that addresses this? The vendor supplied a diamond sharpening wheel to fit to our sharpener but it only touches the TCT, none of the bands have made it to needing this yet anyway.

My experience is limited, I had 10 bands made up and sent over from China (I've not even been able to find a supplier in NZ) and their performance is pretty amazing. Unfortunately they must have annealed the welds incorrectly and the first few all snapped on the weld within an hour of use. I found if I put them in the welder and bumped them to cool blue I solve this problem (i.e. the snap will be somewhere else on the band). So now I have the same agent offering a deal on 150m of coil, for about 2.4x the price I pay for carbon band coil, and I'm pretty tempted to pull the trigger.

I'd be a lot more tempted if someone was to say they got more than 2 days use out of them, maybe 1-2 sharpenings. I remember seeing Matt cremonas video about carbide bands who's experience seems similar to mine, the body would fatigue before sharpening was neccesary.

I've also found if you're feeding slowly (i.e. slabbing a max width log) they will eat through metal without any fuss at all, again and again it seems. There's a bit of a pattern change in surface finish for a few seconds after the strike then it's business as usual for the rest of the day.
Hitting metal while feeding fast however (ripping boards off a cant) completely destroys the band, the tooth must engage the metal deep enough that the band body is deformed and the TCT is ripped clean off. Usually I know where to expect the possibility of metal so I don't think this is too much of a factor...

2.4x sounds like a lot more to spend on a band when I write it out here but sheesh I sure do love not having to sharpen or set them, and it is really nice to not be approaching dull during its use but rather staying in that upper sharpness level right to its end.

Bit of a ramble sorry but would be interested to hear of anyone else's thoughts/experience 

[KWood255]

Hi Josh,

I have been running Woodmizer razortip carbide bands for the last 3 years, almost exclusively. These were 1.25x.045 on my LT40 and now 1.50x055 on my LT70. I have no experience with any other carbide blades, nor any blades aside from Woodmizer for that matter.

I went from doing band changes every couple hours, to days.

I had one bad batch of WM bands that broke on the welds within an hour or 2. The rest have been great. These were eventually replaced by WM.

I go back and forth with my run time, depending somewhat on what species I'm sawing. I have found with jack pine, typically run the carbide until it breaks. Our white spruce is more challenging to saw flat, so I will swap out once performance becomes compromised. Being that I work with softwood 95%+ of the time and clean (winter harvest) logs am seeing about 4000bf before removing the band.

I encounter near zero metal strikes, so I cannot speak to that. I think in the last 6-7 years I struck 2 nails, and 1 bullet.

I have noticed increase blade life on my LT70...I can only assume the wider/heavier band combined with larger drive wheels helps.

About 3 years ago I had ordered a WM sharpener/setter combo that was going to be over $6000cdn. As it was during the Covid days, it was expected to take months to arrive. About the same time I was introduced to the carbide bands. For me, it made sense to swap to carbide and forget about resharpening standard blades. With blade costs always on the rise, I may one day regret cancelling the S/S order, but not yet.

[barbender]

I'd venture a guess that those blades, while still sawing straight are no longer sharp and that's why they are snapping prematurely. I wouldn't worry about polishing the gullet- I'd be more concerned with sharpening the tooth!

I haven't tried the carbides yet, though I would like to. I hate changing blades. If I could get 2-3x the sharp life it would probably be worth it.

[JoshNZ]

Sorry mashed the keys this morn. They're not snapping from being dull, ive trimmed the bands and rewelded to use on my shop bandsaw, if they didn't get destroyed when snapping they get a second life there running fine. You can see the carbide tip is still fully formed at the edge.

I guarantee you will get more than 2-3x sharp life. More likely 10x at least, is what I'm seeing. The snapping after 2-3 days is worrying but I think if I ran a stopwatch on actual sawing time, it might be close to what I get with carbon bands with all of their sharpenings. If you threw time saved not sharpening/swapping into the equation + the CBN wheel (crazy price here) it might even outweigh carbon bands.

Yes I think larger wheel diameter would certainly help. Mine are 19" wheels from memory, which is a bit small for .045" band.

Good to hear of your experience, how do they compare pricewise to carbon bands in terms of percentage?

[KWood255]

Good to hear of your experience, how do they compare pricewise to carbon bands in terms of percentage?

The Woodmizer carbide 184"x1.50x.055"s run about $160 (Canadian) each. The WM Doublehard is around $60 or so here. 

[Ianab]

Although they are going to cost 2.4X the amount, have you factored in the downtime of not having to change and sharpen the band? At say 5 mins per band change, pretty soon you have lost (or gained) an hour of sawing over the life, of either band. 

It may be that you are right about the carbides eventual failure starting with stress cracks in the gullet, as that's how regular bands usually fail. I wonder if the cam on a normal sharpener could be modified to only retouch the gullet, retracting the wheel far enough to miss the carbide tooth completely? But how much that would increase the band like is debatable. If the carbide band has done 10X the rotations on the mill, that's like a band that's on it's 10th resharp, and if those started breaking you would shrug and way "well I got a decent run out of those".

[jpassardi]

I'm interested to hear others experience with them. Compared to Doublehards they're a hair over 3X the cost. They claim to have up to 3X the life. If that's accurate, assuming no metal strikes it's a wash in initial cost.
The savings comes in if you sharpen your own standard blades and don't have diamond to do carbide. Granted, sharpening takes time.

[longtime lurker]

I might be speaking out of turn here... I know just a little bit about wide band resaws and nothing about small bandmill bands... but I reckon there's a chance I have more experience with tungsten carbide teeth in wood applications than most y'all and that's got to be worth a 2 cent opinion.

We all know the Chinese are not exactly renowned for steel quality and body failures could be the result of inconsistencies in the alloying or annealing process. But if a band runs all day the first day it's probably OK.

Pull it off and sharpen it. Won't need much, just a touch up. 

https://forestryforum.com/gallery/displayimage.php?pid=358727

That's a tungsten carbide tooth and when we stopped Friday it was still sawing OK.

https://forestryforum.com/gallery/displayimage.php?pid=358728

That's the same tooth at 10X magnification and as you can see it's awful blunt. Sharp carbide has nice crisp edges and a polished look. If they look grey/white coloured on the edge of the tooth its light refracting off surface pits and they need attention

That's the nature of tungsten carbide... it'll keep cutting ok even when it's blunt. And you really don't want to run it to dead blunt because then it requires too much grinding to bring them back. Like a butchers knife frequent light sharpening is the way to go, it's just that being tungsten frequent is relative... it'll go a lot further between sharpening than hardened steel. 3 times the sharp life sounds about right... about when you'd be changing your third hardened steel band out you should be sharpening the carbide.

My suggestion is an end of day touch up to the band... if it still fails after 3 days  with resharpening then it's not that and it's something else and I was wrong. But I really think barbender was on target.

[Bradm]

I've been making and sharpening carbide cutting tools for both wood and metal for over 20 years and carbide needs to be sharpened before it "feels" dull.  If it feels dull, it's been run far too long.  Look at the edges and how the light reflects off it; if you can see a line along the edge that means it's time to sharpen.  I also recommend giving a touch up sharpen at the end of each day.

[Dave Shepard]

I dot mind a blade change. It's a chance to get some water and step behind a tree.

[Bruno of NH]

I ran 50 Chinese carbide bands last year.
The only one I broke was a longevity test. Didn't brake on the weld. They cut slow ,to slow for me. They make a beautiful looking board.This was all soft wood. They might be better suited for hardwood. In softwood the wood fiber builds up on the tooth.
I do like the Chinese bi-metal and carbon bands.
They don't want you to buy them , they push the carbide. It's because they charge 3x more for them.
I can get multiple sharpings out of the bi-metal and carbon steel. 
All Chinese suppliers aren't the same remember that.
With the tariffs in place I don't think there will be a cost savings anymore, unless the European bands companies go up alot.
You might as well stay with Woodmizer silver tips. 
I'm set up to buy all the welding , cutting and grinding machines from a Chinese company with a private label on coil stock.
I was thinking on doing it but , I'm on the fence.
The bi-metal and carbon steel Chinese bands are just as good as any band I have used.

[John S]

Just attended a WM workshop, they discussed sharpening and emphasized sharpening down through the gullet to remove hairline stress. cracks.

[Andries]

Full profile sharpening, right to the bottom of the gullet, is the biggest and best reason to use CBN grinding wheels.

[Bruno of NH]

The Chinese company I have delt with makes a 1/4 diamond 1/2 cbn 1/4 diamond for the carbide bands they are around $280 us 

[barbender]

My non scientific testing has concluded that full profile grinding to remove stress cracks is BS. There are other reasons to full profile grind that are of more importance to me than that, like maintaining the gullet depth. 

If you want to develop some stress cracks in short order, try grinding the gullet too heavily. I ordered a box of 10° blades on accident, so I just ran them. My sharpener is set up for Turbo 7's, so I gently ran them around 3x to reshape the gullets. 

Every one of them broke on the second sharpening. These were .045's, which I would usually get 6-8 sharpenings out of.

[Stephen1]

BB my favourite method of testing! 

I've run Carbides and I have the diamond stone to sharpen. I usually only got 1.5 days of running, I would sharpen after a day and then they break. Yes you can go slow an hit  hardware and they keep going but I don't have the patience to go slow. I want to saw the log and move on.  
 I also hit lots of metal which was the biggest decision to go back to carbon blades. 
It really hurts to trash a blade on the 1st cut and it's your log. I have a customer who only wants Carbide blades as it saves him planning after. I charge accordingly. 
I still have 8 used resharpened carbides on the wall, was 12, and every once in a while I'll get one down, run it, and then throw it away as it was on the wall because I tried to sharpen it after hitting hardware. I'm getting old and forget more and more. 

[Peter Drouin]

I bought a pile of them from WM once. They cut okay. I sharpened them a couple of times and found the tooth would turn sideways after a while. The face of the tooth is not square with the blade's body.

The Cat on the Mill is too much for them, or I was cutting too fast, I don't know. I went back to DH.