Thread: 1.3 TPI resaw blade problems

Is the Sydney Bluegum flat on the bottom or is it a round such as a log?

It's flat, I jointed the face and edge that's against the fence and table respectively.

Well now having spoken to Henry's they suspect a dud blade and are sending me another so I'm hoping for a different experience

Redgy

A couple of things spring to mind,

If the planed face is not flat, say if it has a small high point in the middle this then acts like a pivot and when the blade engages the wood it rocks the wood causing a vibration,

Also with a new blade/sharp teeth and if the hook angle is a bit aggresive (>10°) the blade will sometimes tend to pull itself into the work and make for a very shuddering type of cutting action, this can be exacerbated if the blade is tracking forward on the wheels, if this were happening to me I would set the blade further back on the wheels and maybe have the blade ride on the thrust bearings, not a lot, but just a little, let the blade dull a little and then retry after moving the blade forward off the thrust washers,

Also a severe grabbing can be caused by a tooth or two having more set than the rest, have a look on your cut face and see if there is a distinct line at some distinct spacing, it will depend on your feed rate how far apart this line will be.



Pete

I've got the same problem with my 1 1/4' 1.2 TPI blade.
What I deduced was that it is self feeding because of the hook angle, and the thicker the material the worse it is.
ie The more teeth in the cut, the more it wants to eat wood A bit scary when I cut 300mm thick bluegum.
In fact it was so agressive it would pull the blade forward over the camber of the wheel.
An 1 1/4 .040 thick blade needs some tension on it and I had it riding on the back of the camber.
I found a deliberate slow feed rate helped, but I suspect that it's just too agressive for a manual feed.
No point in having a blade like that if you can't use it.
I reckon 2 to 3 TPI would be a better option. How fast do we really need it to cut anyway?
As a comparison I cut the same timber on my metalwork bandsaw which runs approx 12 TPI and although slower ( not much ) at no point did I see my life flash before my eyes.
Kimbies still intact too

@ Pete, thanks for the detailed response. Yep the planed face is flat and the same piece of timber with a 3tpi blade no issues. I have tried your other suggestions and normally run the blade back a bit anyway (gullets centered on crown as per Allan Snodgrass? method).

Interestingly, and disappointingly, the second blade they sent me has the same problem. The new blade is a 2 tpi, 1 inch bi-metal Lennox Woodmaster with a less aggressive set.
What I have found with this 2tpi blade (and also the 1.3tpi) is that it moves back & forth on the wheel. It's clearly visible, no thrust or side bearings touching top or bottom and no matter where I set it on the wheel, centered or back, it moves. I setup a dial indicator on the back edge of the blade and spun by hand, the variation is almost 2mm. The 1.3tpi is about 1.2mm. So I suspect these blades are not flat or planar (not sure of the right term) The crappy blade that came with the saw (3tpi, 1 inch, carbon steel, no brand) has about 0.2mm front to back movement. I probably should've taken some pics but I hope I have explained it well enough.

So back to the newest (2tpi) blade I set it up on the back of the wheel (which can take a 1 1/2 inch blade), then I moved the top thrust bearing (euro style metal disc) and bottom thrust bearing (ball bearing) forward so the blade was touching them always. This was very noisy and not how I want to run the saw, but anyway the grabbing was less but still there. I'm not game to try the 1.3tpi blade. I have max out the tension which made no difference.

Am I missing something basic? Is this front to back "wobble" something normal for bi-metal "quality" blades? Or am I asking too much from my 3hp 16" machine?

As a side note I have touched up the crappy blade that came with it with a dremel and it cuts sweet if not a bit slow....maybe I just send the "good" ones back for a refund.

Cheers
Redgy

Hi Redgy,
With the blade moving back and forth like you say could well be an alignment issue at the weld, if you have a large flat table/surface set the blade on the surface (teeth up) and see if you can see gaps under the blade.

Another check will be to look at your wheels just to make sure they are running true, make sure the center of the crown is running true. Long shot but maybe something is going on with the tyre or the maching under the tyre.

Another cause of the blade moving back and forth is if the blade has developed a crack, this usually starts at the gullet and progresses thru the blade body towards the back, they will also propagate from the back as well, run a finger nail on the blade (near the gullet/also the back) as you rotate by hand (power off), if there is a crack you will feel it, this is a fatigue failure and takes some time to develope, to me it doesn't sound like these blades have done a lot of work as yet. The smaller the wheel diameter the more bending stress the blade undergoes and the more likely fatigue cracks will occour which is exacerbated by high blade tension and high blade speed, mine is just under 2000m/min, I wouldn't put yours as high. Another cause of blade cracking is if when they are sharpened (either new or at resharpen) and the gullet is reshaped and the wheel is too course, the resultant rough finish can allow a crack to propagate more easily, I had a few issues with this with a particular saw sharpener, my current bloke only touches the teeth tips.
Blade cracking is something I check if I think it's moving about too much, it's a bit of a moment when they go bang unexpectedly.

I also have bought the Lennox Woodmaster B from Henry Bros. without any issues for my 19" saw, I buy the 1 tpi 1 1/4" wide.

Pete

Hmmm food for thought in this thread, I am seeing the same issue with a similar blade. Mine is 1.3 TPI and 1".

I don't have a dial indicator but will try and determine the exact amount that the blade moves forward on the wheel or away from the thrust bearing...

https://www.woodworkforums.com/showth...=166960&page=3

Cheers

Simon