Thread: What went wrong!!

Jon

Hard to know without being there, but you can only do a process of elimination.

First thing is to check the dogs that hold your log in place. Ironically the smaller the log, the more clamping is required. With a big log, the weight holds it in place and the clamps stop it rolling.

Sometimes a brand new blade may be prone to grabbing because the hook angle is a little aggressive. Again the relatively lighter weight of a small log will increase the susceptibility to being "grabbed."

At least with a bandsaw all the force is exerted at 90 deg to the log whereas a circular saw might try to make an improvised boomerang!

I would think 10 deg hook angle would be fine.

Regards
Paul

I'd be wondering if the log had some foriegn object and one side of the blade just happened to hit it thus removing all the set on that side


Pete

Originally Posted by pjt

I'd be wondering if the log had some foriegn object and one side of the blade just happened to hit it thus removing all the set on that side


Pete

Good suggestion Pete.

If the set is lost on one side the blade either dives or climbs as happened with the first blade.

However, it could well have hit a foreign object (backyard trees are famous for this and the reason why sawmills won't mill those trees) and if that is the case there will be damaged teeth somewhere on the blade, but not for the complete circumference.

Regards
Paul

More often than not with bandsaws, you lose set on one side of the blade more than the other. To my thinking as well, I have a set of 10 degree blades that I only use for softwoods such as pine and paulownia, for hardwoods I use 7 or 4 degree blades depending on what Im cutting. A few degrees doesnt sound like much but 10s would be inclined to bite too much and try to take too much material for the gullets to handle. What this means is your gullets are chockas full of sawdust to an excess, therefore reducing your set to zero even though the blade is set. The leading edge or tooth edge then heats up more than the back and a waving she will go What can also happen if the log has been laying around for a while is the end of the log can have started to dry out and hardened, causing the blade to dive or climb into the log. And not that I think this was what you did but one day my offsider forgot to invert the blade after sharpening and put it on the machine back to front. I got it to cut about 2 feet into the log before it dived and bogged down before I realised it was running backwards

Nifty,
You had me worried, I couldn't remember If I had turned the Blade back the right way after sharpening. I went down to the Shed and checked an I did turn it back the right way. I had a talk to Brad at Henry Bros and he suggested to Bring the Hook Angle back to 8 Deg, This will also take some of the Set off as well. What type of Profiler are you using? I have an Early model Dinasaw which can only go down as low as 8 Deg. I will attempt to try agian next weekend and see how I go. Watch this space!!!!

I use a woodmizer setter and a woodmizer proffesional CBN sharpener. The grinding wheels are the same shape as the tooth and gullet profile so we use different wheels for different profile teeth.

Jon

I can't remember if I mentioned to you that we used a couple of modifications to the standard blade. One was to deepen the gullet as the blade was sharpened. This improved the ability of the blade to clear sawdust. The second was to create effectively a skip tooth blade.

The way the skip tooth was achieved was to set the profiler high and every other tooth had the top ground off. Thus a 3/4 pitch blade now became a 11/2 pitch. This further increased the ability to remove sawdust and was probably, when I think about it, why a hook angle of 12 deg worked ok.

The big disadvantage was that it was yet another operation in the sharpening cycle, although not each time of sharpening. These raker teeth were lowered about 1mm below the cutting teeth.

It was fine for most of the hardwoods I cut except stringybark. For some reason I always had trouble with that timber. I didn't ever try a lower hook angle.

Regards
Paul

Paul,
When you say every other tooth had the top ground off , did you set the profiler to step 2 teeth at a time?

Be careful diving into the realms of making rakers smaller than set teeth and the like at this early stage newjohn, observe machine behavior first with what you have and slowly adjust your blades to suit

Originally Posted by newjon

Paul,
When you say every other tooth had the top ground off , did you set the profiler to step 2 teeth at a time?

Jon

No. Every other tooth was ground down. Sometimes the set teeth. Sometimes the straight tooth. I don't neccessarily advocate it as it is more work in the sharpening process. It was the way John Laidlaw advocated and in those days I went along with it.

He recommended a 1" pitch for softwoods and the 3/4" for hardwoods, but modified in the way I have described.

I had three marks on the profiler for 3/4, 1 and 11/2.

Since returning to bandsaw milling, in my limited way, I have not done this "skip tooth" technique. However I am using the Lenox stellite tips now whereas before I think the brand was Simmonds red streak.

I still deepen the gullies each time I sharpen to increase the ability to remove sawdust.

Regards
Paul

Originally Posted by nifty

Be careful diving into the realms of making rakers smaller than set teeth and the like at this early stage newjohn, observe machine behavior first with what you have and slowly adjust your blades to suit

Yes. I agree with this. Certainly try to work with what you have first. The problem is that a single blade will probably not suit all woods.

In the end my point is not to be afraid to experiment a little. Be aware it will take up a large amount of time, be expensive and often is irreversible if it all turns to s**t .

Regards
Paul

Originally Posted by Bushmiller

Yes. I agree with this. Certainly try to work with what you have first. The problem is that a single blade will probably not suit all woods.

In the end my point is not to be afraid to experiment a little. Be aware it will take up a large amount of time, be expensive and often is irreversible if it all turns to s**t .

Regards
Paul

Couldnt agree more Paul. Being that your saw is homemade, learn its habits and adjust the blade to suit, you cant do it the other way around. Question, have you levelled the blade or as if to say do you know that the blade is hitting the log square?

Nifty I did level the blade when I was origianlly setting up the Mill. I believe it is still OK as I cut the Budgeroo without an issue the Wekend before. After Cutting the Budgeroo I Resawed some Gidgee Flitches . The blade started Diving on the Second Flitch and I stopped for the Weekend
I will kiss Sharpen the New Blade and deepen the Gullet and see how I go this weekend.

Gidgee umm I reakon that would kill a blade pretty quick from whats been mentioned in the past by other band millers, would that be the hardest timber you have to mill Newjon