gwr
Established Member
Hi and sorry for asking on the OP,s thread I would like to ask Steve if his tutorial DVD,s are available in any other format. Thanks
bandsaw tracking and tensioning
- Thread starter Noho12C
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CHJ
Established Member
I pay only a cursory attention to the position of the blade on the wheels and set the blade to run 'north-south' in relation to the table alignment with the tracking system that tilts the upper wheel, then any sign of blade starting to drift when cutting indicates that teeth on one side are loosing their edge (maybe due to damage) and it's time to change or sharpen the blade. I personally find any tendency to drift is on a par with 'that blade feels a little blunt' (slow cutting progress) and should be changed.MikeG.":9w5ujun8 said:
On a slightly different tact, as long as I have a blade with enough set to provide clearance for the rear edge of the blade whilst cutting circles (and therefore no tendency to twist it) I never have any problems mixing circle cutting with re-sawing against the fence.
As I'm not into fine (2-3mm) cabinet veneer cutting and surface finish is not paramount I do tend to use blades with fewer teeth and a good set, therefore the rear of the blade is following on behind in the wide kerf cavity not influencing the blades direction of cut.
Gonna check for that DVD ! Thanks for the info !
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Sent from my VKY-L09 using Tapatalk
Interesting thread!
I don't think I get drift on my bandsaw (or maybe I do but I'm too daft to notice it) and I'm wondering if because my machine, an old Kity model has flat wheels.
It got me thinking, what is it that causes drift, is it the alignment of the blade relative to the curve of the wheel's crowned edges?
I'm rubbish at explaining this, so made a crude diagram.
Is this diagram correct...Steve?
I don't think I get drift on my bandsaw (or maybe I do but I'm too daft to notice it) and I'm wondering if because my machine, an old Kity model has flat wheels.
It got me thinking, what is it that causes drift, is it the alignment of the blade relative to the curve of the wheel's crowned edges?
I'm rubbish at explaining this, so made a crude diagram.
Is this diagram correct...Steve?
Attachments
deema
Established Member
There are three types of wheels used in bandsaws, those with tyres, of which there are crowned and flat and those that don’t have tyres, typically Resaws. If you have a crowned wheel, where the centre of the wheel is slightly proud and domed, the blade must be set so that the gullets run just ahead of the crown apace, or the centre of the wheel. This supports the blade and tensions it where it is needed, reduces the wear on the tyres as the teeth will hardly be touching and aids in reducing / eliminating drift. Setting the blade either further forward or further back will increase the amount of drift as the blade teeth are not tensioned correctly WRT to the body of the blade allowing them to twist easier.
If you have a flat wheel, it doesn’t matter where the blade is on the the wheel.
I’ve never heard of a blade being over tensioned, too tight is normally when they snap! It’s very rare that anything over a 1/4” blade can be over tightened by a Bandsaw (not the case with a resaw). It’s better to have too much tension than too little. In any case, too much tension won’t affect the location of the blade, the only thing that will affect its position with tension is the actual rigidity of the Bandsaw. If it’s not very rigid (that’s another way of saying not well built for the job) then it will flex and this will move the blade on the wheel. Typically modern machines can’t run tension for the maximum claimed blade width....usually at least by a 1/4” under what they state.
The three things that are likely to cause your problem are
1. Check the blade, if it moves backward and forward on the wheels when rotated it’s probably not been welded true. Loom for the weld in the blade and you will see that the blade doesn’t run straight, with a ‘kink’ it will not run true in the wheels.
2. The bottom wheel is not aligned properly. A lot of machines have the ability to adjust the tracking of the lower wheel. However this isn’t normally necessary as it’s set by the factory.
3. There is something loose / bearings worn in either or both wheels arrangements.
Drift, a properly setup Bandsaw will not drift. There are a few things that cause it.
1. Not enough tension / blade not set on The crown of the wheel.
2. Guides actually pushing the blade out of alignment - very common.
3. Blade blunt
4. Poor quality blade. The blade has set in the teeth which isn’t even on both sides of the blade. This causes it to cut deeper on one side pulling the blade out of alignment.
5. Incorrect tooth count for the stuff being cut. Typically too higher TPI is used for the thickness being cut. This causes the blade gullets to clog causing drift. The blade will also heat up and blunt very quickly.
If you have a flat wheel, it doesn’t matter where the blade is on the the wheel.
I’ve never heard of a blade being over tensioned, too tight is normally when they snap! It’s very rare that anything over a 1/4” blade can be over tightened by a Bandsaw (not the case with a resaw). It’s better to have too much tension than too little. In any case, too much tension won’t affect the location of the blade, the only thing that will affect its position with tension is the actual rigidity of the Bandsaw. If it’s not very rigid (that’s another way of saying not well built for the job) then it will flex and this will move the blade on the wheel. Typically modern machines can’t run tension for the maximum claimed blade width....usually at least by a 1/4” under what they state.
The three things that are likely to cause your problem are
1. Check the blade, if it moves backward and forward on the wheels when rotated it’s probably not been welded true. Loom for the weld in the blade and you will see that the blade doesn’t run straight, with a ‘kink’ it will not run true in the wheels.
2. The bottom wheel is not aligned properly. A lot of machines have the ability to adjust the tracking of the lower wheel. However this isn’t normally necessary as it’s set by the factory.
3. There is something loose / bearings worn in either or both wheels arrangements.
Drift, a properly setup Bandsaw will not drift. There are a few things that cause it.
1. Not enough tension / blade not set on The crown of the wheel.
2. Guides actually pushing the blade out of alignment - very common.
3. Blade blunt
4. Poor quality blade. The blade has set in the teeth which isn’t even on both sides of the blade. This causes it to cut deeper on one side pulling the blade out of alignment.
5. Incorrect tooth count for the stuff being cut. Typically too higher TPI is used for the thickness being cut. This causes the blade gullets to clog causing drift. The blade will also heat up and blunt very quickly.
Steve Maskery
Established Member
OscarG":1c526meq said:
Ish.
In an ideal world, yes, that is right. But sometimes when the blade is set centrally it still drifts, maybe to do with wear or uneven set. In that case you have to nudge it over fore or aft to compensate for that.
But essentially, yes, your understanding is right.
Steve Maskery
Established Member
gwr":31pfm624 said:
Physical DVDs and MP4 Download. The latter is not automatic at the mo, but email me and I'll sort you out. No delivery charge on Downloads.
MikeG.
Established Member
deema":3w4k76q7 said:
I have a flat tyred wheel. Therefore, the tension of my blade from my co-planar wheels is uniform, and yet the cut runs out. Not only this, but it often runs out with a brand-new blade.....and we're talking quality Tuffsaw blades. I have replaced all the bearings fairly recently, and that made no difference. So I remain to be convinced that drift/ running out is a consequence of the tracking of the blade in my particular circumstance.
Steve Maskery
Established Member
MikeG.":11ytxk8h said:
I wish we'd had this conversation before I came down, it is so much easier to explain on a real machine.
deema":11ytxk8h said:
Ooh, I'm not sure I agree with that, deema, though the rest is fine.
Flat wheels need to be tracked, too. My Scheppach has almost zero crown, and I still have to track it. I aim for the centre, but I don't worry if it is not, just as long as it is running True North.
The reason that flat tyres work is that the top wheel tilts fore or aft according to the tracking knob, so the top of the wheel describes an arc as it is tilted. So the flat surface of the tyre is actually a very short section of an arc. The effect is the same. Because the blade is in tension, it hugs the wheel and because of the angle of the wheel the teeth are either slightly to the right or slightly to the left of the back of the blade, which is why the blade drifts.
It is so much easier to explain in the flesh.
Incidentally, a number of manufacturers recommend that the teeth ride just off the front of the tyre. I've never understood that and I have no idea how you get that and have a True North cut as well (although I do recognise that some people sat that they do, and that is fine and dandy by me). I have approached a number of BS manufacturers and resellers about this and none of them has been able to give me an explanation. "It's always been like that" seems to be the "reason".
powertools
Established Member
Well all I am going to add to this thread is that I have both an old Inca and old Kity bandsaws both are set up as per the manual that came with them and I use both of them with the fence and mitre guides that came with them. The only time that I have had issues with either straight cutting or curved cutting is when the blade is blunt, the blade is to fine for the thickness or I have been trying to feed the wood to fast.
powertools
Established Member
For MikeG.
I notice that you have just been given a bandsaw blade that is 14tpi. What thickness of material do you intend to cut with that?
I notice that you have just been given a bandsaw blade that is 14tpi. What thickness of material do you intend to cut with that?
MikeG.
Established Member
That will get saved for stuff like thin ply, or maybe even perspex. I'll be making clock gears in a year or two...it might get saved for then.
I often use my UJK mitre fence on my axminster bandsaw.
The first time I set my bandsaw up I did the "freehand follow the line, stop the machine, adjust the fence" routine.
Since then (3 years now), The fence isnt moved and if the blade pulls the wood away or pushes it in, I adjust the blade.
I've made a study of bandsaws for the last 5 years and the most common fault is the operator pushing the wood too fast (its all those speeded up utube videos).
The blade should determine the speed of cut. Watch the guides, if the blade suddenly deflects into a guide, youre pushing too hard. If the wood starts to burn, its either a blunt blade or youre not pushing fast enough.
Second is having the blade too taut. Its not a violin string after all.
The first time I set my bandsaw up I did the "freehand follow the line, stop the machine, adjust the fence" routine.
Since then (3 years now), The fence isnt moved and if the blade pulls the wood away or pushes it in, I adjust the blade.
I've made a study of bandsaws for the last 5 years and the most common fault is the operator pushing the wood too fast (its all those speeded up utube videos).
The blade should determine the speed of cut. Watch the guides, if the blade suddenly deflects into a guide, youre pushing too hard. If the wood starts to burn, its either a blunt blade or youre not pushing fast enough.
Second is having the blade too taut. Its not a violin string after all.
