Bandsaws and their blades

Wheels should be dry and clean, no grease allowed. Ditto belt non-slip. This could be yer problem. If the blade stalls on the wheels, off it comes. Guaranteed.

Rgds Simon

I can't keep it dry and clean, it has a suds pump that keeps it wet and greasy

Ah Hah! What are you running in the "suds"? Mine copes with water/soluble oil mix if it isn't too oily, but if I use anything actually oily off it comes. But then mine hasn't got a built in suds pump, it's only the cheapo version.

Can I suggest you nobble the suds and try it dry?

I have tried it dry, I have tried wiping the wheels and the blade, maybe I should get some Gunk and wash it out? Haven't tried that...

Going back to an earlier post, mine won't hold the blade if the set is damaged, however sharp the teeth. Have you tried a new blade? Sounds to me as if the blade is stalling, so is it because the blade to wheel friction is impaired, or is it that the resistance from the work piece is excessive? (Or perhaps both).

Certainly worth trying with the wheels de-greased - any solvent will do - but if the blade is worn (not just blunt) you may have more than one problem. If the blade is worn and greasy, and not entering the kerf vertical, then you have at least three problems.

When the blade comes off, is it jammed in the kerf like mine is, which is down to failure to clear the swarf, or is it free in the cut, which would imply either lack of drive friction or out of true in the drive frame.

I use Starrett 10/14 variable pitch blades (bimetal, cobalt) for everything, with a wax-stick for lubricant. The blades last me a long while in my usage and the only time I have trouble with them snagging/jamming is if my setup has been dodgy to start with.

very long post. Sorry...

Two answers to different posts:-

Blade pitch:- There should be a minimum of three teeth in the cut and as few more as possible. Anything less than a 10/14 variable pitch is only really useful for cutting thin tube. That pitch will do for the thin stuff if you have a very light feed on the 4"x6" saws or a slow hydraulic feed on the 7"x12" saws. I tend to use an 8/12tpi blade for most work and a 6/10tpi blade when cutting more than 3". Obviously, most of the time I use whichever blade I put on last if it's just a single cut, because even a slow cut can be quicker than changing the blade.

Tracking:- It doesn't hurt to clean the wheels, guides, guards, etc every time you change the blade. Woodspoiling bandsaws usually have soft/rubber/polyurethane wheels because they get used with narrower blades that end up with the teeth riding on the wheel. A hard wheel would destroy the set of the blades in short order. Horizontal metal cutting bandsaws don't get abused into cutting circles, jigsaw pieces etc. so they can use blades of the same, larger, width all the time. A metal wheel lasts far better, especially if any coolant is used. Once the tracking has been adjusted so the blade runs lightly against the flange of the driving wheel, the next adjustment is the roller guides.

On the 4"x6" saws, with a single bearing on each side, adjust the guides so they're tight, less a smidge. You need enough clearance so that the weld can get through, any trapped swarf won't stall the blade in the guide and the bearings will last for at least a few blades. For the 7"x12" saws with two bearings side by side in the guides, it's simpler. Adjust the guides so that one bearing of each pair is firmly gripping the blade and the other one can be stopped by firm finger pressure. That'll give you good guidance of the blade without overloading the bearings.

The last adjustment is the blade tension. A saw with any pretensions to industrial use, will have a tension gauge, but the 4"x6" and 7"x12" saws we folks use don't tend to have that. For our saws, the correct blade tension is approximately "As tight as you can get it with one hand on the knob. Trying quite hard really!). after setting the tension, run it some more with the cover open, because the frame will probably have bowed a bit. Once you've got it running cleanly at this tension, it's unlikely to slip off the driving wheel unless you've managed to stall the blade, and that's less likely with the correct tension.


As for coolant choice, because my saw can go for a while without use and because I use it on my lathes, I use ISO46 cutting oil in the 7"x12" bandsaw. I only use it when cutting more than 1" section steel. Everything else gets cut dry. The soluble coolant I use on the surface grinder is enough of a hassle on that machine and I don't want two sets of tanks to worry about rancid coolant in. To be honest, once I've got the permanent airline and compressor setup I hope to install next year, I'll convert the bandsaw to a minimum coolant/mist setup.

I have had a 4 by 6 bandsaw for many years and went through the problems of blades coming off the wheels. After a careful adjustment things worked well for years then a particular blade kept jumping off the wheels again. After checking everything, the blade just would not behave itself and I changed the blade. The new blade worked perfectly and it was only when I was putting the dodgy blade away that I noticed that it was a bit longer than my other spare blade.

​ The problem was the tensioning mechanism had reached the end of its travel before the correct tension was achieved. Since I tension the blades as hard as I can with one hand I was fooled into thinking the blade tension was correct, but it was still slightly slack and the blade would run for a while then fall off the wheels.

​ Now this is where I have to come clean and confess that it was my fault since I make up my own blades from a 30m reel bought off ebay some years ago and I must have made an incorrect measurement. These reels, even if bought at full price, are a good cheap(ish) way of getting blades, they just need to be silver soldered with a scarf joint (see youtube ). I have never had a blade break at a soldered joint despite the high tension I use on the blades.

Doug

Bandersnatch, I've never used the blades you linked to but, use the Intenss constant pitch [10] Great blade life, and nice clean cut. I have tried other makes in the past but I find Starrett ones the best [ for me ]

Cheers.

On my 6 x 4 band saw the free running pulley is adjustable for tilt, also that pulley is the adjustable for length one and it needs to be free from wobble in the slide slot, get that end right and you are well on your way to keeping the blade on. Make sure the blade is well tightened, the only hint my instruction book says , tighten until the blade makes a musical note when plucked, but it doesn't say which note.

Ian S C

Does this look excessively greasy?

Yes, that is an excessively greasy digit.

Edited By charadam on 28/10/2017 19:08:21

I have a chepy cheapy Taiwan bandsaw,had it for the last 12 years or more and no matter what I do,I can,t make it act up ! It just goes on and on,day after day,cutting this,that,and the other.Blade refuses to fall off or stall,or even cut out of true.

Any ideas what I can do to correct this?

Why is there a line of greasy stuff about 2/3 across the wheel?. Is this where the teeth of the blade are running?

I wouldn't expect to see the teeth of the blade contacting the wheels at all, this will knock the set off the blade. This says to me that the blade is too narrow. And I can't help feeling that the friction between the wheel and the blade will be impaired if the blade doesn't sit flat on the wheel, with the teeth overhanging the edge.

Seeing as I brush neat cutting ooil onto my blade and it doesn't make it slip or come off, I don't think grease is the culprit.

Seriously this time - what is that apparent groove in the pulley surface?

If it is a groove, it has reduced your friction area by around 10%.

Maybe enough to permit blade slip.

Maybe that groove is to allow different width bands to be used? Teeth of narrow band running in the groove?

Nooo way! If the narrow blade runs a little off track the kerf will be f**kerfed

* Danny M *

I am starting to feel almost hopeful...

The blade is about an inch wide, it overhangs the entire face of the wheel and the suspicious groove. I have ordered a can of gunk I am going to clean the groove out and the wheel face

The blade tension is set 700-900 kg. They don't say if this is the blade tension or the pull on the wheel. Luckily you do it by taking up the slack then adding 2 full turns. This after 2-3 minutes run time at one and a half turns which they estimate as 800 kg.

Clear as mud, one and a half turns is 800, two turns is 700-900 kg. At 0.9 metric tons I would estimate the musical note to be in the high ping range

I imagine the first part of the tensioning sequence is to allow the blade to stretch and settle on the wheels and the second part is to set the optimum working tension.

My own saw works at high ping also.