Bandsaws and their blades

[Simon Williams 3Participant @simonwilliams3]

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.

[Enough!Participant @enough]

Posted by Simon Williams 3 on 27/10/2017 19:36:37:

But it's other job is cutting say 50 mm round EN8 or similar, and I find the blade jams in the cut. It maybe it needs replacing, but there's sharp teeth on there still, I want my money's worth. If I drip suds onto the cut it helps, but its a faddle to do and it makes a mess.

How do others get on with these blades – do you use coarser blades?

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.

[Mark RandParticipant @markrand96270]

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.

[Douglas JohnstonParticipant @douglasjohnston98463]

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

[Raymond AndersonParticipant @raymondanderson34407]

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.

[Ian S CParticipant @iansc]

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

[RobinParticipant @robin]

Does this look excessively greasy?

[charadamParticipant @charadam]

Yes, that is an excessively greasy digit.

 

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

[larry PhelanParticipant @larryphelan54019]

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?

[Simon Williams 3Participant @simonwilliams3]

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.

[Neil WyattModerator @neilwyatt]

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.

[charadamParticipant @charadam]

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.

[not done it yetParticipant @notdoneityet]

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

[Danny M2ZParticipant @dannym2z]

Posted by not done it yet on 29/10/2017 07:55:48:

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 *

[RobinParticipant @robin]

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

[charadamParticipant @charadam]

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.

[Danny M2ZParticipant @dannym2z]

Posted by Robin on 29/10/2017 09:48:33:

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

Robin, this seems that your blade is too wide as my 6×4 bandsaw blades are more like about 1/2 inch wide. Here is a linky that may be helpful. **LINK**

* Danny M *

[RobinParticipant @robin]

I just drove over to my workshop, tape measure and writing stick in hand. I wiped away the grime of ages to reveal two name plates. There was no blade size so I also measured wheel diameter and separation…

It is a Sealey SM35CEv4 300mm band saw.

The blade size is 93" x 3/4" x 0.81mm so my estimate was a bit dodgy but whaddya do?

In my absence the local denizens have been using it minus the top blade guide and assure me the blade stays on fine and dandy. As the top wheel is currently carrying the blade on it's outside rim, gasp, I rather doubt this is actually the case.

The wheels have a 16.2mm wide flat to support the blade. The strange groove (anomalocanalis?) would accommodate the teeth on a 3/8" blade width

[charadamParticipant @charadam]

I wonder – whatever happened to good old Martyn Duncumb – the OP?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by charadam on 29/10/2017 17:51:06:

I wonder – whatever happened to good old Martyn Duncumb – the OP?

.

It appears that he got the information he wanted, and thanked everyone that had helped.

[quote]

Posted by Martyn Duncumb on 26/10/2017 20:25:44:

Many thanks everyone. Thought that might be the position and am now clear to make my choice.

Martyn

[/quote]

MichaelG.

[RobinParticipant @robin]

I do get a bit carried away and I will confess to being an opinionated old git. If I transgress it is quite okay to tell me to shut up. I am quite used to that so I probably won't shut up, but you might feel better for doing it

[RobinParticipant @robin]

I think I have it, even managed to jam the blade mid-cut without it coming off

Close inspection showed that the tilt on the top wheel is limited by the 2 screws above the tilt adjustment screw.

I took the belt tensioner mechanism apart and it became obvious. Was a proper load bearing pivot really that difficult to achieve?

Once I understood it was easy to add extra tilt and keep the blade in place.

[KWILParticipant @kwil]

Just out of interest, in all the years I have used a 6×4 bandsaw, I have never lubricated the blade. Just keep it clean and properly tensioned and tracked. Use good quality blades and let the saw do the work at the correct pressure.

[larry phelan 1Participant @larryphelan1]

Perhaps I am just lucky,but I bought one of those cheap bandsaws many moons ago [20 years,perhaps ?],and it has never given me any real trouble. I use a 14 TPI blade most of the time and never bother changing the speed. The guides did need to be adjusted early on and the Chinese motor does get fairly hot on long runs,but the Good Book says that this is "Quite normal",and not to worry about it,so I dont. I have cut everything from RSJ to 6mm round,same blade,same speed,same result.

I do have wood cutting band saw,which did give a lot of bother,due to the wheels not being in line and broke many a blade.Time spent tracking the wheels cured that problem,but it re-appeared a few times over the years,and that saw was not made in China,but a lot nearer home !

I t would be well worth while spending a little time with your saw,there is not a whole lot that can go wrong with them which cannot be fixed and they give great service [a good make of blade helps ].

Play around with it before you scrap it.

[Author]

Posts