Setting up a bandsaw?

[natenaaron]

I borrowed a 7x12 metal bandsaw Brand name probably came off twenty years ago.  It is old and according to the owner bullet proof.  His blade was trashed and one condition of borrowing it was putting a new blade on it.  In the grand scheme of things this was not a bad rental fee.  New blade is on but I can't get a straight cut to save my life.  I have squared the clamp with the cut line.  Then squared it with the blade.  I am using a precision machinist's square.  The blade is taught, the saw is not loose in the brackets.  The material is square.

I am at wits end.  Any thoughts?

[Anachronist58]

Post an image? I can't make it out from here.

Robert Taylor

Does the machine have a tracking adjustment?

[natenaaron]

It tracks just fine but yes there is a tracking adjustment.  Yes I inverted my shop just to take the images.

[John B]

Do you use a coolant flow onto the blade whan in use? Heat generated can allow the blade to flex and wander, also blades have to be 'run in' gradually when new or that can cause problems, 

Minimum clearance between supports is necessary, and an appropriate toothed blade for the material size and type being cut.

All roller supports and bearings should be incorrect situ and good working order, 

The one I have to use is a PIA, blade keeps jumping off even when everything is set up as per manual, and when new ones fitted, 

Good luck with sorting it, I even checked  the play in the main pivot point, it still jumps off and wanders. 

[BIGGUNDOCTOR]

I have seen blades put on backwards that still cut. 

Too much downfeed pressure

Side rollers not tight against the blade

Rear roller set too far back so the pressure pushes the bade in between the side rollers and wiping out the tooth set. 

Check the vertical blade travel with a square to see if the whole head is moving on an angle. 

 

[Alan Evans]

Are you expecting too much precision? Have you contacted the owner to compare notes...get him to come and set it up.

Are consecutive cuts parallel or is it wandering erratically? If the cuts are constant you should be able to adjust alignments to present the metal square to the blade.

Is it cutting vertically or wandering sideways as it goes down?

How did you set the tension on the blade? If over tight you may have flexed the frame and taken the idler wheel out of line with the main spindle.

Is the section of the blade between the guides straight? If it has a twist in it...as the carriage drops the contact line of the blade changes. On my saw the guide rollers are mounted on a block which can be rotated to adjust any twist out.

Have you set the fence/fixed vice jaw perpendicular to the blade, and checked it is still square at different heights through the drop arc?

Is it the right size blade for the saw?

I was given an old Elliot saw years ago, which I still have...lovely old thing...It came with a 1/2" blade fitted and a roll of Starret 1/2" blade which I would cut to length and splice into loops with silver solder. I used it for years like that. It was not very accurate...until I visited a friend with the same model saw and realised that it was designed for 5/8" blades...all the time the teeth had been going through the guide wheels and of course the back edge of the blade was not guided at all! I just assumed it was the correct blade and that is how it worked! Hey Ho.

Alan

 

[NickOHH]

With bandsaws you must compensate for drift caused by the blade twisting a little bit as forward pressure is put on it that must be compensated for. take a peice of something metal plastic some kind of sheet , draw a line and push it straight, this shows how much it wanders, if your setting up a rip fence you would want to angle it that much to get a straight cut.

[Alan Evans]

7 hours ago, NickOHH said:

With bandsaws you must compensate for drift caused by the blade twisting a little bit as forward pressure is put on it that must be compensated for. take a peice of something metal plastic some kind of sheet , draw a line and push it straight, this shows how much it wanders, if your setting up a rip fence you would want to angle it that much to get a straight cut.

Ah, I think you are talking about using the bandsaw in a vertical position like a wood one with a table. I thought the OP was talking about using it in the horizontal position with the vice as a cut off saw.

My old Elliot will do both. You can bolt a table onto it when it is lifted into the vertical position like in the OPs photographs.

Which is it natenaaron? A problem in vertical or horizontal mode?

Alan

[Frosty]

There isn't a platten on the saw in the pictures so I don't think he's talking about using it vertically.  The blade guide needs to be moved in as close as will clear the vise. the blade tension may be too loose, I tighten mine by ear to a musical tink, just don't get carried away. I don't see a coolant line of nozzle so it probably doesn't use liquid coolant.

The most common operator error I know of with a cut off bandsaw is too much down pressure. Even an old worn to sloppy cut off bandsaw will cut pretty straight if you feed it slowly enough. Try backing the feed speed way down.

I wouldn't start adjusting the machine's set up till I got the operating adjustments correct and talked to the owner. Messing with the machine's set up adjustments, guide roll tilt for instance, before you know specifics can have you chasing ghosts.

It's pretty hard to trouble shoot these machines without being there. You might be able to find an operator's manual online. Getting the machine's set up right is pretty universal for these machines regardless of make. different makers might do things a little differently but the needs of the band are the same. For example, They all have to twist the band from the drive wheel orientation to vertical past the vise, all the guide rolls nafe to be snug against the blade but not binding tight. etc. etc. Anyway, an operator's manual for any of the better machines should have enough basic info to get this one online.

Frosty The Lucky.

[NickOHH]

4 hours ago, Alan Evans said:

4 hours ago, Alan Evans said:

Ah, I think you are talking about using the bandsaw in a vertical position like a wood one with a table. I thought the OP was talking about using it in the horizontal position with the vice as a cut off saw.

My old Elliot will do both. You can bolt a table onto it when it is lifted into the vertical position like in the OPs photographs.

Which is it natenaaron? A problem in vertical or horizontal mode?

Alan

Most of my bandsaw experience is with vertical bandsaws , but wouldn't blade drift still be an issue to deal Ruth in either position? It's a shorter cut so it wouldn't walk as far, but the blade still has a certain amount of twist to it, every blade is different . Feeding to hard would also cause a more dramatic effect. It would be my thought that as long as there's a band there would be twist, and where there's twist it won't cut straight .

[1forgeur]

Looks like a Carolina saw. It sure looks like mine other than color. Maybe look them up, I know they have a web site, or did. Mine uses a 3/4 x115 inch blade. Mine has a small air cylinder on it with a valve to control the down force. I don't see one on yours, so like Frosty says it may be coming down too hard. I always cut real slow on mine. If you go to the web site they have parts lists for most all the saws they made. I only use mine for wide thick stuff.

[Alan Evans]

7 hours ago, NickOHH said:

Most of my bandsaw experience is with vertical bandsaws , but wouldn't blade drift still be an issue to deal Ruth in either position? It's a shorter cut so it wouldn't walk as far, but the blade still has a certain amount of twist to it, every blade is different . Feeding to hard would also cause a more dramatic effect. It would be my thought that as long as there's a band there would be twist, and where there's twist it won't cut straight .

Yes I quite agree...but we still have not heard from Natenarron whether the problem is in the angle of the vice to the blade i.e inaccurate when looking down on the cut or whether the cut is not coming down vertically through the workpiece which is where your  point would come in.

Alan

[Frosty]

22 minutes ago, Alan Evans said:

Yes I quite agree...but we still have not heard from Natenarron whether the problem is in the angle of the vice to the blade i.e inaccurate when looking down on the cut or whether the cut is not coming down vertically through the workpiece which is where your  point would come in.

Alan

Nate said he used his machinist square to set the vise but maybe not in the vertical plane. When bringing mine back to 90 from making angle cuts I clamp my machinist square in the vise and gauge against the outside of the blade. It's the most accurate method I know of with out having the specific too. It's also THE way to make sure it's set to THE correct angle, use the protractor head  of course.

Frosty The Lucky.

[Alan Evans]

I took the protractor head off mine (which was not the proper original one) and made a higher and longer one from 100x25mm (4x1") which I set with a square reading off the teeth of the blade.

Alan

[Kozzy]

Most wander on mine comes from too much down pressure. It'll cut reasonable square with a slow feed rate but gets quite wonky with high feed rates. 

 It's also important (read that as CRITICAL) to use a good quality blade rather than the cheapest home center blade you can find.  

Finally, if the chips are clearing poorly from the blade teeth that can increase wander--you might have to brush the blade a bit to knock any "riders" off before it returns to the kerf.  Some people use cheap dollar store toothbrushes for this and even drill a hole to mount them on the saw.

[Frosty]

Good points all. Good blades are important. use either variable pitch or follow the rule of thumb for saw blades. Optimum is 3 teeth on the work at all times. If you're cutting 1/2" thick material the ideal TPI is 6. You're unlikely to find blades that coarse so variable TPI blades work well or as well as can be expected. Do NOT use too fine a blade the cuttings can't clear and if you're lucky only float the blade and it'll hardly cut. Soooooo the intuitive reaction is to increase down pressure (feed rate) to make it cut. Then the cuttings can't clear and gall jamming the blade in the kerf. Either the blade will slip on the drive wheel or snap. To get too fine a blade to cut you have to do the counter intuitive thing and reduce the down pressure (feed rate)

Most band cut off saws have a brush wheel clearing the teeth just before it enters the cut or like mine, just after it leaves the cut. Your best bet for cutting properly is the right TPI blade, go too coarse rather than too fine. You can't use too low a feed rate (down pressure) I cut exhaust pipe, 16ga. in mine with 14tpi blades by feeding it SLOWLY.

Do you listen to your saw when it's working, do you understand the band saw's language? When the blade is working it has a distinctive sound a grinding hiss, if it starts to drag the motor down or really sounds like it's grinding it's feeding too fast. If the blade starts singing it's in pain you're feeding it WAY too fast. If it's chattering the vise is either loose or the piece isn't in square or doesn't have enough points of contact with the jaws to prevent vibration. Lugging motor, grinding blade, singing blade, chatter are all signs your saw isn't set correctly.

I do NOT use the water feed because I use coarse, multi pitch blades and feed slowly. This allows the blade to clear the cuttings from the kerf which is what the water soluble oil is for, NOT cooling, clearing out cuttings. Sure my saw COULD cut a little faster but it works nearly perfectly dry and there is an entire system I don't have to worry about failing or have to clean up after.

That's it, as coarse a blade as is available, feed it SLOWLY and pay attention to what it's telling you. Seriously few power tools speak as clearly as a band saw.

Frosty The Lucky.

[Alan Evans]

1 hour ago, Kozzy said:

Finally, if the chips are clearing poorly from the blade teeth that can increase wander--you might have to brush the blade a bit to knock any "riders" off before it returns to the kerf.  Some people use cheap dollar store toothbrushes for this and even drill a hole to mount them on the saw.

On a couple of saws I have seen there were neat little star wheels with spikes that were both driven by, and cleaned the teeth as the blade passed. They were set just after the rear guide.

The OP still hasn't come back to tell us whether the inaccuracy was in the horizontal or vertical plane so whether it is vice alignment or feed speed wobble we don't know.

Alan

[Kozzy]

I started to mention those wheel brushes and deleted it because it was a borrowed saw and I figured it might just start confusing the O.P.  Yes, that work great if you can retrofit that to the system.

I tend to use a coolant wash myself but as Frosty said, it's a pain and can leave a mess.  Also, if I don't use the saw for a while the coolant evaporates and leaves a gummy mess that has to be dealt with before using it again.  I use water based and not oil because oil is just too messy for my shop (saws ALWAYS lose a little coolant).