Portable Bandsaw Cutting Crooked

crocogator106

crocogator106

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I have a second hand Milwaulkee 6230 portable band saw and have it mounted on a SWAG Offroad table. My issue is the saw will not cut a straight line even when using the fence and the miter gauge. I'm not very familiar with these saws but when I am cutting, the top (front) pulley guard moves up and down slightly. This may be normal but I'm not sure. When I put pressure on the blade when cutting something, I can hear a "clunking" noise every blade rotation and with continuous pressure and cutting the "clunking" noise gets worse and the blade will come off. Any ideas? Thanks
 
Have you put a square or 123 block against the blade to see if it is square to the table top? I would guess that it does not sit perpendicular to the table top.
 
Check to be sure the blade is centered on the guides, I had one that the blade would slip in beside one of the guides.
 
I will try that but I don't think that's the problem. The blade is all over the place when cutting and not just off in one particular direction. I have checked the tension and it plenty tight. I've read where it could be the roller bearings.
 
The way to diagnose this is to look at how the saw works.

The drive wheel should be rock solid and have no play. If this wheel wiggles, the bearings are shot.

The top wheel ( idler) should have play whit the blade off, but when tensioned tight should not wiggle. Bad bearings, broken tensioner, bad wheel ... all can be a problem.

The guides should only allow sufficient clearance for the blade to pass through. Often the guides are at an angle to the blade path to "twist" the blade. This is to allow a wider cut, and is normal. Replace if worn out. Adjust if needed, make sure they are locked down tight after adjustment.

The table should be at 90° to the blade.

The Blade - The blade needs enough teeth to have several in the steel at any one time. If a blade cuts in an angle/curve line, it is almost always because the teeth have been damaged on one side by trying to cut a curve. While we all wish that a band saw could jut every curve on our blade, the truth is they are made to only cut straight lines. We can force them to cut curves...but that greatly shortens the life of the blade and the saw. It is better to cut things in a series of straight lines and blend them into a curve on the grinder or with files.
The "CLICK" sound every rotation is usually a sound caused by a bad blade weld or a bad spot in the teeth ( most likely). Sometimes you can straighten the bad teeth with a pair of pliers, but in many cases the blade will eventually break, or you will toss it.


That said, most metal cutting band saws seem to wander to one side in the cut. Don't push too hard, and let the saw blade do the cutting. Also, better blades cut better. Lenox, ands similar, Bi-metal blades are great. Try and avoid twisting the steel to make the cut change direction. This can really damage the blade.
 
The way to diagnose this is to look at how the saw works.

The drive wheel should be rock solid and have no play. If this wheel wiggles, the bearings are shot.

The top wheel ( idler) should have play whit the blade off, but when tensioned tight should not wiggle. Bad bearings, broken tensioner, bad wheel ... all can be a problem.

The guides should only allow sufficient clearance for the blade to pass through. Often the guides are at an angle to the blade path to "twist" the blade. This is to allow a wider cut, and is normal. Replace if worn out. Adjust if needed, make sure they are locked down tight after adjustment.

The table should be at 90° to the blade.

The Blade - The blade needs enough teeth to have several in the steel at any one time. If a blade cuts in an angle/curve line, it is almost always because the teeth have been damaged on one side by trying to cut a curve. While we all wish that a band saw could jut every curve on our blade, the truth is they are made to only cut straight lines. We can force them to cut curves...but that greatly shortens the life of the blade and the saw. It is better to cut things in a series of straight lines and blend them into a curve on the grinder or with files.
The "CLICK" sound every rotation is usually a sound caused by a bad blade weld or a bad spot in the teeth ( most likely). Sometimes you can straighten the bad teeth with a pair of pliers, but in many cases the blade will eventually break, or you will toss it.


That said, most metal cutting band saws seem to wander to one side in the cut. Don't push too hard, and let the saw blade do the cutting. Also, better blades cut better. Lenox, ands similar, Bi-metal blades are great. Try and avoid twisting the steel to make the cut change direction. This can really damage the blade.
 
Stacy - Your responses are always so insightful, its wonderful to be able to read them twice!! :p

Blade tension... maybe? I'll bet the "click" sound is due to either a slight bend in the blade or damaged teeth or bent teeth.

-Peter
 
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When does it clunk? Sometimes the joint of the blade will clunk as it passes through the blank. Also, if your fence is parallel with the blade, you'll never cut a straight line, ever. Every saw I've ever seen requires the fence to be offset slightly, but that's mostly wood saws. My portable band saw is never used for straight lines, so I.have no idea on that.
 
Thanks for all the replies and possible solutions. Stacy, I checked all the drive wheels and they seem to be as you described so I think I can rule out bearings (thank God-lol). On the top or front guide the blade has alot of tension on it on the bearing facing the inside of the saw. So much so that the blade is not straight (or twisted). I really think this is my issue. I think I should align both the top and bottom guides so they are inline with the blade. The blade is brand new but is a cheaper Milwaulkee blade I got from a big box store. It also has 18TPI. I am cutting 6061 aluminum now but I am usually cutting A2 or CPM154 with it. After reading you guys responses I think the clicking is the weld on the blade going through the guide with all the tension on the blade. I am going to play with it some later this evening and try some of everyone's solutions. I really appreciate all the help from everyone. One of the reasons I love this forum. I will post my results in case anyone else has this type of issue.
 
The 2 bearing on the sides of the blade should be, well, on the side of the blade before you tension the lever. The bearing behind the blade will be in use when you load the blade when cutting. You will get really frustrated trying to get the blade against all the bearing at once. Position the blade between both seats bearings and lock her down. I still guess that your blade is not perpendicular to the table in the x and y.
 
For thin stock, you want a very high tooth-per-inch count. The rule of thumb is at least three teeth in the work at any time. This is so the teeth take only small bites, and don't bite off more than they can chew, literally -- they break off easily if you have low-tooth-per inch blade. I'd look for a 24-tooth blade.

With a bandsaw, the blade IS the tool. As mentioned, ordering some better-quality blades will probably help with not only the quality of the cut, but the life of the blade. I agree - Lennox blades seem to be a decent balance of price and life.

For the kind of work we do, which has curves, a wavy-kerf blade cuts a wider path through the work, and allows a tighter curve. I'm fond of them when I can find them.

Bandsaws are awesome, but they're not magic: lighter-duty saws will only cut so fast, and pushing harder just makes them harder to control. Think of it as more like a file and less like a light saber. :) If it's not cutting, your blade is dull and no amount of pushing will make it cut.

Also, get yourself a stick of wax lube. I bought my first one about 25 years ago and it cost $9. I just bought it's replacement last year. The one I use comes in a tube the size and shape of a grease gun cartridge. The search terms is "cutting and tapping lube stick". With religious usage (every cut, every time -- especially on steel, which can overheat a blade) using a proper lube will double or triple your bandsaw blade life.
 
Most of the time the blade pops off from too much pressure "User problem" slow down a bit and let the blade cut. Clean off and ruff up both the drive and adjustment wheel, give the blade something to adhere to. Also look for Krud build up behind the blade (At the table) that prevents it from seating to the back of the drive wheels. Mine also has adjustment on the idler wheel to adjust the blade pitch to ride against the back of the wheels. Finally mine (Not sure about yours) has offset adjustments on all the guide bearings that keep the blade in place.
The blade should ride centered just barely making contact with the guides.
Cut a bunch of straight lines twisting the blade is not a good thing. Good advice in the above posts just reinforcing it.
These work very well on my 16yr old HF bandsaw: http://www.mcmaster.com/#4179a467/=u42ovy
Ths "Thunk" as has been said crappy weld at the blade joint or missing teeth, ask me how I know this. Happens even in new blades they mess up the HT for an inch or so.
 
I think I got it straightened out. I got some new Lenox blades first off. There is no way to adjust the alignment wheels (bearings) so I just took both of them off and cleaned them and put on a little oil. I also checked and my blade was 3 degrees off from the fence so I just adjusted the miter gauge to compensate. The blade is still about 1/4 off from the x-y positions but I am now cutting straight lines. Also I use a little 3in1 oil on the blade before cutting and the blade runs MUCH smoother and cooler and no "clunking" sound. I'm also using much less pressure on pushing the stock through. They are still not perfect cuts but pretty darn close. I just make about 2 passes on the cut end on my grinder and I've got a perfect line. Thanks everyone for all your help and suggestions. I think I used a little of everyone's advice.
 
We have a similar porta-band setup in the shop. One thing I've noticed that has not been mentioned yet...one of the signs that the blade is getting dull is that it will pop off the wheels when cutting
 
Fishinbo said:
If you have set up your band saw properly, it's a dull blade or cutting speed.
Click to expand...

I got the saw second hand and have not changed or altered the saw. How do you set up the saw? I tried to do a search on YouTube for that when I first got the saw and found lots of videos on setting up different tools but no portable band saws.
 
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