Band saw throwing blades ?

Thanks all, you have been a huge help. Going to do some reading then get a good new blade, clean the saw really well (especially the wheels and guides) and then go slow and step by step. Even with the problem I must say I am pleased with what this poor thing have been asked to do. Most of the work I cut are 1/2"-1" thick plates (usually 4"-12" wide). Now, the poor thing is cutting (well was cutting until the blade broke) a 7" steel cube, that has one side torch cut, probably making it very hard at the surface.

After thinking about it, (and looking at the several pounds of cutting dust I have cleaned up so far) the poor blade has done a lot of cutting. Time to get a few new ones and see how it goes :)
 
I have a similar saw and have the same problem on occasion.
The first thing I do is to clean & inspect the blade. It often gets a build-up of oils & metal particles. Then check the wheels for similar build-up & clean it off.
If the blade still pops off, closely check the blade for small cracks. That is an indication that it is time for the blade to be replaced.
Beyond that, you need to check the guide bearings for build-up, or failing bearings. If the blade gets bound and stops for the slightest moment, it will pop off the wheels. Also if you are feeding too fast, and binding the blade, it will pop off the wheels.
The blade guides should be set so that they are .001" wider than the blade thickness. Any tighter and you can guarantee that the blade will bind when swarf particles go through, and then it pops off the wheels.

I am currently rebuilding my saw due to the worm wheel wearing out. Once I got into the unit, I found that the mesh of the worm to the wheel was off center by 1/3rd, so this is turning out to be a big exercise in re-machining the gear box in the arm so the gears mesh correctly.
Now that I have purchased all the parts and augmented my tool collection, I could have purchased a new unit for less. But where is the fun in that?

Good luck!

Ray
 
Ray, rogee, Clint, et. al.,

this is one I have some experience. I have had the same saw and have upgraded it several times over a period of about 4 or 5 years. This thing has been abused and it is not a craftsman. Motor is not protected and I can go on ad infinitium.

blades, yes, must not be worn. All of the below is correct, BUT, the top pulley bushing is worn. Remove the top pulley. The shaft is worn and the pulley bushing is worn, the pulley tilts and the blade comes off, and you cuss. Might as well replace the bushing and shaft. To grease this thing, same way. Driven pulley same thing.

cold saw sounds good. Where is it?

Welding blades: takes practice. I bought a carbide tooth blade 1 ft too long. Learned to weld blades. Use a brick backer, low feed and voltage. Keep trying. You are just heating the blade. It will get red hot..stop. Let it cool and bingo.
:phew: $75 less 1 ft used for practice.
mike
now in Remlap Al
 
Thanks for all the advise :) Once I put a new bi metal blade on (14 tpi was all I could get) it started cutting really well (old one must have been worn out, which doesn't surprise me). It did jump off a few times but took my time adjusting the top wheel "tilt" and the down pressure and looks like I got it :) Finished cutting the 7" block in about 30 min

Now, just have to fix the motor, as the inside fan blade either melted or broke off, and now the motor gets really hot after about 10 min cutting. Maybe I can find a fan blade and mount it on the shaft outside the housing, as anythings better than nothing (or spraying coolant on it ... yea I know, not good with powered items). May have to replace the motor, but will wait until I finally kill this one, as they sure are not cheap (and my brand new 1/2 HP probably isnt big enough as I THINK its a 1HP on it, cant be sure no labels)

Again tanks all, you all helped a lot

Edit:

OK, after all the help you all got me thinking about an obvious problem I have had since I got this. The saw will NOT self start, never has. I have to kick start the pulley belt with my palm to get it going. Checked the motor and the internal fan blade IS there and working, so something is putting a large load on the motor. Since its my first saw, Im not sure how stiff the gearbox should be. If I remove the blade and belt should I be able to spin it freely with my hand or is it going to be stiff ?

Again, thanks for helping
 
Well, decided to check it out and the drive mech moved free and smooth. Opened the motor up and indeed the fan blade (plastic) was melted :( At this point just trying to run the motor blew a breaker.


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Time to try the 1/2 HP one I have. Put it on and it cut 100 times better, plus if it jams the motor just sits there (must be a stall protection) and restarts when the jam is free.

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Finished cutting the large lump into blocks I can use (for a new QCTP), and now the saw works like a charm :)

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Thanks all for the help, nice to have a motor that not only works but doesn't overheat after 5 min

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On that large a cut i would get some coolant on the blade some how, you may be suffering some back of the blade heat distortion that could also cause some problems. When i have had a band saw that was throwing blades I would back off or remove the guides to eliminate them until i get the wheels right

have fun

Art
 
Well, wondered that, but every time I use coolant or cutting oil on this saw it stops cutting and just gums up. During the cutting I would hold the top of the blade in my fingers and the blade was cold, probably due to the mid speed I have it on. The last 2 cuts I did today went well, the blade was stone cold and so was the new motor :) Also, havent chucked a blade since, even when the blade bound up. Looks like all the adjustement advise worked and I couldn't be happier :)
 
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