Recommendation? Band saw maintenance and modification?

K

kbright

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Jun 27, 2004
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I'm not a machinist, but I've been making knives as a hobby for many years.
I have a JET horizontal metal cutting bandsaw, which is modified for vertical use with a table. I'm having a problem with the blade popping off the wheel. This usually happens when I'm pushing hard, and happens with wood or metal. Also full disclosure, I'm a cheap sonofabutch and keep using old blades, dull and missing teeth. I have tried playing with the blade tension but that doesn't help.

I want to keep the blade from coming off.
Do I need to adjust my alignment of the wheels with my roller-bearing blade guides?
Do I need to use better (new) blades?
My wheels are metal, should I add a rubber liner on the wheels?
Is it speeds and feeds? (I don't think so)
Should I junk this Piece OS? Buy a new (cheap) one?
... other comments?

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Once a blade pops off it twist and will not track true after that . You might set your tracking guides closer to your work . Most people leave them wide .Just replace your blade when you need to. WB
 
Here is what is happening:
When you push hard the blade slows down above the piece being cut.
Added to that the missing teeth "catch" the piece being cut and momentarily stop the blade. While all this is happening, the drive wheel is pushing the blade up toward the top wheel.
The blade around the top wheel is now being pushed from one side and back pressured from the other.
It becomes slightly loose and pops off.

On almost all 4X7 and similar Horizontal/vertical bandsaws this is a constant problem. Short of spending $1000 or more to get a commercial metal saw, there isn't too much you can do to prevent this problem. Using the right blade with the right number of teeth helps, but even a 24TPI Lenox blade will pop off. Many folks get good service from the cheap HF blades. Using worn out or damaged blades is foolishness.

Ways to deal with it:
1) Get used to putting the blade back on.
2) Use newer blades in good condition. If a blade is damaged, it will pop off much easier.
3) Tighten the crap out of the tension. Making a larger wheel to tighten the blade helps. You can cut out a 6-8" circle of plywood and bolt/epoxy it to the tension wheel to give better grip and more leverage. An old 6-8" lawnmower wheel can be used to do the same thing. Shop savvy people can come up with other ways.
4) Angle the top wheel back so the blade runs against the back rim of the wheel. This tends to keep it on the wheel a bit better.
5) When the blade pops off after all these hacks, refer to #1.

One great solution is to keep an eye out for an old cast iron Craftsman or other make bandsaw that has a separate motor and a V-belt drive. A 12" or larger model is what you want.You can switch the motor out for a 1HP 3Phase motor and a VFD and make it VS. Put on a 18-24TPI metal blade and saw away at whatever speed is best for the thickness and type of metal. Put on a wood blade and raise the speed to cut up handle material. These old saws can be found anywhere from free to $100.
 
Take a Dremel and grind a half moon where the teeth are missing to let it skip that portion of blade. Change the small table. Get a 7 by 10 /4 inch piece of metal, saw a straight line down the middle to house your blade and match holes to mount.
I find that if your table is too small and limber it allows the piece you are cutting to bend and bad portion of blade to grab it easier.
 
I have the same machine and had the same problem. Tighten the tension. That solved my problem.
 
Photo is uploaded. I finally got the correct link from imgur.com.

Yes, I will spend some money on new bandsaw blades. I like bi-metal but I can't afford Lenox.
I do have a large 12x14 work rest table and I only use this bandsaw in vertical mode.
This is a low-end machine, and not alot of adjustment for wheel alignment. But maybe I can shim the upper wheel mount so it leans back more.
I liked Stacy's description of how the blade crimps, bunches up, and comes off. That does seem to be my issue.
And I also understand how a blade can stretch unevenly.

So, any comments on putting rubber tires on my wheels, like a wood bandsaw?
 
Are the surfaces of the wheels relatively clean and free of buildup? If there's crud built up they may be more prone to walking the blade off the front.
 
Metal saws use the bare wheel without a tire. The tension of a metal saw blade would destroy a rubber tire. That. plus there is usually a coolant flow on most larger metal bandsaws, which wouldn't play well with rubber tires.

I was in the shop yesterday cutting stacks of AEB-L for a batch of oyster knives. The saw is an HF 4X7 mounted permanently as vertical (base removed). I took eight 48" strips, taped them up every 6", and cut through the taped spots to make 64 blanks. That meant I was cutting through a .80" thick bundle (eight layers at .100 each). It cut just fine because the tension was tight.

TIP
I usually use a 12" long piece of 2X4 as a push stick when sawing bars up or slicing a blank from a plate. The end is square at 90° and beveled at an angle so the contact part is about 1/2" high. Besides being safer, it allows you to align the cut direction with the blade better and apply even pressure. I often set it against my chest to apply the pressure with my body while holding the bar of stock down firmly with both hands. By "sighting" down the push stick you can see if the force is being applied straight with the blade or at an angle. Trying to cut at an angle to the straight direction of the blade will cause the blade to twist and bind easier … popping the blade off easily. Drawing the cut line on the stock with a straight edge and marker is also a good idea (the white paint type "metal markers" from places like Fastenal are great for this). This also helps you see if you are pushing the stock straight into the blade.
 
Thanks for the comments and advice. I do use heavy tension, but maybe a larger crank would help me get more tension. So far I have not been breaking blades.
I don't run coolant on the bandsaw, but I also cut quickly, and switch between tasks, so the heat doesn't build much.
I do clean my wheels by CAREFULLY holding sandpaper on the open side of the moving wheels. I cut gummy wood and that does leave a residue, plus sometimes I'm impatient and cut soft epoxy before it has fully hardened. That's a bad habit that gums up my grinder belts too.
 
Added a 5 pound weight as a tension adjust wheel.

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After all the adjustments and changes, it seems to be working better.
Plus I cleaned about 5 pounds of dust and grit out of the frame.
 
killed 3 of those small saws by different makers one ate the worm gear another i cracked the casting for te drive wheel from over tension of the blade. forget how the other one died. was having a good year and wass sick of fighting small saws got lucky and found a used roll in saw for 2500$ (jet made one for liek 1600 i think) i will never look back badly on that buy rubber tires 10' blade huge flat work table and can slab off thin slices off large stock with its self feed. it really is one of those catches hobby gear in the 3-500$ kind of works then next step 99% of the time is well north of 1K$
 
Sounds like a new blade would solve most of your issues. At the end of the day, you're only gonna be able to cut as fast as the blade will allow you to cut. Let the blade do the work and don't force it. Other than that, just make sure your guides and bearings are set and functioning properly, and that you have good tension.

Vertical/Horizontal saws are great tools to have in the shop, but they're not meant to rival a full sized vertical or a roll saw.
 
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