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Thread: Building a bandsaw

  1. #1
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    Building a bandsaw

    I have been thinking about building a bandsaw for some time and after seeing Stu's build I have been getting more antsy. I was thinking about using bicycle wheels for the bandsaw wheels. Any thoughts about if they would be strong enough for that. I am not sure what I would use for tires, maybe bike tires with the tread cut off?
    Last edited by Dave Black; 07-29-2009 at 02:09 AM.

  2. #2
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    I don't think you could get near the tension on bicycle wheels. If you could get some alloy motorcycle wheels, maybe. Better yet, watch for bandsaws being parted out, or thrown away. If I'm wrong, somebody, everybody, set me straight. I can take it.
    My recommendation? Read about someone losing one off the back of a trailer when moving it? Track down what they are going to do with it. Same for someone receiving one destroyed from a shipping company, see what the shipper is to do with the pieces. Might be able to buy it for scrap metal prices. Jim.
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  3. #3
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    Quote Originally Posted by Jim O'Dell View Post
    I don't think you could get near the tension on bicycle wheels. If you could get some alloy motorcycle wheels, maybe. Better yet, watch for bandsaws being parted out, or thrown away. If I'm wrong, somebody, everybody, set me straight. I can take it.
    My recommendation? Read about someone losing one off the back of a trailer when moving it? Track down what they are going to do with it. Same for someone receiving one destroyed from a shipping company, see what the shipper is to do with the pieces. Might be able to buy it for scrap metal prices. Jim.
    Thats what I was thinking, I don't know if I did the math right but I think I remember seeing blade tensions in the 20,000 to 30,000 PSI range. So I figured out the square inchage of the blade and multiplied that by 30,000 and came up with something about 250lb. I don't know if this is right but if it is then a bike wheel should work. People more that 250lbs ride bikes all the time without breaking them. Any thoughts on this logic or the math. I had also thought about the motor cycle wheels and I used to have an old kawasaki that I tore apart to use the disc break on a gokart( powered by a 440CC 2 stroke snow mobile engine) I was building. The rest of the motorcycle got junked, I don't know why I didn't keep the wheels. Also any thoughts if I should use bearing blade guides or blocks.

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    Dave, I'm not real clear on the mechanical physics of it all, but I'm pretty sure the 20,000 to 30,000 psi tension in the blade does not directly translate into the same amount of compression on the wheels. Also, are you figuring the total square inches of the blade, or just the part that's making contact with the wheels at any given time? (I think you'd need to be using the second number for your calculations.)

    Also, a tire releases compressive strength sideways via the sidewalls. Any pressure beyond the PSI of air in the tires is expended sideways. Back when I was in the earthwork testing and inspection business, a lot of folks were surprised to see they got better soil compaction rolling an empty Bobcat loader back and forth over a pad than doing it with a big Cat loader carrying a bucket full of dirt for extra weight. The Bobcat tires were running with 100 psi of air pressure and the Cat was running less than half that. So even though the Cat was a much heavier machine, it was still only putting less than 50 psi of pressure on the soil, but the Bobcat was pushing down with 100 psi.

    Long story short, I don't think a wire-spoked wheel would have the beef to handle what a bandsaw can put on it. If it did, I think we would have seen bandsaws made that way back when wire-spoked wheels were more common on things like automobiles and motorcycles. Also, the more mass you have in the wheels, the more inertia you get powering the blade. That's why heavy cast iron wheels are generally preferable to lightweight aluminum ones. (Although there are plenty of good saws with aluminum wheels.) I'd second Jim's suggestion to look for a junked saw, or perhaps pursue machined motorcycle wheels.
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  5. #5
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    OK Dave, I'm no Engineering Guru, Buuuuut...... in addition to what Vaughn said, (and I definitely agree about the "Mass" thing), I don't know if you have considered the following in your calculations, so....... assuming wanting to tension to 30,000 psi:

    1. the pressure required in the calculations must assume doubling the tension number, OR, maybe you would just need to double the blade width, because you are putting tension on TWO sections of the blade, the cutting section, and the return section, ie; (the up and down sections of blades between the wheels).

    2. the pressure required to tension a blade varies with the width of the blade. (Obviously it takes a lot more pressure to tension a 1" blade than a 1/4" blade).

    I personally think that unless you were making it to only use Small, Low Tension blades, there would be too much flex in a bicycle wheel to have much success at controlling the tracking. JHMO.

    I firmly believe you can build every part for an excellent bandsaw, "IF" you can find a "Good Set" of heavy "Cast" wheels, 'cause the wheels are the most critical part other than frame strength.

    I say find some Proper Wheels and GO FOR IT.

    PS: If you can't find a set of wheels, how about using something like two identical motor flywheels, and weld a proper width strap of metal around the circumference, and then have a machine shop grind the groove for the tire and balance them, OR maybe you could juryrig a setup to grind them yourself. The junk flywheels would definitely give you the Mass you need. Whatcha Think???
    Last edited by Norman Hitt; 07-29-2009 at 08:50 AM.

  6. #6
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    your wheels will need to be strong and balanced and have the ability to house bearings....
    look to some of the band-mill sites for ideas.
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  7. #7
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    Dave, you can certainly build your own bandsaw, but I have to question why you want to do it?

    If you want to do it for the enjoyment of doing it, then go for it, but to save money? I don't think you will save a lot if any money.

    You should be able to find a good bandsaw for a reasonable amount of money, there has to be a few used on the market these days, and there are lots of deals out there on good new units too.

    You need a good set of wheels, good strong wheels, balanced,with good bearings, like Tod said.

    Check to see what someone like Grizzly wants for the wheels with the axles, bearings and such, you might be surprised at how cheap they go
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  8. #8
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    Interesting idea.

    Why?

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    Thumbs up

    Quote Originally Posted by Stuart Ablett View Post
    Dave, you can certainly build your own bandsaw, but I have to question why you want to do it?

    If you want to do it for the enjoyment of doing it, then go for it, but to save money? I don't think you will save a lot if any money.

    You should be able to find a good bandsaw for a reasonable amount of money, there has to be a few used on the market these days, and there are lots of deals out there on good new units too.

    You need a good set of wheels, good strong wheels, balanced,with good bearings, like Tod said.

    Check to see what someone like Grizzly wants for the wheels with the axles, bearings and such, you might be surprised at how cheap they go
    I wanted to build one because I have a CHEAP craftsman 12" and wanted something better. My philosophy for building tools has been to use things that I already have, if I have to buy a bunch of stuff to make the saw then I might as well just buy a new or used saw. Plus if I have to buy stuff to make it, then that takes money out of my sawstop fund (something I can't make) I had my eye on a used delta rockwell 14" BS from a school district but I would rather get the sawstop then that right now. I guess I will just have to keep my eye open for a cheap BS or parts to make one. Well I'm off to work on my dining chairs, I took the week off to get some work done on them, and I can't do that if I'm sitting here
    Last edited by Stuart Ablett; 07-29-2009 at 02:06 PM. Reason: Fixed a busted Smilie

  10. #10
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    Dave, I hear you loud and clear and agree with you thinking. If you happen upon a donor bandsaw, I'll bet you could make a really good saw on the cheap.

    The other thing I thought of with the spoked wheel is that it may not take the loading and unloading when you start to cut something, the rim of the wheel would want to slow down and the hub would not, the spokes would have to take all of that. I know that some of the older BIG bandsaws had spoked wheels, but the spokes in question were a LOT thicker than a bicycle spoke.

    Cheers!
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