Building a bandsaw

Dave Black

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Central PA
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?
 
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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. :p
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.
 
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. :p
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.
 
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.
 
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.:huh::dunno:

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.:thumb::thumb::thumb:

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???:huh:
 
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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.
 
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 :dunno:
 
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 :dunno:

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 :)
 
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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!
 
If you're interested in a donor bandsaw I have a low mileage Hitachi CB13F that fell off the stand and cracked the table trunion. The door nas a ding in it as well but the rest is fine.

$75 and take it away or possibly trade for a bosch or makita tool?
 
If you're interested in a donor bandsaw I have a low mileage Hitachi CB13F that fell off the stand and cracked the table trunion. The door nas a ding in it as well but the rest is fine.

$75 and take it away or possibly trade for a bosch or makita tool?

Thanks for the offer, but I think I will pass for now. I think it would be best for me to save up for a sawstop right not, and I was looking for something bigger. The CB13F is only 12"??

John, you are probably right about strain, I can't remember where I saw the numbers OR how they were labeled, for some reason PSI was stuck in my head.

For now I will keep my eyes open for something cheap or for inspiration to strike
 
My Dad has built 2 band saws. The first one worked just fine, but was really too big for his needs or his shop. He dismantled it and built another, 14" machine. It also works fine.
He's retired now, but was a journeyman machinist his whole career. In fact, he worked in a shop that supplied and maintained custom machinery for other machine shops across the country. It was a small shop, and part of his job was to help develop and build custom machines and refine their "off the shelf" machines. He's a very inventive guy. His approach to the wheels was to laminate two layers of 3/4" MDF together, drill a center, mount a hub with ball bearings in each side, and turn it on an axel mounted to a crude jig attached to a scroll saw. Turning the wheel slowly on the axel mounted a fixed distance from the blade, he cut the circle.
Then, he mounted the same jig to the drill press, at a slight angle. He put a sanding spindle in the chuck and sanded one side of the crown onto the wheel by turning it slowly past the spinning sander. Then, by flipping the wheel over on the spindle and repeating, he sanded both sides of the crown onto the wheel. I didn't watch him do it, but he was able to leave a shoulder on each side of the wheel to keep the urethane tires in place once installed. The tires, by the way, are the standard orange or blue variety available on line or at your friendly neighborhood woodworking store.
The wheels are true, were easy to balance, and have more than enough compressive strength for their purpose. Also, they were cheap, are dimensionally stable, and don't rotate nearly fast enough to risk coming apart from centrifugal force.
To laminate the MDF together, he used ordinary wood glue. The wheel hub / bearing mounts were inexpensive, and the spindles were hardened round stock - also not expensive. He used a standard die spring for the tensioner.
He did the math and determined that these materials would work just fine.
The saw frame he welded together from 4" square tubular steel from the salvage yard. The table is also MDF with a miter slot cut in it. The guides he made himself - similar to Carter ball bearing type. The motor he did buy as a reconditioned unit.
All in, he probably spent about $80 for the saw and another $120 for the motor.
It's a real horse of a saw - a lot heavier duty than my 17" saw, but not as heavy duty as my Crescent 20".
He's pretty happy with it, and he's a pretty tough customer.
Have fun with your project and post some pics as you go.
Paul Hubbman
 
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His approach to the wheels was to laminate two layers of 3/4" MDF together, drill a center, mount a hub with ball bearings in each side, and turn it on an axel mounted to a crude jig attached to a scroll saw. Turning the wheel slowly on the axel mounted a fixed distance from the blade, he cut the circle.
Then, he mounted the same jig to the drill press, at a slight angle. He put a sanding spindle in the chuck and sanded one side of the crown onto the wheel by turning it slowly past the spinning sander. Then, by flipping the wheel over on the spindle and repeating, he sanded both sides of the crown onto the wheel. I didn't watch him do it, but he was able to leave a shoulder on each side of the wheel to keep the urethane tires in place once installed. The tires, by the way, are the standard orange or blue variety available on line or at your friendly neighborhood woodworking store.
The wheels are true, were easy to balance, and have more than enough compressive strength for their purpose. Also, they were cheap, are dimensionally stable, and don't rotate nearly fast enough to risk coming apart from centrifugal force.
To laminate the MDF together, he used ordinary wood glue. The wheel hub / bearing mounts were inexpensive, and the spindles were hardened round stock - also not expensive.
Paul Hubbman

What kind of bearing/hub mounts did he use. Do you have any pics of the insides that you could post. I'm new to this forum but I think that the general consensus is "no pictures, didn't happen" ;). Pictures always are helpfull, I consider myself pretty inventive but there's no use reinventing the wheel, literally in this case.
 
Paul, I too would like to see some pics, I'd seen other saws on the net that used laminated MDF for the wheels, and they seemed to work just fine too.

Cheers!
 
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