making a bandsaw

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Old 09-04-18, 05:48 PM
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Question making a bandsaw

One of my trees died in the drought. I saved the trunk to do some woodworking. I want to cut it lengthwise.

I have vague plans to make my own bandsaw using parts from a small bicycle and the motor from a garage door opener. The motor already drives a chain. The chain will turn the tire. The tire will drive the saw blade. Heck, just by writing it down, it is almost done!

But I have questions: Can I control the speed of this kind of motor? I was thinking of using a dimmer switch (is this too naive?)

How fast should the bandsaw blade move?

Is this the right place to ask these questions? (first time poster)
 
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Old 09-04-18, 07:17 PM
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That type of motor is geared down or run thru pulleys to operate the garage door. That slows down the speed and increases the available torque. You'll need a lot of torque and much more speed than that motor will yield. No real inexpensive way to control the motor speed. A dimmer won't do it.

You would need two tires for the blade..... one driving and one as an idler. They need to be and kept perfectly inline with each other or the blade won't stay on.

Sounds easy but it's not. Good luck with your project.
 
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Old 09-05-18, 04:34 AM
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I will add that that the two wheels that hold the blade need to apply a great deal of pulling pressure to keep the blade taught.
This means a fairly substantial frame to do this which would require a fairly high cost and a lot of time to build.

Cutting a log lengthwise would require what would be called a band saw log mill and would not really be a good first time project.
You would do well to consider a chain saw attachment to cut your log rather than what you plan.
 
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Old 09-05-18, 05:16 AM
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Another option would be to have a portable band saw mill come to your property and saw the log for you. If not this, then go with the chainsaw attachment.

As far as building your own band saw mill, look at the specs for available mills. You will see that the engines needed to drive the blade are quite powerful.
 
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Old 09-05-18, 08:54 AM
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IMO it's best to [if feasible, requires equipment] load the log up and take it to a saw mill or get a portable saw mill to come to you as suggested above.
 
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Old 09-06-18, 05:29 PM
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I was too brief in my explanation. I am approaching retirement and think woodworking would be a nice hobby. Plus, in the city where I live, people discard 'green waste' in the street every day. I can pick up nice pieces of lumber.

So, my immediate need is for my drought tree trunk, but I would like to have a sawmill type bandsaw that I will use several times a year. Plus, I think building my own would be a nice project.
 
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Old 09-06-18, 05:39 PM
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(tires) need to be and kept perfectly inline with each other or the blade won't stay on.
I thought of that also... the bicycle tire is too narrow. My first try will be with under-inflated tires. If that does not work, I may have to rely on the 'u' shape of the rim to keep the blade in place. I would cut away the sidewall of the tire and use the tread portion nestled in the rim for traction on the blade. I would need to use some kind of adhesive or fasteners to keep the tread in place.
 
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Old 09-06-18, 05:58 PM
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the two wheels that hold the blade need to apply a great deal of pulling pressure to keep the blade taught.
I agree that pressure is required. It is not clear if a 'great deal' is the right term. I have a 9" band saw and the pressure does not seem that great.

I was planning to use both wheels of the bicycle. The wheel with the sprocket would be in a fixed position, as would the motor.

The other wheel, the front wheel and the bicycle's "fork", would be adjustable to allow both sliding away from the other wheel, and also to swing away slightly, inline with the blade. It will be keep taught using a spring (and maybe a turnbuckle). Keeping the blade level from end to end may be a problematic because of the 'swing' taughtness scheme I have in mind, so maybe other tilting controls will be needed.
 
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Old 09-06-18, 06:05 PM
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fairly substantial frame to do this which would require a fairly high cost and a lot of time to build.
I plan to use old bed frames, which I have held onto for many, many years. I always thought they would be useful for something.

That is, I plan to use scrap to keep the cost down.
1. someone was throwing away the bicycle.
2. my neighbor was recycling his garage opener simply because it broke. I can fix it.
3. scrap metals I kept around. I probably will have to buy some bolts, springs, etc...
 
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Old 09-06-18, 06:22 PM
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That type of motor is geared down or run thru pulleys to operate the garage door. That slows down the speed and increases the available torque. You'll need a lot of torque and much more speed than that motor will yield.
I need to contemplate this more... I do not know how to determine if it is feasible.

1. my garage door opener pulls a chain several feet in about 5 seconds. Lets just approximate to 1 foot per second.
2. the bicycle sprocket is about 4" in diameter. Maybe a complete turn of the sprocket is one foot of chain. Lets just say it is one revolution per second.
3. the diameter of the rim is about 16" (it is a small girl's bike). Assuming not to much slippage, the blade would move about 3' per second.

It seems like there would be enough cutting action, especially if I have patience and feed the trunk slowly.

I am especially curious if you disagree with my naive mechanics here.
 
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Old 09-06-18, 06:55 PM
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I wonder if you might proceed with your build on a modular basis: build the actual saw first, as proof of concept, then build the log support and rolling structure separately. I would also suggest viewing youtube videos (i searched "diy bandsaw mill") to compare notes and copy ideas.
 
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Old 09-06-18, 09:49 PM
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build on a modular basis
Agree. I had already viewed several youtube videos. Most use various automobile tires and very powerful gasoline engines. I did not see any with bicycle tires and electric motor. I suppose the larger mills are more glamorous. My proposed machine is somewhat modest in comparison.
 
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Old 09-07-18, 07:20 AM
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Think about the thickest part of the log you will be cutting. Compare that thickness to the thickest board you have cut on your existing band saw. If the log is 10 times as thick as what you cut on your shop saw, then you will need 10 times the power to cut the log. Plan carefully, or else your efforts will be wasted.
 
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