Band Saw questions

Is a .5hp motor a good size for a band saw? What other specs would you look for if planning to purchase? I ask due to someone selling a used one though the only specs thus far are the .5hp he lists and it stands 6 feet high. Otherwise, I will call for the rest of the info and questions I need to ask.

Thank you

Reply to
SBH
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Good for a trial to see if you are going to really be interested in using one. I had a 1/2 hp BS once and it is ok for cutting thin soft woods, hardwoods not so good. Basically you can do better with a jig saw. I also like to resaw, if you are thinking of resawing buy one with 2 hp or more, my current BS has 4.5 hp.

Reply to
Leon

What power you need depends on how you will use the saw. Many bandsaws are 1 HP. More important than power is accuracy of cut. Bandsaws are notorious for getting out of tune, so you will have long-term benefits by buying quality.

Reply to
Phisherman

What about the possibility of removing the .5 hp motor and installing a 2hp+ motor in it's place?

Reply to
SBH

Half hp would be a pretty small BS, maybe a desktop unit, good for small work like model making or pattern cutting thin stock, etc.

Main spec of a BS is the throat. You'll see something like 14" or 18". This indicates the distance from the blade to the backbone, or how wide you can cut on the restricted side. A bigger numer is generally a better saw (not exactly but generally bigger is better. 6 feet high doesn't mean anything. You could configure a 12" bandsaw to be 6 feet high.

A typical starting size for a serious bandsaw is 14" and a 20" is industrial grade and bigger than that is only for sepcialized ops (IMNSHO). A typical 14" will have at least 3/4 hp. 18" are pretty much the standard for top end garage models and will have 2 or 3HP.

I get by with a 14" but have my eye out for an 18 or 20 but I don't bandsaw much but would like to do some resaw in the future.

The other capacity is depth. 6" is pretty standard for the small sized models. You can get extensi> Is a .5hp motor a good size for a band saw? What other specs would you lo= ok

Reply to
SonomaProducts.com

The saw may not be built to withstand the extra strain for a reasonable amount of time.

Reply to
Leon

1/2 HP is too small for serious work with hardwoods.

Other specs:

Wheel diameter - bandsaws for hobbyist woodshops will usually run in the 12" to 18" range with the most common probably the 14" size. Versatility/usability is directly related to the wheel diameter. The throat dimension (distance from the backbone to the blade and the largest circle, similar to the throw dimension in drill presses) and usually the maximum resaw dimension - cutting height above the table - increases with wheel diameter.

Resaw height - runs from about 6" to 12" typically for hobbyist type machines. Most of the 14" machines with cast iron frames require a riser block to reach 12". With the newer welded steel frames, what you get is all you have. There's no provision for riser blocks. Bigger is better if you plan on resawing, but using the larger capacity requires more power.

Motor horsepower - normally as the bandsaw size increases, the power of the standard motor also increases. Don't know all the specs for all the saws, but my 16" came with a 1.5 HP motor which I burned up resawing some green maple. Replaced it with a 3 HP Baldor Industrial motor ($$$) and now it works fine.

Minimum and maximum blade widths the saw will handle. The width you'll use is dependent on what you're doing. Narrow blades down to 1/4" for tight curve cutting, wider blades for straight cuts and resawing. Many folks recommend as wide a blade as possible for resawing. 1/2" blades work fine. Wider isn't really necessary. If the saw will tension a

3/4" blade properly, that's all you'll probably ever need.

Blade Length - There are several "standard" lengths in bandsaw blades. In general, the larger the saw, the longer the blade. If the length required is not one of the common standards, blades will have to be custom ordered. That not as bad as it may sound, because many, if not most, suppliers of quality blades weld blades to order even for the "standard" lengths. However, a non-common blade length may prevent your dropping into your local borg and picking up a blade off the shelf.

Number of wheels - virtually all the current crop of bandsaws are two wheel saws. There are some three wheel models out they are relatively rare. They will generally have larger throats and resaw capacity that a 2 wheel saw with the same diameter wheels. I understand they tend to break blades more often than comparable 2 wheel saws but have no experience with them. I surmise that, along with non-"standard" blade lengths may be why they are not very popular.

Whatever you're planning on doing with the bandsaw, consider that you'll wind up wanting to do more and bigger things as you gain expertise with the saw. Plan accordingly.

Tom Veatch Wichita, KS USA

Reply to
Tom Veatch

Reply to
sweet sawdust

I have a 1 horse on my Delta wood and a 1 horse on my horizontal metal band saws.

It depends on what you cut. My delta is a 14" tall version for bowl cutting. I do nominal re-saw on it - but mostly nominal wood work.

Mart> Is a .5hp motor a good size for a band saw? What other specs would you look

Reply to
Martin H. Eastburn

Reply to
SonomaProducts.com

Thank you all for the replies. It helps me make a better decision when purchasing. One more question which many have indicated about "resawing". What exactly is "resawing"?

Thanks

Reply to
SBH

That is when you take a thicker peice of wood and slice it into thinner peices. Often done to create venners. This is how a bandsaw can save you some money. Buy some expensive wood, resaw it and glue it to cheaper wood to make various projects.

Reply to
Lee Michaels

Standing a board on edge and splitting it in half. At the saw mill they cut the boards and maybe plane them to a thickness. Then you can "resaw" them into thinner boards.

They also use the term to > > Is a .5hp motor a good size for a band saw? What other specs would you

Reply to
SonomaProducts.com

Wood from a mill may come rough sawn, (unplaned) S2S (surfaced 2 sides) , S4S (surfaced 4 sides) meaning it has been planed after sawing. The pieces for this "what-not" shelf were *resawn* from a piece of 1 X 4 (actually 3/4 X 3 1/2 finished size)

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Reply to
Max

Slight correction here, resawing is not necessarily splitting in half, I typically resaw and get 5-6 pieces out of a 3/4" thick board.

Reply to
Leon

Valid thought.

Let's look at some numbers. My calculations show replacing a 1.5 HP motor with a 3.0 HP motor increases the maximum load on the lower wheel bearings by about 3%. Yep, that's 3 (three) percent. Don't believe it? Read on.

WARNING! Mathematics follows, continue at your own risk!

What are the forces on a bandsaw? First, understand that the maximum load on the upper wheel (assuming a 2 wheel saw) occurs when the blade is tensioned, but the saw is not running. When the saw is cutting, the load on the upper wheel is actually less than when the saw is not running. So we can ignore the upper wheel and its bearings when looking at the cutting loads supplied by the motor. However, the load on the lower wheel is increased by the cutting loads.

When the saw is cutting, the force necessary to pull the blade through the workpiece comes from the motor through the lower wheel. That force is applied to the blade by the lower wheel, transferred by the blade to the workpiece, and reacted by the bandsaw table support structure. So the load on the table acting downward is equal to the load acting upward on the lower wheel bearing. But what is that load?

First take the case of the motor developing its rated power at its rated speed. Further assume that all processes occur at 100% efficiency. That is a conservative assumption since lower efficiency means lower loads on the wheel bearing and table structure.

Assume a 3HP motor. That means the motor at 100% efficiency provides Power = 3 X 550 X 60 = 33,000 foot-pounds/minute

Assume the blade moves at 3000 feet/minute when the motor is turning at its rated speed. That value is from the specifications for my bandsaw and is, I believe, a fairly typical value for woodcutting bandsaws.

Force on the blade = 33,000/3000 = 11 pounds.

So, a 3 HP motor developing is full rated power at its rated speed during a cut will pull downward on the table and upward on the lower wheel with a force of 11 pounds. Dividing by 3 (for a 1 HP motor) yields 3.667 pounds per horsepower load on the internal parts of the saw. Round it off to 4 pounds per horsepower for simplicity.

If you think that's a trivial load and can't possibly be the maximum load developed within an operating bandsaw, you are absolutely correct. The calculations used rated speed and power. The problem is the motor doesn't develop maximum torque at its rated speed. Maximum torque is developed when the motor is very nearly stalled out and is barely turning if it's turning at all. And it's the maximum torque that produces the maximum load on the bandsaw.

I'm no motor expert and don't know how much higher the maximum torque may be than the "rated" torque. But, capacitor start induction motors are built that way so they will have a high starting torque. For these purposes, I'm going to estimate that the maximum torque of a capacitor start, induction motor that would typically be used for a bandsaw would be on the order of 5 times the running torque. Perhaps a motor expert can improve on that estimate.

If the 5x estimate is anywhere close to the right ballpark, look for something on the order of 20 pounds per motor horsepower to be the maximum load applied to the table structure and lower wheel bearing by the motor.

1 HP = 20 pounds 2 HP = 40 pounds 3 HP = 60 pounds

So unless my estimated maximum torque is wildly low, the load added to the bandsaw components by the motor is really fairly small.

To get the full load in the lower wheel bearing, you have to take into account the load due to the blade tension. That load is proportional to the width and thickness of the blade and the tensile stress in the tensioned blade..

According to the guys at Suffolk Machinery, the makers of Timberwolf blades, the tension should be such that a stress of about 12,500 psi is developed in the blade.

So if we assume a 1" blade, .035 thick, 12500 psi equates to a tension load of 437.5 pounds. Since the blade has a wrap angle of 180 degrees on the wheel, the wheel bearing sees double that value, or 875 pounds of side loading.

With a static load of 875 pounds from the blade tension, the added maximum load of 60 pounds from a 3 HP or 30 pounds from a 1.5 HP motor doesn't seem to be anything to lose much sleep about. That's why I never hesitated to replace the 1.5 HP motor on my bandsaw with a 3 HP motor . It increases the load on the bandsaw wheel bearings from 905 pounds to 935 pounds - about a 3% increase.

Tom Veatch Wichita, KS USA

Reply to
Tom Veatch

Yeah, but.... You've got one of those $320,000 Laguna bandsaws and a 1/2 micron thick 3" wide titanium/diamond equipped bandsaw blade to do your resawing.

What is everybody else supposed to do? You could of course invite is all over to your place to use your bandsaw and when a few of us accidentally cut a few fingers off, we promise not so sue if we can have all your woodworking tools.

:)

Reply to
Upscale

I did not read it all, but did any of that take into account the increased ability to resaw much wider boards which would also put more strain on guides? Did it take into account faster feed rates which would also create more strain on bearings and guides. Did it take into account the ability to cut larger heavier pieces which might damage marginal trunions and or tables? I was sorta indicating premature failure because of the extra capacity during actual use, not just from turning the BS on. My old BS was pretty much all aluminum as far as the frame/housing was concerned. I viewed the smaller hp motor as being a safety measure to keep the frame from distorting and twisting, a condition that would be present when cutting heavier and thicker pieces of wood with a larger hp motor. I was pretty impress with your detail however. ;~) Perhaps a larger motor on a "fan" would not have as much potential to do harm.

Reply to
Leon

That is a 1/2 micron thick 3" wide titanium/diamond "Special Edition" bandsaw blade, smarty pants! ROTFL

LOL,,,, But surely with a marginal, well my first BS could resaw into 3 or

4 pieces, a 2 bu 4. ;~)
Reply to
Leon

If you had plowed through all that, I'd be tempted to advise you to "get a life". 8-)

No, I didn't consider the weight of the workpiece on the table and trunnions, or the effect on the guides, just the additional loads that a larger motor could possibly apply to the structure during a cut that used the motor to its maximum power/torque output.

To be honest about it, I was surprised to find, especially with the largest blade my bandsaw is "rated" to use, the structural load due to tensioning the blade is huge! So large, in fact, that the added loads on a bandsaw from cutting at maximum developed motor power/torque fades almost to insignificance.

But, it's important to note that those numbers are not blanket justification for arbitrarily or thoughtlessly increasing motor power on any tool, bandsaw or otherwise. Your cautionary statement is still very much on point and valid.

At the very least, when someone modifies a tool by increasing the motor size, or any other significant change for that matter, they can toss the warrantee in the burn barrel. And on the other end of the spectrum, they could very easily increase the risk of serious damage to the tool and themselves. We, as customers, rarely know the basis for all the sizing decisions made by the tool designers.

Tom Veatch Wichita, KS USA

Reply to
Tom Veatch

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