Various bandsaw questions...long

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wrote:

I don't think there is a right answer to this question.
There are also relationships that involve diminishing returns and opportunity costs.
Tracking down a decent price on a vintage tool can be a hobby in itself, which some folks greatly enjoy. For that enjoyment those folks give up the opportunity to use their time actually woodworking.
Spending more money for a new, high-quality tool gives up the opportunity cost on the money, but returns it in time available to actually use the thing.
For instance, if I were to spend weekends or time off traveling around looking at used machines, the money available to me would dry up. If I continue to make useful things and improvements to my home that my wife finds beautiful, I keep the harmony when I drop $$$ on a good tool. She's seen what her friends pay for such improvements, and understands the value. In fact, some of her acquaintances have provided an extra income stream. <G>
If I were retired, I would probably have much more time available to find and restore used machinery, and likely have less money, which would make finding them more worthwhile.
The key is for each individual to create a balance between the two extremes that works the best for them, based on the amount of time an money available. Also, some localities are better for finding used tools than others.
Barry
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Stephen M wrote:

Marketing. The DIY crowd prefers bench top, light duty stuff - cute and less intimidating than a BIG HEAVY SCARY Monster (the latter being the exact thing that appeals to many of us here). So for their biggest market they make the "petite" model and make the conversion to "a real bandsaw" an option for those who are inclined to want MORE POWER, Bigger, Beefier tools.

Regarding ridgidity - use to be thick walled cast iron = rigidity. Once again, the Europeans closely examined that assumption and found that there were other ways of getting rigidity without adding a lot of wieght in cast iron. The box and box plus triangle bandsaws we see today can be just as rigid, if not more rigid, than all cast iron models- AND weigh less.

A GOOD rack and pinion "blade guide" means not having to tweek your blade guides every time you raise or lower the blade guide + guard. If it doesn't move up and down while remaining square to the table you start cutting trapezoids and not rectangles. Tapered veneer is not good.

The 2.5 HP TEFC on the LT 16SEC has got to be 75 or more pounds, with the cast iron table and fence coming to another 40-50 pounds. But the 16SEC weighs about 375 so it'd be a bit of a challenge to get to a second floor.
DO NOT remove the wheels. That's asking for a ticket to Set Up Hell.
While on the subject - you want dynamically balanced wheels - and cast iron at that. Wheel weight = inertia = more continuous cutting power when the teeth hit harder areas. Dynamically balanced wheels mean smoother cutting and that's a really good thing.

The less the blade can move left/right or twist the better. Cool Blocks and the other direct contact guides have been found to work well for a long time now. But they wear and that means they need more frequent adjusting. The ceramic guides are direct contact, they don't wear very quickly AND they dissipate heat well - heat being an enemy of band saw blades.
I picked up a set at a WWing show and eventually got around to installing them. Required hacksawing a little thick sheet metal but they work pretty well. Unlike the bearing guides, the ceramic guides will work well with narrow blades as well as wider blades and you can set the front of the side guides just behind the teeth, behind their set. Of course if you have a blade with a less than smooth joint they can be a problem.

Detensioning the blade is actually doing several things. First, and obvious, it takes the tension off the blade and blades like that. But it also decompresses the tension spring which is the shock absorber on your bandsaw. That spring, when kept compressed too long will loose some of its springyness. That means less shock absorption and that's not good. Finally, detensioning the blade also takes pressure off the bearings on the upper and lower wheels. Bearings last longer that way.
As for quick release blade tension feature - is the time savings by not turning a knob three or four revolutions really significant? If you change blades often - 1/4" for tight turns and delicate stuff, 1/2' for normal things and maybe some resawing, 3/4" for beefier big cuts and maybe once in a while a 1 inch blade for slicing up a mini-log. If you have to adjust the tension after each blade change a "one size fits all" quick release could be a problem since the proper tension for a 1 inch blade is quite different from that of a 1/4 inch blade. Over time the spring's strength will lessen so if you rely on a set of initial tension points for each blade width you could have a problem with undertensioning down the road

I've got the LT 16SEC - 2.5 HP TEFC motor, 12+ inch resaw, rack and pinion guides - though plastic rack and pinion, and stamped steel trunion. Works well though I'd prefer a cast iron trunion.
Torben is a bandsaw nut - loves doing laminated pieces using stuff he bandsawed himself. If LT carries a bandsaw Torben probably has used that model. If it doesn't work for him they probably won't be selling it.
NOTE: if you can get a model with a table that'll tilt BOTH WAYS you can cut dovetail pins without having to make an angled support jig. The LT16SEC only tilts one way - dammit.
ALSO - mobility kit - you will move this thing several times at least. Shoving/rocking/walking a 6+ foot tall 250-400 pound beast around is not fun.

AH - the age old "buy more than I need and never use the extra capacity/ capability/power" vs "buy what I think I NEED now and then have to buy another one sooner or later". To that I say "Buy Once, Cry Once" (if you can afford it)
You WILL have a really nice piece of wood that's wider than 8.5 inches and the thought of ripping it down to 8.5 inches in order to get that bookmatched pair you want will haunt you. AND, if you have a bandsaw, you will find mini-logs of nice stuff that you can saw into boards, sticker and stack and wait a year to dry so you can use it. The wider you can cut the more options you'll have a year later when it comes to picking what you want out of each board. Don't envy you the consumer research but you're going at it in the right way. I'm sure you'll be happy with whatever you eventually buy.
charlie b
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Charlie,
Nice reponse. Thanks for taking the time. I have a couple followup questions to your comments.

What does dynamically balanced mean? Is it like balancing a a car tire? (spin it and add/remove material until it's even?)
. Unlike the bearing guides, the ceramic guides will work

I understand the theory. Do you find that these guides offer a imperical improvement, or is it tough to say without a proper control group (same saw/blade/wood etc.. with alternative guides)?

Lost you there... Who's "they".

Thanks, I had not thought of that.
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They make an _absolute_ improvement, but don't let the teeth touch 'em, or it's hone for dull. For that, cool blocks or such.
If you have a badly ground join on your blade, touch it up or find another supplier.

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On Fri, 23 Jan 2004 09:10:52 -0500, "Stephen M"
| |Charlie, | |Nice reponse. Thanks for taking the time.
I second that. | |> DO NOT remove the wheels. That's asking for a ticket to Set Up Hell. |> |> While on the subject - you want dynamically balanced wheels - and cast |> iron at that. Wheel weight = inertia = more continuous cutting power |> when the teeth hit harder areas. Dynamically balanced wheels mean |> smoother cutting and that's a really good thing. | |What does dynamically balanced mean? Is it like balancing a a car tire? |(spin it and add/remove material until it's even?)
In my youth I ran an automotive machine shop where we did engine balancing so maybe I can explain. There are two types of out of balance forces that can be generated in rotating objects:
Stewart-Warner, the maker of my balancing equipment called these "force" and "couple", although they are commonly called "static" and "dynamic" respectively. Usually the term "dynamic balancing" is used to indicate that the balancing was done while the object was rotating, but depending on the object, this may or may not be anything more than hype.
To explain this, I will use a pair of wheels from a bandsaw. Let's say that our wheels are cast iron and 1" thick at the rim and hub. When the manufacturer machined the castings, he bored the hole in the hub slightly off-center and then machined the rim concentric with the hole. If we measure the runout at the rim with a dial indicator, everything looks fine; perfectly round and concentric. (From what I've seen of woodworking machinery, this is not a hypothetical)
First let's use just one wheel and assume that it has a set screw for locking it on the shaft We place the wheel on the middle of a perfectly ground shaft of say 2 feet long and lock it down. We then suspend this shaft horizontally on a set of totally frictionless bearings located at the ends of the shaft. Since the "meat" of the wheel is off-center, there is a spot on the wheel that is "heavier" than anywhere else and that spot causes the shaft to rotate until the heavy spot rests at the location closest to the center of the Earth. There is a "force" proportional to the mass and its distance from the center of the shaft that causes this rotation.
This is pretty intuitive and should be clear to all. We all should have a feel for what happens when we try to spin this shaft up. At low enough speed nothing much happens but as the rpm increases, this weight flying around starts trying to turn our perfect bearings into junk.
If we go back to our "static" case where the only rotation is due to the off-center mass we can, by trial and error, drill holes in the spokes or along the rim of the wheel until we remove the heavy spot so that when turned to any position and released, the wheel remains motionless. We have removed the force and the wheel is statically balanced. Alternatively, we could add an equal weight opposite the heavy spot and accomplish the same thing. (I used to use modeling clay to achieve balance and then weigh the clay and knowing the density of the metal, know how much to drill out.)
If we now bring this shaft/wheel assembly up to operating speed, it should run very smoothly, thus it is also "dynamically" balanced, although we didn't spin it up to achieve this. So what's the big deal about dynamically balanced bandsaw wheels you ask. In a word (or two), not much, other than it indicates that they *were* balanced.
Where is does matter can be explained by another example: Let's mount two wheels on our shaft and space them 12" apart. Let's assume that the manufacturer has implement process controls that have reduced variability to zero (six sigma). (We won't ask about the off-center hole bore) So, both wheels are identically flawed. We also assume that the wheels can be indexed with respect to each other anywhere we want them.
Unless we routinely win the Powerball, there will be some angular separation between the heavy spots other than 180 degrees. In any other case the shaft will rotate so that it stops with the heavy spots equally spaced about a downward pointing line bisecting the smaller included angle between them. We now have too little information to know exactly where the heavy spots are. All we know is that they are equally spaced with respect to the virtual "heavy spot" and they aren't 180 degrees apart. By trial and error, we can rotate one wheel with respect to the other until we position the two heavy spots 180 degrees apart, where they exactly counteract each other. Our assembly is now statically balanced. Are we done? No, let's see what happens when we spin it up.
Because the two heavy spots are separated 12" from each other along the length of the shaft, they try to "do their own thing." At any instant in time one mass is trying to move the end of the shaft in one direction while the other mass is trying to move the other end of the shaft in the opposite direction. Unrestrained, the shaft would wobble around the point midway between the wheels. So when our shaft is at rest, i.e. static, it is in balance but when it is rotating, the two forces "couple" to each other and the assembly is "dynamically" out of balance.
The only way to correct this is to spin it up and measure, and correct, the forces independently. Note that with a given amount of off center mass, the effect is worse the farther apart the two wheels are along the shaft. Conversely, if we slide the two wheels together, since they are relatively thin, the effect is negligible and our static balancing method is probably good enough.
Lest anyone think that the static method I describe isn't used, we had a couple of industrial strength crankshaft grinders that used grinding wheels 36" in diameter and two or more inches wide. The wheels had a center hole about eight inches in diameter and were mounted on a hub that captured the wheel between two flanges. Since the wheels were molded, the holes weren't terribly accurate and the wheel was never concentric when mounted. The hub contained a set of sliding weights and we did mount it to a shaft and put it on a set of bearings and tweaked the weights just as I described earlier.
When we figured it was close enough to not self-destruct (it happened once...you think a table saw kick back is something....) we would diamond dress it round and rebalance.
Since tire balancing was mentioned, if you're old enough to remember the old skinny tires, you might remember "bubble balancers." These balanced the tire/wheel assembly statically by suspending the assembly horizontally on a point and using a bubble level to see which direction the tire moved. Weights were added on the high side until the tire was level.
With today's wider tires (the wheels on my Camaro SS are 9" wide) it matters on which side of the wheel the balance weights are fixed, especially at 130 mph.
I know this doesn't have anything to do with woodworking but I don't know much about woodworking so I've gotta write about something else :-)
Whew.
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Wes Stewart wrote:

Thanks, it was an interesting (and educational) read.
--
Ed
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Stephen M wrote:
snip

You got most of it right but they don't add weight but drill out some of the cast iron to get the balance.

The euro guides that came with the LT16SEC had bearings on either side of the blade which parallel the blade. They've got a relatively large diameter so the thrust bearing behind the blade can't be directly behind them. Go here to see the upper and lower guides - second set of images on the page www.wood-workers.com/users/charlieb/BandSaw.html I added images of the ceramic guides just for you.

"They" = Laguna Tools. Torben is the founder and president
snip
charlie b
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