that's why I continue to disagree with your assessment of a
"problem". NOW do you get it, Michael?? ") Nice try
though and as someone more profound that myself has said
many times, "thanks for playing". NOW can we drop this
non-argument? 'Cause if YOU don't drop it, you'll be
arguing with yourself next.
Michael Daly wrote:
Would it? You are assuming the blade is going to track on center of the
bottom wheel, but what if it does not?
I was at a Scott Phillips demo about bandsaw setup and he dismissed the
co-planer thing also. To him, tracking the top wheel and proper tension is
needed for true running.
I make no such assumption. The blade will ride on the part of the tire
that allows it to come into equilibrium with the forces on it. But unless
the curvature of the tire match _exactly_ to the degree of out-of-plane,
the blade will be twisted.
I'm talking about stress on the blade.
Imaging someone telling you that a frame in a car doesn't have to be straight.
They drive around with a bent frame and think everything is fine. They say
the auto engineers don't know anything about cars and body shops that straighten
frames are ripping people off. Does that make it ok to have a bent car frame?
Is that in turn the same as saying that no one should have a straight frame?
Just because you can make it work, doesn't mean that it's all right. I like
to see things running square and true. You can true your equipment with a
sledge hammer for all I care, but don't tell me it's right. It's not like
aligning the bandsaw wheels is a big deal - it takes a few minutes. If you
have that much trouble with it, are you sure this is the hobby for you?
If out of plane is ok, how much is ok? 1/4"? 1/2"? 2"? 10"? Let's hear
some facts about this out-of-plane acceptability.
I can tell you aren't into empirical testing, are you
Michael? Instead of using JUST logic, you should do some
TESTING of your hypothesis. Then you would undoubtedly
change your tune.
Michael Daly wrote:
I'm not saying that one should not carefully adjust the
guides and set the blade to track near the center of the top
wheel, but the coplanar "thing" is really much ado about
nothing. The wheels of my Powermatic are about 1/16" out of
being perfectly aligned, when under tension for a 5/8"
blade. The blade runs true, quietly, and cuts fine. When I
shim the upper wheel so that it is truly coplanar while
under tension, then the blade doesn't track nearly as well
due to the slight tilt of the upper wheel. I see no gain in
messing with the factory set-up of the BS. I DO pay VERY
particular attention to setting the Carter guides "by the
book", so to speak. And all is well with my bandsawing
operations... To suggest that I am not picky about setting
up my equipment is a laugher.
Michael Daly wrote:
I'm not saying no one SHOULD have coplaner, but you don't necessarily HAVE
to have it to be operating properly. Plenty of cars on the road do have
frames not aligned.
I don't know as I've not done any testing. My saw seems to be very close and
hte blade tracks just fine so I'm not going to change anything, nor will I
do any more checks of it unless a problem occurs. What I am interested in
is a perfect cut. As long as I get that, the rest is just a bother.
You must have awfully mushy tires. I can barely see any deflection
in the surface of mine. They're crowned, but kinda flat (i.e.
long-radius curvature) too. Behavior with a 1/4" blade will be
very different than that of a 3/4". I put more faith in coplanar
than in some undefined capacity of the tires to fix any potential
stress problems in a blade that's running at over 10,000psi and
a couple of thousand feet per minute!
I read somewhere that engineers keep their cars in better condition
than the average driver. I wonder why? I'm an engineer and I tend
to prefer to keep things set up well and running well. But then
I don't have unlimited faith in the materials we use in our world.
Every time this comes up, the guys that say it's unimportant eventually
admit that they have a BS that's fairly true or is a high-end model that's
quite true out of the factory. But the guys asking the questions about
coplanar have the chiwanese quasijunk that is way out of adjustment
and performs accordingly.
Open question remains - if out of plane is acceptable, what are its
limits? If no one can answer that with a realistic answer, then
I'll stick with the folks like Duginske who actually know what
they're talking about.
Most tires are a rubber compound. Rubber compounds are usually designed to
deflect or move in some manner or they would just use steel or aluminum.
Must be a reason. As an engineer, you know that.
Junk is junk no matter how it is adjusted. Thee is more at work there than
Nothing wrong wit co-planer or any adjustments being as good as possible.
There is a point where it just becomes too anal. I'm not knocking Duginske
(I have his book) but I've also seen the work Phillips has done.
I didn't say they don't deflect, I said that I can barely see any deflection.
Big difference. These are hard tires. If there is little deflection, there
is less ability to adjust to misalignment than with a soft tire.
You're avoiding the statement I'm making - the guys that are claiming that
coplanar is not important don't have coplanar problems to begin with. BAD
has a fancy BS that's only 1/16 out - the OP has one that's 3/8 out.
I hope the lurkers are catching on to what's going on here - it's like
a guy with a $300 LN or LV plane telling the guy with the $20 Footprint plane
that sole flatness isn't an issue. Duh!
Ok then - what's level of adjustment is too anal? 0.001"? 1/16"? 1/3"? 3"?
I see the hand waving and lip flapping, but I'm asking for a real answer.
If you or anyone else thinks that coplanar isn't an issue - then give us
the real answer on what level of misalignment _is_ an issue so folks can
judge how they're doing.
If you can't, then my answer is that you should do the best job you can at
making it coplanar and don't ignore it - even if you think it's tracking
reasonably. Why? For the same reason I spent a lot of time flattening
the sole of an old Millers Falls plane I bought at a garage sale for $4
- because it's better that way!
Any amount that still allows the blade to track properly is acceptable. If
my blade is cutting straight, making curves with east, re=sawing accurately,
then it is close enough. I've not done any research nor have I owned many
brands of saw to give you hard data. It either works, or it doesn't.
We're not talking about a precision cutting machine here Mike. But, in
any event, I'll try to sum it up with an analogy.
Being an engineer, I'm sure you know that older cars had points that
required adjustment in order for the engines to run properly. I
remember an old Mustang I worked on in high school - I could never get
that thing running quite right. Did everything by the book - points
were perfect, timing was perfect, vacuum advance was perfect, all
according to the book.
When I asked the instructor what could be wrong, he said that sometimes
you start with the factory settings and tune according to feel. Once I
figured out what he meant, I adjusted the points and timing a bit and
that Mustang purred.
Same thing for a bandsaw. The problem with most bandsaws is that you
can't state a blanket "no more than 1/8" out of coplanar", because of
manufacturing issues - cast or sheet metal frame, single or double wall
construction, aluminum or cast wheels, rubber or urethane tires, size of
crown, type of bearing, etc.
Most hobbyists don't really care about the fatigue on a band, as we
don't use our tools in a production environment, and if they read all
the books by Duginske, they already know to detension the band after
use. I would say that most hobbyists are more concerned about
performance, and in my case that is all I care about. My bandsaw is
close to 50 years old - a sheet metal framed Delta 20" with new
bearings, tires, even paint. No matter what band I use on her, she's a
bit outta whack. I could shim and check, shim and check, shim and
check. Or, I can leave well enough alone and cut wood.
I don't have a newer bandsaw to compare to, so I have no idea how much
out of factory spec the new Deltas, Jets, or Lagunas might be.
Is Duginske wrong? Not necessarily. But is perfectly coplanar
necessary for a well tuned 67 Mustang? I'll leave it to you to decide.
I think that unless the bandsaw is a real loser, the only significant
issue is tire type and geometry.
That's entirely possible. However, I keep it in the realm of the
possible that for some situations, fatigue _might_ reduce the life
of the blade. Without doing some calcs, I don't know. However,
the conservative engineer part of me says "do it right and don't
even consider the possibility." Setting up a bandsaw is not
hard, so don't make an issue of _not_ setting it up right.
I've already said that perfect is not possible, but "good enough" is.
"Coplanar is a myth" doesn't even address good enough. Since making
the bandsaw reasonably coplanar is straightforward, do it and if you're
still having problems, you know to look elsewhere for a solution.
If you mean geometry of the crown, I'd agree. The problem with geometry
is dealing with a particular band or tensioning device/spring. A 1/8"
band on my 20" Delta may require the upper wheel to be at a severe
angle, thus negating or accentuating the OOC (out of coplanar)
condition. OTOH, a 1" resaw blade requires so much tension that the
wheel could be forced true.
In these cases, geometry is directly affected by the size, type, and
material construction of the band - not to mention the weld/solder
joint, which could open up another can of worms...
Agreed. But just what is *right*? There is clinical right, which is
probably close to what you espouse. There is functional right, which is
more of a gray area and works on the premise of feel instead of original
spec. In reality, no one is wrong. I use the book as a starting point.
If it works, I leave it. If it doesn't, I tune it according to common
sense and feel. Am I "more right" than you? I don't really care, but my
way works for me.
Agreed, but aren't you contradicting yourself a bit here? First thing I
learned as a network engineer is that similar is spelled "different".
Reasonably coplanar is not coplanar, therefore "coplanar is a myth" is
technically correct. :-)
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.