I have recently purchased an older (green) Jet 20 inch bandsaw and have
started reconditioning it. (An absolutely awsome saw, but that is another
story). Basicly I am replacing some worn belts and tires, as well as
cleaning and aligning it, etc. I have Mark Duginske's book and have been
following the advice in the book, but the book has raised some questions.
After testing the coplanerity of the saw I found the the upper wheel was
slightly behind the lower wheel. This is a condition which Duginske says is
common and can be corrected with a spacer washer behind the bearing on the
upper wheel. I agree that this non-coplanarity is common, since I have seen
it in other bandsaws such as my very cheep 14 inch clone. But, why does it
always seems to be in the same direction with the upper wheel being further
back than the lower wheel? That coincidence seems odd enough to me that I
wonder if the saw manufacturers have have been doing it for some unknown
reason.
Does anyone know if bandsaw manufacturers purposely build in this kind of
offset into the alignment on purpose? If it is easy to adjust, why is it so
common in saws and mostly in the same direction? What kind of advantage
could it have? The blade tention does not seem capable of warping the
wheels in this manner. This saw even has adjustments for tuning the
position of the wheels, but they seem to have been purposely aligned with
the wheels very parallel, but offset in depth.
I will probably try running the saw both as it is and with the wheels fully
coplaner once I have the tires replaced and the saw put back together so I
can see how much of a difference there is. However, I doubt I am
experienced enough to notice much of a difference, and was wondering if
anyone knew more about this common irregularity.
Inquireing minds want to know.
On Wed, 22 Mar 2006 12:34:19 -0800, "tom saksa" <[email protected]>
wrote:
>I have recently purchased an older (green) Jet 20 inch bandsaw and have
>started reconditioning it. (An absolutely awsome saw, but that is another
>story). Basicly I am replacing some worn belts and tires, as well as
>cleaning and aligning it, etc. I have Mark Duginske's book and have been
>following the advice in the book, but the book has raised some questions.
>
>After testing the coplanerity of the saw I found the the upper wheel was
>slightly behind the lower wheel. This is a condition which Duginske says is
>common and can be corrected with a spacer washer behind the bearing on the
>upper wheel. I agree that this non-coplanarity is common, since I have seen
>it in other bandsaws such as my very cheep 14 inch clone. But, why does it
>always seems to be in the same direction with the upper wheel being further
>back than the lower wheel? That coincidence seems odd enough to me that I
>wonder if the saw manufacturers have have been doing it for some unknown
>reason.
It may be that when full tension is applied the planarity can change,
and would tend to bring the upper wheel forward. Just guessing
though.
-Leuf
tom saksa wrote:
> I have recently purchased an older (green) Jet 20 inch bandsaw and have
> started reconditioning it. (An absolutely awsome saw, but that is another
> story). Basicly I am replacing some worn belts and tires, as well as
> cleaning and aligning it, etc. I have Mark Duginske's book and have been
> following the advice in the book, but the book has raised some questions.
>
> After testing the coplanerity of the saw I found the the upper wheel was
> slightly behind the lower wheel. This is a condition which Duginske says is
> common and can be corrected with a spacer washer behind the bearing on the
> upper wheel. I agree that this non-coplanarity is common, since I have seen
> it in other bandsaws such as my very cheep 14 inch clone. But, why does it
> always seems to be in the same direction with the upper wheel being further
> back than the lower wheel? That coincidence seems odd enough to me that I
> wonder if the saw manufacturers have have been doing it for some unknown
> reason.
>
> Does anyone know if bandsaw manufacturers purposely build in this kind of
> offset into the alignment on purpose? If it is easy to adjust, why is it so
> common in saws and mostly in the same direction? What kind of advantage
> could it have? The blade tention does not seem capable of warping the
> wheels in this manner. This saw even has adjustments for tuning the
> position of the wheels, but they seem to have been purposely aligned with
> the wheels very parallel, but offset in depth.
>
> I will probably try running the saw both as it is and with the wheels fully
> coplaner once I have the tires replaced and the saw put back together so I
> can see how much of a difference there is. However, I doubt I am
> experienced enough to notice much of a difference, and was wondering if
> anyone knew more about this common irregularity.
>
> Inquireing minds want to know.
>
>
I found tracking to go from perfect to abysmal by following the books
advice. It seems to me that the Powermatic knows a hell of a lot more
about band saw geometry than duginske. Other than that, the book had
some useful tips.
I immediately removed the washer once I saw how poorly the blades
tracked. I've been running a variety of blades from 3/16 to 5/8" on my
PM and they all track beautifully. I don't really know what Duginske
was thinking. Maybe some other brands/models need re-engineering??? (I
doubt it, but not having messed around with any others, I'll leave that
question for others to answer)
Dave
I have found that you can coplane your upper and lower wheels but when
you put tension on the blade it will not be in coplane. The solutition
is to check the coplane after it has the tension applied and make the
adjustment to bring it into coplane. It will track dead on. Check out
thread below
http://groups.google.com/group/rec.woodworking/browse_frm/thread/91f56902d02eb7b4?hl=en
David wrote:
> I found tracking to go from perfect to abysmal by following the books
> advice. It seems to me that the Powermatic knows a hell of a lot more
> about band saw geometry than duginske. Other than that, the book had
> some useful tips.
>
> Dave
LOL.. I guessed you learned the lesson "If it works, don't mess with
it".
I bought Duginske's book as well with my first bandsaw, but the saw
seemed to work pretty well, so I didn't want to risk any tweaking that
might be hard to undo.. Same with my 2nd saw. It tracks about 98%
perfectly.. I don't want to risk fooling with it and going down to 60%
perfectly (and wasting a Saturday). It is a nice book though.
David wrote:
> I found tracking to go from perfect to abysmal by following the books
> advice. It seems to me that the Powermatic knows a hell of a lot more
> about band saw geometry than duginske. Other than that, the book had
> some useful tips.
Which powermatic do you have, and what do you think of it?
Chris
"David" <[email protected]> wrote in message
news:[email protected]...
> that's not entirely true, I'm afraid. I set my PM to be coplanar with
> tension and it still didn't track properly. I took out the shim, and it
> tracks perfectly. Like I said before, Powermatic knows a lot more about
> building a bandsaw properly than Duginske.
>
They know more about their design, that's for sure. Writing a book to
detail general principles can't fit all the specifics.
Thanks for the information. I have finished replacing the tire on the upper
wheel which was the one in the worst condition and the saw is now tracking
very well. I will replace the lower tire when I have more time. That tire
is in better condition, and I found it quite time consuming to completly
remove the tire, and properly clean all the glue, and rust from the first
wheel, so replaceing that one can wait.
Since the saw is now tracking well I have very little desire to experiment
further in wheel alighment. But this saw has made me question some of the
conventional wisdom on aligning bandsaw wheels.
This saw has a massive frame and a huge tentioning spring. But even though
it is capable of putting much more tention than needed on the blades I am
using, the wheels shows no measureable deflection with a very highly
tentioned 1 inch blade. I very much doubt that the non-coplanarity I
observed in wheel alignment has anything to do with deflection, wear, or
anything similar.
The saw also has three adjustments for the upper wheel. One has a handle,
and is used to adjust tracking like my 14 inch saw, and two others that look
as if they can be used to adjust wheel alignment (both twist, and
coplanarity). They are locked in place and noted in the assembly diagram as
"factory set, do not adjust".
It really seems like the saw was not manufactured or set accidentally to
this degree of non-coplanerity. It appears to have been adjusted this way
on purpose. For now I will assume that the folks that made the saw know
best and will just enjoy having a well made tool.
Tom
"tom saksa" <[email protected]> wrote in message
news:[email protected]...
>I have recently purchased an older (green) Jet 20 inch bandsaw and have
>started reconditioning it. (An absolutely awsome saw, but that is another
>story). Basicly I am replacing some worn belts and tires, as well as
>cleaning and aligning it, etc. I have Mark Duginske's book and have been
>following the advice in the book, but the book has raised some questions.
>
> After testing the coplanerity of the saw I found the the upper wheel was
> slightly behind the lower wheel. This is a condition which Duginske says
> is common and can be corrected with a spacer washer behind the bearing on
> the upper wheel. I agree that this non-coplanarity is common, since I
> have seen it in other bandsaws such as my very cheep 14 inch clone. But,
> why does it always seems to be in the same direction with the upper wheel
> being further back than the lower wheel? That coincidence seems odd
> enough to me that I wonder if the saw manufacturers have have been doing
> it for some unknown reason.
>
> Does anyone know if bandsaw manufacturers purposely build in this kind of
> offset into the alignment on purpose? If it is easy to adjust, why is it
> so common in saws and mostly in the same direction? What kind of
> advantage could it have? The blade tention does not seem capable of
> warping the wheels in this manner. This saw even has adjustments for
> tuning the position of the wheels, but they seem to have been purposely
> aligned with the wheels very parallel, but offset in depth.
>
> I will probably try running the saw both as it is and with the wheels
> fully coplaner once I have the tires replaced and the saw put back
> together so I can see how much of a difference there is. However, I doubt
> I am experienced enough to notice much of a difference, and was wondering
> if anyone knew more about this common irregularity.
>
> Inquireing minds want to know.
>
>
"David" <[email protected]> wrote in message
news:[email protected]...
> :) Yup! I was suckered into wasting my time trying to re-engineer what
> was already a well thought out band saw. Duginske needs to retract his
> whole damn treatise on wheel alignment. He talks a good game, but the
> actuality is that the saws are made (at least the PM) to track correctly
> as they come off the assembly line. You are right: if it isn't broke,
> don't "fix" it!
>
Stop and think a moment. You track by pitching the top wheel. The bore
from the factory is to compensate for average flex only - strength of
materials. Tracking is still done by changing the pitch, where you can run
out of correction authority on the odd blade if you're not set up co-planar
at zero adjust.
"bf" <[email protected]> wrote in message
> I bought Duginske's book as well with my first bandsaw, but the saw
> seemed to work pretty well, so I didn't want to risk any tweaking that
> might be hard to undo.. Same with my 2nd saw. It tracks about 98%
> perfectly.. I don't want to risk fooling with it and going down to 60%
> perfectly (and wasting a Saturday). It is a nice book though.
Any way you look at it, tweaking is going to have to happen, either now or
later when you're in the middle of something and it stops working properly.
Me, I prefer to partially tweak and learn a great deal of adjustability
options right in the beginning. The machine is cleaner (assuming it isn't
too covered with shipping grease) and if there is anything wrong with the
machine, it's better to know sooner when you're still in the newbie customer
stage and have some options available.
Duginske says that if the wheels are not coplanar (while under tension)
beyond a certain degree, then it is probably not a good idea to try to make
them
track properly by adjusting the wheel angle, i.e. the tracking adjuster.
This makes sense. If the wheels are way out of coplanar then you'll end
up tilting the upper wheel a lot to get it to track properly. You'll have
wheels that are not in the same plane and the top wheel tilted excessively
to compensate.
I think it is essential to check the coplanarity only while the wheels are
under tension. If not coplanar, then add the washer.
I added a height increase block (riser block) to my almost-new Delta
28-475X. Under tension the wheels were out of coplanar (top wheel
too far back). Duginske's methods seemed to work for me: I
added a washer and the wheels were in the same plane. I make
small adjustments with the tracker adjustment as needed for
different blades.
The original poster wonders why many band saws seem to have
the same pattern of the top wheel being too far back. I'm just
guessing, but I can imagine they are made this way intentionally
because it is always easy to add a washer to the top wheel but
much harder (impossible?) to move the top wheel back or make
any adjustment to the bottom wheel.
"tom saksa" <[email protected]> wrote in message
news:[email protected]...
>I have recently purchased an older (green) Jet 20 inch bandsaw and have
>started reconditioning it. (An absolutely awsome saw, but that is another
>story). Basicly I am replacing some worn belts and tires, as well as
>cleaning and aligning it, etc. I have Mark Duginske's book and have been
>following the advice in the book, but the book has raised some questions.
>
> After testing the coplanerity of the saw I found the the upper wheel was
> slightly behind the lower wheel. This is a condition which Duginske says
> is common and can be corrected with a spacer washer behind the bearing on
> the upper wheel. I agree that this non-coplanarity is common, since I
> have seen it in other bandsaws such as my very cheep 14 inch clone. But,
> why does it always seems to be in the same direction with the upper wheel
> being further back than the lower wheel? That coincidence seems odd
> enough to me that I wonder if the saw manufacturers have have been doing
> it for some unknown reason.
>
> Does anyone know if bandsaw manufacturers purposely build in this kind of
> offset into the alignment on purpose? If it is easy to adjust, why is it
> so common in saws and mostly in the same direction? What kind of
> advantage could it have? The blade tention does not seem capable of
> warping the wheels in this manner. This saw even has adjustments for
> tuning the position of the wheels, but they seem to have been purposely
> aligned with the wheels very parallel, but offset in depth.
>
> I will probably try running the saw both as it is and with the wheels
> fully coplaner once I have the tires replaced and the saw put back
> together so I can see how much of a difference there is. However, I doubt
> I am experienced enough to notice much of a difference, and was wondering
> if anyone knew more about this common irregularity.
>
> Inquireing minds want to know.
>
>
bf wrote:
> David wrote:
>
>>I found tracking to go from perfect to abysmal by following the books
>>advice. It seems to me that the Powermatic knows a hell of a lot more
>>about band saw geometry than duginske. Other than that, the book had
>>some useful tips.
>>
>>Dave
>
>
> LOL.. I guessed you learned the lesson "If it works, don't mess with
> it".
> I bought Duginske's book as well with my first bandsaw, but the saw
> seemed to work pretty well, so I didn't want to risk any tweaking that
> might be hard to undo.. Same with my 2nd saw. It tracks about 98%
> perfectly.. I don't want to risk fooling with it and going down to 60%
> perfectly (and wasting a Saturday). It is a nice book though.
>
:) Yup! I was suckered into wasting my time trying to re-engineer what
was already a well thought out band saw. Duginske needs to retract his
whole damn treatise on wheel alignment. He talks a good game, but the
actuality is that the saws are made (at least the PM) to track correctly
as they come off the assembly line. You are right: if it isn't broke,
don't "fix" it!
Dave
Chris Friesen wrote:
> David wrote:
>
>> I found tracking to go from perfect to abysmal by following the books
>> advice. It seems to me that the Powermatic knows a hell of a lot more
>> about band saw geometry than duginske. Other than that, the book had
>> some useful tips.
>
>
> Which powermatic do you have, and what do you think of it?
>
> Chris
Chris, I've got the 14" unit that is in current production with the flat
belt, light, and sawdust blower (never sure what the proper term is for
that tubing that blows the cut line clean). I LOVE it! It runs like
the proverbial sewing machine, tracks perfectly. I like the guides, the
tensioner, the height of the table, the dust collection. To me it is
lightyears better than a Delta. I owned 2 Deltas and wouldn't' give you
a nickel for either one. Being tall, I have no desire for the pricier
BS's because their tables are so low (Laguna, etc). Besides, I don't
really feel that spending more money would get me any big improvement
over the Powermatic.
dave
sdppm wrote:
> I have found that you can coplane your upper and lower wheels but when
> you put tension on the blade it will not be in coplane. The solutition
> is to check the coplane after it has the tension applied and make the
> adjustment to bring it into coplane. It will track dead on. Check out
> thread below
>
> http://groups.google.com/group/rec.woodworking/browse_frm/thread/91f56902d02eb7b4?hl=en
>
that's not entirely true, I'm afraid. I set my PM to be coplanar with
tension and it still didn't track properly. I took out the shim, and it
tracks perfectly. Like I said before, Powermatic knows a lot more about
building a bandsaw properly than Duginske.
Dave
On Wed, 22 Mar 2006 12:34:19 -0800, "tom saksa" <[email protected]>
wrote:
>I have recently purchased an older (green) Jet 20 inch bandsaw and have
>started reconditioning it. (An absolutely awsome saw, but that is another
>story). Basicly I am replacing some worn belts and tires, as well as
>cleaning and aligning it, etc. I have Mark Duginske's book and have been
>following the advice in the book, but the book has raised some questions.
>
>After testing the coplanerity of the saw I found the the upper wheel was
>slightly behind the lower wheel. This is a condition which Duginske says is
>common and can be corrected with a spacer washer behind the bearing on the
>upper wheel. I agree that this non-coplanarity is common, since I have seen
>it in other bandsaws such as my very cheep 14 inch clone. But, why does it
>always seems to be in the same direction with the upper wheel being further
>back than the lower wheel? That coincidence seems odd enough to me that I
>wonder if the saw manufacturers have have been doing it for some unknown
>reason.
>
>Does anyone know if bandsaw manufacturers purposely build in this kind of
>offset into the alignment on purpose? If it is easy to adjust, why is it so
>common in saws and mostly in the same direction? What kind of advantage
>could it have? The blade tention does not seem capable of warping the
>wheels in this manner. This saw even has adjustments for tuning the
>position of the wheels, but they seem to have been purposely aligned with
>the wheels very parallel, but offset in depth.
>
>I will probably try running the saw both as it is and with the wheels fully
>coplaner once I have the tires replaced and the saw put back together so I
>can see how much of a difference there is. However, I doubt I am
>experienced enough to notice much of a difference, and was wondering if
>anyone knew more about this common irregularity.
>
>Inquireing minds want to know.
I don't think any manufacturer intentionally builds an offset but they
do build a slight angle (small fraction of a degree) into the shaft
bore. It is for the purpose of compensating for the deflection that
occurs with blade tension and to facilitate tracking.
Frank
>
David wrote:
> sdppm wrote:
>
>> I have found that you can coplane your upper and lower wheels but when
>> you put tension on the blade it will not be in coplane. The solutition
>> is to check the coplane after it has the tension applied and make the
>> adjustment to bring it into coplane. It will track dead on. Check out
>> thread below
>>
>> http://groups.google.com/group/rec.woodworking/browse_frm/thread/91f56902d02eb7b4?hl=en
>>
>>
> that's not entirely true, I'm afraid. I set my PM to be coplanar with
> tension and it still didn't track properly. I took out the shim, and it
> tracks perfectly. Like I said before, Powermatic knows a lot more about
> building a bandsaw properly than Duginske.
Must be black magic.
er
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