Remember the old saying, "A Flying Red Horse can't tell the difference
from 1,000 ft"?
Ask the guys in metrology about the magnitude of built in errors of
single ended vs differential measurements.
Measurements under discussion are single ended.
45 degrees is always described (by careful persons) as 45 +/-
So the typical way to get a full circle out of 45 degree wedges is to
four wedges for the left half, join four wedges for the right half,
and joint both
halves to make the final joints fit. Another way is to temporary-
mount the items
side-to-side with the crack, run it through the table saw to open that
a straight 1/8" void, then close the joint. Kerfing was what Roy
called it, though his technique used a handsaw...
Very true! The words "dead on" are somewhat of a misnomer.
Everything has some error if you look closely enough.
I've heard of this. It's a popular technique among those who do
segmented turnings. The joints will all be tight but the circle
becomes a bit less circular. The lathe guys end up having to make the
walls of their turnings a bit thicker so that they can then turn them
In other words, cut both pieces at the same time. Yes, I've used this
technique (long, long ago). You pretty much want to assemble the
whole thing first. For something like a frame, where you have to
maintain equal lengths on opposite sides, you'll end up cutting
through all of the joints - gap or no.
There's a third option that you didn't mention. That is, cut the
pieces accurately enough to avoid the gap in the first place. Then
you don't have to use these or any other methods to rework the
joint(s). It takes a bit more skill and knowledge but it's much
faster and cleaner in the end. The other techniques are good for
those who are not interested in developing their machinery skills.
Home of the TS-Aligner.com
I would at this point suggest to first take Frank's advice and start cutting
some wood. While exacting tolerances are a plus, sometimes we cannot take
full advantages of these fine settings because of the quality of the
material that we cut and or out technique can be sub par to the machine
First see how the saw cuts at a 45 degree bevel. If you don't see any kerf
marks or burning you should be good to go.
We often get a bit too wrapped up in using a dial indicator to measure
If you are not happy with the cutting results call Powermatic and get them
> The manufacture then rolls it over to 45 and checks the alignment
If the only problem is that the axis of rotation of the arbor is not
parallel to the table, then shimming the table relative to the cabinet
can fix the problem.
If there is other slop and play in the mechanism, I agree that there
isn't much that can be done.
On a contractors saw, this problem is usually caused by the two trunnions
not being parallel and the answer is to shim one side of one of the
trunnions. I don't know if the same applies to cabinet saws, but they do
have trunnions - perhaps someone else can comment.
It's possible that you're cranking the blade too hard against the 45
or 90 degree stops. I might try cuts at 46 and 89 degrees, just to
see if the stops are the problem.
Hard to imagine how the error can increase no matter which way you
tilt the table.
Y'know - after many years of lurking and occasional posting in this
newsgroup and having to deal with the seasonal trolls that surface, it's
nice to be reminded of the good stuff - like someone actually helping
OK, enough sentiment - gotta go make some noise & sawdust!
Well this has been an eye opening thread and I think I've seen the
light. You see, when I needed to upgrade my table saw I went back to
"salvage" (the place where freight damgage, dealer inventory resets,
individuals who do not believe in the laws of random variability, and
the rare individual who actually has a real problem send their units
back to) and asked Jerry if he had a Unisaw. Says Frank I've got this
one that came back "alledged defective" (the usual RMA cause) but I've
checked it and can't find the reason (the usual outcome) it's within
specs., so I say let me go pay finance and I'll back my truck up. I
never checked the saw for alignment that day or ever.
Now that was 13 years ago or so, and I've made a whole lot of
furniture since then with this saw and while my friends and realtives
comment favorably on my work, as the builder I know where all the
flaws are that they don't see.
I've always assumed that the flaws were human error, where I measure a
little wrong, or skipped a step here or there, or whatever. But now
I'm beginning to think I can blame all those flaws on the saw.
So I guess I need to get one of those gadgets that Ed sells and get to
tweaking this saw so I can achieve the perfection that I know exists
out there somewhere.
I built a 12"x12"x12" box made with 1/4" plywood, and 4 of the edges
were joined with a box joint. I built a prototype before I had Ed's
tool, and then built the real one after. It was a LOT easier getting
everything lined up precisely square after using the TS Aligner Jr.
Ed even helped me figure out how to align the cross-cut sled
precisely. This "just make sawdust" is fine for some jobs. But when
errors are multiplied, adjusting a fit afterwards can be a PITA.
For many years I used my father's tablesaw (still in use today) but
the first table saw I purchased was a Sears Crapsman (about 25 years
ago). I learned a heck of a lot of woodworking on that machine and
never received a single negative comment from anyone about the quality
of my work. There was always a healthy amount of test cuts, re-
working joints and "creative fixes" involved in the process and I
figured that it was all a matter of skill (and a lack thereof). If I
could refine my skills enough then these problems would go away. But,
it didn't quite work out that way. Instead, I learned which tasks and
design elements proved to be the most troublesome and time consuming
so that I could avoid them. It struck me one day when I was trying to
talk a customer (an interior designer) out of doing what she wanted me
to do (mitered corners). I was being a brainless moron: going nowhere
and doing nothing. Pretty soon I'd be making kitchen cabinets as a
sub-contractor instead of furniture for designers.
Having the benefit of a formal education, I had the ability to work
through a problem in a logical manner. I could examine symptoms,
recognize specific causes, and develop systematic solutions to resolve
them. I purchased the proper instruments (dial indicator, magnetic
base, calipers, etc.) so that I could examine my machines to determine
what could be done to reduce or eliminate the test cuts, re-work, and
"creative fixes". Basically, I had decided to devote myself to
improving my machinery skills.
It didn't take me long to recognize major problem areas. The first
thing I did was replace the rip fence. It proved to be an
astoundingly amazing improvement. So much so that I decided that the
entire saw was a lost cause. I replaced it with the Unisaw that I
have today and realized yet another quantum leap in the quality of
work that came right off the machine. I probably could have continued
to use the Sears saw and optimize its performance but I was impatient.
During this same time, I was developing tools and techniques for
eliminating test cuts and rework. With the help of a machinist friend
and some engineers, I combined these tools and techniques into the
first TS-Aligner. That was in the spring of 1990 - more than 17 years
ago. I tested it on a commission from a designer that I would have
flatly turned down a year earlier: a night stand made in the shape of
an "A". Every joint came together at a compound angle (including the
dovetailed drawer sides). I pulled it off without a test cut. No re-
work. It was done to budget in record time.
For years I had fought against a poorly maintained junker saw thinking
that my woodworking skills were deficient. In reality, it was my
machinery skills that needed help. The quality of my wood work was
never the issue, it was the enormous time and effort that went into
making anything that went beyond simple square joinery, stock molding
profiles, curves, angles, shapes, etc. I was wasting time and effort
fixing everything that the machine did wrong - leading me to avoid
projects that could stretch and develop my woodworking skills.
There are a number of people who want to turn this into flame fest
against machinery and its proper alignment. They cite their personal
anecdotes about how many years they have been producing fine
woodworking without any regard for alignment. In addition to being
exasperating, this is nothing more than a straw man argument. The
issue has nothing to do with $2000 saws and alignment to within a
"thousandths of a gnat's ass". Amazing woodworking has been done for
thousands of years before table saws were even invented. Nobody is
saying that you have to spend a certain amount of money, or have a
certain machine, or align it in a certain way before you can do fine
woodworking. People who rant and rave on this point expose themselves
as extremely insecure.
This thread is about helping one person to make the most of a recent
machinery investment. It's about helping him to learn and apply some
machinery skills. It is not a waste of time; it is a way to avoid
wasting a lot of time and effort. People who can't sit by without
ridiculing him and continually citing examples of how well they get by
without any machinery skills are saying a lot more about themselves
than they realize.
Home of the TS-Aligner
Sorry about the delay in responding. I've been pretty busy and
haven't even been able to manage even one post per day.
Hmmmm....and I was thinking that the thread was starting to sound like
the glorification of ignorance. Funny how two people can look at the
same thing and get two completely different impressions.
Spam? No, it was just a story - much like the one that Frank told. I
wrote it with the hope that I could inspire some to approach their
woodworking in a more intelligent manner (and perhaps discourage
others from ridiculing them in the process).
I received a number of email messages in response. This one pretty
much represents the overall sentiment:
"I hope the idiocy here doesn't prevent you from participating in the
future. It generally prevents me, but I learn a lot just by watching.
I learn because folks like you dare to participate, financial interest
The group used to be a lot more active and it was pretty rare that
people would get flamed and ridiculed for asking legitimate questions
or making a genuine request for help. At the worst, people would get
told to search the archives. It would seem that things have become a
Pious? Holier that thou? Hmmm....again, two people can see things in
completely different ways. The situation reminds me of how Galileo
was treated when his innovative ideas threatened the pious ignorance
of the time.
OK, I've spent all day looking for one of these gilded thrones.
Nobody in Boise has any in stock (no surprise there!). They all say
that they can order one (gee, I could have done that for myself, so
what purpose do the local shops serve?). So, until the throne arrives
we will just have to live with a flat world located at the center of
the solar system. I'll keep you posted on any progress. In the
meantime, we need to get hold of someone in Rome and let them know
about the delay. We certainly don't want any councils declaring
anything rash before the actual proclamation occurs. After all, if
they arrest me before the throne arrives then I'll be charged with
crimes that haven't yet occurred. What a mess! Next time we'll need
to think of a better platform for these announcements; something that
can be obtained locally. ;-)
Home of the TS-Aligner
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