Hi. I finally decided to replace my table saw drive belt with a link belt.
When I removed the belt cover I discovered that the pulley was loose on the
motor shaft. The only thing keeping it on was the belt rubbing against the
inside of the belt guard/cover. That part of the cover is nicely polished
I have realigned the motor so the cover fits better, but I'm still having
trouble keeping the pulley on the shaft. There's a key in the key slot, and
a set screw in the pulley that I've tightened down as much as I can. It
might hold this time, but the first few tries it came loose after only a few
seconds under power.
There doesn't seem to be any mechanical fixture for keeping the pulley from
sliding on the shaft. Should I put some loctite on it? (I've never
actually used loctite myself; what kind should I get?) Or is there a better
The instruction manual just shows a photo of someone pounding the pulley
onto the shaft with a hammer and a block of wood. I'm way past that now.
There's some blue coating on the last 1/2" of the shaft. If I don't
position the pulley near the end of the shaft there isn't enough clearance
inside the belt cover. It seems like it would be better if the pulley were
closer to the motor housing (and bearing). I sometimes hear a clicking
noise, once per revolution, as the motor spins down. It didn't do that
before, and I speculate it started because of the repositioned pulley.
What's your best advice? Thanks.
- Owen -
I have always read instructions that the two furthest away edges of the
two pulleys are to be aligned to a straight edge. Sometimes that
requires adjusting both pulleys on their respective shafts. Drive belt
should be centered in the opening of the belt cover, per my old craftsman
The forces on the drive belt usually are to the shortest distance between
the two pulleys and all that. Also check the shafts of the arbor and the
motor are both at 90 degrees to the rotation plane of the drive belt (or
as best as you can do sometimes.)
Check the end of the set screw, it should be flat or slightly convex.
the idea is to maximize the surface area of the set screw; maximum
friction when tightened down. Set screws are cheap to replace. If in
doubt, replace set screw.
Just think slowly through how to reduce the forces that will cause the
motor pulley to wander across the shaft. It should not take a very large
force to keep the pulley in place.
BTW: there is a home made tool involving a screen door turn buckle,
threaded rod, and scrap wood that will stretch the two pulleys apart as
you adjust the motor shaft, and align the two pulleys. Fist time I use
such a tool my band saw drive belt noise reduced to almost nothing.
On Sat, 26 Jan 2008 15:51:30 -0500, "Owen Lawrence"
When I bought my link belt "system", it came with new "premium"
pulleys. And they worked REALLY well. I'd look into replacing the
Before the change, my saw couldn't pass the nickel test with the
nickel laying flat. Now it passes with the nickel on edge.
I'd replace the sheave (pulley).
It's probably die cast aluminum and damaged beyond repair.
Position the new sheave as close to the drive end bearing as possible and
use some LocTite on the set screw to insure it stays in place.
Adjust motor on mounting plate as required to line up with sheave on the
As far as the belt guard is concerned, I'd probably s**t can it, but that is
A transmission house or Grainger will have both the sheave and LocTite.
A new setscrew usually solved the problem for me. They are cheap and
available at most HW stores. In stubborn cases I've doubled up and put
a second setscrew on top of the first. Shorter length setscrews are
avail ... This has never failed to hold.
The clicking is the slight bit of slop in the loose shaft/key/pulley.
It is something to listen for in the future when you use your saw as
you will know the pulley is loosening. I would say the reason why the
set screw is no longer holding is because often times the set screw
will form a depression in the key. The setscrew will want to locate in
this depression when you try to reinstall the pulley and often times
wont allow you to get it as tight as it needs to be. Also, when your
pulley is loose for a while it can deform the key and even the keyway
making a less than optimal fit. This slop will tend to work the pulley
loose after you have tightened it. The best thing to try first is to
get a new set screw and either get a new key or flip your current key
over (if its not a half moon). As the other reply stated, keys and set
screws are cheap, changing them wouldnt cost more than a dollar or
two. If you can get a knurled cup set screw they are the best as they
actually bite into the key.
I wouldnt put any locktite on the shaft/pulley connection but you
could use some removable loctite on the set screw. I would however try
to fix the problem without it as you may have a tough time getting the
set screw broke loose after you locktite it in. A better option would
be to get a slightly longer set screw than the one you have (perhaps
1/4-3/8 longer) and getting a jam nut. Lock down your set screw then
lock the jam nut against the body of the pulley. This would stop the
set screw from backing out. Just make sure you dont get a set screw
too long because often times a socket head set screw (allen) will
crack if the socket is not supported in a tapping.
We have a contractors saw that we use on jobs and it has a pulley that
comes loose like this on occasion.
Since you say that the pulley comes loose VERY easily, and that it's
"way past that now":
Sounds like the pulley has worn itself loose on the shaft. I wonder if
the "blue stuff" is what someone else used to try to fill the gap?????
Would it be possible to get a new pulley? I'm assuming that the
pulley is made of softer stuff than the shaft. To check this, you need
to measure the shaft diameter to see if it has worn more in one spot
than in some non-used portion.
Pulley looseness of more than about 0.002" can cause the problem you
have. That's why "the book" shows the pulley being "hammered" onto the
shaft. It should fit snuggly.
There are other ways to address this issue, but they require some
machining and accurate meeasuring skills and tools.
If you want some thoughts, email me off list.
Owen Lawrence wrote:
On Sat, 26 Jan 2008 15:51:30 -0500, "Owen Lawrence"
Remove the set screw. Then tighten the set screw that's still in
there. Finally, reinstall and retighten the set screw you removed.
Double set screws have been known to have been applied in several
instances. Tightening the one on top gives you the impression you are
accomplishing something but in actuality, you're simply tightening it
against the bottom one which isn't changing at all.
As others have said, spring for a couple of new pulleys. Get the ones
that are machined instead of cast. It will smooth out your vibration
as well as staying on the shaft. A little Locktite on a setscrew of
your new pulleys should prevent them from backing out. Locktite comes
in several grades. You want the one that allows you to loosen the
"There's a difference between doing things right, and doing the right
A machined pulley will be an improvement over the cast ones usually
found on these saws, but for now to get you by - try using a second
set screw behind the first one to lock things in place. Odds are that
your clicking noise is the motor start mechanism, quite a normal sound
but now your ears are out looking for trouble.
Thanks for all the replies so far. I called Busy Bee Tools, the vendor of
my saw, and they said that the blue colouring on the end of the shaft was
machinist's bluing (not an adhesive). He recommended Loctite, and a new
key, setscrew, or pulley if it's too loose. I haven't had a moment to
myself since I posted my questions so I can't tell you yet how the problem
was (rather, will be) solved.
For the record, my pulley IS a machined steel pulley. There is a single
setscrew, and it doesn't seem to be sloppy. It bites into the key, but I'm
considering replacing it. (Trips to the store are costly, even if what I
buy isn't.) They key may be worn a bit; I have another length of it in my
toolbox so I'll probably just replace it while I'm at it. A new pulley is
only $10, so if it does fit better I'd say it's worth it. I can always use
the old one in some other project.
I will not leave the guard off. End of that discussion.
Phil, I'd like to hear more about that screen door turnbuckle alignment
tool. Do you have any pictures or diagrams of it?
- Owen -
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