i used a speaker and a scope to balance this blower
now i want to see if i can use that same method to balance my jointer
this plywood will protect me from the cutter head while i'm probing for vibrations
so the weird thing i'm seeing is more vibration on the ends of the bearing blocks than on the
sides of them which suggests the problem is something other than imbalance of the head
so somehow this seems to be rocking back and forth this way not moving
this way whoa this block is wiggling back and forth by almost 0.1 millimeters
by about 3 000 let's just try turning it down here yeah so something is causing this bearing block to
rock back and forth and the most likely thing i imagine is if the bearing is on there crooked then
as the head spins this bearing would kind of go like this so time to take this jointer apart again
so if i just spin it like that i can't visually see the blocks wiggle
but they both have a little bit of slack to them and that's the slack in the bearing not
so much the blocks so now if i just put a little bit of tension on this thing with a rubber band
and now we can see these wiggle by quite a lot
so this looks quite bad but it's actually the seal here that's popped out partially
let's pop that back in doesn't look too bad like this but it's on there crooked
so i'd really have to spin the head to see that and it does have a bit of play
and now with just the bearings i can't particularly see them wiggle
oh no i can see this one wiggle a bit i can certainly feel it wiggle
it's a bearing from turkey i suspect these might
not be quite as good as the german or the swedish bearings
but checking the bearing itself i can't tell that it has any misalignment just a little bit of slack
so a problem is i don't have a press for putting this back on
so i'll have to improvise a bit what could possibly go wrong with it
[Applause]
so holding this bearing under tension with this rubber band here
i can see it wobble but just barely so
i think that bearing was seated on there a bit crooked before
well the bearing on this side is quite noticeably worse
well that might have made a minor difference i think i'll try pulling that one off too
i've got an m8 thread in the end of this thing
that used to attach a little gear i'll try to use that to squeeze that bearing back on
so with tension on it i can't say that this wobble is any less than it was before
but if i take the tension off
it doesn't move at all because the amount of slop in the bearing
is more than the amount of wiggles so as long as that bearing is where it likes to be
the uh the wobble is within the slop so i'll be okay
so i think as long as my bearing blocks are aligned i'll be okay and these are
good flat on the table but looking on here the bearing surfaces are not properly aligned
i didn't want to lower this one too much so i made a shim and sanded that one to match the taper
i'm just going to glue that on a little bit so it stays in place
still seeing wiggle but about 10 times less than before
still a tiny bit of misalignment
i think i'll call that good enough
still getting some bearing noise
still kind of loud but not as bad as it was before i could probably hear the bearing
and this feels like there's some home here and here
[Music] i'm still picking up some hum which is probably some imbalance but uh most of the noise
is much higher pitched and i think that's from a bad bearing got it mostly back together now
and the loudest sound now isn't from the head being out of balance it's just high
pitched bearing noises especially the one on the back i think [Music] this one is the loudest
but this belt vibration is bugging me and i'm starting to think it's because of this pulley
this pulley is actually a crown pulley so that this belt rides in the middle like a flat belt
the problem is i don't have enough slack side to side so the belt often rubs against the
flanges here which are there to keep the belt from falling off if things are badly misaligned but
that rubbing on the side kind of plucks the belt a little bit so i need more space in the middle
do
[Music]
now i'm just going to trim the shape of that crown a little bit so it's in the middle again
[Music]
a lot less belt vibration though never hits that bearing i tried taping this brass nut at
different positions inside the drive pulley but it never made any noticeable difference
in terms of measuring vibrations with this thing so i don't think the balance is much of an issue
but i also noticed the vibration level seems to go up and down with time
and i can see a sort of strobe effect between
the 120 hertz flicker of the lights and the cutter head
so this rotation is very close to 120 turns per second
and something else is vibrating at 120 hertz now the motor itself is
actually very steady but it seems to have a rotational vibration of about 120 hertz
and i realized with 60 hertz power coming in the power peaks 120 times per second and is also
completely gone 120 times per second and with the motor turning the power into torque that means the
torque is essentially modulated with 120 hertz so that's a source of 120 hertz vibrations
and there's harmonics of that vibration every 120 hertz as well
and then also the belt has a resonant frequency of about
65 to 68 hertz which of course will change as there is a torque on it so that may also have its
own set of vibrations but if it was just the 120 hertz and its harmonics
i don't think i'd mind the sound so much it's the bearing noise that's really annoying
so i ordered some swedish skf brand ball bearings to put in there
but uh i'll deal with that later as for a lot of these noises i'm now chasing
i probably just never noticed those before because the head was that much
louder and the noise is actually planing still drowns out all the noises [Music]
you