hey Jonathan here at topsaw this channel topsaw is all things wood from
tree work to wood work I teach high school woodshop during the week and I do
tree work on the weekends ideally bringing those logs in to mill him at
the school so we have wood to make wood projects today is going to talk about
the difference between a random orbital sander and a finished sander the
advantages of each one the disadvantages why you would want one or the other and
then I was going to go through why an orbital sander works they're actually
really ingenious I'll take that one apart on the left and show you how it
gets that random action so before I start let me just talk a little bit
about sandpaper Illume there's a lot of different types
of sandpaper a lot of discussions on it but the most common type is aluminum
oxide sandpaper and then the grit difference so this is a quarter sheet
four and a half by five and a half it's a quarter of the full sheet nine by
eleven this grit right here is 150 this grit right here is 100 this is really
pretty coarse this is kind of like a medium coarse medium grit and what that
number means is how many parts of sand that are per square inch so the lower
the number the bigger the sand particles the higher the number the finer the
sandpaper so a hundreds really coarse it'll take off a lot of wood but scratch
the wood up 150 it's kind of a medium 180 a medium and about a 220 is kind of
a finer sandpaper it really depends on what sort of projects you're building if
you're building a stepstool 220 is a good grit to finish on if you're
building a picture frame where your eyes are going to be really close and
checking the the finish of the product then you probably want to go more all
the way up to a 320 or even finer how sandpaper works is what you really do is
you're taking these little pieces of sand
in between the grains of the wood so when you go across those grains you
scratch them but when you go with the grains if it's fine enough paper the
grains are in between the grains of the wood ok then let me talk about the two
different Sanders a little bit again this is a random orbital sander and as
it spins around there's a random pattern in it because of a cam inside there
which is super cool if it was just circular it would spin in a circular
fashion creating circular scratches across the grain but the randomness of
it moves it around in the oscillating way so that you don't see those
scratches this is a finish sander it's a quarter sheet finish sander and you fold
the page or you tear the paper in a quarter sheets and you put it on there
okay here's another finish sander this is an old Black & Decker half sheet
finish sander it's a half sheet because it uses a half seat of the sandpaper and
this is another orbital this is a craftsman random orbital these are five
inch Sanders there's really no difference between this one and the
DeWalt except I kind of like the DeWalt brand a little bit more seems a little
hard here okay the big advantage of the random orbital
sander is you could actually sand a lot faster so the way the sandpaper is held
on to the random orbital is velcro this one's actually falling apart a little
bit here so you just kind of harder to take that grit off so there's a pad it's
just a Velcro attachment and you just peel it on and off the holes are to get
the dust up out of the work area this pad is worn out is from school so this
one was all worn out I brought it home to replace it it's really easy to
replace so changing the sandpaper on here is
really easy to do and really nice because when you use sandpaper you got
to step all the way through the grits so you started at a coarse grit like 120
150 and then you move up to a 180 to move the scratch marks from that then
you step up to a 2:22 remove the scratch marks from the 180 on the finish sander
over here you got it usually by a full sheet of sandpaper that's nine by eleven
you tear that and a half to get four and a half by eleven tear that and a half to
get four and a half by five and a half so these are usually four and a half by
five and a half once you tear them you undo these clips and then the paper
comes in and out those things there so it doesn't see it's not hard to do but
for some reason the students never step up on the finish sander they won't
change the paper out and go to different grits
so changing the sandpaper big advantage for the random orbital put this velcro
and that big advantage is you use all of the right grits and go through it the
second is the random orbital goes pretty fast and efficiently and the finished
Sanders a little slow students hate sanding but it's really a big part of
the project and it's what gives you a good finish the good sanding really
allows you to allows the material to take in whatever way you're gonna seal
that wood up so paper is easier on the random orbital than the finish sander
it's also more efficient and faster on the orbital than the fitness sander easy
use of both kind of easy to use safety wise or both kind of equally safety
probably the biggest danger is you know playing around with it with it being
plugged in and getting electrocuted but if you touch them while they're running
it won't cut you it you know probably take off a top layer of skin but it
won't won't hurt you so then why do people have finished Sanders well the
finish sander does have some advantages the square base is really nice if you're
trying to stay in the bottom self of a bookshelf that's fixed you know like in
here with that finish sander you can come right up to the edge and sand and
it goes kind of slow so you don't screw anything up with an orbital when you do
that you usually cut a groove with that into the backboard so that's that's a
one advantage of fitness sander has over the orbital the second advantage and
disadvantage that the finished sander has is that it goes pretty slow so you
don't take off a lot of wood that's an advantage because you don't want to
start sanding and create a varying different planes of your board or your
project so on the finish sander you go slow enough and you can check whether
you're putting in you know dips and valleys but the disadvantage is is it
goes slow so this thing because it moves just in a little oscillating pattern you
could get right up to edges without damaging a back it goes slow so it
doesn't do create any valleys and on the orbital you could take off wood pretty
quickly and then step up through the sand papers you could get up to an edge
but if there's a back board you got to be really conscientious not to mark it
up and groove it with this I mean with that efficiency and the rate of sanding
the other thing you could do to is you could stand right through the plywood in
no time go right through the veneer and then ruin that whole part with the
finish sander it's so slow you don't really do that as often so that's the
primary differences between the two they both currently have 220 grit on them but
it's kind of a fine grit I'll show you how they both sand the goo way to check
how they sand let's just use a pencil and mark up a board like that and then
let me turn on this orbital
you can see it took that pencil mark right off pretty quickly it's pretty
smooth finish pretty cherry here's the finish sander in the same pencil mark
a little bit of pencil mark left right there a little bit slower kind of the
same finish on both of them I do move them with the grain always so you can't
see them next to each other a different they are if you only had to buy one I
would buy the random orbital so you could do your rough sanding and then
move up and also uses a fine sander so the key is to use the right paper at the
right time and not jump from one to one 22 to 20 but to step up through every
different grit so 120 150 180 220 okay so that's the big difference between the
two I was gonna pull this random orbital apart just to show you how cool it is so
again this thing's worn out here you see the velcro just attaches to it I think
it's a t20 Torx I'll hold these things on you know just pause it here and pull
it so I'm going to loosen up these three bolts here and pull this velcro pad off
this isn't very expensive to replace I think times like five or ten bucks and
you probably get a year or two you a full use out of these before you replace
them let me pull that off I'm just gonna pause it here for a second and pull that
off so there's a Velcro pad I'll just pull
it off there the bolts on there and then this thing you just get it at your
regular home-improvement store when that starts coming apart like that it's time
to replace it when it starts to wear and the velcro doesn't stick to it
one thing that really wears these things out fast which are not designed to do is
when students go up on an angle with them they're really not designed to do
that it put waves and your board as well they should always be held flat and
moved around okay so this is the inside here and you could see here this is a
circular motor alright so this thing is just spinning around just a regular
motor and then this thing right here is offset so as this thing sir circulates
around in round your actual attachment point
cotton to free spin here in an eccentric center point so that's where the
randomness comes in and that's what prevents circular grain patterns on
there this is also a t20 Torx let me see if I can pull this off I think I'm gonna
have to pause here and do that again so loosen that bolt up I'll just pull this
bolt off and then this piece comes off the mounting board that comes off right
there alright so that's actually circular but
the attachment point is this cam right so as this thing spins around it's off
off-center and that's what gives it as randomness so you could see it's not
quite the center spot there's just a teeny bit randomness but that's what
allows this thing on here to spin around in all directions and gives it the
ability not to create a circular standing pattern really very very clever
invention alright well hopefully that helped you identify the differences
between a random orbital and a finish sander they both have their place in a
shop if I could only get one I probably get the random orbital and then also I
just love the inventiveness of how cool these random orbitals are it was really
a very clever idea whoever came up with this I did did so hope you enjoyed the
video if you learned a little bit about sanding and tools if you're in my class
thanks for watching this video and be gentle on the tool so we can make cool
projects alright thank you for watching