Finishing Sanders?

[Bruce Page]

What is the advantage of a finishing sander like the PC505 over a random orbital sander like the PC333? When finish sanding, I use a 333 and go up through the grits stopping at 220. Then I hand sand using a sanding block & 220.
At around $170 for the 505, it must be doing something that I don’t understand. Please enlighten me.

Thanks

[Ed Cafarella]

I have both sanders, the 505 is BIG and aggresive. I use it to hog off lots of material just shy of a belt sander. it does a fairly nice job but the ROS leaves less marks.

[Dave Anderson]

Originally posted by Ed Cafarella
...but the ROS leaves less marks.

I have never been able to "master" the use of a random orbit sander. :(

What is the secret to success? I've tried to start the machine and after reaching full rpm putting it to the workpiece, I've tried to put it to the workpiece before reaching full revs -- the result is always the same - deep swirl marks that are next to impossible to remove.

I've resorted to using my PC-340 finish sander and hand sanding but I'd like to use the ROS if I could figure out HOW to use it!

[Dave Arbuckle]

Cuz, I've asked a lot of people to demonstrate their sander technique to me (yeah, I get some strange looks at the restaurants ;)).

The most common error I've seen, by far, is placing a lot of pressure on the machine. I place zero down pressure on the machine, allowing just its weight to do the job. Side benefits are that it is less tiring, sandpaper lasts longer, and the machine actually works faster.

I always allow the machine to come fully up to speed before using it.

Dave

[Bruce Page]

Originally posted by Ed Cafarella
I have both sanders, the 505 is BIG and aggresive. I use it to hog off lots of material just shy of a belt sander. it does a fairly nice job but the ROS leaves less marks.


Hello Ed,

Your response surprises me. I thought a “finishing” sander like the 505 would be used with the finer grits and as a last step prior to applying a finish. My 333 works fine but sometimes, particularly on lighter colored woods, it can leave the wood muddied or dull looking when I apply the finish.


If you can count your money, you don’t have a billion dollars. -- J. Paul Getty

[Ed Cafarella]

Hey Dave, I think you're having the same experience I had. when I was new to woodworking i bought a 4 1/2" Ryobi ROS and as sooon as i turned it on the ting would spin out of control and i'd always have to be really careful when putting it on the workpiece to avoid damage. I then boought a 5" PC333VS ROS and saw what a real ROS should do. It doesn't really "spin" it just kiind of "wiggles" and turns from side to side even when it's not on the workpiece.

[Bruce Page]

Originally posted by Dave Anderson
I have never been able to "master" the use of a random orbit sander. :(


Dave, in addition to what Dave Arbuckle stated, you also need to put down and lift off the sander squarely to the wood. The most common mistake as Dave said, is applying too much down force. I apply some pressure with the courser grits but let the sander “float “ when using 180 & higher.


Why are our days numbered and not, say, lettered? -- Woody Allen

[Dave Anderson]

I'd love to see the look on those people's faces in the restaurant when you ask them to "show me your technique":eek:

Thanks for the tip on downward pressure. I haven't used my ROS in quite a while but I don't remember really bearing down on it.

I, too, would let it come up to full speed but my problem was when I made first contact with the workpiece - the very first thing was deep swirl marks as the sandpaper hit the wood. This happened EVERY time and happened before I really had a chance to start sanding. Touch the wood = swirl marks. :mad: Happened whether using 60, 100 or 150 grit paper.

Gotta be pilot error! Right now, I'd rather hit myself in the head with a hammer <u>again</u> (long story folks but documented in the BP archives) than use that damn ROS. Grrrrrrrrrr.

[Dave Anderson]

Originally posted by Ed Cafarella
Hey Dave, I think you're having the same experience I had. when I was new to woodworking i bought a 4 1/2" Ryobi ROS

Bingo! You may have hit the nail on the head! That's the same stupid ROS I have, got it on like day-three of my woodworking life.

Man, I hate that stupid little sander!

Oh well, another tool lesson learned and another "good" tool added to the "but, Honey I NEED" list.

Thanks to all for your help on this! Probably still some pilot error involved but maybe it's not ALL my fault!

[Ed Cafarella]

I still have it, use it on "non-essential" items. The better ROS's don't do that and if they do, there is a litle part above the disc that probably has broken.

[Jason Roehl]

Dave Anderson,

Here's how to tell if a ROS even has a remote chance of being usable: turn it on holding it off of any workpiece. If the pad starts spinning at a very high speed, the ROS is worthless (at least, you have to start it ON the workpiece). If it looks like it is spinning in a very small circle (like 3/32" for the PC333), then it is probably a good sander--it has an anti-freespin feature, usually a small belt attached to the pad and a fixed pulley.

Old models of the 333 did not have this (more than about 5 years ago), plus they were lower amperage than they were now (2.4A now vs. 1.7A). I've got two of the things, one of which has seen lots of hard use, and has only worn out a pad and an anti-freespin belt. I don't leave home without it. :cool:

[David Rose]

the sander on the wood. Even the 333 can dig in a little if you cant it just a bit.

Yeah, why *is* the finish sander more aggressive?

David

[Halsey MCCombs]

I find starting my ROS on the wood and moving it at the same time I have no problems.Halsey

[Phil Phelps]

..I think lack of patience causes people to apply pressure. Actually, the pressure inhibits the action of the sander. Has anyone tried finer grits? Just because wet or dry paper comes in sheets doesn't mean you can't use it on the ROS. You'll be surprised.

[Jim Baker]

I have a fairly new PC333 and so far have not experienced any swirling problems except when I get impatient and press down harder than I know I should.

[Christian Aufreiter]

Hi,

generally it is said a finish (orbital) sander should be switched on an then be put down on the wood.
A ROS (without pad brake!!!) should be put down on the wood and the be switched on.
Nevertheless, I never tried this because my Festool ES 150/3 ROS has a pad brake and doesn't leave any swirls.

Regards,

Christian

[Tom Gattiker]

....say start on the wood (I am pretty sure). Dave, maybe it is your sander. I have been using one for about 6 months and I have never had a problem with it. (Trust me if there were a way to screw something up with the tool, I'd have done it!) Some ROS's appear to be much more user friendly than others. I cannot remember my model no. but it is the one that retails for about $59.