I had an older model of the Porter Cable 5" random orbit sander that finally bit the dust a year of so ago. Great sander, never left swirl marks on anything. Since then, I have bought and cursed at the Ridgid, DeWalt, and Porter Cable sanders for leaving swirl marks on my pieces. Very faint on bare wood, but clearly visible when I apply stain or other finish to the piece. Anyone have any ideas on how to fix my sanders to prevent this? Or is it back to the old 1/4 sheet sanders for 180 and 220 final sandings??
Be sure to completely wipe off the work between grits and don't skip grits for "better' results. You need to have a very small random orbit if you are going to use a ROS for the final standings.
Start the sander above the work and slowly lower it onto the work, then lift it off while it is still running. Do not press down on it at all, the weight of the sander is sufficient. Move it very slowly and steadily over the wood, do not stroke the wood with the sander. Clean the paper frequently using one of those gum rubber blocks. Don't skip any grits on your way down and finish with a finer grit than you have been using. Finish with light hand-sanding in the direction of the grain using a sanding block and paper one step up from the last stage of ROS sanding.
Or, for softwoods,
don't sand at all, use a #3 or #4 smoothing plane, or a Knight hand-made wooden bodied smoother.
Or, for hardwoods,
don't sand at all, use a smoothing plane and follow with a cabinet scraper if need be.
Or, (so I've been told) for a very hard wood like ebony or rosewood follow the cabinet scraper with hand sanding starting with 400 grit, and keep going down in grits until the unfinished wood is glossy. You can get paper down to
2000 grit at auto parts stores and can get white corundum paper by mail order.
Sanding is a PIA. Planing and scraping is a joy, at least until your thumbs get sore. Then you'll start hunting for scraper planes.
Every sander leaves some kind of marks. With a ROS the thing is to not let any swirls from the coarse grits slip through to the end, or introduce new ones by some foreign matter getting into the works, so that when you are done you just have uniform very fine swirls. Then a light hand sanding is all you need.
Your old ROS probably did the same thing, you've just gotten better and are looking harder at your work and expecting more. This is a good thing.
While the advice is generally good and certainly not letting large grit carry over is mandatory, I'll agree w/ marc that I've not had problems w/ old P-C's leaving detectable swirl on pieces even after staining/finishing.
I can't comment on new P-C's or other varieties as I only have old P-C's.
I would expect that from any and would tend to put blame on paper and final grit more than the sander itself, but again I've none others to compare to...
I still go to my old Speed block orbital for the next to final sanding. Final, after a setup with water, is always by hand. Everything said in the thread is true. Clean between and keep things flat without pressing. But it's better to go with a small-orbit orbital, versus Randomfor the last, in my experience.
BTW, there are so many grits of paper out there that the phrase "don't skip a grit" is even more meaningless than usual where start and end are unspecified. Don't make big jumps in number or expect to sand longer. Also, make sure you're in the same system, or you'll wonder why the P400 doesn't do any better than CAMI 320.
Add to that, Leon's suggestion to blow off the grit from the previous sand-paper, and you WILL get results. Do not skip grades. In the final stages, look for good dust removal and minimal pressure on the sander. Keep your paper fresh and your target clean.
*now I'm putting on some mittens so I won't be tempted type and extoll the virtues of a Rotex sander..*
For flat cut surfaces, use better quality saw blades with dampeners. You won't need to sand or scrape sawn surfaces after cutting. Items sell for >
$1000, never a touch of sandpaper and look better than sanded ever can. (glossier, like scraping results)
Something else to try for general sanding, YMMV, lightly mist (not wet) the work first to raise the grain, sand, then allow to fully dry.
Use suction during sanding, hook up a shopvac/dust collector to the sander, not just a dust bag, to the dust port of the orbital sander.
Also I use an Oil-less (airbrush) air compressor to remove dust from work and sanding pad. Not too much air pressure on the work or you'll be "sandblasting".
A word of warning about that technique, older PC ROS sanders will dig a divot in the surface almost instantly with that approach. Those old PC sanders had no brake and would go into spin mode rather than random.
Awh, you just have not gotten to use a really good sander yet. ;~)
Yeah I have not yet parted or retired my Sped Bloc. It is still relative new at 2 years old It replaced a Sped Bloc that lasted 18 years. But darn it puts up a cloud of dust. I wonder if the Festool Finish sander is as good.
you buy the vacuum attachment, and attach it to a Fein II or CT22...NO dust.. hell, the sander sticks to the surface... I can't imagine The Green/Black Boys doing a better job......but then again, I have made that error in judgement before...
I got my little Bosch for 49 dollars, IIRC.. and just love it. I Get out my hole-punch set and whack away and make a stack of 6-hole 1/4 sheets sandpapers. Even the dust collection that comes with it is quite effective...but just for a little while. To change the paper is just a snap.. easiest ever.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.