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I am interested in how “Finish Sanders” work. If they are orbital it would seem that the sanded surface would be plagued with the little half moons that take the stain differently.
Is one better off doing it the old fashioned way, by hand?
Jerry Thompson
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Orbital sanders will indeed leave circular scratches, if too coarse of paper is used. When I used these sanders, I never used anything coarser than 180 grit, but 220 would be better. I have switched to random orbit sanders, because they have fewer tendencies to leave a noticeable scratch pattern, and are much more aggressive than plain orbital sanders. Other things that will influence the quality of the sanded surface are the speed at which you move the sander, the pressure you apply, and the size of the orbit. Also, it is necessary to keep the pad flat on the work, in order to prevent gouging. You should move the sander slowly over the surface; I aim for about 6 inches in 2 seconds. The more pressure you apply the slower the motor will turn, due to the increased load, and this will lead to scratches, and will actually slow the progress down. The weight of the sander will provide plenty of pressure to keep the paper cutting. The larger the orbit, the faster the sanding action, but this also increases the likelihood of scratches. I hand plane almost everything I do, so I just give a light sanding with a random orbit sander loaded with 320 grit paper. For veneered surfaces, I start with 180, and go up through 320, being very careful to keep the sander flat. I also clean the surface between grits. Sometimes I follow with a hand sanding with 320 grit paper, especially if I have to raise the grain.
*Rob, good primer.Jerry, I own a couple of orbital sanders and use them very little. I am a firm believer in the use of hand planes, cabinet scrapers, and card scrapers in preparing the surface for the finish.In doing so you are cutting or slicing the wood, not abrading it which not only gives a smoother surface but makes the application of the finish easier to control, IMHO. Additionally, it actually takes about half the time than sanding. 'Bout the only time I sand is between finish coats. FWIW.Dano
*Danford is correct, about planes, and scrapers being faster. I have made several projects, such as sideboards, secretaries, and desks that have taken up to 7 weeks of full time labor. On these pieces, I would judge that the total time I spent sanding bare wood, to be less than 1 hour each. You will find that the surface left by a plane will not have much raised grain, when a water- based finish is applied. A scraped surface will have some raised grain, so a light sanding will be necessary, this is why I sand even the planed surface; with 320 grit paper, to give a uniform surface for the finish coats. 99% of my furniture is made from mahogany, which can be somewhat stringy, but close grain woods may cut cleaner with a scraper, and may require little or no sanding. This has been the case on the few pieces of cherry I have used.
*The key is to begin with the proper grit and work up to the final grit without skipping. Each succeeding grit should remove the marks from the prior sanding. Finally, I always hand sand with the grain as my final step.Also, it's possible to oversand and end up just burnishing the wood. I find that 180 grit is fine for softwood and 220 about right for hardwoods. If you plan to stain using a pigment stain, hardwoods should only be sanded to 180. Any finer, and the pigment will have nothing to adhere to.Final smoothing occurs from light sanding after the first coat of finish.
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