Q. What are some of the major applications for contour sanding applications, and how do you deal with the deep contour jobs?
Ron Kohnke, president, Opti-Sand: One of the biggest applications is sanding mouldings both prior to finishing and also sanding between finish coats. We also have a number of machines being used for sanding flooring, paneling, siding, face-frame stock and other applications. When the depth of a moulding profile, from the lowest point to the highest is greater than ¾ in., it is possible to have a variation in sanding quality. Many times this can be overcome by tilting the sanding heads to minimize the height variations.
Matt Deckard, president/co-owner, Sand-Tech, Inc.: Most of our customers are kitchen and entry door manufacturers. We also do moulding sanding. Here at Sand-Tech, Inc., we prefer to use the QuickWood Quick-Strip System. This system is an array of staggered brushes/abrasives in a paddle wheel style configuration. This configuration comes in different brush/abrasive trim lengths to accommodate depth of profile and sanding efficiency. This combination will clean up the profile on the product very well, and it will break the edges consistently. This is very similar to the old Wolfe Head sanding system, but it's more user-friendly, has a longer abrasive life and is more cost-effective.
Q. How do you determine the optimum grit size for contour sander applications, relative to the wood species being used?
Kohnke, Opti-Sand: This is an interesting question. Opti-Sand sanders use flexible finger sanding wheels that use a combination of centrifugal force and, more importantly, pressure from the tampico fibers to push and hold the sandpaper fingers into a profile and against the wood to do the sanding. By varying the height of the sanding wheel and by varying the spindle speed, we get more or less sanding pressure. Thus, we can make the same grit sandpaper be more or less aggressive. This allows us more flexibility on which grit to use for different wood species. When you have a relatively fixed sanding plane, such as with some types of profile sanders, the grit selection becomes more critical.
Deckard, Sand-Tech: We have found through 12 years of testing competitors' abrasives as well as our own, that the QuickWood brush backed type of sanding head is the most effective and cost efficient way to sand your flat profiled products as well as mouldings.
The brush back abrasives are used in both automatic machines and manual hand-held machines. The sandpaper is separate from the brush, and after the sandpaper is used for 1,000 to 1,500 (depends on operator) hours in automatic operation, it can be slid out from the brush and replaced. The brushes are reusable and can stand at least two to three changes of abrasive.
We have found in door manufacturing with about 90 percent of our applications a 220-grit scratch pattern before stain application gives you the most uniform and consistent color of your different species wood products. This gives you great color match and stain consistency without the blotchy look customers sometimes get from just widebelt/orbital sanding before stain application.
The remaining 10 percent usually uses 180 grit to accomplish the same finish, but open the wood up a little more due to widebelt or orbital polishing using their finer grits.
When customers are having issues with their moulding vendor and are presanding before the coating application, we have found that using the QuickWood Quick-Strip System in a 40mm trim length and 150 grit that many of the tooling marks most vendors have can be addressed without changing the profile of their workpieces. Our grit ranges from 60 to 600.
Q. What are the particular applications for so-called "flap/flutter" sanders, and how do these applications differ from standard contour/profile sanders?
Kohnke, Opti-Sand: As mentioned, Opti-Sand sanders use flexible finger sanding wheels to sand all types of mouldings and linear parts. These sanding wheels have a number of rows around the circumference of the wheel. Each row consists of a strip of sandpaper that has been cut into "finger" widths of about 1/8, 3/16, ¼, 7/8 in. or wider. The sandpaper fingers are backed up, or supported, by a row of tampico fibers. The tampico fibers and centrifugal force push and hold the sandpaper fingers into the moulding profile to do the sanding. It is the various finger widths that allow the sandpaper to sand both the detail and flat parts of the profile. With this type of wheel we can remove cutter marks, handling marks, rub marks and lines from light nicks in the moulder knives. It is quick and easy to go from one profile to the next with little or no setup time. This allows the sander to easily and economically sand short run profiles.
The standard profile sanders usually have either profiled wheels or belts with profiled shoes or a combination of both. They sand the same profiles and remove the same defects as a sander using flexible finger sanding wheels. The standard profile sanders can be more aggressive and actually remove chatter marks. The time to change from one profile to the next is usually fairly long; thus it is not as economical to sand short run profiles.
Deckard, Sand-Tech: A "flap/flutter" sander can be used for any product that is flat or even profiled. Some examples are cabinet doors, entryway doors, table tops, desks, bookcase trim and several other products.
Many other sanding manufacturers use a shaped wheel for every profile with tooling changes between each profile, just as tool changing on a moulder or shaper.
The QuickWood Quick-Strip System will conform to every profile, due to its flexible brushes that quickly flex with every profile as it comes to the sanding head.