Wood Sander FAQ

Q: How much stock can I remove in one pass?

A: Stock removal on a widebelt sander is determined more by the  abrasive belt than by the machine. Each abrasive belt is designed to  remove a certain amount of stock, and if that amount is surpassed, the  life of the belt is affected. As a rule, you will need to use the lower  grit belts for heavy stock removal (36-80 grit belts can remove  approximately 1/8 inch to 1/32 inch respectively) and medium grit belts  for lighter stock removal (100- 120 grit belts can remove approximately  1/32 inch to 1/64 inch respectively). Belts in grits from 150 on up  should only be used for finishing and are not considered cutting belts.  Other factors affecting stock removal are: abrasive belt speed, type of  sanding head, feed speed and available horsepower.

Q: What are holddown shoes, and when do I need them?

A: Holddown shoes in a widebelt sander are similar to chip-breaker  shoes in a planer. They are used to control the part as it passes  through the machine, prevent dubbed or sniped lead and trailing edges,  and to allow for shorter parts to be run. Specific uses are: short  parts, narrow parts, parts under 1/4 inch thick, veneered panels, or  any time you need to hold close tolerances.

Q: What is a segmented platen?

A: When sanding veneered panels or sealer/lacquer, utmost control is  required. To accomplish this, the platen (or shoe) is made up of  individual segments which receive sanding pressure individually  (pneumatically or electronically). These segments are controlled by a  CNC controller that, along with a sensing unit, can be programmed to  activate only when needed. By doing this, you have the ability to  conform to the irregularities of the panel and sand without the fear of  sanding through the sealer or veneer.

Q: How many sanding heads do I need?

A: This depends on your production needs and the end finish required.  If your production will not allow for multiple=

Q: Should we sand with a drum or a platen?

A: Generally speaking, a drum is used for stock removal and a platen is  used for finish sanding; however, drums are also used for finish  sanding in some applications. A rule of thumb would be, if you need to  remove more than 0.003 to 0.004 inch, you should use a drum, otherwise  a platen may be used. The difference between the two is also seen in  the finish. A drum will produce a short scratch pattern, but it is  deeper on a given grit. A platen will produce a longer scratch that is  not as deep. You really need to determine stock removal requirements  and desired finish to decide which will fit your individual needs.

Q: What is sealer sanding?

A: Sealer (lacquer) is the first coating applied to your product after  finish sanding or staining. The purpose of this is to fill in or "seal"  the wood pores and protect the wood. A negative effect to applying  sealer is, that being a liquid, it raises the grain of the wood,  producing a rough surface. Sealer sanding is performed to create a  flat, smooth surface with the proper texture, so that the next coat  (also known as the top coat) will adhere properly. Methods used for  sealer sanding are: hand sanding, widebelt sanding, brush sanders (both  hand held and feed-through), and with feed- through orbital sanders.

Q: When should a vacuum belt be used in feeding a sander?

A: There are two circumstances for which the vacuum belt is  appropriate. The first one occurs when you need to run parts that are  shorter than the distance from the infeed pressure roll to the outfeed  pressure roll. Without it, the parts to be sanded may slip or stall in  the machine.  A second situation is when thin products must be sanded. Parts less  than one-half inch in thickness will have a tendency to bow and curl.  The vacuum belt assists the pressure rolls to flatten and hold the  parts during the sanding operation. If they are not held flat, too much  sanding may take place on the corners that curl up.

Q: Are there advantages to a planer/sander over abrasive planning?

A: Yes. They are mostly related to power consumption and media costs,  which are lower with a planer/sander. An abrasive planer will use high  horsepower motors with very coarse sanding belts. The latter are  expensive, and usually need to be replaced two or three times a day  (depending on the type of product being sanded). A planer/sander uses  about half the horsepower of a conventional abrasive planer, on  average, and the cutter inserts will last several months. These  replaceable inserts have four sides, and one edge will produce around  150,000 board feet of product.  Another advantage of the planer/sander is in media costs. An abrasive  planer uses 24- or 36-grit belts, and leaves very deep scratches. To  remove these, an additional sequence of 60-, 100- and 120-grit sanding  belts must be run to achieve the same finish as that produced by a  planer/sander running one knife head and one sanding belt.

Q: When should a crossbelt sander be used?

A: A cross belt sander is used primarily in veneer tape removal  applications. The cross belt sander is designed to run across the grain  of the wood, which is an aggressive sanding method. Because of this  design, veneer tape is removed with one head, whereas two heads need to  be used with other wide belt methods. Cross belt sanders also are used  on long panels in which the grain runs in the narrow direction, such as  desk tops and front panels. In processing these, the cross belt is  located on the out feed of the machine, and the scratch pattern  produced by the belt goes with the grain.