Flap wheels are designed to sand pieces with contour or a profile. This can be on a door, a furniture part, a hobby project part or anything else that is not flat in design.
Anyone can sand a flat component but having a work piece with contours creates some challenges. Utilizing flap wheels takes away the challenges of sanding a profiled or contour surface.
Flap wheels are designed to be flexible and conform themselves to the shape being sanded. Flap wheels flex to the different dimensions and shapes of the work piece and sand both high and low areas with the same effectiveness. It will be gentle around edges as the sandpaper fingers will flex out and let the higher part be sanded at the same time as the lower parts of a profile.
Flap wheels sands best at spindle speed between 300 rpm and 800 rpm, and the wheels are rate for max speed of 1200 rpm
5 Things Flap Wheels are used for.
1. Edge Break (Breaking of sharp edges)
When a cabinet door or molding part is ready for stain and sealer coat its very important that sharp edges are eliminated. Sharp edges are a weak area in the finish as there is not enough mass for stain, sealer, and top coat to properly adhere. Picture a knife and you are trying to apply stain to the sharp edge, it just will not stick to the sharp edge. Breaking (slight rounding) of the edges eliminates this issue and has become a standard practice in the cabinet and door industry. A flap wheel does an even break of the edges so the parts are ready for stain and sealer coat.
2. De-nibbing (Removing of loose fibers)
When the work piece is ready to stain and seal or paint, there is one last step to insure a quality finish.If you examine the work piece closely you will always find loose fibers from the sanding operation that are part of the surface of the wood.These fibers are what you feel after a sealer coat or primer has been applied and cured. The surface of your material is now rough. This is the result of the fibers absorbing sealer or primer and expanding and then drying.
Use of flap wheel sanding prior to stain or priming will eliminate these loose fibers. This process is called de-nibbing. De-nibbing a product will make for a much smother seal coat and result in much less sealer or primer sanding prior to top coat. You gain the added benefit of using less sealer also as now you are not trying to cover the fibers as they have been removed.
3. Uniform Stain Color
When sanding a work piece and applying stain, many times the color will not be consistent. This is primarily due to different sanding techniques or pressures being used in different areas of the work surface. It is very difficult to try and sand a flat area the same as a contoured or profiled area. As a result the pore openings in the surface of your material will be different and absorb stain at a different rate.
This causes uneven color match or balance. Flap wheels will sand 3 dimensional products evenly. Your pore opening will be uniform and as a result you get a superior color balance throughout the work piece.
4. Sanding Sealer Without Cutting Though The Edges.
When hand sanding a stain and sealer work piece one must always be careful of the edges to not sand through and white line the work piece. Flap wheels are designed to handle this fine sanding without removing the sealer and causing burn through or white lines in the finish. In a study completed in Germany it was found that most woodworking shops hand sanding removed too much sealer and had to repair many pieces prior to top coat.
By using the flap wheel sanding approach you achieve the correct amount of sealer scuffing to create a superb bond with the top coat without white lining or burning through the stain. This will give your product better protection for the future.
5. Reduce Hand Sanding
The speed of sanding with a flap wheel compared to hand sanding is just incredible.Studies show that using a spindle and a flap wheel are more than 10 times faster than hand sanding.This frees you up to do more or other things. The quality of the sand is many times better than a hand sanding as it will always be uniform.
These flap wheels can be used on any spindle from 2" to 36" in length and can be used on any arbor that your spindle might have from 1/4" to 2".
Save yourself the time of hand sanding and know that the product you create is protected with a superior and uniform finish with excellent quality.