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Kentool Sup-R Sander Tungsten Carbide Sanding Block Product Evaluation

May 05, 2015

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Airfield Models ( Sup-R Sander Tungsten Carbide Sanding Block Product Evaluation

There are two primary reasons that I do not use commercial sanding blocks.  The first reason is that the method used to retain the sandpaper is wasteful.

The second reason is that the sandpaper is loose on the block such that particles can get between the paper and the block which can gouge the work.  Additionally, if the paper isn't flat, it can do strange things such as curl and cut groove in the wood or round over edges unintentionally.

Kentool sent me three Sup-R Sander Tungsten Carbide sanding blocks to try out.  The blocks are conventional size and shape, but have one significant difference they do not use sandpaper.  These blocks have neither of the problems listed above.  But that doesn't necessarily mean they will be good blocks.  This is what I found out.

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Kentool Sup-R Sanders  Tungsten Carbide Sanding BlockSup-R Sanders are plastic blocks having a tungsten carbide sanding surface.  The blocks are color-coded (fine, medium and coarse) for easy identification.  Other than the grit, the blocks are identical in size and shape.

Each block is approximately 2-3/4" wide x 5-1/4" long.  The tungsten carbide sanding surface is permanently adhered to the block and is smaller than the outside dimension all the way around by approximately 1/16"

The blocks are comprised of top and bottom pieces that separate to store the included brass wire brush used to clean particles from the block.

Because the sanding surface is made from tungsten it should last a very long time.  The tool carries a lifetime warranty, but I do not know if that warranty applies to the surface wearing out or just to defects.  The manufacturer's recommended list price is $13.60 each.

I used these blocks as much as possible while working on my DoodleBug 330 project a profile fuselage, control-line stunter.  In addition to various grades of balsa, I used the blocks to sand maple motor mounts, birch plywood, soft aluminum and dural aluminum.

I like the size of the block, but would prefer them to be a little heavier.  It would not be difficult to add weight to the blocks by pouring leftover epoxy in the bottom.

Sup-R Sanders excel in two places that make them worth their weight in gold sanding plywood and aluminum.  Normal sandpaper wears out very quickly when edge-sanding plywood.  Because I glue paper to blocks, I always dread it when I have to sand plywood task because doing so means the paper will need to be changed sometimes more than once before the job is finished.

I used these blocks for that same task and they were not phased a bit.  That means my sandpaper blocks will last a lot longer now.

All three blocks remove stock quickly when sanding balsa.  The coarse block tears away balsa at an incredibly fast rate which will make it excellent for roughing in wing tips blocks and similar tasks.  I would say that the coarse block falls somewhere between a wood rasp and 120 grit paper.  Roughly it is probably about equivalent to 60 or 80 grit paper.

I chose to cut the landing gear from dural aluminum plate.  The edges of the gear were fairly ragged after cutting them with my scroll saw.  I have never had good success using metal files on aluminum.  They clog up quickly with galled aluminum and I generally find files awkward to work with.

These blocks did not clog or dull and made short work of the task.  The Sup-R Sanders felt much more comfortable than metal files and were easier for me to control.

Kentool Sup-R Sander Tungsten Carbide Sanding BlockThe blocks have only two short-comings.  The first is that the blocks seem too flexible. They are stiff enough to remain flat on softer woods because less pressure is applied while sanding.

I have not actually tried to sand a hardwood plank flat with any of these blocks, so it may not actually be a problem.  However, it is something that I would pay attention to until I was more confident in the block.

A thicker bottom would ensure the block could not flex.  I would like it to be at least 1/4 and preferably 1/2 thick.

The second item is that the blocks can not sand all the way into a corner because the tungsten pads are slightly smaller than the bottom of the block.

Kentool does not indicate the grit equivalency of the blocks which would be nice, but is not really necessary.  The fine grit would actually be considered medium to coarse on soft balsa wood.  Therefore, Sup-R sanders can replace coarse and some medium blocks, but fine sandpaper blocks will still be necessary.

Overall I like these tools and recommend them.  They are a welcome addition to my sanding tools and will save me a great deal of time and money from replacing sandpaper.



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Copyright 2004 Paul K. Johnson