Sunday, April 8, 2012

Archtop Guitar Build - Safe-T Planer

(Cue up the retro 80's new-wave Men Without Hats song)
S-A-F-E-T-Y Safe-T planer...

The Safe-T planer is a tool that looks anything but what it's name proclaims, "Safe."  Imagine three razor sharp blades rotating in a drill press at 3100 RPM with no safety guards between your fingers and the blades and I think you can see what I mean.  The photos in the instruction manual show men with shop aprons and pipes in their mouths using the tool to make picture frames.  This harkens back to a time when Popular Mechanics predicted that we would all be flying cars to work by the late 1980's.  There is no way that a tool like this would ever make it past the lawyers in this day and age, yet many guitar makers swear by the tool while others claim that they own one and would never dream of using it.  How dangerous is this tool?

The Safe-T planer was manufactured by Wagner and features three cutting blades that are housed in an aluminum disk with a steel spindle.  The blades must be aligned with index marks scribed in the bottom of the disk and are held in place by three screws that are accessed from the top.  The tool comes in two varieties, one for a drill press and the other for a radial arm saw so be careful to get the correct one for your workshop.  There is an abrasive disk included in the kit that mounts on a spindle for sharpening the blades.  This disk has the correct radius on it's edge for regrinding the cutter heads.

I built a table extension for the drill press and sealed it with shellac.  The table was buffed to a satin finish which I think is important so that the work piece slides easily across the surface and to prevent dust and chips from accumulating under the work piece and raising it on the table. 

The table must be set absolutely flat to the disk.  A wire scribe with a 4 inch radius can be made from a coat hanger and mounted in the drill press chuck.  This can be slowly spun to check that the table is completely flat in respect to the cutter.  I saw one video on line where the person put a very small shim under the table on the feed side so that the cutters only cut on the leading edge.  He claimed that this eliminated burning and seems like a good idea if you don't mind having light scallops cut into the surface.  The important concept that I am getting at is this.  If you look at a rotating disk on edge, it has an infinate radius (ie is flat) and if you rotate the disk 90 degrees it has a radius equal to whatever radius the disk has.  If however you rotate the disk at an angle between 0 and 90 you will cut an elispe with either a very large radius (at shallow angles) or one approaching the radius of the disk as you near 90 degrees.  The tool manual describes using the tool to cut scalloped edges for raised door panels and picture frames by running the tool at some angle to the work piece.  This is a very useful aspect to this tool and one that I plan on taking advantage of in the future...

The tool seemed to be very sharp right out of the box and cut though maple with great ease.  It throws small chips at a prodidgous rate so a very powerful vac system with a large feed would be needed to keep up with the tool.  Surprisingly, the tool does not want to hog or pull the piece if it is fed against the rotation of the planer.  It operates quietly and smoothly and at no time during the hours that I used it did I ever feel unsafe. 

The most dangerous tool is a dull one so I removed the cutters and lightly sharpened them using the abrasive disk.  I used a drill press vise with a "C-clamp" mounted to prevent the cutter from rotating (as described on the Stewart Mac web site).  After a fine wire was formed at the cutter's edge, I stopped and removed this burr with my finger nail.  After remounting the cutters, I was amazed at the improvement in performance.  It cut well to begin with but was even better with the oxidized edge of the cutter head removed.

During the two to three hours that I took to cut the top and back plates, I sharpened the cutters twice.  The second time I held the cutters by hand to sharpen them (like the manual shows) and I have to say this is the way I will do this in the future.  There is a lot of fiddling around to get the table height set just right with the vise/c-clamp set up that is avoided by doing this by hand.  You remove such a small amount of cutter head that it literally takes seconds to make the regrind.

My final assessment is that this is a very useful, versitile and safe tool to use provided you know what you are doing and keep the tool sharp.  The most dangerous time when using a tool is when you get overly comfortable with it and start taking short cuts and pushing the limits with the tool.  As long as you keep this in mind and give it the respect it deserves I don't think it will give you any problems.

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