Not all tool or machine manufacturers write fully understandable details in their instruction manuals.  There are a lot of well written instruction manuals but there are probably even more that are really vague and leave a lot of guesswork for the woodworker.

I had an experience with this very thing soon after purchasing my Porter Cable Model 4212 Dovetailing jig.  For the most part, the manual that came with the jig was fairly well written and covered a lot of the details of setting up the jig, locating the work piece in the jig, how to arrange the parts of the jig for the type of dovetail or box joint that you were going to make.  It covered alignment of the templates, where and how to mount the jig, how to set the jig up to reduce tearout, how to set the router bit depths, etc.  The manual is very well planted with photos throughout.

The manual overall was pretty in-depth for the most part.  The manual was not flawless however, in that it was vague in a couple of the written instructions which caused me to create quite a bit of new scrap for my "bonepile".  I realize of course that a more experienced woodworker (I'm fairly new at this) might have more intuitively known what to do in certain procedures where the manual left a little to be desired.

For example, in the section that covered positioning the work piece into the jig, the manual stated in step 4: - "Align the vertical workpiece (A) Fig. 4 flush against the bottom side of the template.  Center and clamp the workpiece between the farthest finger to the left and the nearest finger to the right of the template".

As far as aligning the vertical workpiece, I found no problem accomplishing this.  The last half of the Step 4 instructions however, was not only ambiguous (at least to me), the accompanying photo (shown here on the right) illustrating the part of the step that was faulty.  Let me explain.  In the photo, can you see that the workpiece is centered between the "farthest finger to the left" and "the nearest finger to the right" in the template.  In other words, it shows equal distance of spacing from the left side of the workpiece and the left most finger edge and the right edge of the closest right finger of the jig. That is exactly how I placed my first workpieces in the template the first time I tried using the jig.

The result?  There was a mismatch in overall height of the tail pieces and the pin pieces in the outcome of the assembled drawers!  What I discovered (after much frustration and scrapped work pieces) is that you need to totally ignore the right side placement of the work piece and simply place the left edges of the work pieces exactly at the center of the 1st left hand cavity made by the left fingers of the jig.  When I tried this, I had perfect fitting dovetails on my drawers.

A few weeks ago, I read an article by Tom Hintz, owner and web master at Newwoodworker.com that covered in great detail these kinds of problems with instruction manuals and equipment manuals in a lot of cases.  The article gets into some of the reasons why this occurs and what we as woodworkers may be able to do to help out in these situations.  The article is well worth reading and can be found on his web site.  Go there and read it!

I would be interested in any comments you viewers have about similar experiences that you may have had with faulty, ambiguous or mis-leading manuals.  If you have and care to share them with us, E-Mail us and let us know.

Dave
dave@oldaveswoodshop.com