How to Cut a V-Groove Mat - with a Logan V-Groove Cutter

Set the mat guide on the scale 1/2 inch less than the location on the mat where you want the V-Groove to appear.  For example, if you want the V-groove to appear 1-3/4" in from the mat's edge, set the mat guide for 1-1/4".

Place the mat in the cutter face up with the left edge against the mat guide.

Lower the guide rail into the mat and set the guide rail stop for the location of the V-Groove on the mat.  Note: It's not necessary to offset this stop by a half inch.

Set the scale on the V-Groove stop for the location of the V-Groove.  Note: It is not necessary to offset this by a half inch either.

Slide the V-Groove stop back on the guide rail until the stem comes into contact with the top edge of the mat.  Then tighten the stop in place.

With the V-Groove Cutter in contact with the mat guide stop, lower the lever on the left, inserting the blade, and cut by pushing away from yourself.

Cut until the V-Groove cutter contacts the V-Groove stop.

Lift the lever on the left to retract the blade and lower the lever on the right, engaging the other blade.  Pull back, cutting, until the V-Groove cutter contacts the bottom stop again.  Then retract the blade.

The two opposing cuts form a V-shaped groove that appears to be cut in the surface of the mat.  However, most often you will have cut all the way through and have to tape on the back of the mat with acid-free masking tape or white artist's tape.  Next, rotate the mat a quarter turn, reposition the V-Groove stop so the stem is back in contact with the top edge of the mat, and repeat the cutting procedure.  After you have made two cuts, you can inspect the over cut/under cut situation and diagnose the solution based on what you see.  Here, the over cut is occurring at the beginning of the cut, which would require a resetting of the guide rail stop.

If the over cut/under cut is occurring at the top of the cut, readjust the setting on the scale of the V-Groove stop by the proper amount.  For example, if you have 1/16" over cut, you will have to reset the stop 1/16" narrower to rid yourself of it.

If the over cut is occuring at the bottom of the cut (as it is in our example) you'll need to readjust the guide rail stop on the scale by the degree of the over cut to get rid of it.  Whatever readjustments (recalibrations) you make now will always be required for the unique marriage of this particular V-Groove Cutter with this particular mat cutter.  In other words, if you have to offset by 1/16" narrower on the top stop to get a perfect corner, you will always have to offset by that amount to get a perfect corner, regardless of the mat.  

If the required recalibation is less than 1/16", you can make a fine tune adjustment by turning the small screw that makes contact with the guide rail stop.

To make a fine tune adjustment at the top of the cut, turn the square post that makes contact with the V-Groove stop.

Once you've made your adjustments and recalibrations to acheive perfect corners you can rest assured that these same modifications will hold true for every mat you cut.