Need help with layout for octagon mats


CGF, Certified Grumble Framer
Jul 20, 2005
Yesterday I got an order for a long (horizontal) doilee to be stitch mounted and double matted in an octagon.
How does one do the layout for this?
Can anyone explain how to layout a perfect half inch reveal for an octagon?

I just forsee a few problems like not being to see the cuts of the top mat once I ATG the bottom mat to be cut.
eric, what is the size of the mat you want to cut for this doilee?
Artistieric ;
When I didn't have a CMC i did a lot of this sort of thing. A tool I found very valueble and also inexpensive is a Quilters ruler. It is clear and is graduated in 1/8 of an inch gridds with 1/16 markings. .You can lay the rule on top of a mark or cut and make a second mark at what ever 1/8 in. incrament you wish if the line is straight.If the lines are curved you can substitute a compass set for whatever incrament tou wish and follow the cut or mark with the compass pointer. ( this is a mute point with Octagons normally ,but could work as well).

The only things to remember are to cut the top mat first ( to use as a template for the marking of the following mats( even third and more) and in the case of Octagons and other acute angles remember the the over cut will be slightly larger then with a standard 90 deg. cut from the rear of the mat in relation to the face of the mat, so slightly undercutting may help.

It is also helpful to remember that if you want a true 1/4 inch second mat to set your rule at sligltly less ( maybe 3/16 or so) to accomodate the with of the lead in the pencil .Or you will need to adjust the cut to be either fuller or less ( let the line stand ot remove the line) to get an accurate measurement.
PS: there are also Compass type attchments that can be added to your guide bar to achieve the same thing with certain cutters when cutting things that have straight sides and angled corners.
Eric, I would recommend buying the Mat Cutting book that Vivian Kistler has out, this design is in there along with alot of other great designs. If it the design I am thinking of, it is quite simple. Lay out the desired width of your mat, as normal, then just measure down from the corners the desired length. When cutting, leave the angles in the corners.

If you have a CMC, Great! If you have access to a CMC, good! If you have a manual mat cutter, you can do the job, but remember that measuring and holding the margins of the second mat is based on the precision of the mat guide. When you add an Angle Guide to the Mat Guide.....You're in business! :D


A plug, yes....but a true statement, nonetheless.