In this post we explore the steps and calculations needed to create a custom frame

Tools Used

• Tape Measure
• Calculator
• Calipers (tape measure is also adequate)

Taking Measurements

The first step is to grab the measurements of the source material. In this case we are creating two frames, which measure:

• 8”x10”, 1” margin
• 24”x36”, 3/4” margin

Calculating Frame Size

The rough frame design we’re going to be making today are shown below:

• Moulding - The physical structure of the frame
• Frame/Artwork Size - The maximum size of paper that will fit inside the frame
• Window/Mat Size - The viewable area of the artwork
• Moulding Width - The total width of a side of the frame
• Rabbet - An inset portion of the frame that layers fit into
• Rabbet Lip - The portion of the moulding that the artwork seats into
• Rabbet Depth - The capacity of the frame to contain layers of backing and glass and artwork

Citations from victorian frame company and frame destination

To figure out all how big everything needs to be follow these steps:

1 - Frame Size

The frame size is the maximum sized artwork that will fit inbetween the rabbets. A larger frame can be used with a mat.

Standard frame sizes (in inches) are:

• 5x7 - Photographic print size
• 8x10 - Common artwork size, commonly used with a mat to frame a 5x7 photo
• 8.5x11 - Standard US paper size frequently used to frame certificates
• 11x14 - Commonly used to frame a 8x10 prints with a mat
• 16x20 - Larger frame for paintings or a centerpiece of a wall
• 20x24 - Large frame
• 24x36 - Standard poster size

Researched from picture salon and frame usa

2 - Choosing a Window/Rabbet Lip

The window is the visible portion inside of the frame. Usually it is 1/2" smaller than the frame size, allowing for a 1/4" lip.

3 - Moulding Width

There are fewer standards regarding the width of the moulding surrounding the picture, this is based on aesthetic and what tools and materials are available. In this case based on available material a 2" moulding width is used to match the stock on hand.

4 - Rabbet Width/Lip

The rabbet is the step around the frame that holds the backing materials in place. It will obscure the mat slightly and limit the maximum possible window. Most frames use a 1/4” lip though in this case to make manufacturing easier this frame will use 3/8” rabbet width

5 - Rabbet Depth

The Rabbet Depth is how much material will fit inside the frame.

• Glass - The transparent material that protects the print
• Mat - The cut out border around the print
• Print - The artwork being displayed
• Backing - A structural layer that holds the print in place
• Point - A specialized nail that is hammered into the frame and holds the layers against the rabbet

Each of the layers is measured:

Layer	Thickness (inch)
Glass	0.10
Mat	0.01
Print	0.01
Backing	0.05
Point	0.15

The total thickness is 0.32", meaning 0.375" or 3/8" will leave adequate clearance for any future needs

6 - Moulding Height

With a rabbet width and depth of 3/8" we can leave an additional 3/8" of material remaining meaning the total thickness of moulding is 3/4"

Putting it all together

Putting all of those numbers together this is the exact frame profile:

post-editing note: If I had seen this to-scale drawing before making the part I would have narrowed it sooner

Calculating Outsize Size

The outside size is based on a stackup of

• Moulding Width - Width of the material
• Rabbet Width - Inset amount subtracted from the material
• Allowance - Extra width on the rabbet to allow for inexactly cut prints, backing, and glass
• Frame Size - Goal inner size

Adding together the various widths:

step	calculation (inches)
full formula	(moulding width - rabbet width) * 2 + allowance + frame size
base moulding width	2"
minus rabbet width	2 - 0.375 = 1.625"
doubled because two sides	1.625 * 2 = 3.25"
plus allowance	3.25 + 0.25 = 3.5"
total outside width	3.5 + 8 = 11.5"
total outside height	3.5 + 10 = 13.5"

And thus we get:

Freecad Document

In the follow up post Making a Frame: Practice this design is brought to life