Help Cutting a Low Pitch Arch

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BatesMotel

BatesMotel

MGF, Master Grumble Framer
Joined
Feb 18, 2008
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Conshohocken, PA
Copy of Niekelski.jpg

I have a job that needs an arch mat with rounded corners at the bottom. I don’t have a wizard and one of our fellow Grumblers is going to the trouble of cutting this mat for me on hers. I was able to figure out the corners at the bottom is a 4” circle. The top however isn’t a typical circular top, the pitch is very shallow. The center height is 19 ¼ and the sides are 15 ¼ making it 4 inches at the utmost center. Not having a Wizard I’m not sure if this is something that can be done and how one would enter into the computer to get the right cut. I will upload a photo of the Image I need cut so you can see what I mean. Thanks for your help with this one!
 
Yep, just an arch top and the parameters can be entered to match the height you need.
 
Yep, as Jeff said, that should be pretty easy to achieve with an arch top and rounded corner rectangle bottom corners. Your photo image can be entered and used as a guide to set the parameters correctly.
:cool: Rick
 
I would be inclined to trace the shape onto a piece of paper. That way you can use basic drafting skills to calculate the radius of the slight curve.
Are you planning on capturing the image slightly? Also remember that if you capture the edge on the corners, the radius decreases by the amount captured. For instance, if you have a 2" radius, and capture 1/4" the radius of the mat corner will be 1 3/4". The reverse is true if you are going to float the piece inside the mat window. The radius increases by the same amount of space shown outside the image.
 
Perhaps you can manipulate the CMC's software to achieve the proper arc, but that might require several test cuts before you get it right. To cut a mat opening for any odd shape, my usual process is to photograph the item, import it to the CAD program, and then trace it. In the Wizard program, I guess that would be Pathtrace.

Tracing is relatively fast and enables precise duplication of any odd shape.
 
I might try it first using a basic wiz template, but like Jim I will often photograph or scan an image and then trace it.
 
I'm the lucky one who is cutting Carla's mat. I wanted to do it in the template where each corner can be different (#111.) This should be very simple. However, the template won't let you do an Roman arched top with curved corners on the bottom. Why, I'll never know?!
Susan
 
Susang, you can use a rounded corner template for the bottom and then the roman for the top. Make the mats meet midway and then right click on join group. Bingo Bango you have one opening the way you want.
 
Back in the stone age, I would have traced it with a piece of tracing paper and a soft pencil, flipped it, taped it to the back of a piece of matboard, traced over it again to transfer the line and then used the Keeton for the straight lines and a Dahl cube for the arcs and circles.
 
No, I wouldn't.

First off, I would determine the height and width of the image and create a mat with that size using 104. We know that the parameters for that need to be set to 2". Now we need to add another opening of 307 that is the same width as the 104 opening. Put this one at the top so that they overlap. Reduce the size of the 104 opening so that the top corners don't show.

Click on the 307 parameters and set the arch height appropriately. From looking at the photo, I would guess it is around 3 1/2". Set the radius for 2" and then lower the step width (this will be a negative number) till the arches line up visually.

Select both openings and then right click to group them. Take this to the cut screen and then to Pathtrace.

In Pathtrace click on Edit:Explode All. Now join the arc on the left to the center one skipping the little flair. Do this to the other side too. Now select that segment and click Tangify Segments. This should make a nice clean transition between the arcs.

Now just set the bevels and cut.
 
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