Dumb question about miters

[Danno30008]

Hey everyone:

Ok, this is gonna sound kinda dunb but I need to find a better way of measuring and cutting my miters for the frames I am building.
What is a simple way to calculate the length of both sides if you are making a picture frame? I usually cut a 1/4" groove on the back for the photo and glass to fit into and then just align the piece up backwards, and cut a million times to get it right. It is a royal pain in the a**. So, if my inside dinensions are say 8" x 10" and the material is 1 1/4" wide, how do I determine the length of all sides of the frame, say to the longest outside point of the miter?
Hope this makes sense to someone because I feel like I am speaking in English and writing in Chineese..:mad:
Thanks in advance for any and all help.

Take care
Dan in Atlanta.

[JasonB]

Hey Danno, all you gotta do is add the width of your material, times two, to your inside demension. So for an 8x10 it would be... 8 + 2 1/2=10 1/2 & 10 + 2 1/2=12 1/2. Your frame consists of four parts; a left & right, and a top & bottom, hence the "times two", you gotta add 1 1/4" for the left, and 1 1/4" for the right. Same with the top and bottom.

Heres what I do, cut everything big, 1/16"-1/8" would be more than enough.
Mitre one end on all your pieces.
then set up a stop for your lefts and rights and mitre the other end of them, then, do the same for your tops and bottoms.
This way all your parts come out equal and your frame will be square. (you still gotta check though!:D)

And I like to set my mitre at just a hair over 45 degrees.

[Danno30008]

Thanks Jason:

So, how do you take in account the rabit joint on the back of the frame, or does it not matter?

Why don't you set your miter at 45 degrees?

Thanks again and take care

Dan

[Don]

Hey, Dan. Jason has got you going in the right direction. I'll add this - He sets his mitre a bit over to ensure that the "tips" of his parts touch when assembling, a joint that is open on the inside a bit is much more tolerable than an open outside corner.

What he is trying to describe to you on the measurements is this. You allow that your material is 1-1/4" wide, I'm assuming this is overall (Jason is assuming this is the width of the material minus the rabbet (groove). So say your material is 1-1/4" wide, but you've made a 1/4 x 1/4 rabbet for the glass, photo and backing. This means that you have a "net" frame width of 1", right? So in this case, if you want a frame for an 8 x 10 then you simply need to add 2 inches to the total, your parts would be 10 x 12 overall. Plus, Jason is properly advising adding 1/16 or 1/8 to the length of those parts to allow for "fudge factor and positioning". Your frame parts would be 10-1/8" x 12-1/8".

Show us some pics, D