Trouble getting a square panel

[rvallen224]

Hello everyone, I hope someone will be able to help me with this recurring problem. I'll do my best to describe what's happening. I have roll out trays that I'm building with dovetailed sides and have completed those. I'm working now on the 1/2" birch ply drawer bottoms. I am having trouble getting all four corners to read square with my framing square. To make it easy to visualize, for example, I have a panel that measures 26" on the top and bottom and 22 1/4" on the sides. If you label the corners starting with the top left as 1 - 4 going clockwise, corners 1 and 3 appear to be "square" and corners 4 and 2 are out of square between 1/16" and 1/8". When measuring corner 2, the gap appears down at corner 3. When measuring corner 4, the gap appears up at corner 1. I measure the diagonals and from corner 1 to 3 it measures 34 3/16" and from corner 2 to 4 it measures 34 1/4". It doesn't seem like much, but when you put the square on corners 2 and 4 and have close to 1/8" gap it bothers me - particularly since I can't seem to figure out how to correct it and I wanted to drawer bottom to help me keep the drawer itself square.

I have checked and adjusted the framing square by setting it on a flat edge of the panel and marking a line and then flipping the square over to check if it aligns with my first line - and it does almost perfectly (or within 1/32"). If I recut the objectionable opposite corners to square them up, will that not alter the currently square corners I already have?

I have had this problem in the past cutting up panels for cabinet sides with no success in really resolving it. For some reason opposite corners appear to be 90 deg. square and the other opposite corners appear to be out of square by approx. equal amounts. If someone could help me figure out how to correct this error I would really appreciate it. I recently made a crosscut sled thinking this would be my answer and used it for these bottoms as I thought that would fix my problem, but I had trouble getting the fit just right in the miter groove and had some play left and right ever so slightly. And needless to say, I'm having the same problem I've been having.

Thanks in advance for any suggestions! Reggie

[Bob Rozaieski]

Hello everyone, I hope someone will be able to help me with this recurring problem. I'll do my best to describe what's happening. I have roll out trays that I'm building with dovetailed sides and have completed those. I'm working now on the 1/2" birch ply drawer bottoms. I am having trouble getting all four corners to read square with my framing square. To make it easy to visualize, for example, I have a panel that measures 26" on the top and bottom and 22 1/4" on the sides. If you label the corners starting with the top left as 1 - 4 going clockwise, corners 1 and 3 appear to be "square" and corners 4 and 2 are out of square between 1/16" and 1/8". When measuring corner 2, the gap appears down at corner 3. When measuring corner 4, the gap appears up at corner 1. I measure the diagonals and from corner 1 to 3 it measures 34 3/16" and from corner 2 to 4 it measures 34 1/4". It doesn't seem like much, but when you put the square on corners 2 and 4 and have close to 1/8" gap it bothers me - particularly since I can't seem to figure out how to correct it and I wanted to drawer bottom to help me keep the drawer itself square.

I have checked and adjusted the framing square by setting it on a flat edge of the panel and marking a line and then flipping the square over to check if it aligns with my first line - and it does almost perfectly (or within 1/32"). If I recut the objectionable opposite corners to square them up, will that not alter the currently square corners I already have?

I have had this problem in the past cutting up panels for cabinet sides with no success in really resolving it. For some reason opposite corners appear to be 90 deg. square and the other opposite corners appear to be out of square by approx. equal amounts. If someone could help me figure out how to correct this error I would really appreciate it. I recently made a crosscut sled thinking this would be my answer and used it for these bottoms as I thought that would fix my problem, but I had trouble getting the fit just right in the miter groove and had some play left and right ever so slightly. And needless to say, I'm having the same problem I've been having.

Thanks in advance for any suggestions! Reggie

Couple of things to check:

1. Make sure that you always reference the same edge of the panel off of the sled's fence. I.e., flip the panel and keep the same edge against the fence and the opposite face against the table, rather than spinning the panel and keeping the same face against the table but the opposite edge against the fence.
   
2. Make sure your sled's fence is square to the blade. If it's loose in the miter slot, you won't get a consistent cut. Shim the runners with masking tape until there is no slop. Then retrue the fence to the blade.
   
3. Make sure the two edges are parallel to each other. Even if you make 2 cuts square to the edge against the sled's fence, if the far edge isn't dead on parallel to the reference edge, the panel will never be square.
   

[bgrella]

One: As Bob mentioned get the slop out of your runners. You will never get consistent results otherwise.

Two: I wrote a cool article on how to square a sled fence dead-on-accurate using a dial indicator (~shudder~)

Check it out when you have time here.