If there's a sheet of thin plywood/MDF that forms the back of the unit like there usually is, glue it (but probably not wood glue, need something that will work well with MDF). But also, they usually give you a pack of little finishing nails to nail it on with. Go out and buy more of these and but two or three times as many nails as they give you. Makes a big difference.
https://a.co/d/03t6jZQH
Problem is that’s its pressboard, so the strength increase will be limited . Use some small wood so you don’t penetrate the other side .
The unit is likely wobbly because it doesn't have a continuous one piece back. A one piece back will give the cabinet the greatest racking strength. So long as you're not going to see the back of the cabinet because it's going up against a wall, I would get a piece of 1/8" masonite ( MDF hardboard ) cut to the size of the cabinet less about 1/2" to 3/4" . Take the doors off the cabinet temporarily. Lay the cabinet face down on carpet or a moving blanket. Measure the back of the cabinet diagonally both ways to make sure it's sitting square. Lay the masonite on the back of the cabinet. Use #6 x 3/4" round top screws to fasten the masonite to the cabinet. I would prey drill a pilot hole with a small drill bit every 6 " around the perimeter and on the vertical sections in the middle. Drive four screws, one in each corner to lock the position. Finish the rest of the screws. Set the cabinet back upright and reinstall the doors.
This should stiffen it up substantially and if you have to move it you can still take it apart.
One thing that helps is to glue all the joints. Realistically you’re not going to ever take it apart again.
Totally yeah, by glue all the joints do you mean just glue the whole seam in the back all around with wood glue?
Yes. Just make sure the corners are square and use wood glue in the seam.
You can’t use wood glue on the finished surfaces, it won’t adhere
If there's a sheet of thin plywood/MDF that forms the back of the unit like there usually is, glue it (but probably not wood glue, need something that will work well with MDF). But also, they usually give you a pack of little finishing nails to nail it on with. Go out and buy more of these and but two or three times as many nails as they give you. Makes a big difference.
Clarification here that by drilling an extra hole, I meant doing that in order to possibly install an l shaped metal bracket in each corner^
https://a.co/d/03t6jZQH Problem is that’s its pressboard, so the strength increase will be limited . Use some small wood so you don’t penetrate the other side .
The unit is likely wobbly because it doesn't have a continuous one piece back. A one piece back will give the cabinet the greatest racking strength. So long as you're not going to see the back of the cabinet because it's going up against a wall, I would get a piece of 1/8" masonite ( MDF hardboard ) cut to the size of the cabinet less about 1/2" to 3/4" . Take the doors off the cabinet temporarily. Lay the cabinet face down on carpet or a moving blanket. Measure the back of the cabinet diagonally both ways to make sure it's sitting square. Lay the masonite on the back of the cabinet. Use #6 x 3/4" round top screws to fasten the masonite to the cabinet. I would prey drill a pilot hole with a small drill bit every 6 " around the perimeter and on the vertical sections in the middle. Drive four screws, one in each corner to lock the position. Finish the rest of the screws. Set the cabinet back upright and reinstall the doors. This should stiffen it up substantially and if you have to move it you can still take it apart.
45 angle corner braces.