I bought a schwinn boundary 29" and the axle is missing does anyone have or know the size axle i need to get it together?
Can you describe how the axle is missing?
Understand that the axle is the part that goes inside the hub which balances the wheel in the frame and allows the hub to turn.
If you need an axle, that means the entire hub should be taken apart.
What you might possibly mean (and truly need) is called a skewer.
This is the part that fixes through the axle on quick release hubs and locks the wheel down inside the frame. You should be able to get any basic rear skewer to do this job. Check your local bike shops before ordering online and you might be able to save a few dollars.
The only thing there is the hub the axle skewer spacers and bearings are missing