Schrader inner tube gets cut by Presta sized hole in rim
The cheapest solution is to try and remove the burrs or sharp edges that are cutting the tube. This can be done with a small file or a piece of emery cloth cut into a small strip and pushed through the hole. If the rim is double walled it will be difficult to get at the inner edges. The alternative is to purchase a set of schrader to presta adapter sleeves. While they are available on line a trip to your Local Bike Shop will verify that the drilled holes are large enough to accept the adapter. Then use Presta tubes and you should be trouble fee.