diff --git a/hexrd/nf_config/config.py b/hexrd/nf_config/config.py
new file mode 100644
index 000000000..74c620629
--- /dev/null
+++ b/hexrd/nf_config/config.py
@@ -0,0 +1,80 @@
+"""Base Config class"""
+
+import logging
+import os
+
+from .utils import null
+
+logger = logging.getLogger('hexrd.config')
+
+class Config(object):
+
+    _dirty = False
+
+    def __init__(self, cfg):
+        self._cfg = cfg
+
+    @property
+    def dirty(self):
+        return self._dirty
+
+    def get(self, key, default=null):
+        args = key.split(':')
+        args, item = args[:-1], args[-1]
+        temp = self._cfg
+        for arg in args:
+            temp = temp.get(arg, {})
+            # intermediate block may be None:
+            temp = {} if temp is None else temp
+        try:
+            res = temp[item]
+        except KeyError:
+            if default is not null:
+                logger.info(
+                    '%s not specified, defaulting to %s', key, default
+                    )
+                res = temp.get(item, default)
+            else:
+                raise RuntimeError(
+                    '%s must be specified in configuration file' % key
+                    )
+        return res
+
+    def set(self, key, val):
+        args = key.split(':')
+        args, item = args[:-1], args[-1]
+        temp = self._cfg
+        for arg in args:
+            temp = temp.get(arg, {})
+            # intermediate block may be None:
+            temp = {} if temp is None else temp
+        if temp.get(item, null) != val:
+            temp[item] = val
+            self._dirty = True
+
+    def dump(self, filename):
+        import yaml
+
+        with open(filename, 'w') as f:
+            yaml.dump(self._cfg, f)
+        self._dirty = False
+
+    @staticmethod
+    def check_filename(fname, wdir):
+        """Check whether filename is valid relative to working directory
+
+        fname - the name of the file
+
+        Returns the absolute path of the filename if the file exists
+
+        If fname is an absolute path, use that; otherwise take it as a path
+        relative to the working directory.
+"""
+        temp = fname
+        if not os.path.isabs(fname):
+            temp = os.path.join(wdir, temp)
+        if os.path.exists(temp):
+            return temp
+        raise IOError(
+            'file: "%s" not found' % temp
+            )
diff --git a/hexrd/nf_config/experiment.py b/hexrd/nf_config/experiment.py
index 3abfadab6..96f5f134a 100644
--- a/hexrd/nf_config/experiment.py
+++ b/hexrd/nf_config/experiment.py
@@ -2,13 +2,15 @@
 import os
 import numpy as np
 
-from hexrd import config as Config
+from .config import Config
 
 
 logger = logging.getLogger('hexrd.config')
 
 
 class ExperimentConfig(Config):
+    def __init__(self, cfg):
+        self._cfg = cfg
 
     @property
     def beam_energy(self):
diff --git a/hexrd/nf_config/images.py b/hexrd/nf_config/images.py
index 433c6c6b5..e0e49bfdf 100644
--- a/hexrd/nf_config/images.py
+++ b/hexrd/nf_config/images.py
@@ -1,7 +1,7 @@
 import logging
 import os
 
-from hexrd import config as Config
+from .config import Config
 
 
 logger = logging.getLogger('hexrd.config')
@@ -12,6 +12,8 @@
 
 
 class ImagesConfig(Config):
+    def __init__(self, cfg):
+        self._cfg = cfg
 
     @property
     def data_folder(self):
diff --git a/hexrd/nf_config/input_files.py b/hexrd/nf_config/input_files.py
index 4de10500b..e92fd7b9d 100644
--- a/hexrd/nf_config/input_files.py
+++ b/hexrd/nf_config/input_files.py
@@ -1,14 +1,16 @@
 import logging
 import os
 
-from hexrd import config as Config
+from .config import Config
 
 
 logger = logging.getLogger('hexrd.config')
 
 
 class InputConfig(Config):
-
+    def __init__(self, cfg):
+        self._cfg = cfg
+        
     @property
     def det_file(self):
         temp = self._cfg.get('input_files:det_file')
diff --git a/hexrd/nf_config/multiprocessing.py b/hexrd/nf_config/multiprocessing.py
index 60fc9288a..d5e206782 100644
--- a/hexrd/nf_config/multiprocessing.py
+++ b/hexrd/nf_config/multiprocessing.py
@@ -3,13 +3,15 @@
 import psutil
 import multiprocessing as mp
 
-from hexrd import config as Config
+from .config import Config
 
 
 logger = logging.getLogger('hexrd.config')
 
 
 class MultiprocessingConfig(Config):
+    def __init__(self, cfg):
+        self._cfg = cfg
 
     @property
     def num_cpus(self):
diff --git a/hexrd/nf_config/nf_root.py b/hexrd/nf_config/nf_root.py
index afd005325..ab80b243f 100644
--- a/hexrd/nf_config/nf_root.py
+++ b/hexrd/nf_config/nf_root.py
@@ -5,7 +5,7 @@
 from hexrd.constants import shared_ims_key
 from hexrd import imageseries
 
-from hexrd import config as Config
+from .config import Config
 from .multiprocessing import MultiprocessingConfig
 from .reconstruction import ReconstructionConfig
 from .images import ImagesConfig
@@ -17,7 +17,9 @@
 
 
 class NFRootConfig(Config):
-
+    def __init__(self, cfg):
+        self._cfg = cfg
+        
     @property
     def main_dir(self):
         return self._cfg.get('main_dir')
diff --git a/hexrd/nf_config/reconstruction.py b/hexrd/nf_config/reconstruction.py
index 1e689bfac..ec755449c 100644
--- a/hexrd/nf_config/reconstruction.py
+++ b/hexrd/nf_config/reconstruction.py
@@ -1,12 +1,14 @@
 import logging
 import os
-from hexrd import config as Config
+from .config import Config
 
 
 logger = logging.getLogger('hexrd.config')
 
 
 class ReconstructionConfig(Config):
+    def __init__(self, cfg):
+        self._cfg = cfg
 
     @property
     def tomography(self):
diff --git a/hexrd/nf_config/tomography.py b/hexrd/nf_config/tomography.py
index 1f0a67c22..d6629344a 100644
--- a/hexrd/nf_config/tomography.py
+++ b/hexrd/nf_config/tomography.py
@@ -1,13 +1,15 @@
 import logging
 import os
 
-from hexrd import config as Config
+from .config import Config
 
 
 logger = logging.getLogger('hexrd.config')
 
 
 class TomographyConfig(Config):
+    def __init__(self, cfg):
+        self._cfg = cfg
 
     @property
     def data_folder(self):