diff --git a/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/BlockData.java b/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/BlockData.java
index e024bf1a3..d2e862387 100644
--- a/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/BlockData.java
+++ b/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/BlockData.java
@@ -72,14 +72,12 @@ public BlockData(
 			final F blockFactory, // knows how it was created for assembly later?
 			final P solveTypeParameters,
 			final int id,
-			final ArrayList< Function< Double, Double > > weightF,
 			final ResolvedTileSpecCollection rtsc )
 	{
 		this.id = id;
 		this.blockFactory = blockFactory;
 		this.solveTypeParameters = solveTypeParameters;
 		this.rtsc = rtsc;
-		this.weightF = weightF;
 
 		this.sectionIdToZMap = new HashMap<>();
 
@@ -94,7 +92,13 @@ public BlockData(
 	public Map<String, ArrayList<Double>> sectionIdToZMap() { return sectionIdToZMap; }
 
 	public int getId() { return id; }
-	public double getWeight( final double location, final int dim ) { return weightF.get( dim ).apply( location ); }
+	public ArrayList< Function< Double, Double > > weightFunctions()
+	{
+		if ( weightF == null )
+			this.weightF = blockFactory.createWeightFunctions( this );
+
+		return weightF;
+	}
 
 	public P solveTypeParameters() { return solveTypeParameters; }
 	public F blockFactory() { return blockFactory; }
@@ -105,8 +109,6 @@ public BlockData(
 
 	public HashMap< Integer, HashSet< String > > zToTileId() { return zToTileId; }
 
-	public ArrayList< Function< Double, Double > > weightFunctions() { return weightF; }
-
 	/**
 	 * Fetches basic data for all TileSpecs
 	 *
diff --git a/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/blockfactories/BlockFactory.java b/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/blockfactories/BlockFactory.java
index 225b7f9d5..0961d9bed 100644
--- a/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/blockfactories/BlockFactory.java
+++ b/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/blockfactories/BlockFactory.java
@@ -1,9 +1,11 @@
 package org.janelia.render.client.newsolver.blockfactories;
 
 import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.function.Function;
 
-import org.janelia.alignment.spec.ResolvedTileSpecCollection;
 import org.janelia.render.client.newsolver.BlockCollection;
+import org.janelia.render.client.newsolver.BlockData;
 import org.janelia.render.client.newsolver.blocksolveparameters.BlockDataSolveParameters;
 
 import mpicbg.models.CoordinateTransform;
@@ -15,4 +17,6 @@ public abstract class BlockFactory< F extends BlockFactory< F > > implements Ser
 
 	public abstract <M extends Model< M >, R extends CoordinateTransform, P extends BlockDataSolveParameters< M, P > > BlockCollection< M, R, P, F > defineBlockCollection(
 			final ParameterProvider< M, P > blockSolveParameterProvider );
+
+	public abstract ArrayList< Function< Double, Double > > createWeightFunctions( final BlockData< ?, ?, ?, F > block );
 }
diff --git a/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/blockfactories/ZBlockFactory.java b/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/blockfactories/ZBlockFactory.java
index dece15d2e..0b16ee1b0 100644
--- a/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/blockfactories/ZBlockFactory.java
+++ b/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/blockfactories/ZBlockFactory.java
@@ -72,19 +72,11 @@ public <M extends Model< M >, R extends CoordinateTransform, P extends BlockData
 
 				System.out.println( "Loaded " + rtsc.getTileIds().size() + " tiles.");
 
-				// we also define our own distance functions
-				// here, xy doesn't matter, only z
-				final ArrayList< Function< Double, Double > > weightF = new ArrayList<>();
-				weightF.add( (Function< Double, Double > & Serializable )(x) -> 0.0 );
-				weightF.add( (Function< Double, Double > & Serializable )(y) -> 0.0 );
-				weightF.add( (Function< Double, Double > & Serializable )(z) -> Math.abs( z - ( initBlock.maxZ() - initBlock.minZ() ) / 2 ) );
-
 				final BlockData< M, R, P, ZBlockFactory > block = 
 						new BlockData<>(
 								this,
 								blockSolveParameterProvider.create( rtsc ),
 								initBlock.getId(),
-								weightF,
 								rtsc );
 
 				blockDataList.add( block );
@@ -182,4 +174,20 @@ public static List< ZBlockInit > defineBlockLayout( final int minZ, final int ma
 		// we can return them in one list since each object knows if it is right or left
 		return Stream.concat( leftSets.stream(), rightSets.stream() ).collect( Collectors.toList() );
 	}
+
+	@Override
+	public ArrayList<Function<Double, Double>> createWeightFunctions( final BlockData<?, ?, ?, ZBlockFactory > block)
+	{
+		// we also define our own distance functions
+		// here, xy doesn't matter, only z
+		final ArrayList< Function< Double, Double > > weightF = new ArrayList<>();
+
+		weightF.add( (Function< Double, Double > & Serializable )(x) -> 0.0 );
+		weightF.add( (Function< Double, Double > & Serializable )(y) -> 0.0 );
+		// TODO: has to be between 0 and 1
+		// TODO: needs the Block to know
+		weightF.add( (Function< Double, Double > & Serializable )(z) -> Math.abs( z - ( block.maxZ() - block.minZ() ) / 2 ) );
+
+		return weightF;
+	}
 }
diff --git a/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/solvers/affine/AffineAlignBlockWorker.java b/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/solvers/affine/AffineAlignBlockWorker.java
index 0667603ec..bea217af8 100644
--- a/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/solvers/affine/AffineAlignBlockWorker.java
+++ b/render-ws-java-client/src/main/java/org/janelia/render/client/newsolver/solvers/affine/AffineAlignBlockWorker.java
@@ -889,7 +889,6 @@ else if ( graphs.size() == 1 )
 										inputSolveItem.blockData().blockFactory(), // no copy necessary
 										inputSolveItem.blockData().solveTypeParameters(), // no copy necessary
 										id,
-										inputSolveItem.blockData().weightFunctions(), // no copy necessary
 										newRTSC ) );
 
 				++id;