try rendering it with a default metadata, so try something like this:
public TileEntityCrystalRenderer() {
this.model = new ModelMymodell();
}
@Override
public void renderTileEntityAt(TileEntity te, double x, double y, double z, float scale)
{
//int blockmeta = te.getBlockMetadata();
//this.model.meta = blockmeta;
this.model.meta = 0;
GL11.glPushMatrix();
GL11.glTranslatef((float) x + 0.5F, (float) y + 1.5F, (float) z + 0.5F);
ResourceLocation textures = (new ResourceLocation("mymod:textures/blocks/texture.png"));
Minecraft.getMinecraft().renderEngine.bindTexture(textures);
GL11.glPushMatrix();
GL11.glRotatef(180F, 0.0F, 0.0F, 1.0F);
GL11.glEnable(GL11.GL_BLEND);
this.model.render((Entity)null, 0.0F, 0.0F, -0.1F, 0.0F, 0.0F, 0.0625F);
GL11.glDisable(GL11.GL_BLEND);
GL11.glPopMatrix();
GL11.glPopMatrix();
}
That should make your model always render with metadata = 0. Tell me if this works out;