Alloy Blocking

When using alloy blocking, the specific blocking rings to be used in the lab must be set up, and (optionally) the sequence that blocks should be considered, for selecting blocking rings, can be set up to allow Rx-Universe to select the optimal blocking ring for each job.

Block Groups

First, one or more "Block Groups" must be set up, under "Setup", "Surface Block groups".  By default, your Rx-Universe system will have one group, called "Blocks" or something equally generic.  If desired, multiple block groups can be set up - this can allow dynamic selection of different groups of blocks for toric and digital, or for different lens styles or materials.

For example, we could have 2 blocking groups, "BLOCKER 2000" and "PRA BLOCKER" set up in Rx-Universe. The examples in this section will use this example:

Surface Blocks

The specific surface blocks (or blocking rings) to be used for each group must be set up under "Setup", "Surface Blocks".  For each blocking ring, the following must be set up:

Some notes about some of the fields:

Cutout for Seg?

if the ring has a cutout for a bifocal segment, check this box.  If not checked, then Rx-Universe will avoid selecting a blocking ring that will rest on top of a bifocal segment.

Extra Height

When blocking a lens with a steep curve, the front curve may theoretically "hit" the bottom of the block.  In practical terms, though, since the ring is hollow, as are many (but not all) blocks, there can often be some "extra" height given to the block to accommodate these steep curves.  For example, in the following diagram, the front curve can go slightly below the theoretical "bottom" of the blocking chamber:

This field allows the lab to specify how much "extra height" should allowed when checking to see if the front curve of a blank will "bottom out" in the block.

Cutter Crash Thick

This is how thick the lens must be at the block diameter; if the blank is thinner than this value, that will trigger a cutter crash warning.

Outside Diameter

If the Outside Diameter is set, this value is used when checking to ensure the blocking ring is not too large (ie would create cutter crash).

This was added originally for labs using Coburn blocks that are 50mm, blocking blanks on blocks intended for a different base.  This field allows larger diameters to be used for cutter crash checks, but without impacting thickness calculations.

Include as Dynamic

If using automatic block selection, checking this box indicates this blocking ring should be considered in the list of blocks for this blocking group.

Dynamic Sequence

If using automatic block ring selection, indicate the sequence that this particular ring should be considered.  Note that the sequence number must be unique within the blocking group (you cannot have two block rings of the same sequence within the same group).

Max Blank Diameter

If there is a maximum blank diameter for this block ring, enter it here.  Blanks with a diameter larger than this maximum will switch to a different blocking ring (assuming automatic block selection is being used).

Note that this maximum diameter is the diameter of the blank, before cribbing.

Max True Curve

If there is a maximum true front curve that should be used for this blocking ring, enter it here.  Blanks with a true front curve exceeding this maximum will switch to another blocking ring (assuming that automatic blocking ring selection is being used).

For reference, the APPROXIMATE limits of font cuves, in 1.53 index, for common blocking rings are:

Min and Max Crib Diameters

When doing automatic block selection, if the crib for the blank is < minimum crib, or > than the maximum crib, selection will proceed to the next block.

Separate fields are available for Progressive and Non-Progressive designs; this is to allow larger blocks to be selected for progressives, for example, to provide more support for the digital process.

Selecting Default Block Groups

Default block groups can be set for toric and digital jobs, on the "Setup", "System Settings" screen, "Blocking" tab:

For purposes of illustration, if we set two block groups, with blocking rings and sequences as follows:

With the default settings as above, toric jobs will, by default, select the "best" blocking ring from those defined as part of Group 1; digital jobs will select the "best" blocking ring from those defined in Group 2.

In addition to default block groups for toric and digital, the block group can be defined for specific lens styles, and for specific materials, on the corresponding fields, as below:

The block group to be used for selection can also be specified on the order; on the F12/Surface Opts screen:

When looking at specific blocks, in the "Forced Block Size" box, the each block is listed with the block group first, then the size.  For example:
  2:48.0x10.0

would be the 48x10 block from block group 2.

Work Ticket

The work ticket will now show not only the block size to be used, but also which group the block is for: