Editing Instructions:ShopBot 3-Axis CNC Mill (section)

=== Workholding Policies ===
Most profile cuts will cut entirely through the workpiece and into the spoilboard below. In order to cut all the way through the material without unnecessarily damaging the spoilboard, North Forge suggests programming cuts using the following formula:

'''Depth of Cut = Stock Thickness + 0.01”'''

This normally results in cutting all the way through the material without excessively damaging the spoilboard. Always measure stock thickness with calipers, never with tape measures or nominal dimensions.

If your cut penetrates deeper than 0.06” into the spoilboard, please stop and investigate. If the stock is set up correctly and the depth of cut is appropriate, the collet may be dirty or damaged and the tool slipping out, or the secondary spoilboard may not be perfectly parallel to the gantry (for example due to debris between the primary and secondary spoilboard, or issues with the underlying phenolic plenum).

Tips:
* Use a secondary spoilboard wherever possible.
* Zero to the spoilboard, not the top of the stock.
* Use conservative cut depths and nudge down as needed (for example, by using Z nudge function or manually tweaking z zero).
* Test toolpaths on a secondary spoilboard.
* Measure stock with calipers.
==== '''SCREWS''' ====
When using North Forge’s ''secondary'' spoilboard, it is okay to screw the workpiece in place. Do not:

* Screw into the main vacuum spoilboard
* Use nails to secure your stock to the vacuum spoilboard
* Use excessively long screws (ie long enough to pierce both the secondary spoilboard and the vacuum spoilboard).
* Use glue on the screw spoilboard or main spoilboard.

==== '''SPRAY ADHESIVE METHOD''' ====
It is also possible to use spray adhesive to secure the entire workpiece to the secondary spoilboard.

# Use sandpaper to knock down any high spots on the glue spoilboard (if required).
# Cover both the bottom of the workpiece and the appropriate part of the spoilboard with masking tape or painter’s tape.
# Spray both surfaces with spray adhesive (available at most hardware stores).
# Press the two surfaces firmly together and hold for 30 seconds.
# Test the hold by trying to move the workpiece sideways.
Do not use glue on the screw spoilboard or main spoilboard. Do not use screws on the glue spoilboard.

==== Other ====
Other workholding arrangements are possible, including vices, pins, clamps, custom fixtures, and the vacuum system.

If you are cutting all the way through a large workpiece on the vacuum spoilboard, BE CAREFUL. There is a high risk of damaging the vacuum spoilboard. It’s a good idea to test cut settings on a small workpiece and a secondary spoilboard.

The primary goal of workholding is to control the movement of the workpiece in three axes: X, Y, and Z. Always carefully check toolpaths to ensure they will not collide with any fixturing.

TIP: After a cut operation, the ShopBot will move to the “Z Safe height” before moving rapidly to its next position. When using clamps or other fixturing, adjust the Z Safe Height in the CAM software such that the Z safe height is above the clamp or fixture.