Fixturing and Part Holding

Appropriate fixturing (securely fastening  to a cutting surface) of an item to be cut, plays a key role in the success of any project you undertake. Without proper fixturing, you will break more bits, produce inferior and inaccurate cuts and tasks will take longer to complete than necessary.

Fixturing Types

There are several different approaches to fixturing including adhesives, glue, and mechanical.

Adhesives
Adhesive fixturing uses double sided tape of various sizes and strengths to bind the item to be cut with the CNC cutting surface.  The strength of this approach is that is is a quick and cheap.  It requires little to no preparation time to accomplish.  The weakness of this approach is that is can be difficult to separate the item cut from the CNC cutting material. This is especially true on thin cut items.  We have had some of our finished items break in the process of being separated.  Another weaknesses is that its a pain to clean up the backside of the cut item were the adhesive was placed. In some cases, a clean underside is not important. In others, it is critical.  Depending upon the surface of the cut item, we have tried paint scrapers, mineral spirits, and acetylene with mixed results.

Glue
Another approach is to use SuperGlue.  This approach is largely practiced by people cutting metal and circuit boards.  Depending upon the material to cut, it or may not be the best approach.  Once the cut has been completed, simply douse the item with acetylene to loosen up the SuperGlue. We have tried several different types of SuperGlue and have settled upon one.  It will be available for purchase from this website soon.

Clamps
A third fixturing method is clamps. While the simplest to use, they can be more trouble than they are worth.  Clamps must stay out of the way of all moving parts of the CNC machine. Unlike the previous fixturing methods, there is no clean-up activities required.

Mechanical
A fourth approach is to use mechanical fixtures. Mechanical fixtures require more upfront planning than any of the other methods.  Some CNC machines come with predrilled holes for adding fixturing, some do not.  In one of our machines, we added an MDF board and placed holes and screw backing every six inches.  With Mechanical fixtures you can used screws and washers, boards, and several other items as hold downs. There are no clean-up activities required.