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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.
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