Aircraft Clecos Do Not Hold in Drilled Holes.

Clecos are temporary fasteners used in aerospace and sheet metal fabrication to hold two or more pieces of material together during assembly or while drilling holes. They are typically used to ensure that the pieces being joined are properly aligned and that holes are drilled accurately.

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If clecos are not holding in drilled holes, there could be one or more reasons for this issue:

Deburred Hole: If the hole has been over-deburred this may enlarge the hole so the cleco does not hold.  If the hole is deburred and then dimpled this will cause the hole to enlarge during the dimpling process.  It is best to avoid deburring holes that will be dimpled.

Hole Size: Clecos are designed to fit into specific hole sizes. If the holes are too large for the clecos being used, they may not hold securely. Ensure that the holes are drilled to the correct size for the clecos you are using.

Material Thickness: The material thickness can also affect how well clecos hold. If the material is too thin, the clecos may not have enough material to grip onto. Conversely, if the material is too thick, the clecos may not reach the backside of the hole.

Cleco Condition: Clecos can wear out or become damaged over time. Inspect the clecos to make sure they are in good condition, with no bent or damaged parts that could prevent them from holding.

Proper Technique: Using clecos requires proper technique. Make sure that you are inserting them correctly into the holes and applying enough force to secure them in place. Sometimes, a slight twist while inserting the cleco can help it grip better.

Cleco Type: There are different types of clecos, such as spring-loaded clecos and wedge-type clecos. The type of cleco you are using may have specific requirements for installation. Ensure you are using the correct type for your application.

If you have addressed these factors and are still experiencing issues with clecos not holding in drilled holes, it may be necessary to consult with an experienced aerospace or sheet metal professional for further guidance or to consider alternative fastening methods.  One option is to add a correctly sized washer or piece of scrap metal to the back side of the hole so the cleco holds firmly in place.