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2020 Extrusion M6 End Tap Jig with Cam Clamps

Jig to tap aluminum extrusion with a 20mm width and 5mm diameter holes.
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updated January 1, 2025

Description

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Design Constraints

This design is tailored for the following:

  • MUST provide good axial positioning to tap straight
  • SHOULD be quicker to clamp/unclamp than extrusion jigs that require a hex key
  • SHOULD give enough leverage to power tap by hand with no clamps
  • SHOULD print easily

Some considerations I've made to accomplish the above:

  • With clamps, only two faces are required to position the jig
  • A handle gives sufficient leverage to power tap with no clamps. I've found this length works well by experimentation.
  • Cams are used to clamp the workpiece.
  • The extrusion guides keep the T Nuts aligned so it can be slid on easily.

Extrusion Type

This will not work for all 2020. In particular, this will not work for 8020 brand of 20 series extrusion! Make sure you have extrusion that has a 5mm hole for an M6 thread, e.g. this profile:

I use this profile because it's cheap!

Assembly

Additional parts are required:

  • 2x M5x25 Button Head Screws
  • 2x M5 Slide-in T Nut
    • Should be between 9 and 10 mm long to work well

1. Insert cam axle into the cam clamp, and the button head screw through the hole.

2. Tighten nuts in this position (finger tight). You can also threadlocker them in place.

Usage

I'm comfortable using this to power tap this with a hand drill, as long as I use a spiral flute tap and cutting oil. YMMV, be careful, wear eye protection, and have a backup tap!

Insert the workpiece in this position:

And tap in this position:

Printing

I have printed successfully with:

  • 0.3mm layer height
  • 0.4mm nozzle
  • 30% Infill
  • PETG
  • No supports

I've found this is more than strong enough.

Future Work

When the cams are loose, they rotate and slip too much, which can also make it difficult to insert the workpiece. It would be good to provide a slight preload pressing the cams into the workpiece, in order to make the open state static.

The cam clamp dimensions are the result of the first swag. They could be further tuned. Reasons I can imagine to do so are to:

  • reduce the overall dimensions
  • provide more mechanical advantage for a positive clamp
  • use the handle as a mechanical stop

It would be convenient to store a tap in the handle

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Model origin

The author marked this model as their own original creation.

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