Parametric xTool RA2 Rotary (Magnetic and Non-Magnetic) Chuck Jaws and Pegs

Motivation

The xTool RA2 rotary is a great accessory, but the included chuck jaws have a few shortcomings:

• Workpieces with shallow stepped inside geometry (lip) are difficult to get a good and even grip especially when tapered

• Outside mount on the single step jaw sticks too far into the engraving design space

• Diameters max out ~100 mm (outside mount) and ~121 mm (inside mount)

• Inside mount geometry is not optimized for any curvature resulting in minimal surface contact with the workpiece

• Outside mount curvature is optimized for only ~64, 72, and 80 mm diameters

Solution

Design and print custom jaws to accomplish the following objectives:

• Optimized outside and inside mount curvature

• Fully parametric providing customization of all jaw dimensions for maximum contact with the workpiece and minimum interference with the design space

• (Optional) Wings to provide added contact with the workpiece

• (Optional) Outside and/or Inside mount draft to match workpiece taper

• (Optional) Backstop Fence tab to assist with squaring the workpiece up to the RA2 rotation axis (StraightLarge and Wings components only)

  • I do not intend to use this except on workpieces with diameters larger than ~100 mm. On smaller workpieces, I will usually use my Backstop Fence design.

• Labels to make finding the right jaw set easier

I also included the design of the two included jaws as best as I could reverse engineer their measurements with calipers.

Updates

   v1.1

• New! Parametric Text (built-in)

  • Update to the Fusion file - The September 2025 Fusion update added Parametric Text Tools. I've updated all of the text references to use this built-in feature. So, the ParametricText add-in is no longer needed.

   v2.0

• New! RA3 style jaws with embedded magnets and RA3 style pegs with press fit magnets

  • This design combines some of the features of the RA3 T-shaped jaws and cylindrical jaws (I refer to these as pegs) while allowing them to still be mounted with screws to the RA2 jaw slides. It is still fully parametric, incorporating the benefits listed in the solution section above.

  • Tapered and asymmetric pegs are also possible now (reference the included pictures). Once the jaws are tightened, these provide more mechanical grip on the workpiece than the limited friction provided by the stock RA2 or even RA3 jaws for many workpieces.

  • By default, the jaw channels and peg lower geometry match the same geometry of the RA3 jaw channels and pegs. This means they can be used interchangeably when appropriately configured (proper tolerances), printed, and post-processed.

  • The Fusion file contains all jaws (magnetic and non-magnetic) and pegs, so it is now v2.0. The non-magnetic models have not changed, so they maintain their non-versioned filenames (still v1.x basically).

  • The Fusion file and PrusaSlicer Project files contain two primary types of jaw designs with letters corresponding to the RA2 jaw slide holes (innermost at Hole A to outermost at Hole D) with which that part/model is compatible (e.g. a jaw with CD only will mount to holes C and D). The default diameters of the magnetic jaw files are the smallest possible for that hole and channel configuration at the default peg upper diameter base dimension.

Customization

• Given the extensive amount of customization available, I only provided a relatively small set of .stl model files and no .gcode/.bgcode. This is the naming convention of the .stl files (Straight/Wings_OutsideDesignDiameter_InsideDesignDiameter_CatchHeight). Of course, these .stl files can be used if they happen to fit your use case, but the real flexibility and advantage of this design is in customizing jaws for specific workpieces using the Fusion file. If you are not able to get Fusion to work for you, please send me a message (see below) and I will post your requested .stl files at my earliest convenience.

• The Fusion file is included. You can customize the parameters (DESIGN | SOLID | MODIFY | Change Parameters) to suit your workpiece and needs. The most common parameters you should need are Favorited. The non-favorited parameters should work as well but may require more tinkering to repair broken downstream features.

• Here are a few notes to clarify some of the favorited parameters:

  • LargeTargetDiameter – This is the center of the length and curvature for the StraightLarge and Wings components. With the CatchDepth at its default of 5 mm, the outside mount diameter will be 5 mm less and the inside mount diameter will be 5 mm more than this parameter. Do not directly change either of those as that will certainly break the timeline. Instead, do the math in reverse to determine the optimum LargeTargetDiameter.

  • Catch Height – This is the total height of the part of the jaw that sticks up from the base geometry of all four jaw components. Since the base height defaults to 7 mm, any number less than 7 will result in a very (but potentially necessary) shallow catch for an inside mount, but no catch for an outside mount.

  • DraftAngleOutside/Inside – Both of these are configured such that a positive number will draft a taper inward on the catch while a negative (-) number will draft a catch outward. Think about the placement of the workpiece on the jaws to determine which sign is appropriate. Here is a geometry refresher that may help you determine the taper angle of a simple tapered cup given the diameter of the top and bottom of the cup and its total height:

using an iPhone Calculator app, do the math inside the [] (e.g. ((100-80)/2)/200 = 0.05) then turn your phone sideways, make sure the word Rad is not displayed where the calculator displays numbers, tap 2nd, and tan-1 to get 2.86°

• Two of the features in the timeline reflect a red warning. That is intentional as those features will activate if CatchHeight is set to less than the BaseHeight (default 7 mm) at which point other features will turn red in their place. Just ignore those warnings.

• (The ParametricText add-in is no longer necessary with v1.1) I used the ParametricText add-in to dynamically update the labels. If you want to use this add-in as well, you can follow the directions to install it, then close and re-open the provided .f3d file. After you are 100% complete with changing your parameters, you will need to edit a sketch in the first (base) component named StraightLarge (even if you do not want that component) then navigate to (DESIGN | SOLID | MODIFY | Change Text Parameters) and click OK. That should update all the dynamically configured text fields. If this does not work or you prefer, you can simply update the individual sketch text instead.

• The backstop fence and draft (i.e. taper) features are suppressed by default. You can find them in the timeline by using the Selection Sets feature in the navigation tree and then unsuppress none/any/all of them (make sure you set both taper angles (default 2°) as necessary depending on which features you unsuppress. Of course, the diameter range possible with that jaw will be altered due to the taper and labels may need to be adjusted or suppressed.

I designed and prototyped on a Prusa MK4 (Non-Magnetic) and a Prusa CORE One (Magnetic).

Let me know (Messenger | Printables.com) if you have any questions.

Materials

• Magnetic Jaws

  • (3-4 per jaw) 6x3 neodymium magnets – I used these from Amazon.com

• Magnetic Pegs

  • (2 per peg by default) 4x2 neodymium magnets – I used these from Amazon.com

Printing

See the attached .3mf for my settings and model orientation. I recommend printing most pieces as oriented but consider setting any of the straight pieces on their side if they have a tall catch for proper layer orientation to account for stresses at the base of the catch. I also recommend printing with 100% perimeters.

   Seams

• Seam placement is especially important for the magnetic jaws and pegs. Slice in an orientation that will align the seams for easier post-processing. In the included RA2MagneticRotaryChuckJaws_v2_0.3mf and RA2MagneticRotaryChuckPegs_v2_0.3mf PrusaSlicer Project files, I oriented the models to put the seams in the most ideal orientation (facing towards the back of the build plate) with Seam position set to Rear.

   Magnets

• If you plan to embed magnets during the magnetic jaw prints, ensure you have the following ready to go before starting the print:

  • Magnets

    • Each jaw needs one magnet for each channel (i.e. 3-4 per jaw)

  • Pause(s) inserted at each layer immediately after an embedded magnet slot (the same layer that bridges to close the slot). These pauses should already be inserted in each of the PrusaSlicer Project files but double-check before printing.

  • A plan for your desired polarity orientation.

    • To match existing RA3 peg polarity, I recommend you insert all jaw magnets with South facing up.

Post-Processing

   Seams and Tight Tolerances

• The magnetic pegs and jaw channels are intentionally designed with tight tolerances. Therefore, the following steps are recommended:

  • Remove the printed seams as much as possible, especially on the lower part of the pegs. I was able to easily remove them using a file. Sandpaper could also be used.

  • Even after sanding, the pegs may be a little tight. Gradually continue to sand them until a proper fit is achieved. Once they fit (even if a little snug), continued use should eventually smooth out any remaining inconsistencies. You can also adjust the tolerance (using the Fusion file) and reprint.

   Magnets

• Insert the magnets in the end of the pegs. To match existing RA3 peg polarity, I recommend you insert all peg magnets with South facing up. If the tolerances are correct, they should press fit snug enough to avoid coming out when the peg is removed from a printed magnetic jaw and/or RA3 jaw.

   Peg Grip

• Most 3D printing filament does not provide a great grip. TPU may provide marginal benefit. Other options worth trying:

  • Use a tapered peg customized for the workpiece

  • I have had success with Plasti Dip spray to add a rubberized layer to the peg for better friction. The finished result is very similar to the RA3 pegs.

Installation

The RA2 chuck jaw slides each have four holes (e.g. A-D from the inside-out). Holes B-C and C-D are 7.5 mm spacing. StraightLarge and Wings components have that spacing and can be installed in either position. This provides an additional 15.0 mm of diameter possible in addition to the slide travel itself (~29.4 mm diameter). But, as this graph depicts in green, the curvature of the jaws is optimized using Holes B-C. I recommend customizing and printing the jaws to match the size, curvature, and (optionally) taper of your workpiece as close as possible.

Shameless Plug

If this model helped you solve a problem, save some time, or in any way made your life a little easier then please consider clicking the Like button and posting your Makes! If it fell short after clicking on the title of the model, please let me know (Messenger | Printables.com). Either way, Thank you!

Related

   Complete exhaust configuration

      Adapters - Convert machine exhausts to ducting diameter and/or MagDuct

• xTool P2 Exhaust Duct Adapter (configured as 4 in)

• MagDuct xTool F2 Ultra UV Slip Adapter

• MagDuct CORE One Exhaust Adapter and Gasket

      Ducting

• AC Infinity 4" ducting

• AC Infinity 6" ducting

• xTool pipe (included w/ xTool IF2 2.0 and xTool F2 Ultra UV)

• xTool 72.5 mm ducting (included w/ xTool P2)

      Couplers - Convert flexible ducting or pipe/rigid ducting to MagDuct

• MagDuct Flexible Ducting

• MagDuct Pipe/Rigid Ducting

      Connectors - Convert ducting for attachment to inline fan or external surface

• Duct Expander (configured as 4 to 6 in expander)

• Ducting to Window Insert Connector (attached to a piece of 1/4" acrylic inserted in the channels of my double hung windows which allows for quick installation/uninstallation (configured as 148.0 mm (6") and 72.5 mm exhaust port)

      Inline Exhaust Fans

• AC Infinity 6" Inline Fan (High CFM)

• xTool IF2 2.0 Inline Fan (High Static Pressure/Suction)

      Mounts - Securely mount MagDuct components to a surface using a third-party mount

• MagDuct Ring RAM Mount (1 in)

      Accessories

• MagDuct Fume Extraction Nozzle and Screen - Direct smoke and fumes (e.g., soldering) into exhaust ducting

• MagDuct Generic Accessories - Control airflow volume and chamber temperature (e.g., enclosed 3D printers)

   xTool Accessories