I’ve gotten some great feedback and interest from online communities about this router build, but I’ve been surprised that most of the people who have reached out about potentially using or modifying this design have been more interested in the 4×4 version than the 2×4 version I am currently building. While I have some downtime during the build waiting for more parts to show up, I thought I would take the time to flesh out what a 4×4 version of this router would actually look like.
Major Changes
The big changes are that the base structure obviously needs to be longer (including a longer rail and screw), but also the Y axis screw diameter needs to be increased from 16mm to 20mm. Making the structure slightly longer is just more T slot extrusion and more bolts but changing the screw diameter has a ton of extra implications. The support bearings and ball nut change size, then as a consequence pretty much every part that touches them (bearing support plates, ball nut mounting plate) changes size as well. Additionally, because the spacing of the screw from the rail changes with the new bearings, the motor mount even needs to be adjusted slightly.
This new configuration adds 600mm of travel to the Y axis which preserves most of the ‘excess’ Y axis space from the original design (useful for tool change area) while re-using many of the same parts from the X axis to maintain commonality. The big downside is that all cables and tubes need to be 1 meter longer. It can be very hard to ‘grow’ a cable, so if someone plans on potentially upgrading in the future then just getting an extra meter of cable from the beginning is probably a better idea.
The following list shows the substitutions and additions by subassembly, excluding details from the vacuum table. From what I can tell the upgrade costs about $650 in new extrusion, $500 in new rails/screws, something for the lower shear panel, and maybe a few hundred dollars of extra plates/hardware. The only waste is about $250 in extrusion, $350 in rails/screws, and the old lower shear panel.
Base
Substitutions
- 2 x CNCR-BASE-TSE-RM (rail mount) 40160 extrusions replaced with longer versions
- 2 x SFU1610-800 screws replaced with SFU2010-1500 screws (same as X axis)
- BK/BF bearing mounts and ball nut replaced with SFU2010 compatible versions (same as X axis)
- 2 x HGR20-1200 screw replaced with HGR 20-1800 screw
- 2 x CNCR-BBM (bearing block mount) replaced with slightly larger version for new BK/BF spacing
- 2 x CNCR-BASE-MM (motor mount) replaced with nearly identical version with slight motor spacing adjustment
- Could probably redesign this part to mount on slots for cross-compatibility, it only needs to shift by a few mm
- 2 x CNCR-BASE-SG (side guard) replaced with longer version
- 2 x Steel cable increased to 6′ long
- 1 x E-Chain replaced with longer version, matching X axis length
- 1 x CNCR-BASE-LSP (lower shear panel) replaced with larger version
Additions
- 2 x CNCR-BASE-TSE-IM (same as the existing inner cross member) 4080 extrusions, added in parallel
- 6 x CNCR-BASE-TSE-MBM (middle blocking member) 40120 extrusion blocking members added to pad out table length
- Tons of similar hardware to attach the above (M8x60 for blocking, M8x12 for SG, M5 for rail)
Stand
Substitutions
- 2 x CNCR-STAND-SS (side stringers) replaced with longer version
Gantry
Substitutions
- 2 x CNCR-GANT-BNM (ball nut mount) replaced with larger version
- 2 x Ball Nut (SFU1610 replaced with SFU2010), and larger diameter mounting hardware
Models and Documentation
A new 4×4 configuration was added to many subassemblies and the top-level assembly. Many parts got a new configuration to account for the new screw size as well (bearing block mount, motor mount, ball nut mount). Hopefully this will help keep the 4×2 and 4×4 models in sync as any changes are added in future versions. The drawings will use tables to manage multiple-configuration parts (similar to how mirrored parts are handled), but the displayed configuration will usually be associated with the 4×2 configuration.
The latest model data, which incorporates all of the changes for the 4×4 configuration, can be found in this release of the GitHub repository. There are also drawings (for many base and gantry parts) along with parasolid files published with the release.