Yes and so can you!
Yes, the dual NEMA17 version of the PrintNC was designed specifically for anyone who already has an existing CNC build using Nema 17’s or 23’s and wanting to upgrade it to a more capable machine but keep the cost low by using their existing components
The NEMA23 version is recommended for anyone building from scratch.
The PrintNC stl files are available for two frame cross sections:
75 mm x 50 mm for metric countries
3 inch x 2 inch for imperial countries
STLs can be generated for other cross section dimensions by modifying the publicly published STEP files or requesting custom STLs for a small fee in the store.
The linear kit for sale in the store provides an approximate working area of 1050 mm x 650 mm x 65 mm (41” x 25” x 2.5”)
Larger or smaller can easily be adapted without sacrificing performance.
First of all the orientation of the X and Y axis (x wider than Y axis) in the standard size PrintNC was chosen to give you a better access to the work area without limitations to the rigidity. When scaling/planning the PrintNC workspace larger it is better to change the orientation in a way that the Y axis is the longer one of both to avid loss of rigidity and avoid chattering. Going on the X workspace larger than 1000mm (39") will, depending on the weigth of the used Z assembly (used spindle etc.), most likely cause a bit of sagging in the X steel beam and the chance of bending forces in Y direction. In that cases increasing the thickness of the X steal beam can avoid this to a certain amount. As seen in many other CNC designs planning/building the PrintNC in extreme dimensions will need some practical experience, trials and will be more the exeption in the main stream of builds.
The machine can be built for approximately $1000 USD including the parts not currently available from the Three Design Store. Everything you need to build a PrintNC except a spindle, steel box section, and stepper motors can be found for about $850 AUD(~$585 USD) plus shipping if you buy from the Three Design Store. The standard size kits will build a machine with an approximate working area of 1050 mm x 650 mm (41” x 25”).
The parts which would be purchased from the store includes:
1 linear motion kit ($549 AUD/~$375 USD)
1 printed parts kit ($195 AUD/~$135 USD)
1 assorted small parts kit ($35 AUD/ ~$25 USD)
1 aluminum face plate ($75 AUD/~$50 USD)
5 stepper motors ($50-$75 USD)
1 stepper motor controller
RAMPS 1.4 + drivers(
$50 USD) Steel box section ($75-$175 USD) + shipping if applicable
Low cost spindle (~$100 USD)
Steel is ~3 stiffer than Aluminum. Wall thickness recommended for steel section is 2.5mm (0.1″) Do not go thicker than 5mm or 0.2″
Yes, a machine that is deeper than it is wide is the best way to maximize rigidity. However, the PrintNC design is incredibly rigid and the benefits of having a wide machine outweigh the inconsequential loss in rigidity.
HGR rails and carriages by design are quite tolerant of inconsistencies in the mounting surface and mounting accuracy. This aspect of their design is different from many smaller standard rails such as MGN12 and is one of the reasons they were chosen for the PrintNC. HIWIN spec for HGR20 rail allows for 0.13mm of variation in the mounting surface while still remaining within the design and performance specifications for long term reliability in high duty cycle commercial environment at maximum load. HGR20 rails are also vastly over-specified for the gantry weight and any cutting forces that the PNC generates so we are working at the bottom end of their performance envelope which extends service life and reliability.
The use of 1 block per rail is a conscious design decision made after numerous iterations of the machine.
Adding a second block WILL increase the useful lifetime of your rails, however, we expect the useful lifetime on a single block will be more than adequate. HGR20 rails are overkill for a CNC router experiencing these loads. In addition, usage of a hobby router is a fraction of continuous duty machinery (for which the rails are rated)
The numerous benefits listed above, including reduced upfront cost, far outweighs the low risk and number of incidents of wear (currently 0). Rails are now inexpensive enough to simply replace them if the time ever comes.
the PrintNC is an open-source design that encourages modifications to suit your needs. You can certainly add a second block or switch to long-style blocks, if you so desire.