Plastic Monstrosity -- The 3D Printed CNC for 4x8' Plywood by spiffcow

Last crawled date: 3 years ago

This is my massive CNC capable of cutting a full 4x8 sheet of plywood with room to spare! This is optimized specifically for cutting plywood, and I believe this is probably the least expensive way to build a CNC capable of accurately cutting plywood in a reasonable amount of time. There are other designs out there, but I've yet to see another one that maintains performance and accuracy while keeping the overall price below $1000 for a 4x8' cutting area. I really enjoyed designing and building this, and I hope it can help lower the barrier of entry for makers looking to build the kind of things you see on OpenDesk or WikiHouse.
Bill of Materials
Thanks to kaoskido for helping me organize this! If you see anything missing, please let me know!

Amazon apparently doesn't want to let me use their affiliate program to link to items, so I'm going to start selling hardware kits in the near future, which should reduce the cost compared to buying all these individually.
Hardware
3x 1KG PETG filament: ~$57
1x 1500mm OpenBuilds C Beam linear rail: ~$40
1x 250mm OpenBuilds C Beam linear rail: ~8
1x OpenBuilds Anti-Backlash leadscrew nut: ~$11
1x 20 pack 625ZZ bearings: $7
1x 20 pack 608ZZ bearnings: ~$10
2x 8 pack polycarbonate mini V wheel kits: ~$60
1x 5 pack 20 tooth GT2 pulleys with 6.35mm bore: ~$10
2x 100 pack 12mm M5 screws: $30
1x 50 pack 25mm M5 screws: ~$11
1x 50 pack 30mm M5 screws: ~$11
2x 10 pack 75mm M5 screws: ~$15
5x 25 pack 5mm sliding T nuts: ~$40
1x 50 pack thin M5 nuts: ~$5
1x 100 pack M5 lock nut: ~$9
1x [50 pack 1.5" long 5/16" bolts]https://www.amazon.com/gp/product/B01MTU6TL0/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=spiffcow-20&creative=9325&linkCode=as2&creativeASIN=B01MTU6TL0&linkId=7fa1210ccd086d92cf7b8477c7755251): ~$10
1x 10 pack 3.5" long 5/16" bolts: ~$6
2x 10 pack 5/16" lock nuts: ~$7
2x 5m run of GT2 belt, 10mm width: ~$27 (note: the 10mm width is very important)
2x 2" conduit from Home Depot (10 ft): ~$42
1x 1/4" up cut router bit: ~$19
1x 300mm 4 start 8mm lead screw: ~$10
Hardware total: ~$430
Electronics
3x 269 oz. in. NEMA23 stepper motor: ~$78
1x 78 oz. in. NEMA17 stepper motor: ~$16
1x MKS SBase controller: ~$60
1x 100 ft 4 conductor 22AWG stranded wire: ~$29
1x 360W 24V power supply: ~$18
1x JST connector set: ~$16
Electronics total: ~$217
Spindle (choose 1)
Makita Compact Router: ~$100
DeWalt DWP611 Router: ~$100
Overall cost
~$750 + the cost of building a table (roughly $100 or so), assuming you don't already have any of the parts.
Change Log
Update 2018-04-19
Added improved short axis carriage plates.
Update 2018-04-14
Added a dust shoe. It mounts to the rear of the C Beam.
Update 2018-04-04
Added a print list and bill of materials!
Also, stay tuned for a dust collector attachment (hopefully in the next couple weeks :)
Update 2018-01-13
Added an 80mm spindle Z axis piece.
Update 2017-12-03
I fixed the print orientation for the gantry parts and the endcap. Remember to enable supports on the gantry.
Update 2017-12-01
If you're having trouble with slight variations in plywood height, I have created a simple Z probe that you can use in conjunction with bed height autocorrection (I'm using Smoothieware, so I have it do the height probing and correction in the firmware).https://www.thingiverse.com/thing:2685926
Sorry for the lack of updates. I still don't have a BoM ready, much less a build guide. I've had a lot of other projects going on, and this is all just a hobby for me at the moment, so the amount of time I can allot for it is pretty minimal. Maybe I'll try to sell kits or something in the future -- if you'd be interested in such a thing, let me know.
Update 2017-11-04
Added guardPlate.stl. Reduce the belt bearings on the short axis to 2 per side (4 total) and place the guardPlate.stl piece along with a 1mm spacer. This prevents the belt from twisting.
Also added a picture of a full chair from OpenDesk cut in a single session. I'm marking the build complete, but will add more documentation in the future.
Update 2017-09-20
I added the following:
Makita compact router mount Z axis (makita.stl)
DWP-611 mount Z axis (dwp611.stl) - untested
pieces optimized for 60.3mm OD conduit (50NB)
Update 2017-08-21
Added components for the short axis belt for use with motors that have a shorter shaft. The belts are closer to the motor, but the new end supports take up an additional 30mm on the short axis.