DIY CNC Router Build : Part 1 - The Beginning, the Table and Rough Gantry
For some time now, far too long really, we have discussed building a CNC router so that we can expand our abilities from only metal, to plastic, wood, carbon fiber, and machining aluminum. Well, we finally took the plunge! If you read the blog on our first plasma cutter, we used a Gecko G540 to update the machine to run after our HobbyCNC board burned up. We figured we would use it temporarily, with some Nema 23 stepper motors until we needed more power down the road, since we already had the G540 from the first plasma build. Well, as it turns out, the G540 and Nema 23 motors were strong enough for this build, as of the time of this writing.
Anyway, the spec of this build:
- A little larger than a 4x8 foot cutting area, so we can move the gantry clear out of the way for removing parts/loading material
- G540 driver
- 2.2kw Chinese watercooled spindle (https://www.amazon.com/gp/product/B01MXLXRTY/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
- Nema 23 381 oz/in 3.5A stepper motors (https://www.amazon.com/gp/product/B007QMCQ9S/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
- 100mm Z axis from Amazon (https://www.amazon.com/gp/product/B075PCNZMB/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
- Old Dell PC with an LPT port
- 20 pitch rack and pinion with a 3:1 gear reduction
- 1" round Thompson linear rails for the Y axis (reclaimed from the local scrap yard)
- 3/4" round Thompson linear rails for the X axis (reclaimed from the local scrap yard)
- 3" square 80/30 aluminum extrusion for the gantry cross members (reclaimed from the local scrap yard
- Scratch built frame and gantry uprights
Our goal was to build a solid machine, without breaking the bank. We salvaged the linear rails from the local scrap yard. We found some machines that hard parts we needed, and we pulled the parts for the use on this machine. They were a little rusty, but with some sandpaper, scotchbrite, and some WD-40, they cleaned right up.
We threw some sketches together, cut some metal and then put our main table together:
Once we got the main table frame together, we put together some mounting brackets for the linear rails and rack, and then cut them out on our CNC plasma table. Then we designed some uprights, based on the dimensions of all our components, and cut them out too. Our first iteration of our gantry uprights had the linear rails on the bottom, and the rack above. This increased the possible stress from the spindle to the uprights, given the longer moment arm of the taller upright. In the long run, we ended up placing the linear rails on top, and the rack below, which stiffened up the gantry, laterally, and also kept the rack a little further from the dust.
Originally, we had planned on using two layers of 1/4" steel plate on each end to add mass to the gantry, to reduce chatter. However, we ended up using just one, to reduce weight. The empty rectangle is where the motor will mount. We made it removable, should we decide to swap to Nema 34 motors down the road.