Frame: I have changed the uprights in the gantry to two pieces of 300 mm C-beam, instead of the four pieces of 250 mm 20x60. I have also decided to extend the frame i Y direction to 750 mm (since I use 700 mm linear rail), and limit the Y travel to 370 mm. I was thinking about maximizing to 450 mm since I'm only using the nut block, but choosed to limit it to 370 mm. This will give me the opportunity to make an encosure attached to the C-beam machine frame without the table travel to hit the enclosure. I have ordered two new pieces of aluminum extrusion in 750 mm length for the sides. I will use my two extra spares of 20x60 (from the sides) to attach in between the (new) sides, and also to give the SBR16 rail a more rigid attachment.
Z axis: To start with I will use the original setup for Z axis, and in the future I will cut a new larger Z plate with the wheels on the outside of the C-beam, something like the XLplate but with a rigid holder for my router. The Z travel is not really defined yet since I have not choosen table yet, but I’m aiming for something around 40 mm.
X axis: XL gantry plate - gives approx 370 mm of travel.
Y axis: For the Y axis I will only use the nut block (no gantry plate) and 700 mm SBR16 linear rail. The table will be raised a bit to clear the Y stepper motor, and have approx 370 mm of travel.
Control: I will control it by using a RPi running bCNC -> Arduino Nano running GRBL -> TB6600 stepper drivers -> 425 oz steppers driven by 40V power.
Spindle: The spindle will be a Makita RT0700/0701 (10.000 - 30.000 rpm), and use a precision collet 1/8" from German company CNC_PLUS.
I chose to build the C-beam Machine since it seems to be fairly rigid and accurate, and the size fits my needs. I have been thinking about to build a CNC machine for a while, and decided that 2018 is the year it will happend. I ordered a C-beam kit from China on the 1st of January, and I got it 10 days later. Fantastic. Even better, the quality seems really good. The aluminium extrusons are really nice, and judging from the look of the cuts the quality of the aluminium looks good. And as a bonus all the cuts are done with perfekt lengths and perpendicular. I was not expecting this.
I read about some of the C-beam builds before ordering my kit, and decided to do some of the changes that Metalguru had done in 'Improved CBM' build, mainly to change the uprights of the gantry to C-beam. I’m also thinking of a simple shield to prevent the chips from ending up inside the Y axis C-beam and intog the linear rail.
So I was able to change the 4 pieces of 20x60 to 2 pieces of 300mm C-beam for the uprights of the gantry in the order, and also added 2 pieces of XL gantry plates. I have also ordered 2 pieces of 700mm SBR16 rail for table support. The table will be raised a bit to clear the Y stepper motor. And in the middle of the build I added longer frame in the Y direction, and ordered two pieces of 750 mm aluminum extrusion.
My first idea was to have the XL gantry plates for X and Z axis, where the Z C-beam is flipped, but after building most of the machine I’m having second thougts. I want the X axis sitting as low as possibly for rigidity, and with the original setup the spindle and tool can be lifted above the bottom of the Z C-beam (compared with flipped Z C-beam, the tool will always protrude below the bottom of the Z C-beam, making me to need taller gantry for the same thickness of material to cut). Therefore the original setup seems better.
I'll post updates in the discussion as I go along.
C-beam Machine - Modesty
Modified C-beam Machine. Taller (30 cm) C-beam uprights in gantry, and longer 750 mm frame in Y direction. XL gantry plates on X and Y. Y will have additional 700 mm SBR16 rails as extra support and slightly raised bed to fit above stepper motor. Approx. machinable area of 370 x 370 mm.
- Build License:
- CC - Attribution - CC BY
Inspired byMetalGuru - Improved CBM