Sweet dreams CNC - more than one step beyond...

[sweetdream]

Does chocolate in the 'fridge' at -70°C count?

..chocolate counts only if you can eat it!

[sweetdream]

As mentioned the frame was initially going to be 80mm box section, measuring the steppers showed that by careful arrangement, the frame could act as the stepper motor mounts, saving the costs of dedicated mounts [pic] this worked rather well on the X and Y axis but as there was no box section on the Z, it couldn't be done there. The Z axis had its own design spec, small, as compact as physically possible and strong, very strong.. The Z stepper mount needed to be adjustable in one axis (same as the X as it happened) but solid in every other. 4 pieces of 10mm alloy sorted that.

Getting the spindle as close to the gantry as possible, mainly to reduce the leverage effect from the spindle under load, was another area I spent some time on. It's ended up 140mm from the centre of the spindle to the centre of the Y axis and the Z axis is 144mm wide! This minimises the amount of table space lost to the spindle. The only parts on the table, profiled rail, and ball screws that have to be there but cannot be used by the Spindle when the Z axis is 1mm off the stop switches is 146mm on the Y Axis, 73mm each side.

It should also be remembered that smaller chunks of 20mm ECO plate are cheaper than Large chunks of 20mm ECO plate! :-)

[pic]

The height [?] is where the space was found to mount the cooling system pump / reservoir and the Z axis stepper pulley arrangements. A couple of junction boxes take care of the wiring and act as an anchor for the twin runs of echain.


Very happy with the result, the Z axis stays within the confines of the 4 Y axis trucks wherever it moves, the Horns do their job and the 5mm thick steel triangulated plates that were shown not to be necessary on the simulation, but for the sake of 30mins welding, "over engineering" was preferred to "always wondering". lol.

[sweetdream]

I mentioned earlier about the 'boring soldering'! One of the things I anticipated happening when I started running a new untested machine, at least for the first few times, was that you needed eyes on a swivel! Even by phasing the testing to only specific circuits, there comes a point where you have more new bits running than you have eyes to watch them! The automation of voltage and temperature checking etc. meant that I could focus on stopping the spindle diving into the sacrificial bed or any other undesired behaviours.

The wiring shown is for 5 LCD screens mounted into a console at the front of the CNC. The screens show various information about the machine without have to go look for it or fret about it. This is in addition to the touch screen mounted onto the frame, but facing away form the swarf! :-)

The Blue LED section in the wiring pic (above) alerts you by turning red if anything goes outside the parameters you set. For the startup tests, this was set somewhat conservatively! :-) During the tuning phase these parameters were relaxed somewhat as the machine was dialled in.

The screens are augmented by override buttons, for instance, capable of turning fans on if they are off, or off if they are on. They are fed from 2 CaT5 cables, one from the Z one from the rear wiring.