CNC Project X Axis Y Axis Z Axis Control electronics
Cable Chain "Slimchain"®
This is a cheap, simple and effective method to repeatably move cables along a fixed path.
What is needed is a suitable length of steel shim 0.015" or 0.381mm by 1.5" or 38.1mm next make some plastic saddles a simple square section is all that is needed,drill the steel shim at regular intervals to suite the saddles, see photo 1-3.
Drill and tap the saddles to a suitable size and fix to the steel shim see photo 1-3.
Next is a little more complicated, what you need to do is to make two retaining brackets, either folded out of aluminium or machined out of block, which ever method you choose you next need to make 4 bronze bushes and fit these from the inside of the end bracket then turn a steel pin to fit the bushes and mill it in half, and assemble see photo 4,5.
Next drill tow matching holes in both the steel shim and the rotating steel pins and screw together, fit to the machine photo 4,5. and run the wiring through
It would be of course useful to make the saddles just big enough to take the biggest cable you need to run, if you feel that the weight of the cables is such that the shim is overloaded simply add another shim the action of screwing two shims together will more than double the strength of the chain.
The example above in photo1 ~ 3 shows 9 x 10 AWG wires which are surprisingly heavy and as you can see are adequately supported.
Provided that you do not try to run the shim through a tight 90 degrees bend regularly and the ends can move when loaded with cables this method of cable tidying will last as long as the machine.
Wiring practice.
i have used two methods to wire my machine, the first was to pull through what ever wire came to hand and tie wrap it together to bundle it, i have found out to my cost that this was not a good idea.
every thing worked, fine i could run the machine and make it perform all exercises, BUT when i turn on the spindle motor that is it, false limit triggering , steppers drifting, odd and unexplained triggering every where, i did manage to significantly reduce the interference, by adding a few capacitors across the limit switches and filtering the spindle supply, but it was never right.
I have now rewired the machine using the following method,
Use good quality screened cable, suitable to carry the current, my cable is 16 strands of each 0.2mm thick and tinned, this cable in fee air is rated at 3 amps constant current, as steppers do not draw constant current but is pulsed, therefore a much higher current pulse will pass along the cable, i will not go into resistive losses that is up to you to calculate, but let it be said i can run my drives at full power without any noticeable loss.
Grounding is very important and a star earth should be used, this is where all earth cables end before going to the main system earth ( wall plug or ground stake)
I have made the controller chassis the grounding star point and all cable connectors are grounded to the controller and all screens are terminated to the connector shells, and are not terminated at the far end as this will cause a ground loop, BAD THING!!
Try not running sense and power cables along side by side, as any noise on the power cable may well couple into the sense cables and cause false triggering and spurious alarms.
Always use a screened cable to each limit switch try not to cut corners by running one cable and splitting to two or more switches or sense inputs
Fit a 0.1uF capacitor across each limit switch, this will help to reduce the spurious signals on these wires and give a better signal when the switch is operated.
It was a mistake not to do this first time but having spent nearly two and one half years building i wanted to see it move!! albeit to my cost.
After all having spent loadsadosh on shafts,
ballscrew's and bearings why not just a bit more wonger on the right cable,
as the benefits are that the machine will work better first time and look good
too!!