Comments sought on new build: A CNC Router for RC Gliders and Planes

[JAZZCNC]

I'll still at a later date put a 240V relay in and put a resistor across it to drain it quicker in case someone goes in the panel within that time.

Yes I would do this anyway neil because if your not isolating the drives enable signal then the motors will remain powered until caps drained and this will cause them to run on slightly before fully drained.

[njhussey]

The door isolator turns off all power so it's just for drainging the caps in case someone puts their hand on something.....although I've got hot glue over the soldered terminals on the caps so you shouldn't be able to shock yourself...

[JAZZCNC]

The door isolator turns off all power so it's just for drainging the caps in case someone puts their hand on something.....although I've got hot glue over the soldered terminals on the caps so you shouldn't be able to shoch yourself...

Ok understand that side but still same applies has when you E-stop the machine will run on.!

[njhussey]

I'm having the Estops (and AM882 alarms) go through a relay (and Pilz??) which will kill the power, the limits I was going to wire through a relay and to the enable of the drives.....

[routercnc]

Hi Neil,

Looking through your build log on post #555 showing the control box -

Looks like the positive red DC output cable from the capacitors is going into an MCB. Is this correct and is this how you are intending to add a fuse? I'm a bit confused as I'd expect the MCB to be on the mains AC input side, and instead to see blade fuses on the DC output. Can you elaborate as I'm about to start my linear PSU build.

Thanks

[njhussey]

Hi Neil,

Looking through your build log on post #555 showing the control box -

Looks like the positive red DC output cable from the capacitors is going into an MCB. Is this correct and is this how you are intending to add a fuse? I'm a bit confused as I'd expect the MCB to be on the mains AC input side, and instead to see blade fuses on the DC output. Can you elaborate as I'm about to start my linear PSU build.

Thanks

I'm looking to get some of these but had forgotten about the MCB's. I was going to use them but I'm not sure they're the right thing at all! Lookig at something like these http://uk.rs-online.com/web/p/fused-...inals/8239552/ although I do quite like the idea of the 12V fuse holder EddyCurrent uses but not sure for a work environment?

[routercnc]

Hi Neil,

Ok, thanks. Then I'll stay with my original plan which is 6A MCB type D on AC side of PSU, and automotive blade fuses on the 70V DC side. I plan to fit a trial 1A fuse on the DC then jog an axis to deliberately blow the fuse. Then I can make sure that it blows cleanly and there is no residual arcing from the 70V. I'll then fit the intended rating. I think Eddy and Irving both went this way.

But the DIN mounted fuse probably is the way to go for how your machine will be used industrially. Do you know if the 5x20mm fuses need to be specific for DC? This was where I got stuck with this option because reading around AC and DC currents seem to require a different type of fuse and so I went back to the automotive type which are definitely for DC. I wondered if that was why the fuse wire was such a curly shape on the DC blade fuse instead of the straight wires in the AC ones, to make sure there was a clean burn/break rather than continual heating, expansion, and arcing.

I'm not coming from a strong electronic knowledge-base so the above are just my views / thoughts.

As for the rest of your build looking very professional now, well done.