routercnc_MK3

[routercnc]

Irving,
Thanks for the info. Yes, by 'other bits' I was referring to additional resistors to limit the current. It's not clear from the description but as this appears to be a module I think they must already be there. Thank you for the general explanation, that clears up the areas I was thinking about.
As for adding complexity etc. my main reason for looking into this was to reduce or eliminate false e-stops on the limit circuit. The homes and probe would be direct to the BoB as before. It is only the limits I was considering going to 24v via a relay. I think that is where the benefit will be - but when the new driver and BoB system has arrived I'll try it all direct to the BoB and see what happens.

Jazz, thankyou that confirms how I thought this would all operate. And yes, good point about no probe on a relay.
The reason I looked at a module system mounted to a board was to have simple wire connections. I had looked at automotive relays as these use standard spade terminals and had a mounting bracket, but then wondered about current resistors and diode spike protection and whether this was inside the relay box or not. Basically I don't want to have to build a PCB circuit board for this, just spade or terminal blocks onto something which works. So would the automotive type be OK?
I also looked at solid state relays but will avoid on that advice. I quite like hearing a click anyway to confirm all is well.

Eddy,
Thank you, I did look at that as well but it talked about PIC and Arduino and I didn't know what to make of it. But the diagram makes sense so thanks for posting that. I've decided to try out the BoB all direct and see what happens. If there is just one false e-stop I will add something like that - should be straight forward and there is plenty of space in the new control box I have planned out.

Thanks

[JAZZCNC]

So would the automotive type be OK?
I also looked at solid state relays but will avoid on that advice. I quite like hearing a click anyway to confirm all is well.

Yes they would work ok provided contacts rating is correct but why not just use a Din rail mounted relay as they have proper clamp terminals and are easy to access and remove.
With relay either put a doide across coil or get the type which have one built in to stop back EMF. I prefer external diode then if it blows I can just change and they cost penny's not pounds like they want to charge extra for built in version.!!

[irving2008]

With relay either put a doide across coil or get the type which have one built in to stop back EMF. I prefer external diode then if it blows I can just change and they cost penny's not pounds like they want to charge extra for built in version.!!

That's coz the diode in the relay is often a high current fast schottky diode with a known clamp voltage and thus guaranteed safe with almost any drive transistor, MOSFET, or IC - while I agree they don't cost £££s they aren't cheap and there's additional testing plus they save assembly and test costs elsewhere. An external diode would almost certainly be an 1N4xxx series of general purpose devices and cost pennies, plus if it gets disconnected more expensive driver could be compromised.

[EddyCurrent]

Eddy,
Thank you, I did look at that as well but it talked about PIC and Arduino and I didn't know what to make of it. But the diagram makes sense so thanks for posting that. I've decided to try out the BoB all direct and see what happens. If there is just one false e-stop I will add something like that - should be straight forward and there is plenty of space in the new control box I have planned out.

Yes, the link was just to show where I got the diagram from.

@Irving, I have a board like the one in the diagram, there is a moveable link so that VCC can be tied to Gnd or JD-vcc

[routercnc]

Few more bits for the upgrade parts.

Left = replaces some wooden parts which held the Z axis stepper motor, plus the Y axis ballscrew nut

Back right = Bracket which connects the new Z plate (20mm aluminium) to the Z ballnut

Front = Bracket which holds the bearing at the lower end of the Z ballscrew. Purpose designed compact unit to limit the amount of Z plate pocketing to retain Z plate stiffness. Machined the bearing pocket with a roughing cut, leaving 0.2mm dia undersize, then finished with full depth cut at final 20mm diameter. Really nice finish. Bearing arrived today (ID6xOD19xdepth6) and is a lovely gentle press fit into the bore. The end of the ballscrew will be turned down to leave a 6mm dia spigot.



As you can see I like to print out some basic drawings with a few key dimensions on as I find this helps overcheck the machining etc. I've also started sketching the outline of the part on the blank with a felt pen to see where it will cut, where to clamp, make sure the machining is occuring roughly where it should be etc. All for now.