CNC plotter 1800 x 80cm, first build, questions and queries.

[borntofight00]

So far so good!

I'm going to largely ignore your voltage measurements - because I don't understand quite what you've written...

Bad wording, sorry. Anyway, you are correct.

1) My first question is - has you witnessed the actual computer that you're using with Mach3 successfully drive this board? ..

No, unfortunately I wasn't able to see everything working. I was given two PC's during system collection with the information that one of them was used with this equipment and should still be ok.

2) Are you using a full 25w wired parallel cable between the computer and the BoB?..

I'm using brand new 25w parallel cable and I tested each pin for continuity, all fine.

3) Of interest - on the BoB - there's a 3-pin jumper header labelled "JP1" - there should be a shorting pin connecting two of the pins together - which two?

This shorting pin is connecting pins 2 & 3 (COM=GND)

4) Would you be confident to ***CAREFULLY*** measure the voltage on pin-1 of the 25-W D-type that the computer plugs into, with the system powered. I'm talking about connecting the meter black lead to 0V and carefully probing the PCB where the pin-3 is, and measuring the voltage with the X-Axis moved in one direction, then again with the X-Axis moved in the opposite direction. In one direction you're expecting a voltage less than perhaps 0.8V and in the other direction greater than perhaps 2.5V.

I managed to measure a voltage for X, Y and Z axis (just in case) and I was getting just a little bit above 2.5V and 0.07V (not too low?)

5) Much easier - could you do this again on the PC. insert a couple of pins or bits of stripped solid strand wire (paperclip?) into pin 3 and pin 25 of the PC parallel port and measure for each direction of X-axis travel. If you can provide a photo of this for our amusement (and validation) - this is getting to the point where we should be able to understand the PC->BoB communication - I think the BoB's basically functional, so this is important to understand why the BoB is not seeing the commands from the PC.

Take a look at the pictures attached, for your amusement :) I’m measuring 3.35V & 0.036V, almost identical on pins 3 to 9.

From what I understand, there is a communication between PC and BOB, but there is no signal to the outputs .. as you can see at the picture, BOB is a little bit messy so would it be a good idea to give it a good clean with isopropanol for example?

Another thing that I have spotted is LED next to PC power terminals which was illuminating for some time while PC was running but the rest of the system wasn’t powered. At some point, it disappeared .. is it normal?

I really appreciate the time you spend pointing me in the right direction.

[mnewsholme]

on the photo of the breakout board. If you look at the 8 pin chip to the right of the 25 pin connector in the bottom left corner. It doesn't look to be seated in its socket correctly. Should just push in to seat fully. Quite common for chips to work out of sockets over a period of time.

[borntofight00]

Hi and big apologies for not coming back earlier, however I had to do urgent house maintenance job which took me the last few days!

on the photo of the breakout board. If you look at the 8 pin chip to the right of the 25 pin connector in the bottom left corner. It doesn't look to be seated in its socket correctly. Should just push in to seat fully. Quite common for chips to work out of sockets over a period of time.

I’ve spotted this straight after my first post and pushed in back into its place, thanks!

So, you wired the supply and the outputs pulsed and the output LEDs blinked?

Well, I should explain a little bit better .. they are blinking when touching +5V terminal as same as previously supplying 5V to stepper motors. Once hardwired, all output LEDs are off.

My instinct is that the board is at some level functional - I'll offer to test the board for you to a level that I can diagnose the behaviour of each major functional block - but I don't know how that sits with your time-frame - it might be quicker just to get a BoB ordered in the post).

Doddy, if you have some spare time and willingness to help, I would appreciate! I don’t really have any deadlines, just trying to make some regular progress but please if at any point you will think that something is not right with Bob, let me know and I’ll get a new one as instead of wasting your time on this, I could ask some other questions. Is it worth investing in this type BoB or are there better options in let’s say £100 budget?

In a meantime I’ve sent an email to CNC4PC asking them for some more information about wiring and below is what I received:

‘this is an isolated board, so it has two power terminals. Make sure you are using both. The side that interacts with the PC can be powered with a USB cable. Make sure you put a jumper across the EN and the +5vdc next to it.’

Still don’t explain why all the outputs are inhibited when 5V is wired to PC power terminals. What do you think??

[Doddy]

Hi and big apologies for not coming back earlier, however I had to do urgent house maintenance job which took me the last few days!

I’ve spotted this straight after my first post and pushed in back into its place, thanks!

Well, I should explain a little bit better .. they are blinking when touching +5V terminal as same as previously supplying 5V to stepper motors. Once hardwired, all output LEDs are off.

Doddy, if you have some spare time and willingness to help, I would appreciate! I don’t really have any deadlines, just trying to make some regular progress but please if at any point you will think that something is not right with Bob, let me know and I’ll get a new one as instead of wasting your time on this, I could ask some other questions. Is it worth investing in this type BoB or are there better options in let’s say £100 budget?

In a meantime I’ve sent an email to CNC4PC asking them for some more information about wiring and below is what I received:

‘this is an isolated board, so it has two power terminals. Make sure you are using both. The side that interacts with the PC can be powered with a USB cable. Make sure you put a jumper across the EN and the +5vdc next to it.’

Still don’t explain why all the outputs are inhibited when 5V is wired to PC power terminals. What do you think??

Happily take a look for you - will PM address - if you find a solution in the meantime that's good.

The response from CNC4PC corroborates the info offered earlier - that all makes sense. Their suggestion of using the PC USB is notionally to maintain the isolation on the BoB - that requires that the PC supply is isolated from the CNC Supply - by no means guaranteed. But doesn't affect the price of fish for this exercise.

The inhibited outputs when wired to the PC power terminals - that's the bit I don't understand and prime for investigation - at this point you've done all according to the book.

Question of BoBs - I like the look of this one - it's a well thought out design, however, I tend to go cheap (£5 BoBs) - if I can understand the interfacing to it (e.g. hooking onto an UC300ETH then I have NO qualms of a £5 BoB.).. whereas parallel connection to a PC I can appreciate the rugged nature of this BoB. Everyone else here will have their own opinion.