exxos blog - random goings on

[exxos]

Back to the 3-D printer as the driver boards just arrived..

Of course they are upside down! so I need to one solder the pins and put them on the other side.

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The pinout is slightly different as well. M2 which as far as I can tell be logic low, and M1,M1 logic high. The original board has a reference voltage which seems to be generated from the logic board at 1.37V. As this is below the logic high threshold (2volts) and is going to leave that pin as it is.

FAULT on the new PCB is actually VCC on the old one. So I will just cut that pin off.

Annoyingly the motor pinout are totally different. I had already swapped the two centre pins on one of the motors connectors. The looks like I will have to put them back, then swap pin 11 & 13 instead

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Hours of fun ahead.....

EDIT:

Oddly this chart seems to be different than the one I saw the other day..

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So I guess I will have just have to cut that VREF pin, And just bodge wire the PCB pad to M1 instead.

OTOH As far as I can tell, M2 is floating on the dreamer PCB, which would mean it would need to be logic low to match. But maybe 32 steps would be better anyway

[exxos]

The puzzling over the wiring, ironically the colour code seem to not change, despite the pinout is on the board been totally different I did not look into it much but I think the A and B coils were actually reversed, but after simply trying it, did not seem to matter.

Pins removed and refitted on the other side of the board..

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Boards fitted for a initial test..

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The current wiring where one wire is cut for me to meet the current.

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Initially I saw various currents up to about 1.25A which must be the default setting for the module.


Could not find a screwdriver for the stupid small preset.. Managed to flip it around 45degree..

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Retesting the current I saw it jump up to about 2.22A so that should be good enough as before I was barely hitting 1.00amps.

They do run hot so I fitted a longer heatsink..

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The heatsink is offset because the chip is on the edge of the board. So the chip is actually in the middle of the heatsink as it is located.

Now to do some more calibration stuff..

[exxos]

So there is good news and bad news

The good news is it works, and I did not need to recalibrate the motors. I ran the filament at 1000mm/min (16mm/sec) and did this easily without slipping or tripping up. I did not try any other speeds as I ran into small problem...

This brings me on to the bad news, that the heatsinks are just not capable cooling the chip It printed the first layer of my 50mm square fine, then the motor started making clicking noises. It was not slipping or anything, turns out the board's overheating and presumably thermal protection is shutting down the chip and the motor

So I need to come up with a solution for cooling the boards better. My initial thought was to use the Panasonic carbon transfer sheet. Stick it on top of the PCB and ticket onto a heatsink may be bolted the side of the printer internally. But with the sheet been rather expensive..

I'm trying to think if I could somehow get a block of metal exactly the right height and width, and bolted onto the bottom metal base of the printer. But this would have to be done rather accurately.

My current thought is to have a heatsink and use the logic boards mounting screws to also hold a heatsink above the entire board. This way I could get whatever size blocks would basically fit, and interface the driver PCBs to the larger heatsink.

[PhilC]

@exxos My printer has a cooling fan blowing across the board with heatsinks like the small ones you initially fitted on top of the driver chips. These are higher current drivers (can't remember which tho)

[exxos]

@exxos My printer has a cooling fan blowing across the board with heatsinks like the small ones you initially fitted on top of the driver chips. These are higher current drivers (can't remember which tho)

It does have a small fan blowing across the board,But I don't think even a small fan mounted right next to the drivers will keep such a small heatsink cool

I guess it depends what driver chips you have, and what currents you are driving them at..

[exxos]

Onward..

Added a nut under the board to lift it up a little to plot where the bar would end up in relation to the PCB and the bottom plate of the printer.

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Later started using washers for more fine tuning. The tape is there to hold all the washers in place as I simply did not have 10 sets of hands

I needed a simple way to align the bar on the driver boards. So I used some double sided sticky tape..

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Bar cut to size and look on the driver boards.

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A lot more tape on the top. Theory being that the bar would stick to the bottom of the case when I removed it afterwards..

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Well that was the theory anyway, had a bit of a unexpected side-effect

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Bar location marked out.

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Holes drilled. The left bar looks like it has two holes. It was just typical that the 2mm drill bit snapped off inside so had to drill another hole

Arctic Silver five the best paste on the planet added

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Bolted in..

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I only had TO220 silicone washers. They were good enough for this application anyway. Even if the bar shifts or whatever reason, they should not short out the pins because the silicone washer should prevent that from happening.

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All back together.. Kind of..

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First test print

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Added a couple more washes under the circuit board to lift it up a little higher.

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And finally I actually managed to print more than 30 seconds! yay!

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I need to do the tedious calibrating everything again now.

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And I am sad to say I am out of pink filament And to think I use the entire reel printing out test squares

[exxos]

Put the pink ABS on the left as I plan to use dissolvable filament on the left. I forgot to up the temperature for the ABS. And extruding the filament actually physically pushed the heater block out of its assembly I guess I really need to change that for a screw-in thread I think I have a bit too much filament extrusion power now

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[PhilC]

[exxos]

PMSL.. dual extrusion is a bit off

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Oh and out of the blue my printer lost all its settings and went nuts, seems it has forgotten it has a EEPROM now. So I had to work out all my settings again and hardcode them into my start-up script

I also had a bad solder joint on one of the steps setting pins on the driver board. The left extruder was running at 10x the rate of the right one. That is now fixed!

[exxos]

What a total nightmare

I had huge problems getting the extruder offsets to behave. The printer was thinking it was at the leftmost position when it actually wasn't. Of the problem was settings are lost each time I reboot printer and secondly settings in simplify 3-D do not seem to actually do anything In the end I wrote a script to set everything up from scratch. Had a total blockage on the deviate excluder which was fun as well.

Is PVA stuff is a total nightmare. It just constantly oozes regardless of temperature. So I have to print like 40mm time to get it to flow hence the square at the back being printed with the PVA. Then once it is flowing I then let it print the supports. There should be a "ooze tower" for it as well but not sure that is working yet either.

In any case this is the very first "successful" test run.