Standalone controller V4.0

Powder and inkjet printing
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dragonator
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Re: Standalone controller V4.0

Post by dragonator »

If both controllers return 300/300 and prime ejects ink on both, The most likely culprit is that the buffer is not printed. Can you verify that on the printing controller the buffer (BRL) is emptying when it is printing, and filling when you send an image? Something might cause one controller not to actually print from the buffer.

If the V4 still does not print, try this: https://github.com/yvodehaas/Inkjet-commander
This is the software latest for the V4, but does not really work for the V3 anymore. This can only print images, and not control printers, but it can use all functions on the V4, and should work. If this doesn't we need to dig a bit deeper to see what is going wrong.

Differing voltages do not overly worry me right now.
rofl
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Re: Standalone controller V4.0

Post by rofl »

dragonator,

but the problems now is that V4 controller (with inkjet commander) actually primes and tests (300/300) fine both HP heads: with my custom binder and neat HP4 with black ink. Whereas V3 controller (which used to print before and worked) primes well neat HP45 head (original black ink), but it does not prime the same HP45 head with the custom binder that I used to prime successfully with my V4 controller. For some reason I think that my V3 would print fine images with black original HP45...

Perhaps I was not clear, but I have:

X head: HP45 with custom binder
Y head: new HP45 with original black ink

V4 controller: Primes X AND Y, tests 300/300 both.
V3 controller: Does NOT prime X, but primes Y, tests 300/300 both.

So to conclude, both prime Y, i.e. new head, but custom binder works only with V4...

DO you think this can be software issue? I had a wild guess that if logic of nozzle control is different, is it possible that V4 does something better compared to V3?

Thanks
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Re: Standalone controller V4.0

Post by dragonator »

Then I did indeed misunderstand. I think I understand your new explanation. If a printhead refilled with a new binder works on both controllers, and an original printhead with ink only works on the V4 and not on the V3, then something is indeed off. This is not something Software.

What you are experiencing seems like it is something that I have noted before, but not yet characterized, and do not have a hard fix for. I know that HP actually varies the voltage to the printhead to have the ideal voltage for a printhead. It does this by firing a set of nozzles and measuring the temperature increase, and then varying the voltage. The voltage that increases the temperature the least is picked. This voltage provides enough energy to vaporize the ink in the chamber, but does not provide extra heat. So far I have only run controllers at a simple 12V. The controllers have a way to input different voltages, but I have never tested it. Another hint is that I cannot eject all 14 nozzles at the same time, even though HP seems to be able to do it. I need to eject in 3 different pulses. I have tested changing this around and this is actually a setting in the controller, but I never got it stable.

I have noticed it when printing with my inkjet gantry. It prints small images with ink just fine, but when printing larger images the ink cuts out, especially when there are sections that need all nozzles or a lot of them on. I think the head overheats and stops firing efficiently. This also damages printheads. The printheads with 20% IPA, 80% water print an order of magnitude better without any dropouts.

I suspect this is what is affecting you, though I do not know for sure. Varying the voltage of VHD might actually provide a voltage that prints stable either higher or lower. Given the voltages you measured, it might actually need more power. It is weird that even priming does not eject ink. It uses the same functions that print normally, but usually priming does at least eject some ink.
rofl
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Re: Standalone controller V4.0

Post by rofl »

Thanks, dragonator.

I will do one last thing. I will connect my V4 controller jig to the gantry of the printer (I would just connect it), i.e. it will own the same power conditions as V3 that is already mounted. If then V4 fails to prime it, I would believe that this is related to input voltage, but let's give it a try and I will get back to you after this test.

Thanks.
rofl
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Re: Standalone controller V4.0

Post by rofl »

dragonator,

it appears that voltage could have been an issue (11.5V instead of 12V). Yesterday I solved PSU problem, voltage got back to around ~12V and situation improved significantly. I still did not print, but priming and some basic image printing seems to be better although some nozzles sometimes still do not eject ink properly, but I still have to work with the binder itself and perhaps to sonicate head more thoroughly to make all of the nozzles spray (controller tests 300/300).

If this binder works, I might make a good step towards trying to print out of metal powders.

Thanks again.
rofl
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Re: Standalone controller V4.0

Post by rofl »

dragonator,

I tried to run some printing tests with Oasis Controller and V4 driver, but I observe some shifting of swipes... If you look closely, you might see uneven edges in a trendy pattern. The only thing I changed in firmware was that pin swap I mentioned earlier, but everything else is the same. Do you have any ideas? Also, I noticed that with V4 HP45 tends to heat up pretty quickly and controlling software shows very often temperatures above 75C or even 120C. What can cause this?

Thanks.
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dragonator
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Re: Standalone controller V4.0

Post by dragonator »

When I try and hold a ruler to the lines, I have a hard time finding a walking error. There is definitely a small shift on the right most bit, but over the rest I have a hard time spotting a stair step. It looks more like a zigzag. Can you verify that the head is perpendicular to the axis? It seems to me that while it would not be the only cause, it might make it a bit worse.

Encoder walking and position errors have been seen before, but not ever in the scale that I spent much time on it. The workaround in Oasis was that I wrote the position before every sweep, while I was sitting still. I still noticed an error on the first sweep at some times. I think I made it to only update on every layer afterward. The issue of the encoder wandering slightly can come from the fact that the interrupt is stopped whenever you are starting a burst. To set up DMA, interrupts are forbidden. I do not know how encoder pulses that come in are handled in this time. This cannot explain the error on the first layer, but might explain some small wandering.

As for the temperature, do not see it as an accurate measurement. The HP45 itself already does some estimation, and I have made the formula that calculates the temperature based on 2 HP45 printheads. It works, and shows a temperature, but even I have gotten 60C on cold printheads.
rofl
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Re: Standalone controller V4.0

Post by rofl »

dragonator,

Yes, it is like a zig zag, but it is more visible with a naked eye. Head is really perpendicular to the axis. I spent a lot of time aligning everything explicitly. I will test some more later and see how that goes.

Apart from that, what are your plans with HP45 and further work? Do you treat this as more or less concluded project for yourself and you have no motivation to get back? Or do you have any plans getting back and working some more?

Thanks.
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Re: Standalone controller V4.0

Post by dragonator »

I will have to post this at some point in more detail, but until further notice I do not plan on continuing the HP45 stuff. I might pick up small projects including it, but I have no real interest in pursuing the HP45 as a core project. The V4 will be fully shared, and the firmware and software are already on github. I still plan to make a detailed page with all sources on this site as well, but I have had that on the list for the past 2 months, so no deadline on that.

HP45 has become mostly a software project, and I have concluded that I really do not enjoy coding that much. I enjoy making projects work with it, but not the process itself. All projects in the past few years that included a lot of code have either stalled, or I hated it the last few months. The HP45 itself has also proven temperamental, sometimes being perfectly stable, and other times just randomly dying with no good reason. Support for random people making the controllers has been even more limited time away. The difficulty getting a rolling inkjet gantry working for even a minute was the final straw. I do not want to sell the V4 controller and be responsible for supporting it knowing that it is fragile at best, and I do not really enjoy it as a project.

I still have the V4 stock I made when I still had the intention of selling, which I am slowly selling off, but after that I will not get new stock. I might pick the HP45 up as a project in the future, but for now I am a bit done with it. I have other projects that I want to be doing again.

Questions will still be answered of course, but I do not think big fixes from my side will be likely.
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