Rant Have we been lied to about how sensitive a solvent print head is? (e.g. DX5)

[Atari]

I've basically abandoned my DX5 based Mimaki JV33 for some time. The DX5 head was super clogged, the test print was mangled all over the place. There's even a visible "scratch" across the head.

So I figure, what the heck, I'll pull the head off the machine and clean it real good.

Using a fresh damper (to not make matters worse by injecting unwanted particles), I plug the damper on each of the manifolds connectors and manually inject, with as little PSI/pressure as possible, a stream of head cleaner through the head. If it's at all difficult then I try to PULL a little instead. Eventually, everything seems to be spraying again ok.

So I then clean the head up very neatly and inspect it using a jewelers loop.

This is the part that surprised me....

This thing is built LIKE A TANK.

The majority of the print head itself is a SOLID METAL PLATEN. I imagine this is for the purpose of heating the head platen to keep the viscosity of the ink high (so it will flow/spray). Like 95% of that face of the print head is SOLID METAL. Not a billion little jets like some of us are thinking - but solid metal. on the DX5 there are 8 very thin line grooves (for the 8 channels of ink I assume)... like this if you're looking down at the head:

|| || || ||
|| || || ||
|| || || ||

and from the side:

--/\--/\----/\--/\----/\--/\----/\--/\--

Something like that anyway.

So here's the thing... when I looked with magnification, I can see that within those grooves some of the little nozzels are clogged or shiny (damage, maybe).

But at this point I am thinking that if you had a microscope and some way of "sanding" a nozzle line/groove, then using flushing the channel to expel any sanded material that got in there, then you could probably repair any head with minor surface damage.

What do you think?


***WARNING: Of course take this with a grain of salt and don't attempt any of this on your own equipment unless you're planning to replace or junk the head anyway. Which is basically where I was.

 

[Atari]

I'm thinking if you had a steady hand for sanding...

a set of something like these:
12-piece Micro File Set

and some type of stero microscope, or a 200x zoom USB digital microscope with a friend to hold it....

...then physical surface damage resulting in problems like "deflected" nozzles could be easily repaired.

 

[Solventinkjet]

DX5 head nozzle paths are created using a photolithographic method which is the same process they use to make micro processors. The nozzles themselves have to be a very specific diameter and shape in order to allow the ink to fire at the right consistency and velocity. If that very specific diameter and shape is messed with at all, you will get a poor print at best. The difference in accuracy between a photolithographic process and manually sanding down the surface is like the difference between a child drawing a picture of their family verse a Rembrandt. It's just not doable without a huge investment.

The shininess of the damaged nozzles you are seeing is the Teflon coating being eroded away from the ink passing through.

Inkjet printers do not heat up the ink in order to print. The head does heat up due to electrical resistance and the vibrations of the piezo crystals but that is just a natural outcome. In fact if it heats up too much it will throw an error saying something is wrong which is usually a short in the circuit.

The reason you had more success when you pulled back on the syringe is because there is a filter in the manifold. If it is super clogged than pulling back removes some of the debris.

I'm not trying to discourage you but figured I would give my .02. There are ways to recover clogged heads but if the nozzles are deformed or damaged, there is no recovery. And on old heads it's almost always deformed nozzles that cause failure other than electrical issues. Now Ricoh heads are a different story. Epson based heads are more of a consumable whereas heads that Ricoh makes are more industrial and recoverable which is why they are used on the more high end machines like UV Flat Beds etc.

 

[ddarlak]

I struggled with cleaning solvent heads for years, every time I read about solvent heads I have to chuckle...I have been using Latex printers for about 6 years, snap in a new $115 head and off to the races...

not to mention HP gives you a new head if the old head is still under warranty, I have "traded" in at least 15 heads for free over that time.

Latex is the way to go

 

[bigblocktrader]

I've basically abandoned my DX5 based Mimaki JV33 for some time. The DX5 head was super clogged, the test print was mangled all over the place. There's even a visible "scratch" across the head.

So I figure, what the heck, I'll pull the head off the machine and clean it real good.

Using a fresh damper (to not make matters worse by injecting unwanted particles), I plug the damper on each of the manifolds connectors and manually inject, with as little PSI/pressure as possible, a stream of head cleaner through the head. If it's at all difficult then I try to PULL a little instead. Eventually, everything seems to be spraying again ok.

So I then clean the head up very neatly and inspect it using a jewelers loop.

This is the part that surprised me....

This thing is built LIKE A TANK.

The majority of the print head itself is a SOLID METAL PLATEN. I imagine this is for the purpose of heating the head platen to keep the viscosity of the ink high (so it will flow/spray). Like 95% of that face of the print head is SOLID METAL. Not a billion little jets like some of us are thinking - but solid metal. on the DX5 there are 8 very thin line grooves (for the 8 channels of ink I assume)... like this if you're looking down at the head:

|| || || ||
|| || || ||
|| || || ||

and from the side:

--/\--/\----/\--/\----/\--/\----/\--/\--

Something like that anyway.

So here's the thing... when I looked with magnification, I can see that within those grooves some of the little nozzels are clogged or shiny (damage, maybe).

But at this point I am thinking that if you had a microscope and some way of "sanding" a nozzle line/groove, then using flushing the channel to expel any sanded material that got in there, then you could probably repair any head with minor surface damage.

What do you think?


***WARNING: Of course take this with a grain of salt and don't attempt any of this on your own equipment unless you're planning to replace or junk the head anyway. Which is basically where I was.

i did same thing to dx 4 that was laying in spare parts box for two years, before throwing out one day
I got curious did every thing you mention including a lot of air , I'm using it today sometimes things go your way,

 

[MikePro]

i STILL have a dozen Jv3 printheads (dx3), that I had tried to restore years back but mainly kept them around for diagnosis. So yeah, i've tried this too.... no dice.
you can't fix a scratched printhead, you may get to a working point but you'll always have prints that are less than 100% & tiles that won't match-color at the seams.
those printheads are expensive, yes, but those machines ARE tanks worthy of proper part replacement that will keep it running for another decade.

if this is an ongoing issue for some, then I highly recommend you jump on the HP Latex bandwagon. $100 printhead replacement, takes about 5min plus 10min automatic alignment print/calibration. Exactly similiar to the desktop printer technology, except each printhead is powered by a replaceable 750mL ink cartridge rather than simply replacing it everytime the printhead is empty.

 

[Atari]

When you look at the underside of a DX5 print head, it's hard to see how something like "head strike" on banner material would ever be able to cause damage to the print head. It's solid metal....

Looks basically like this...

(image from Microscopy-uk.org.uk)

.... but on a DX5 the nozzles are protected further because they are inside a channel/groove on the heads platen/face.

I'm betting "deflections" and things like this are caused more by debris coming in upstream in the ink and getting lodged somewhere in the manifold's ports cambers or in the head itself.

When I was using a big bulk ink system, it used heavy duty solvent inline filters (the disk kind). If you tried not to use those filters (about $12/each) you would run into problems with channels dropping out or you could even "ruin your print head"