[zoltan]

Hi,

I am curious if somebody from here tried to build such a machine. I mean the impact head - MPX60 has a diamond tip and MPX70 has 9 pins with carbide tip; it uses just one at the time - and its driver. I think that the head and its driver is quite similar to matrix printer head/driver. Any opinion?

Zoltan

[zoltan]

Hi,

No answer, no opinion? Maybe can somebody give me some clues about how the driver is working?? Or maybe help me to understand how it works? I searching about information how it is interfaced, what information is send tio the driver and how the driver is working but could find out nothing besides some piano acuators which seems to be close to the principle I belive this machine is using for making the impact dots. Any help??

Thank you.

Zoltan

[chuckknigh]

I've never heard of it before, but it looks interesting.

Assuming that it uses the same technology as the old dot matrix printers, then each dot is either on or off -- black or white, or in this case, polished or indented.

It should just "jab" a dot into the material, everywhere a dot should be printed...and printing black and white or halftone pictures is built into Windows.

They probably just beefed up an old dot matrix impact printer, gave it a diamond tip instead of simple steel, and use a printer driver for the output. It wouldn't be all that hard.

I have a heavy duty linear solenoid that would probably do this...but it'd be WAAAY too oversized for this application. Something small and delicate would be more in order.

I really would start with one of the newer USB dot matrix printers (I have customers who use them for multipart forms) and hack it from there. Their 24 pin heads print beautifully, and hacking the mechanicals would be relatively straightforward. They'd end up working with a Windows printer driver, too...which would make it SO easy to use.

Alternately, you'll need something capable of printing out a dot matrix -- precise X and Y coordinates, and then make a dot. Sounds like a CNC application to me...

-- Chuck Knight

[zoltan]

Hi,

Thank you for answer. I was thinking the same way but I have no clue about how to replace the matrix head with a solenoid head and how to relate the impact force with the black/half tone pixel. Could you, please, expalin me what you intend to do in more details in order to experiment this? Could you, please, explain this as I did not understand very well :"I really would start with one of the newer USB dot matrix printers (I have customers who use them for multipart forms) and hack it from there."

Thank you.

Zoltan

[chuckknigh]

The "matrix head" is already a solenoid head.

What an impact printer does, is move in a precise X-Y grid over a flat piece of paper. Admittedly it does it by friction, moving the paper, but that's just a decent analog to a moving table CNC design.

The printer head has 9 or 24 pins, each pin is software controllable and strikes that paper (through a ribbon) with significant force. There is usually a spring loaded adjustment which allows you to adjust the impact force, so you can handle multiple part "carbonless" forms.

Imagine, for a moment, that you took a polished piece of a thin (but soft) metal and placed it in the printer, instead of paper. Each time that pins in the head "hit" the metal, it would make a mark, like a scratch. That dot would be dull, instead of shiny.

From looking at the pictures, I think the dots actually represent the "white" in the image, so you might have to print negative images.

Do this enough times, and you have a decent looking printout, but on metal. Simple.

The next step is to modify the printer so that you can handle thicker materials...and suddenly you have a printing solution very much like the Roland.

-- Chuck Knight

P.S. The Roland is only $750, online. When doing a search on it, I found a place where it was on sale. Try googling for that model and you'll find it, too.

[zoltan]

Hi,

Thank you for opinion. I found out a way to do what Metaza is doing. First of all I found out a miniature electromagnetic airvalve at 12V. I modified it for by replacing the plunger. I found out some broken end mills of 1 mm diameter with the other end conical, very sharp end. I cut the end mill 1 cm from conical end and I mounted the piece of end mill into the plunger mount, then I mounted the airvalve assembly on Z axis plate. I made a plate of 0.5 mm thickness small one which I connected to Z limit switch and one crocodile connected to the other pin of Zlimit switch. The crocodile grips the metallic part of airvalve. I am using this for zeroing the Z axis. The idea I have seen here and on Shopbot forum. This way I am getting always 0.5 mm (little bit less due to the sping inside of airvalve and inertia of Z axis, but is almost the same each time) from the tip of end mill which is now the plunger of airvalve (actually this is the solenoid assembly which is playing the role of small hammer which is creating the dots in the material). After I zeroing the Z axis I switched, with a switch I mounted in the controller case, the Z axis Dir and Step from driver through an AND gate which output is connected to an amplifier supplied with 0-24 V power supply and a current limiting circuit. This way each -Z step is a hit of the mini hammer. Then I took a bmp and converted in a dot diffusion rendering to Gcode. I did not find out other software for doing this beside Mach3 by Lazy Cam. Unfortunately, the last version of Lazy Cam has a bug and the generated Gcode has errors. I told to Art and I understood that he knows and would fix the bugs. Actually he told me that the fix will be done by yesterday but probably he was too busy. Because of this I used the function of dot diffusion rendering from Mach3 stable version 1.84 which has no Lazy Cam, the function is through the import feature of BMP. I generated the Gcodes for few bmps - inverted and not inverted images. The results are spectacular. To generate the Gcode is not difficult you just need to pay attention to statistics in order to keep the pixel ratio and not generating huge files. As I can vary the distance from hammer tip and material, frequency of steps by motor tuning, current variation through the solenoid, and other parameters, I still have a lot of experiment, but the results are only good or very very good. If Art or somebody else can refine and maybe automate little bit the process of dots to Gcode it will be great. This tool can be mounted on any CNC router and it is easy to build. The difference between what Roland is saying that Metaza is doing, applying different force to the hammer depending on grayscale and what I did is that my experiment is generating different number of hits on the same dot based on the grayscale, obtaining a bigger or smaller dot size.

This is already long story of short story.

I will let you know what I found out through my experiments. I got a lot from CncZone I hope to start to give back a little by sharings my finds/experiences.


PS:Sorry for bad English

Zoltan

[skippy]

Zoltan, the electromagnetic airvalve solution will be very slow in terms of strikes per minute compared to a solenoid actuated unit (dot matrix head). I found several A3 dot matrix printers in the rubbish and they are built like tanks. Big companies (like banks for example) still use them (internal reports I believe) and replace them on a regular basis. As you said, I guess the problem would be in the software to drive them for what you want to do (grayscales).

[chuckknigh]

I'm delighted that it's working for you! Congratulations on getting a machine up and running!!!

One request, though. Do you have any pictures of your finished results? I would love to see what a homebuilt machine can do, with regards to grayscaled pictures.

-- Chuck Knight

[zoltan]

Hi,

Due to cheap camera it was more than difficult to get a picture of piece done this way. I uploaded also the picture (she is my girl this year at highschool graduation) that was engraved prepared with CDR12.

Zoltan

[candle]

but but all what dot matrix printhead is is a solenoid! just find proper voltage and pinout to use it
you may easly do in from nature having printer partially disassembled - printheads usually are on connectors fitted with one or two screws
nice girl! er.. i mean work

[chuckknigh]

What amazing results! I'm genuinely impressed...is this your first attempt at a machine? If so, I'm REALLY impressed.

The results look GREAT!

-- Chuck Knight

[Tweakie]

Hi Everybody,

I am only trailing about 5 years behind you guys but thanks to Andrea ( Robot Factory ) and one of his magnets this is my first, successful, impact printed picture.

Tweakie.

[RomanLini]

Very impressive! What material and inking process? And do you have a photo of the machine?

[Tweakie]

Hi,

The material is a non-PVC, black plastic, engraving laminate with a brushed aluminium look-alike surface. No inking, that is just how it turned out.

My machine is here Tweakie, Tweakie.CNC, CNC, router, mill, engraver, vinyl cutter, laser.

Tweakie.

[RomanLini]

Thanks Tweakie that's a very cool machine!

I also liked your low-power laser marking too!

[Tweakie]

Thank you sir.

Tweakie.