A PCB printer for photoresist which uses a PHR-803T Blue-Ray pickup

Hi,

About a year ago, my brother and I engaged on a quixotic project to build from scratch a low-cost PCB direct printer for photoresist.

Finally we did it using a Blue Ray™ optical pickup (PHR-803T) and his UV laser/electronics to sensitize Dry-film. We "printed" all the plastic parts of the printer with our Reprap.

The optical pickup is used through his own connector without any modification. We deduced the pinout using reverse engineering and designed a driver for an Arduino UNO to control it. Basically, we can adjust the laser power, turn the laser on/off, move the focus lens servo and read the photodiode array signal. The pickup control allowed us implementing a laser auto-focus algorithm based on the astigmatic method. Is the same method use it to focus the laser beam on the Blue Ray™ disc.

DiyouPCB is a prototype and it's still not perfect: we have some resonance and vibration issues that affect the quality of printing, but it's a first step to have an alternative method to indirect homemade PCB fab. methods as the famous toner transfer.

We shared all the information about how to build it and use it in our site DiyouPCB

Our next project will be to build an UV resin 3D printer using also the PHR-803T.

Charlie&Victor

Nice work, and a good writeup on the project..

This is very cool!

You should use GT2 belts, current reprap uses them as they are designed for linear motion, less backlash. T2.5 as you say are timing belts

Edited 2 time(s). Last edit at 02/07/2014 02:49AM by Dust.

16-Tooth T2.5 - 5mm shaft Pulleys
T2.5 x 64cm Timing Belt
Bronze bushes
Steel Shafts 6mm x 20mm, Idle Pulleys shafts
[www.diyouware.com.]

Dust is correct you should be using GT2 belts and pulleys.

A toothed belt riding on top of a smooth profile is poor engineering.
You shouldn't be using bronze bushings as idler pulleys,
proper pulleys mated to the GT2 belts is required to reduce linear error.



In addition, If you decide to stay with the bronze bushings you need to anchor the steel shafts, as there is the opportunity at each
change of pulley direction for them to snap or flex out of position (i.e. backlash).

Some notes and links about GT2 belts can be found in this thread:
[forums.reprap.org]

Edited 2 time(s). Last edit at 02/07/2014 11:57AM by A2.

I think I read nophead stating somewhere that T5 / T2.5 profiles generating backlash is an urban legend.

I personally believe that if something works for you without being a source of problems, you shouldn't change it because other people think it's better


Sorry for getting slightly out of topic Mecatronic, that's a nice projet you achieved there.

---

Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

@DeuxVis:
Mecatronic has indicated that he is not happy with the print quality.
Here are the examples that he posted, I was addressing these issues.:
[www.diyouware.com.]

Quote
Mecatronic
Reviewing the software we do not appreciate any major defect so we analyze the mechanical design.

The belts were tight and the motors adjusted to the correct current.
The guides apparently swinging well.
We were searching what could happend in CNC forums and we found that is a frequent problem generated by belt backlash.
It usually happens when the motor change direction.
But belts were new and properly tensioned so we could not improve too much.
Finally we modified the firmware in order to compensate the backslash.
We add a few extra steps to the motors when they change direction.
This type of adjustment is usual in CNC software.

The other problem was that at certain speeds the lines appeared as bitten.

@Mecatronic:
In addition to the suggestions above, you can add a thin sheet of cork between the stepper motor,
and the mounting flange/frame to help with some (not all) of the resonance.
The motor is not clamped down hard against the cork, just snug, best I can describe it, use a torque wrench to validate.

New! Nema 17 Cork Gaskets, as recommended by Bre Pettis
[www.makerbot.com]

stepper motor NEMA 17 Cork Gasket
[www.ebay.ch]


There are possibly better solutions, for example:

Astrosyn International Technology Ltd
Flange mounted vibration damper
[astrosyn.com]

Mini Kossel - After Stepper Dampers
[www.youtube.com]

Rostock Max Before and After Astrosyn Stepper Dampers
[www.youtube.com]


You can also try to use Nylon bolts to help reduce the transmission of vibration into the frame of the machine.

Lots of ideas can be found in this thread:
Major Acoustic Noise - any suggestions?
[groups.google.com]

Low-frequency noise reduction: any experiences?
[groups.google.com]

Edited 2 time(s). Last edit at 02/07/2014 09:40AM by A2.

Thanks for a deserved correction A2.

---

Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

Old school stepper motor dampener.
This might help too.

X2 CNC stepper dampers printed on a Makerbot Rep2X
[www.youtube.com]

Edited 1 time(s). Last edit at 02/07/2014 12:08PM by A2.

HI Guys,

Thank you very much for all your help.

We will evaluate everything, although we have poor expectatives about complety solve the vibration problem, mainly because the laser beam is so small (less than 0.1mm) than any small perturbance move it. Probably will should use servomotors + encoders and leadscrews but sacrificing speed and cost.


Regards,

Victor.-

Consider supporting the fame on dampeners, and enclose it in a sealed chamber.

what about using either 5mm s/s threaded rod or 8mm s/s threaded rod for a leadscrew instead of belts?

---

Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]

It may give better (and faster) results if you fed it with the PCB trace & pad vectors rather than a raster image. Most PCB CAD tools can output in a vector format suitable for pen plotters (e.g. HPGL). It should not be a huge software task to use the vectors to control your XY motors (and the pen-up / pen-down commands to switch the laser). I used to use a real pen plotter to draw a PCB master using ink on plastic film at 4 X full size for photography and it makes very good quality drawings. You set the pen width in the PCB CAD tool - in your case that would be the size of the spot that the laser sensitises.

Dave

I have considered this as a future project myself.
(total noob at the moment...still waiting on some bits for my first machine - a Kossel)

I have some experience at board manufacture, and my first thought was to investigate the possibility of using filament as resist and printing directly onto copper clad board - that is, removing the whole UV sensitive coating, exposure and subsequent development process from the workflow altogether. easier and cheaper!

I was going to start out putting samples of various print materials into a tank of iron chloride for a day or so and seeing which was least reactive.
then all that you need is a way to convert a standard gerber file from your PCB design suite to STL and bobs your uncle.