Printing Printers

The projected image is right at 5x4" which was our target.

 

Yep. That is how DLP works. Layer at a shot
It is weird to watch since the project or is flashing on/off as the layers are advanced.
We will have it all sealed up in the black painted enclosure when finished.

Just realized today that we need vent fans for the bottom box... that projector puts out a ton of rather warm* air.
I was going to just cover the sides with curtin-like cloth covers, but I'll put a couple of fans (a push on one side and a pull on the other) in there as well. At least 5 inch, maybe 10 inch.


*warm for us (and it isn't really cool here)

 

Looks like we will be using GRBL for the firmware on an Arduino Uno with a single motor controller card.
On the PC we will be using Creation Workshop
That will give us everything we need from a software and electronics perspective..

I still have to do the math to work out the Z steps per MM

 

Or (waffling here) we may just use an Arduijno Mega with a Ramps 1.4 and Sprinter firmware
I will post details of the electronics once we get it decided.

 

OK, Arduino Mega, Ramps 1.4 and Sprinter firmware it is.
Testing this with CreationWorkshop which is apparently a really good choice for this style of printer.
After much spelunking the Software will connect and the motors will spin
Also the projector appears to function.

Next will be to wire it all up in the box and start testing

(frankly the Arduino Mega and RAMPS are overkill for this since it has one motor -- the Z -- possibly two endstops and no thermistors.)

 

OK, after a few long frustrating days...

I have altered direction a bit. Maybe

So with CreationWorkshop and the Arduino/Ramps/stepper drivers, etc. We were testing things and could NOT get reliable movement from the Z stepper. I went through and calibrated stepper drivers, swapped stepper drivers, swapped software, swapped firmware...pulled hair... (sadly I'll still need a haircut soon)

I am pretty sure at this point that there is a problem with the RAMPS or the Arduino. Something is giving it troubles. The stepper will not reliably step... out of 10 steps maybe 4 work, MAYBE 6... no more.

I disconnected a robo stepper and plugged that in to eliminate the possibility of an actual flakey stepper and LO! that one also was unreliable. So, not a stepper issue. Went through 2 sets (from different vendors) of stepper drivers and they all behaved the same soooo... Not much left there. Sadly I do not have another RAMPS or Mega on hand (I ordered them a week ago, but they are still a few weeks out on the boat from China).

In reality an Arduino UNO with a single motor controller is enough. Can't run Marlin or Spinter on that. I Can run TeaCup or GRBL.
So went ahead and pulled those latest labels from github and we will experiment with that. Worst case I'll have to go get another RAMPS from somewhere not so distant, but the Mega/Ramps combo was way over-slay for driving one stepper...

 

So I used the RepRap calulator to figure out what the Z steps/mm will be:


Result Leadscrew pitch Step angle Stepping Gear ratio

----------------------------------------------------------------------
1600.00 2 1.8° 1/16th 1 : 1


If you are like me and hate TEH MATHS then this is your friend:
http://prusaprinters.org/calculator/

 

Well, this was a frustrating weekend for this project.
We worked on the electronics side, only to end up butting our heads on some issues.
First, I have a couple of spare arduino Mega boards, but only one spare RAMPS. After attempting for hours to get the Arduino/RAMPS/Pololu stuff working (and failing) I have come to the conclusion we have a bad RAMPS. Went through a dozen different Pololu cards (from two different vendors) and could not get a single channel (we only need one motor) to work correctly on that RAMPS. Not, a one. They would not consistently move the steppers. In the interest of ruling out everything I even wired in a stepper from the Robo and that worked the same (which is to say, not at all). So the steppers are fine, the arduino is fine the pololu cards are probably fine (or all stinking defective -- which I doubt) but the RAMPS must be toast. Crap.

So I figured we could use an Uno (rather than a Mega) and a single channel motor controller, BUT nothing works with the H-Bridge shield (none of the firmware) they all want something akin to the ramps even if it is a single-channel stepper driver board. I even considered (brief insanity) rewriting GRBL to support that since it used to in version 0.7... but I got over it.

I did consider the GRBL specific motherboard (which replaces the Arduino and the RAMPS) but those are over 90 dollars... nope. Nice, but I don't NEED 3 axis control plus 2 extruders....

So I ordered a few of the easydriver boards via prime (these are like 2 bucks each) and will have them in a few days... aggravating.

So all that is left is:
1) Finalizing the electronics/software combo. CreativeWorkshop is a given, but probably with GRBL as the firmware.
We will use an Uno and a single motor driver.
2) Testing
3) Assembling the top cover/door.

 

So looking at the EasyDriver this will be pretty simple (almost said 'easy') to adapt.


We just need to make sure that the pins on the Arduino we choose are the ones that GRBL is defining for the Z axis STEP/DIR and it should just work.

 

To relate this back to the Robo the Uno will replace the Mega and this little board replaces the RAMPS and stepper driver card.

 

OK, after much (much) experimenting I am back to the use of a RAMPS/MEGA. Still way overkill.
Had what seemed to be a defective RAMPS that was messing with me, I now have a replacement in-hand and will be testing it with the dummy setup and making sure the Z axis works correctly.

Got distracted with a big job on the Robo and had to put this on hold for a bit.

 

I did, the easy driver was having issues with the stepper control. It was not really linear and it is not very adjustable.
So I went back with the Mega/Ramps (because I have them) and then ran into the issue where the RAMPS was not behaving correctly on the Z axis. Only the Z perplexingly enough. Even swapping the stepper drivers didn't help.

So I am swapping to a replacement RAMPS and testing that as soon as I can. Just ended up with a big project on the Robo side which sort of put a dent in my working on this one for a week

I do have the new ramps (and even more stepper drivers) that came in a few days ago so I will be testing at least the electronics side again.

It has been a real pisser since everything else was ready to go and I really did not anticipate issues with the sparky bits.

 

A good theory, but I was using a 30amp bench supply for the 12v side doing this testing. Granted, not putting that in the printer
I suppose it is possible, but then why would X and Y axis drive the stepper correctly?

It was only the Z that was misbehaving. If I sent it a command to step 100mm it would often just humm/buzz/sing and not turn (the stepper). Tried 5 different steppers so we can rule out a bum stepper. Tried 5 different stepper drivers (I think those ok too). It just about had to be the ramps. If I swapped the stepper to the X or Y it was stepping as expected.

Now I could probably have hacked up the firmware to make it work on any axis (since it really only needs the Z) but I'd rather use a working RAMPS

If it was the P/S (or something other than the RAMPS) I will find out as soon as I test again. Hopefully this weekend, early next week at latest. I SHOULD be able to cobble the test rig back together and test the electronics this weekend regardless of my other projects.

 

The easydriver is that exact sort of setup and I hooked that up to the Uno (actually, I tried two different ones--the easydrivers).
I was not able to get very consistent results. Same sort of behavior I was seeing with the RAMPs on the Z axis.

So (sez I) it must be the stepper itself (even though I had five different ones, they are one box) so I disconnect one of the Robo steppers and tried that... same stuff. Inconsistent steppage.

I am going to try it next with the RAMPS and the steppers... See if the new RAMPS behaves the same way.