Another 3D printer

[Monkey with a mill]

Greetings. I did not wish to appear as though I was co opting Craynerd's thread, so I decided to start my own. I have been building this printer for a few months now. It is composed of a RAMPS 1.4 and running on pronterface. It is 1.5 foot square and is this large because it will eventually be a small recycling/ manufacturing center. At the base opposite the ATX power supply will sit a plastic grinder/ extruder that will make the plastic filament needed from old bottles. It will be similar to the grinder found at www.filabot.com. There will also be a 3D scanner attached that will use the build platform as the scanning platform based on the scanner similar to the concept from www.david-laserscanner.com. It currently runs off a netbook that has the CAD program on it.

Anyway, I do have a question to ask. The Z axes stepper motors are not working correctly. With one attached, it will run fairly well, but after a while it starts to stutter. With 2 Z axes steppers attached, they generally won't rotate at all, or at the most one or to rotations and then stop. The only way to fix it is to turn off the power supply and unplug the Arduino, then plug it all back in. Based on a suggestion by jgroom, I turned my attention to the stepper drivers. The y axes is so hot that I can't touch it, but the others are fine. I was wondering how to adjust the potentiometers, and if being out of wack would cause the excess heat and bad rotations?

Sorry for being so long winded!

[Brass_Machine]

Questions...

1. How is the ATX PS configured to supply power? Voltage etc...
2. What is the connect between the netbook and printer?
3. What is the rating on the steppers?

I know that some laptops are not known for being good controllers for CNC machines...

[Monkey with a mill]

The Arduino Mega is powered by 12 volts, with the green PS_On jumped to ground and a load (10 ohm resistor) on the 5V rail as per the instructions. The Arduino is attached to the computer via usb port, which is the only way to do it on this model. As to the rating on the stepper, they are Kysan 1124090 Nema 17's. I attached the spec sheet for the stepper motor, as well as the stepper driver if that helps. 

[raynerd]

Eric - if you go with the standard reprap Arduino with a RAMPS or similar shield for the electronics, you are communicating over USB and so laptops don`t seem to have any problems. My understanding is that laptops become an issue with CNC when using parallel ports for the coms.

Also Eric, I used an ATX to supply my power and it worked really well until I added the heatbed and then I couldn`t draw enough current so I swapped to a cheapo chinese 12v some stupidly high current supply.

Monkey with a mill - I didn`t see this and answered your question over on my thread so I`ll post here as well. You have phrased your question slightly different here but I think my reply might still help.

Hello, just returned from a weeks holiday today so sorry for the delay but jgroom certainly has my +1 for the problem. Seems to me like the trimmer on the pololu driver needs setting...



Have you tried to increase the current to the motor coils using the trimmer (little black thing bottom of the above picture) If not, be very careful with it, if you wack it up too much it`ll toast the driver. AND it is STUPIDLY sensitive. Turn it all the way anticlockwise and then slowly slowly turn in back around until both motors move comfortably. To set your other motor currents, push against the axis and you have the current right when you can`t quite stop the motors with your hands. I`ve tried to do the calculations and set it using the little voltage reference point but the method above works out better and is 100% easier.

[Monkey with a mill]

Thank you, that was indeed the problem. After adjusting the trim pots all axes work perfectly. I also descovered that I had to flip the direction of the z axes travel in the firmware because instead of the Extruder moving upward in a normal prusa setup, mine is stationary on the z axes and the platform moves up and down. When the gcode is generated, it's meant for a normal prusa and so the platform was moving up as it printed! It was an easy fix, now comes the long, arduous task of squaring everything up.

[raynerd]

Are you using Sprinter or Marlin firmware just out of interest?

Chris

[Monkey with a mill]

I am using sprinter.

[raynerd]

Yes, same here. I gave Marlin a go but couldn`t get it running configured despite all the people using it.

[Monkey with a mill]

All the electronics are working great but now I am having an unusual problem. As the extruder runs, the nozzle is slowly pushed out. I am wondering if any one has any advise on the best way to stop this. The hot end is my take based on other peoples designs. The standoff/ thermal shield is 1 piece of round teflon with a 1.75 mm hole drilled through. The heater block is threaded to the outside, and the nozzle is threaded inside the teflon, with a washer used to transfer heat from the block to the nozzle. It works great as far as the heat transfer is concerned, and the threading on either side of the teflon was meant to put pressure on it to keep it from slipping, but somehow I need to lock the nozzle in place.

[Monkey with a mill]

I found a way to stop the nozzle from rotating out. By drilling a hole perpendicular in the heater block and through the teflon, then tapping the hole, I was able to use an 8/32 socket headed bolt as a friction hold. Here are some pictures, sorry for the quality, I took them with my phone. It is holding well. The problem now is that the plastic that is being printed is not sticking to the platform, but rather balling up and sticking to the side of the nozzle. Any suggestions on how to solve this ?

[Monkey with a mill]

I have not abandoned this project, I simple move at the speed of smell. The X and Y axis have been completely redesigned. Bushings were replaced with roller bearings. The platform support is now rock solid and the extruder has been strengthened with stainless steel bolts. Its been printing mustache rings nicely.