Sunday, January 17, 2010

Software and First Prints

Lately, work has been crushing me. I have still managed to put some time in almost every day and made some good progress during this last week. Here are the highlights.

Installed Software
  • Arduino Environment - I had this software already installed but I made sure I was using the current version. I had to configure the IDE to be used with a Sanguino Microcontroller. The instructions are here. This all seemed to work fine.
  • Firmware - I had some problems getting the firmware to compile. In fact it never did. While browsing through the MakerBot Google group I found that I did not need to compile these as they come with and can be installed by ReplicatorG. It would have been nice to have known that up front as it would have saved me a bunch of time.
  • ReplicatorG - I down loaded ReplicatorG from here. At first this would not work on my computer. When it ran a Java run time window would pop up and say something like. "Could not find main class, progam terminated." I reinstalled Java and it didn't fix the problem. Then I read on the RepRap forums that a complete uninstall and then reinstall should fix it. So, I tried that and it did. I made a copy of machine.xlm and then added the xml code McWireReplicatorG.xml You need to do "View Page Source to see the XML code in the browser and then copy and paste using a text editor.
  • Python - I down loaded Python from here
  • Skeinforge - I down loaded from here. I decided to change the environment path to include python so Skeinforge could be run from my tool bar. I made a batch file containing "python skeinforge.py" and stuck a shortcut in my tool bar. 
Power up

  • Extruder Test -  I am currently using HDPE for my extrusions. I'm seeing that ABS is popular and PLA is coming on strong but these were not in stock when I ordered my things from MakerBot so I got HDPE. From the MakerBot Store site: "This is HDPE plastic aka High Density Polyethylene aka Milk Jug plastic. This is a nice, smooth, high quality plastic. It comes as a filament in 5lb coils with a diameter of 3mm.
    This plastic is cheaper than ABS, but has a higher shrinkage factor which makes printing large objects more difficult. It does have a much lower coefficient of friction so you can print things that are very smooth.
    "
  • Endstop Test - The endstops work great but are useless. In fact they are worse than useless. When an endstop is triggered, the ReplicatorG and the motherboard freezes up. I think they pickup noise also so I removed all 6 endstops. 


First Prints
My first prints were piles of goo. But, I have learned a bunch about the tool chain during this last week. Basically it's pretty easy. Once you go through it a few times. The instructions are here.


The key is to get the skeinforge settings right. I started with the settings from Binary Construct blog.
"Here are some of the more important skeingforge settings I am using:
PWM Motor Speed: 215 to 225 (depending on the object)
Extruder Temp: 225 C
Speed: 80mm/s (i think the threaded drive has some effect on this no being accurate)
Layer Height: 0.7mm"


These settings allowed me to start printing test cubes that are15mm on a side. These are kind of like the "hello world" of 3D printing.

Tweaking Skeinforge


I have been learning about Skeinforge settings from Bits From Bytes Blog. I think I have tweaked the McWire to the best of it's ability. The prints are very useable but slow and course. The basic problem with it is that the X and Y sleds move to slow because of the gearing with respect to the minimum extruder flow rate. Right now I'm running at 200/255 PWM rate on the extruder motor. Any slower risks a chance of stalling. The 80mm/s in the above settings is being limited by the settings in ReplicatorG. I Adjusted those and found they are best left where they are.  So for right now there is not much, if any, of the desired filament stretch during the extrusion process. This could be fixed by going to a larger thread pitch on the drive screws.







Here are the key skeinforge settings I have going right now.


6 comments:

BodgeIt said...

Cool Just need to finish my new extruder connect up the X and Z axis with end stops then I will be I will be looking at your documentation regarding the firmware and software.

Conseils said...

In looking through the images you have been kind enough to post on the 'printed' parts. I have the feeling that the raft is not consistent accross the print.

The easiest print to see this on is the round object. The raft on the right and left of the image are noticebly different. In particular the right half seems more preferable. What do you think?

Quite worried about your comments on the relative speeds as I have metric threads at the moment and suspect these are finer than yours. Of course it should be straight forward to move to an 8mm thread and get a 1.5mm thread pitch. That's around 0.06" in christian units.

Glad to hear you are busy in the new year by the way.

CharlesGantt said...

Looking good man. Those look better than all of the first prints I have seen from other McWire RepStraps. You will be on the Mendel path in no time. Cant wait to see some more prints.

Krafter said...

I finally got mine working again this weekend. My first print turned out surprisingly well. I printed one of the Makerbot pulleys. Not because I need one, it just looked like a simple enough object. It really turned out well.

The next few, not so good. I did a few cubes and they have the right general shape but too much ABS and I don't think the Z axis moved up enough between layers. All stuff I can tweak.

My biggest concern right now is I continue to have a random issue where a axis, the X today, just shifts. So I was about 14 layers into printing the shot glass and suddenly the X axis has shifted 2mm. No idea why.

I added cooling because I thought that was the cause so I doubt thats the cause. That leaves the possibility of noise in the data line.

And I cracked the idler wheel. Thankfully I have an extra. I went ahead and ordered some extras from Makergear which has lots of spare parts for the extruder.

Still having fun though. I keep looking at that complete pulley with amazement. To think I build something that made that. Its amazing.

-- Chris

DrZen said...

Great post!
I make the same repstrap but have some difficult to extrude.
May you:
- write the exact skeinforge version (which screenshots refer)?
- may you post (for downloading) your skeinforge profile for makerbok HDPE and mcWire repstrap?

Weretiger said...
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