I’ve been busy modeling!

I’ve put together three entries for the engineer vs designer absurd iPhone contest. It’s been a lot of fun, and it’s a great excuse to jump into openSCAD and start actually creating things, as opposed to duplicating things that others have built.

So far I have built a wheeled iphone case with a broomstick handle,

a shuttered iPhone case

and an iPhone trailer hitch!

Check them out on thingiverse, and design some of your own!

rename your ramps or gen6 ftdi serial connection

You can change the name of your ftdi serial connection with a little bit of magic that piotr whipped up. That means that you can have multiple machines connected and give them logical names. In this example I changed mine from the random character string to PRUSAG6.

All of the info is from dangerous prototypes

This shows the app after I selected my gen6 serial connection and hit read

This is what I changed it to. You can’t give it any more characters than I did.

After a restart, my pronterface clearly shows me which serial port I should be using! It’s not a huge thing, but it does help to take a minor annoyance away. When I have two machines hooked up it will be a godsend though.

Note: this won’t work with an UNO, because it uses a different chip.

OpenSCAD tip: How to get formatting.

I’ve been diving into learning openSCAD lately, and it has sometimes been a rough road. One thing that has really helped me has been occasionally copying my script into a blank arduino window, letting it auto-format (command-t) , and then pasting it back into openSCAD. The formatting really helps illustrate where the brackets line up. You could do this with many other coding apps (ie not arduino) but that is the one I have handy, and one that most people who print will have installed as well.

Before:

After:

How to monitor your reprap remotely with skype!

I was pretty pleased with myself when I thought of this. It is super simple, but it works well. I have been very nervous to run down to do the laundry, or to check the mail while I am printing. Not that my machine has problems, but I want to be there if it does. I looked into all kinds of different nanny-cams, and streaming webcam setups before I figured out the absolute simplest possible option.

1) Set up a new skype account on the machine by my printer.
2) In the privacy setting of the preferences, configure skype to only allow calls from people in your contacts

3) in the calls section, set it to auto answer calls and automatically start video when connected.


4) add yourself to the contact list
5) call yourself from your iphone!

Now, smarter people than I will pipe in here and say that having an always-on video conncetion on the internet is a setup for disaster. I only turn this on when I am running out of the room for a bit, and I turn it off when I return. The security settings ought to do a good job of not letting strangers peek in on your prints, but I don’t think I will run naked in front of the camera just to be safe.

recovering from a pause in pronterface

Today on IRC Kliment was kind enough to help me figure out something that has bugged me for quite some time now.

Whenever I pause a print in pronterface, jog the z axis, and then resume the print it slows down to a crawl. Kliment explained to me that the z jog sends its own f command, which is a speed setting for the next move. The z axis moves much slower than any other axis, so that when I return to the unpaused print, all of the axis are moving at the (slow) z speed.

Even if my explanation of the problem doesn’t make much sense, the fix is easy. Just jog x or y before you unpause the print. I usually jog .1mm right and then left and then hit resume. Now it starts right up again at the correct speed!

10 seconds away from a quieter reprap

I made this video so you could listen to the before and after. Unfortunately, I’m in there yappin’ for most of it.

I was recently at a reprap meetup and there were two brothers with mendelmax machines there. They were eerily quiet. The printers, not the brothers. I was thinking about it on the ride home today and I remembered that they were also on a padded table, so I decided to test it out.

Now don’t get me wrong. I’m still itching for a mendelmax. This helps in the meantime though.

how to salvage a failed print

Today I was printing a part on my prusa and it stopped extruding. I still don’t know why, but I do know that the printhead was a full cm above where the piece was, and it was happily just spinning along.

Since my part was essentially the same outline at the point where it was as where it stopped extruding, I thought up a quick hack to salvage the print.

In pronterface I paused the printer. Next I got it extruding again. I typed M114 and then enter into the dialog box at the bottom right corner. That sends a command to the printer to report back its position. Check out the Z value that it gave back to you. I then jogged the extruder down until it was just smushing into the print. I typed “G92 Z” ,then the z value from above, and enter.

That tells the printer that it is now at the point that it was really at previously. Since I lost all of that print while the printer wasn’t extruding, it essentially just chops that part out and tells it to start printing on top of the print again. I feel like this isn’t making any sense, so hopefully I can clarify it later. I then hit resume, and watched my new (shorter) print finish up!

Note: as you can see in the top photo, there is a line that is probably pretty weak on that part. A bit of ABS glue will definitely help strengthen that up (while making it look ugly) and I think that if I were faster to catch the stopped extrusion, then the print still would have been hot enough for it to bond properly.