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.

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.

Using a Bowden cable on the reprap prusa cold end


This post is to document something that I thought was fairly standard , but after talking to a few people I discovered it isn’t. Some people (I’m looking at you jkeegan) even thought it wasn’t possible. I have been using thin hdpe tubing for some time to enable my extruder to unspool filament by itself.

The benefit of the tubing is that it removes the effect that pulling has on the carriage positioning. The cable has a small washer between it and the extruder, and butts against a 3mm hole I drilled in the handle of my extension cord reel. That arrangement allows all of the pulling force of the extruder to be focused on spinning the reel as opposed to lifting the z axis off of the bed.

I used this setup most of the time I was working with the cupcake, and just set it up again for my gen 6 prusa.

Downsides: it does probably require more torque. You also need to be smart about using as little hdpe tubing as possible, as it seems like the friction scales non linearly. You also want the line to be as straight as possible between the spool and the extruder. My setup in the video is about as long as you want it to be. I could easily see using 10cm of tubing and simply setting the spool on the top of my prusa. That ought to have very little drag compared to the current rig. PTFE tubing might be worth looking into as well

I may end up building a bracket to allow mounting the reel on top. That seems like it would be a pretty manageable setup.

Just because I know someone will end up asking where I got that reel from: home depot is the answer, but you can also find it at amazon here

The hdpe tubing I believe is used for cold water lines such as ice makers. I picked it up at home depot as well.

Nail Files – Reprap tools list

I’ll admit it. I went into cvs and walked out with two packages of nail files and a snapple. What of it?

Despite the weird looks from cashiers, nail files are absolutely _perfect_ for cleaning up prints. You can do fine sanding, clean up seams, or round off those sharp corners from a kapton heated bed. The best thing? It’s less than $2 for a pack of ten. Pick them up with your groceries, or use them as a cart stuffer on amazon so you can get up over the $25 minimum for free shipping.

Wow, most of them on amazon are a bad deal, but you can pick up a gross of them for $9 with free shipping!

reprap tools shopping list – Irwin self-adjusting wire strippers.

reprap tools - self adjusting wire stripper
I’m really excited about some tools I have found recently, so I figured I would start a recurring series of posts about them. There will be some simple cheap ones, and some expensive ones. Hopefully they are useful to someone else!

If you want a sneak peek, then you can check out the amazon list I made.

Here is the first review: keep your eyes peeled for more!

Irwin Industrial self-adjusting wire strippers.

You can certainly get good results with a traditional wire stripper, but this is faster and can be done one-handed and in awkward situations. Once I unwrapped it, I ran around the house looking for wires to strip (not always a good idea) and happily found a few solid core and stranded wires. This stripper was like magic. You can set a depth stop or you can eyeball how much wire you would like to strip. It has a simple cutter (probably better for solid core) as well as a few crimpers built into the handle. The plastic covers on the steel handle really give the tool a solid feel in your hand.

The best thing is that this is roughly the same price as a good quality pair of traditional wire strippers. I got mine from amazon for about $16, and you may be able to do better off by shopping around. If you do see them in-store, pick them up and feel them. It is a solidly built tool.

Why?

I think the usefulness of this is obvious, but it will assist you in doing all of the wiring for your reprap. Your motors, endstops, power cables, heated bed, extruders and thermistors all need to be stripped / cabled and attached to your electronics. It is super useful beyond the reprap as well. Automotive, audio video, and home electrical all are made easier with this.

One last note: If you do end up getting this from amazon, then definitely browse through the rest of my reprap tools list. You might get that cart-filler to become eligible for free shipping, or you might find something that will knock your socks off.

Why Kapton rocks

I have never been a big believer in using kapton tape as a heated bed surface. I never saw much benefit, and whenever I used it I ended up cutting it or scratching it very easily trying to get the parts off.

When I use blue tape I generally heat the bed up to 90-110. I print the part, and then as soon as it is finished I pry it off with a chisel. This ends up with a lot of damage to the blue tape, but it is pretty cheap to replace, and easy to pull up a single strip at a time.

The turning point for me came when I tried to do the same procedure on my kapton bed. The adhesive simply wasn’t strong enough to keep the tape on the bed and it ended up bending and lifting and tearing. I knew that was not supposed to happen, so I stopped and looked at what I was doing, and realized that the point of kapton is that it loses grip as it cools. That means you need to cool the bed in order to get the part off! I feel silly admitting that it took me so long to see I was being impatient.

Now that I have that figured out I print, cool, and then generally I can snap the piece off fairly easily. I wipe the surface down with nail polish remover on a cotton ball before every print. Sometimes I still need to get the chisel out and put the tip under one edge of the piece, but once one corner pops free, the whole piece is free. No more prying from every corner.

My one complaint is that I only have 1″ wide kapton. 2 or 3″ would be much nicer. I’ve also been meaning to get some PET tape with a high temp adhesive to test against.