Wednesday, December 22, 2010

RepRap: Droid Mount

My wife and I upgraded to Droid X phones this year. As soon as we got them we realized they outperformed our old Garman GPS and have been using the phones for GPS ever since. My wife quickly identified the need for a droid mount to hold the phone while driving. A few weeks ago I designed and printed the following mount.

It worked decent for a week and then warped! I'm using PLA plastic and its full blown winter right now. My wife had the heat on and the part that holds the phone warped. You can see the warp below. I redesigned using the strength of triangles and increasing the depth of the part.

While redesigning I had an idea. Though the three degrees of freedom design worked fairly well, I wanted a bit more freedom. I made a bundle of 25 strands of floral wire and wrapped it with electrical tape. I then incorporated it in the design. The wire serves a dual purpose. It allows virtually any position to be obtained and it absorbs pot hole shock.

Here it is installed! I'm happy!

If you have a Droid X and would like to make this mount, here it is on Thingiverse. I included the OpenSCad source file. If you want a mount, but have a different type of phone, it shouldn't be too hard to create a derivative of my design for your phone specs.

RepRap: Production Mode: Bed #6 and #7

Bed #7 is the last bed and completes the set. In the next few weeks I will post these sets on Thingiverse and add links to these entries.

I intentionally left out the tooth pulleys from the large batches because I've found that they come out cleaner if printed separately. Bed #6 is just for printing the large z tooth pulleys, and bed #7 is for printing the smaller tooth pulleys that go on the motor shafts. You only need three small pulleys for a Mendel set, but I've found that printing six at a time increases quality by letting them cool between layers. I took some pictures of the pulleys with some extra belt, showing that they are functional. These pulleys are the toughest parts of the print to get right. It's a good idea to have some extra belt lying around to prove they are functional pulleys.

Tuesday, December 14, 2010

RepRap: Production Mode: Bed #2

Because of my background in Computer Science I tend to complicate problems beyond necessity and must step back in order to arrive at a simpler solution.

Problem: How do you divide all Mendel parts into 5 sets of equal print time and bed size? The goal is to have 5 twelve hour print jobs that can be started in the morning and evening.

Complicated Solution: In Computer Science this problem would be classified as a knapsack problem, with print time and bed size equally playing into the "cost" of each item. I more than considered coding one of the knapsack solutions and running it on part data before stepping away.

Simple Solution: Assume that a long print time is always equal to a large bed size with each part. Create a list of parts with name and print time. Order the list by print time. Treat the parts like people and ask them to count off in order from 1 to 5. Group all 1s together for your first set. Group all 2s together for your second set and so on.

The simple solution can be carried out in a spreadsheet in less than a minute, and it gives sets that would take between 11 and 13 hours to print, according to data from It's then only a matter of tweaking the sets by taking a larger part from one of the larger sets and swapping it for a smaller part from a smaller set. I did this a few times until I had 5 sets that should each take almost exactly 12 hours to print.

Here are some images of the first set.

In the next few weeks I will add this series of STLs to Thingiverse.

Monday, December 13, 2010

RepRap: Production Mode: Bed #1

A lot of people are printing Mendels these days. This is really good for the community and for growth. I started printing Mendels for others in November, and have printed and sold two sets so far. I'm currently working on printing my third set of parts and decided to take the time to blog about the whole process. With this being my third go I hope it will be seamless. I will be writing an entry for each bed of parts I print, and releasing the production files I am using as I go. I feel this is one more way I can give back to the community.

The first production file that I will be using was done for me, and is up on thingiverse here. All other production files I am in the process of making myself.

The following images show a production file with all the parts you need to make a Wade extruder. Depending on your feed rate this file will take anywhere from 3 to 8 hours to print.