Extruders Galore

For DIY 3D printing, there seems to be no shortage of extruder designs on the web. In terms of reliability and print quality, these designs seem to be all over the map with no clear indication of which one actually works best. Looking over some of the more popular designs, I've been able to find components of each that I would like to have in my 'ideal' design.

MakerBot Industries is now producing it's 5th generation of thermoplastic extruders so its seemed appropriate to identify the strongest, and weakest attributes of their design. Early thermoplast extruders used Nichrome wire wrapped around hollow all-thread. These designs were clumsy and prone to shorts and uneven heating. MakerBot instead uses surface mount power resisters instead, and a stainless steel thermal block to distribute the heat evenly.

Weaknesses include the dc gear motor, and the tension screw that keeps the filament in contact with drive pulley.

Another site, MakerGear, produces extruders that use a stepper motor to more precisely control the filament feed. The motor is also used in conjunction with a 13:1 gear reduction, resulting in an extremely powerful feed mechanism.

The Brutstruder is another opensource option available on thingiverse.com. This design's most powerful advantage are the spring's it utilizes to keep the filament constantly pressed against the drive pulley. According to its author, the Brutstruder is capable of lifting 27 lbs-

The ideal extruder for my printer will combine all of these elements: geared stepper motor, surface mount power resistors, and spring tensioning.

Postcards

Assembly update

Nearly finished with the main structural assembly, ran out of 1/2 inch bolts today so had to put off completion until I can make a trip to the hardware store tomorrow. The last bits to be added will be the drive screws and motors responsible for linear control of each axis. I'm going to be fabricating the mounting plates and shaft couplings this weekend, and the machine should be ready to turn on sometime over spring break (Feb 28th- march 4th)

Technical Design and Early Fabrication

Having worked on the nitty-gritty details of the technical design for my rapid fabricator since Christmas, I began fabricating components last week. The first pieces to be machined were corner gussets for the 80/20 frame. While similar supports are available through the manufacturer, it was far less expensive to spend a few hours making my own.

The last 2 days have been devoted to machining the linear bearing assemblies for the X-Y-Z axis. Each tracking mechanism required machining on 3 sides, as a result it look much longer to fabricate and maintain a constant level of precision between operations. Again, 80/20 manufactures linear bearings, but at roughly $200 apiece. I chose instead to make my own at less than a tenth of the cost.

Dimensional Drawings

Milling bearing mounting plates

Cutting bearing Bushings on a speed lathe

Final Bearing assemblies

I love ANONYMOUS

This is a re-post from towleroad.com. It's a letter from a group of concientous hackers that have sucessfully targeted government websites during the protests in Egypt and Visa after some shady dealings with the american government to stop the flow of funding to Wikileaks. The letter is addressed to the Westboro Church-

I think it's pretty badass.

"We, the collective super-consciousness known as ANONYMOUS - the Voice of Free Speech & the Advocate of the People - have long heard you issue your venomous statements of hatred, and we have witnessed your flagrant and absurd displays of inimitable bigotry and intolerant fanaticism. We have always regarded you and your ilk as an assembly of graceless sociopaths and maniacal chauvinists & religious zealots, however benign, who act out for the sake of attention & in the name of religion.

Being such aggressive proponents for the Freedom of Speech & Freedom of Information as we are, we have hitherto allowed you to continue preaching your benighted gospel of hatred and your theatrical exhibitions of, not only your fascist views, but your utter lack of Christ-like attributes.

ANONYMOUS cannot abide this behavior any longer. The time for us to be idle spectators in your inhumane treatment of fellow Man has reached its apex, and we shall now be moved to action. Thus, we give you a warning: Cease & desist your protest campaign in the year 2011, return to your homes in Kansas, & close your public Web sites.

Should you ignore this warning, you will meet with the vicious retaliatory arm of ANONYMOUS: We will target your public Websites, and the propaganda & detestable doctrine that you promote will be eradicated; the damage incurred will be irreversible, and neither your institution nor your congregation will ever be able to fully recover. It is in your best interest to comply now, while the option to do so is still being offered, because we will not relent until you cease the conduction & promotion of all your bigoted operations & doctrines.

The warning has been given. What happens from here shall be determined by you."

...and the response is predictably hilarious and saddening.

Parts!

My mail-order parts started arriving today! Inside the first box... A shiny new Driver board!