PrintrBot at First Glance

 

PrintrBot First Glance

The Printrbot Jr. first attracted me with its small foot print and low price. The PrintrBot is available as a kit for under $400

My kit arrived two weeks after I ordered it. It arrived well packed, as shown below. Note that the printer shipped with an ATX power supply, not the smaller laptop supply, as those were out of stock. Note that later they send me the laptop supply and was able to keep the ATX. This was good because I wanted to upgrade to the heated bed.

The main construction material is 1/4" five-ply plywood. Assembly went well, but it did take me longer to compete the build then indicated on the manufactures web site. As with the other kit build printers you will spend a considerable amount of time tuning the machine.

You can find the assembly instruction here:

Printrbot Jr. Build Instructions

The extruder instructions can be found here:

Printrbot Extruder Instructions


Tools Needed

These are some of the tools I used to build the Printrbot Jr.


Controller

The controller used on the Printrbot Jr. (shown above) is a printrboard. While not the best board available for 3D printers it's also not the worst. It does have the provision for adding an extrusion fan and a heated bed. It does not support a second extruder. 

Upgrades

My unit did not come with an extrusion fan. I had to purchase it separately. The fan (shown below) is now included with both the kit and assembled versions of the printer. The fan helps when printing small prints. It especially helps when printing with PLA because oft its lower temperature. On additional benefit of the included fan is that it helps cool the transition area of the hot-end. Again this helps when printing with PLA.

OK, I said the Printrbot Jr was $399, well kinda. Personally I will not purchase a 3D printer that does not have a heated bed. I highly recommend that you include the Printrbot Jr. Heated bed upgrade if you decide to purchase the Printrbot Jr. This will add an additional $99 to your purchase.

The heated bed shown above, comes with a new bed mount system that makes it very easy to level your bed. The upgrade show an ATX power supply as an option. You will need this addition as the original power supply that comes with the printer is not large enough to power the heated bed.


The heated bed upgrade comes with a 5 mil Kapton sheet shown above. It has a silicon adhesive that is meant to attach directly to the bed. The problem is that I could not my ABS to stick to the sheet no matter what I tried. I tried various temperatures between 65c and 130c with no success. I tried various extrusion temperatures. I tried various bed heights. Nothing worked. 

I have several sizes of 1 mil Kapton tape rolls. I decided to put some down in strips as shown above. It worked perfect the first time. The bed was set to 90c and the extruder to 230c.

letterprint1.jpg

I have a test print (shown above) that I perform to test adhesion to the bed. The small letters are good tests. If the extruded plastic is not sticking properly the ends will curl. The print went very well. The extruded plastic stuck to the bed on the first test. See it in action below.

The tape I used can be purchased here: 1/2" Kapton Tape

Extruder

Normally I prefer direct drive extruders. They are faster and have proven to have better retraction characteristics. The Printrbot extruder is not direct drive, but its close. It utilizes two gears with herringbone gears. The small pinion gear drives the larger gear, which is connected to the hobbed bolt. A spring loaded bearing presses the filament against the hobbed section of the bolt, thus driving the filament into the hot-end.

extruder.jpg

See the extruder in action below.

 

Early Tests

After assembling the 3D printer, you will need to install and configure the software.

After the initial recommended calibration, and before my own calibration I like to take the printer for a spin to see if the settings are in the ball park. One of the first things I like to print is the hollow cube (Thingiverse 5011). The print (below) came out almost perfect. 

See the print in action below.

Mr Jaws

After I calibrate my filament I take the printer for a ride printing Mr Jaws (Thingiverse #14702). The print (below) came out very well. I did have a little problem with warping on the edges. This print was done on blue tape (before I got my Kapton strips working). The edges were nice and sharp.

See the print in action below.

Here is an early (pre heated bed) PLA test.

Initial Thoughts

Once the adhesion problems on the bed were worked out the printer prints pretty good. One problem I have is that the prints produced on the printrbot Jr. are all over sized. I should be able adjust the stepper settings to calibrate the X, Y, and Z stepper settings.

As per the instructions in the manual, I should have been able to provide some calibration by issuing some M92 codes in the Custom G-code section on the slicer. I tried changing the defaults but they don't seem to change anything.

The Printrbot Jr has a very small foot print but having to place an ATX power supply next to the machine takes up more space and makes it more difficult to transport. The printer has a lot of flex and just moving it from one place to another can though things out. The printer has a folding table that makes it a bit easer to transport but adds to its lack of rigidity.

All in all this is a good starter printer. If you like building and tinkering, you can have a lot of fun with this printer.

 

6/10/2013-Final Thoughts

My opinions have not changed since my last post.  I sold the PrintrBot jr for a fraction of the cost that I paid for it, so I wont be posting any more on this 3D printer

 

6/15/2013-Discontinued

The PrintrBot Jr has been discontinued.

They have replaced it with a new 3D printer called the 2014 Printrbot Simple.

It still suffers from many of the same design flaws as the the Jr, but they have made a few improvements, such as better extruder and filament cooling system.

I still can't recommend this for any thing other than tinkering.