Are you rocking the Five?

When the Plastruder MK5 I ordered hadn’t arrived this last Friday I was a little disappointed because I was hoping to build it over the long weekend.  Luckily it arrived late Saturday!  Huzzah!  My weekend was saved!  I had put off soldering the Relay Board I got with my heated build platform since I haven’t gotten around to picking up a hotplate yet.  However, since the Relay Board was needed to run the Plastruder MK5, I busted out my soldering kit and got to work putting together the Relay Board and Plastruder.¹  Without further ado, here are the things I learned assembling and building my Plastruder MK5:

• When attaching the thumb wheels to the bolts, definitely use a vise.  I tapped the bolts into the thumb wheels with a hammer – and smashed the threads just enough to make the bolts useless.  :/ ²  If I did this again, I would definitely put the nut partway onto the bolt and tap the NUT rather than the bolt itself.  This would keep the force away from the threads and probably keep them from being damaged.
• When threading the nuts onto the retainer mounting plate, I found it easier to put the nuts about halfway onto the bolts – rather than almost all the way to the plate.  If you put them halfway on, it’s easier to tighten each bolt individually.  If the nut is nearly to the plate, you have to simultaneously tighten all screws or tighten them each a little at a time.
• The MK5 thermistor preparation instructions direct you to the MK4 directions for wrapping the thermistor.  The MK4 directions suggest you essentially sandwich the thermistor leads in between two long pieces of Kapton tape.  This is exactly how I built my MK4 plastruder – and it’s just not easy to trap these two thin leads in between pieces of thin sticky tape.  An easier way, and what appears to have been done in the MK5 pictures, is to separate the thermistor leads and wrap the Kapton around the leads – making sure they never touch.
• I would test the thermistor’s resistance and temperature measurement before attaching it to the plastruder.  If there’s something wrong with the thermistor, I would want to know long before I taped it to the plastruder, insulated it, and mounted everything inside the ‘bot.  Both tests are quick and easy to do before you assemble everything – just check the resistance with your multimeter then plug the unattached thermistor leads into the extruder board.  This quick sanity check could save you a lot of time and supplies by not having to undo a lot of work.  This would be a good time to test resistance on the power resistors too.
  With all the wires running from the plastruder and relay board, it can get confusing.  I picked up some heat shrink tubing the last time I was at an electronics store and am using them to color code each of the sets of wires – one small band at each end.  This helps me keep everything straight.  By just looking at the end of the wires and doing a sanity check against the bands on the motor, thermistor, or heating element I can quickly verify I’m wiring everything up correctly.
• I braid the wires together to keep them all in check.  There’s no particular reason for braiding over twist ties other than it just seems more elegant.

What did you learn while building your Plastruder MK5?

1. Photo courtesy of WoodleyWonderWorks [↩]
2. I’m just that strong. [↩]

Jlglover!'s Little Robot Head

We’ve already seen the quality of a MakerBot printed thing once it’s been finished using an acetone/ABS bath and dipped in liquid plastic.  Jlglover!’s little printed robot head is another example of the kind of finishing work that can be applied to a printed piece.  Jlglover! applied six coats of an enamel based paint to his printed piece.  Doing so appears to have removed almost all traces of it’s printed origins.

Metamorphosis in six coats (and a sharpie)

One of the things I like about this approach is that it doesn’t use acetone.  Acetone and it’s vapors can be pretty nasty stuff.  If you’re going to end up painting your printed piece anyhow, there’s no reason not to use this method for finishing.  With a little preliminary sanding, it could be indistinguishable from a smooth molded plastic piece.  Another thing I like about this particular object is that it shows how good a piece can look without any fancy schmancy upgrades.  Based upon the angle of that overhang and a slight warpage to the top right edge, I would guess this part was printed upside down on a non-heated build plate.  However, with this finishing technique, it would be difficult to discern how it was printed.

To anyone who hasn’t handled a printed piece, ABS sands beautifully.  It holds up well to course sandpaper and finishes well with a fine grit sandpaper.  Jlglover! and Ian Johnson have really proven that the final quality of a finished printed piece is entirely dependent upon how much time you’re willing to put into the final product.