Replacing the Glass Print Bed on the Taz 3 Printer

The glass bed on the Makerspace’s Taz 3 printer recently did what glass does- it broke.  Time for a repair and upgrade!

I started by cutting the under carriage down and modifying it for a three point leveling system instead of the stock four point undercarriage/bed plate bending scheme.

Modified undercarriage mounted on the printer

Modified undercarriage mounted on the printer

 

 

 

 

 

 

 

 

 

 

 

 

 

The original heater was separated from the shards of glass and glued to the 12″ x 12″ x 1/4″ cast aluminum tooling plate using high temperature silicone.  3x #10 countersunk screws and springs support the plate on heat resistant teflon blocks.  The whole assembly stands about 1 cm taller than the original bed plate so I printed a small extension for the Z=0 set screw so it would trip the switch from the higher position.  I tested the heating time and found that the bed gets up to 110C in about 16 minutes- a little slow, but we probably won’t be printing much ABS with this open frame machine anyway.  Next- run PID autotune for the bed heater and adjust acceleration (greater moving mass means lower acceleration and print speeds).

New bed plate and undercarriage mounted on the printer

New bed plate and undercarriage mounted on the printer

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Some of you might ask why I would replace the glass bed with a piece of cast aluminum tooling plate.  Thermal performance is one good reason.  Here’s an IR photo of the original glass bed:

 

 

Taz_glass_thermal

IR image of the Taz 3 printer with original glass bed.

 

 

 

 

 

 

 

 

 

 

 

 

Notice the hot and cool spots- 30C temperature variation across the bed.

Here’s what the new aluminum bed plate looks like:

 

Taz_aluminum_Thermal

 

 

Temperature variation is just a few degrees over the entire surface (the bright almost horizontal lines are not hot spots- they are reflections of the X axis guide rails).

 

I have run the PID tuning on the new bed and modified the firmware with the new constants.  It heats from 25C to 100C in about 9 minutes.

I officially declare the Taz printer ready for action.

Chocolate Printer Cooling System Test

This week I attempted the first test of the chocolate printer cooling system.  The cooling system is intended to solidify the chocolate just after it leaves the extruder nozzle so that by the time the next layer is started it will have a solid layer to sit on.  The cooling system consists of a centrifugal blower with a brushless DC motor blowing room air into a styrofoam cooler containing a block of dry ice.  The air passes over the dry ice and gets chilled as the dry ice sublimates directly into very cold CO2 gas.  The chilled air and CO2 mixture exit the box through a port with a hose that will ultimately blow the cold air on the chocolate.  At least, that’s how it is supposed to work.  It blows air at -12C as measured via a thermocouple, but unfortunately, the air exit port ices up in about 2 minutes and blocks the air flow.

There are many possible solutions.  I can add a heater to the exit port to prevent formation of ice, or dry the air going into the box using a dessicant cannister or maybe just use water ice instead of dry ice if the higher temperature will still cool the chocolate adequately.   Maybe using an old miniature freezer with an air hose coiled inside would do the job.  It would be really interesting if I could use the waste heat from a freezer to keep the chocolate liquified and flowing.  Back to the drawing board!

Custom Police Badge

I was a “Grammar Police” officer for Halloween this year.  My costume consisted of some standard police equipment, as well as a dictionary, thesaurus, citation tablet, red pens, and, of course, my lovely custom badge!

 

Step 1: Design.

I scoured the web for pictures of “grammar police” shields, but ended up creating this design in Microsoft Word, using clip art from the web, generic shapes from Word, and shaped text boxes.  It was pretty simple and used the software I had readily available.  The portions of the design that are solid black are the parts that will be etched into relief during the process.

 

Step 2: Create!

With much encouragement & assistance from a fellow Makerspace member, Jon (of Dalek Asylum fame), I crafted this badge using mostly jewelry-making tools & methods.  We first spray-painted a square piece of copper, then used the laser printer to burn away the paint from the sections that were solid black.  This gave us access to the “fields” that would be eaten away in the etching process, giving the piece segments of relief.

After some clean-up (note to self: don’t use abrasive cleaners at this step next time!  and maybe not industrial spray paint, either), we left the copper square to soak in ferric chloride for approximately 45 minutes.  We checked the progress of the etching every 15-20 minutes, and decided that after 45 minutes we had enough of an etch to give the details enough depth to stand out.

After more clean-up to remove the ferric chloride & remaining paint, I had a nice, shiny, scratchy piece of copper with an etched design.  At this point, I really started finding my way around the jewelry bench.  I used a small jewelry saw to cut along the outer lines of the badge, which was frustrating until I found the right rhythm for cutting.  My badge was finally starting to take shape!

From here, I filed the edges smooth & buffed the finish to remove some of those fine scratches.  I gave the piece some dimension by using tools at the jewelry bench to accentuate the “belly” at the bottom of the shield.  Once it felt reasonably even and I was happy with the general appearance, we applied a liver of sulfur gel to the surface of the badge.

The liver of sulfur settled nicely into the etched corners, giving the piece an aged patina and highlighting the small details.  I really like how it settled into the fine lines left by the etching solution around the perimeter of the main field!  The small striations in the copper there give it a very unique appearance.  The patina provided by the liver of sulfur also helped hide some of those fine scratches I mentioned earlier.  We wiped off the excess & applied a museum-quality wax, since the badge will be worn and handled like jewelry, to maintain the patina.

Step 3: Profit(?)

The badge was added to my collection of Grammar Police equipment, which included shiny aviator sunglasses, and a tactical belt (excess nylon webbing with a clasp) with a dictionary, thesaurus, red pens, custom grammar citation padlet, and toy handcuffs.  It was quite the fun costume, and even though none of my trick-or-treat’ers understood, all my friends did!

 

Thus ends the story of my first Makerspace project.  Oh, what fun it was!