jitsbuild-platform [Bukobot 3D Printer Instructions & Docs]

======jit's build:  Platform======

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Shown here is the 8" heated platform.  The other types of platform assemble in a similar way.

If you have one of the other types of platforms, or if you have the newer endstop mounts, see [[http://forum.bukobot.com/index.php?topic=2792.0|this thread]].

If you don't have the heated platform, skip down to [[jitsbuild-platform#mounting the platform|here]].

=====Heated Platform=====

Find this ([[bukobot-parts-list#platform|bag 6a]]):

{{wiki:jitsbuild:platform-heater-kit.png}}

Get out your heated platform.  Leave the glass sheet in its protective packaging.

(You may find an 8"x8" sheet of corrugated paperboard near your glass sheet.  That's intended to be used for insulating the bottom of the heated bed.)

If the lugs aren't already crimped onto one end of the thick red & black zip cord, get out your crimping tool and crimp them on.

Put the screws on the top of the bed and the nuts on the bottom (the top says "HOT SURFACE!" around the edge), as shown below, then attach the spade lugs:

{{wiki:jitsbuild:heater-connections.png}}

Red goes to positive, black to negative. Cover the screw heads and the nearby conductive areas with kapton/polyimide tape to avoid any accidental short circuiting.

The flat side of the lugs goes against the heated bed. Once the connections have been made, it's best to zip tie all four wires to the heater platform as shown.

{{:heater-strain-relief.jpg?800|}}

(In some of the images below, the lugs are shown attached to the top of the platform.  It is recommended that they be attached to the underside instead, as shown above.)

In particular, ensure that the white thermistor cable does not move at all at the point where it is soldered onto the platform (as the platform moves backwards and forwards) otherwise the connection will fail sooner or later at this point. Hence the use of a zip tie in the above picture.

Other warnings: ensure that the you put some tape over the top and bottom of the +ve (+12V) heated bed terminal and over the underside of the heated bed LED and resistor (if either thermistor wire or a grounded wire touches these points then it will permanently damage the Arduino board), also ensure that the -ve terminal does not touch the resistor next to the -ve terminal or it will also damage the LED on the heated bed.

While you're here, look inside the little hole in the middle of the heated bed:

{{wiki:jitsbuild:platform-thermistor.png}}

The tiny thermistor should be touching the side of the hole, or really close to it.  If necessary, move it closer to the wall of the hole.  It must not protrude from the hole. Don't break it. The pre-installed thermistor from Deezmaker is very sensitive, so as long as there is kapton tape (polyimide - the gold tape) covering the bottom and the thermistor is close to the inner wall of the hole, it should be pretty accurate.

(A few heated beds shipped out without the thermistor.  If you got one of these, contact Deezmaker.  You need the thermistor.)

The heated bed should have a layer of thermal insulation under it. Some kits come with a length of White Thermal Ceramic Insulation Cloth; others may have the corrugated paperboard.  You may even have both, though you probably only need one. 

If you are using the cloth, cut it into four equal lengths, about as long as shown below (you may have some left over, which you might find useful on your hot end). Don't cut it so long that it covers the screw holes.  Before peeling off the white plastic that covers the adhesive, lay out the insulation to check how you will apply it (see the below image for an example).

The ends of this woven material tend to unravel, so it's recommended that the cut ends be covered with polyimide tape (not shown here) before adding the insulation to the platform.

Remove the backing on one strip at a time and apply it to the bottom of the heated bed as shown. The bottom says "HELIOS", and the top is the side where "HOT SURFACE!" is printed around the edge. 

{{:headed-platform-insulation.jpg?800}}

You might want to add some polyimide tape around the edges to hold things in place.

Some people find that the insulation can fall off. To prevent this, you can outline the cloth with polyimide (Kapton) tape, half on the cloth and half on board and in between each strip to help the edges from peeling with time.

{{ :img_2389_-_version_2.jpg?800 |}}

Detailed documentation of the heated bed insulation on one build can be found [[heated-bed-preparation|here]].  If you come up with something better, please document it there. You can also find the manufacturer's user guide for the Helios Heated Bed [[http://files.panucatt.com/datasheets/helios_user_guide.pdf|here]].

So far we don't have pictures of the corrugated paper sheet being used to insulate the underside of the bed.  But it seems obvious.

=====Mounting the Platform=====

If you don't have your platform out, get it out.  If you have a glass sheet, leave it in its protective packaging for now.

Find the remaining parts from the platform mount kit ([[bukobot-parts-list#y-carriage|bag 14b]]):

{{wiki:jitsbuild:platform-mount-kit2.png}}

Put nuts into the hexagonal depressions on the two adjuster wheels in the usual way.

Put the two long flat-head screws through the holes in the corners of the front edge of the platform (the back edge of the heated platform has the hookup wires).  Their heads go into the chamfered holes in the top surface of the platform.  Nuts go on the other side:

{{wiki:jitsbuild:platform_underside.png}}

Move the Y carriage to the front, and position the platform on top of it.  If you have the heated platform, the wires lead out toward the back.

The center hole at the back end of the platform goes over the standoff at the back end of the Y carriage.

Put one spring under each of the long screws:

{{wiki:jitsbuild:platform-springs.png}}

Put the short flat-head screw through the hole above the standoff, and screw it down just until you feel just a little resistance.  Do not tighten this screw any further.  (When using the printer, check this screw occasionally;  it might loosen a bit.  Screw it back down, just finger-tight.  If you make this screw really tight, it might cause the bed to warp when you level it.)

(Some printer actions, such as printing fill in thin walls, can move the Y axis back and forth very rapidly, making a buzzing sound.  If you do a lot of this, you may find the screws on either end of the standoff getting loose.  You might want to consider apply thread locker to these threads if this happens.)

Push the long screws down through their holes in the metal plate, and screw adjuster wheels onto them on the underside of the platform, with their nuts facing down (the nuts may pop out when you do this, don't lose them):

{{wiki:jitsbuild:platform-adjusters.png}}

If you have the heated bed, you should insulate the underside of the heated bed before adding the glass plate (described below) to it.  If you have tape from the underside folding over to the top surface, it should only extend a few millimeters from the edge, as you don't want the glass plate sitting on top of that;  trim the tape back if necessary.  Clean the top surface of the heated bed with isopropyl alcohol and let it dry completely, then blow away any lint with canned air.

=====Glass Platform Plate=====

The glass platform plate is installed on top of the main platform, and is the surface where the extruder deposits the material as it creates the part. Because this surface determines the bottom of your part, it's essential that it is very flat. Depending on the material you are using (e.g. PLA vs. ABS), you can treat the glass with different kinds of tape. 

  * PLA: The typical surface used for PLA is blue painter's tape. When using the blue tape, the platform does not need to be heated. For a smoother bottom of your part, you can use the Kapton brand polyimide yellowish tape. When using the polyimide tape, set the platform to be heated to 60 degrees centigrade.
  * ABS: Use the polyimide tape surface for creating ABS parts. Heat the platform to 110c - 120c (start with 110c, and if the material doesn't stick well, try upping the temperature).

If you don't have a heated platform, start at step 3 since you don't need to apply the polyimide tape. If you have the heated platform, you can set up the glass for greatest flexibility using both polyimide tape and blue tape. This approach is documented below.

  - Clean the glass with glass cleaner to remove any residue (don't get glass cleaner on the heated bed or any other part of the printer) and blow off any lint with canned air;  clean both sides
  - Apply the polyimide tape in parallel strips, making sure it is as smooth as possible, and no overlap of the tape. The goal is to make the surface as flat as possible. The tape is very sticky, so a good approach is to angle the tape with just the matching edge lower to align it with the previous strip of tape. Then lay the tape down smoothly and press to seal it to the glass
    - Don't stretch the tape as you apply it, or it won't go down smoothly.
    - Avoid creating any bubbles - this can be hard and you can see there are a few in the example photos
    - Wrap the tape ends under the bottom of the glass, but make sure there is only one thickness anywhere on the bottom to maintain the levelness of the glass
  - Apply 2" blue painter's tape perpendicular to the polyimide tape so that when you remove it (to replace/refresh), you don't peel off the polyimide tape as well. Leave the ends of the tape loose, extending over the edge of the glass
  - Set the glass on your main platform, aligning it over the markings so it is centered. Be sure the glass isn't blocking any screws or sitting on the electrical connections in the back or on any tape that might be folding over from the underside
  - Smooth down the ends of the blue tape on the platform
  - Use small clips to hold the glass in place. If you put the clips over the glass, there's a danger of the extruder head hitting a clip. An alternative that's safer is to put the clips only on the base platform as stops on all four sides. This combined with the tape ends should hold the platform in place. 
    * If you do want hold the glass in place by putting clips on top of the glass then consider these points: 
      * Putting clips on the rear edges of the glass is fairly safe if you are not printing the full bed depth (and you can reduce your maximum bed depth if you want to make sure you never hit them). 
      * Putting clips on the front edge of the glass is safe only if you adjust your Y-axis endstop so that the extruder(s) miss the clips when homing in the X direction at "Y=0". 
      * Putting clips on the right-hand side of the glass is safe if you are not printing the full width of the bed //UNLESS// you have a dual extruder. You should avoid placing clips on the right side of the glass if you have dual extruders.  (But if you are using the smallest size of clips, you may not have problems with the hot end hitting the clips;  you may find that the hot end just glides over the clip handles, touching them but not catching on them.)

{{:glass-polyimide-tape.jpg?800|}}

Apply the polyimide tape as shown, with no overlaps.

{{:glass-applying-blue-tape.jpg?800|}}

Then apply the blue tape perpendicular to the polyimide strips.

{{:glass-finished.jpg?800|}}

Mount the glass on the platform.

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//The contents of this page may be re-used under any of the following licenses:  The [[http://creativecommons.org/licenses/by-sa/3.0/|Creative Commons Attribution-ShareAlike 3.0 Unported License (CC BY-SA 3.0)]], or the [[http://www.gnu.org/copyleft/fdl.html|GNU Free Documentation License (GFDL, version 1.2 or later)]].  Nothing on any of these pages is there to tell you what to do, only what other people have already done.//
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