heated-bed-preparation [Bukobot 3D Printer Instructions & Docs]

===== Preparing the Heated Bed  -  Discussion Page =====

This page is for more detailed discussion and documentation of the preparation of the heated bed for printing.

Mounting the heated bed, hooking up its electrical connections, and leveling it, are documented fairly well elsewhere.

This page is all about thermal insulation, the glass sheet, polyimide tape, blue tape, and so forth.

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It would probably save time and hassle if the platform was fully prepared for printing, on top and underneath, //before// the platform is added to the machine.  However, nobody has actually done this, //and// fully documented it on this wiki.  Most of the rest of the build is mechanically obvious, compared to the thermal complications of the heated platform.  There is some disagreement as to the best methods.  For these reasons, the "jit's build" documentation largely skips over the preparation of the heated platform, at least so far.

Complete, successful platform implementations should be documented here.  There may be a number of ways of doing things, and they are all welcome on this page.  Please contribute.

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=== one way of doing the insulation underneath ===

There is some evidence to suggest that the adhesive on the polyimide tape can withstand high temperatures better than the adhesive on the fabric.  This build assumes that is true and tries to use polyimide tape to secure the fabric in as many places as possible.

Four lengths of fabric have eight long edges, and we can tape five of them down.

Items used:

{{wiki:jitsbuild:bedins0.png}}

Place the bed on a work surface, upside down.  The side that says "HELIOS" should be facing up.

Before you begin, clean the underside of the bed with isopropyl alcohol and let it dry completely.

You have to decide which way to run the strips.  This build runs them from side to side.

The length of each piece is equal to the width of the bed (at its narrowest) minus the width of the polyimide tape.  Cut them out and lay them on the bed to check the length:

{{wiki:jitsbuild:bedins1.png}}

This material tends to fray at the cut ends.  Stop that with short pieces of tape.  The paper backing is still on the fabric;  most of the tape is on the fabric side, with a few millimeters folding over onto the paper backing:

{{wiki:jitsbuild:bedins2.png}}

Grab the paper backing somewhere along the long edge and pull it up a bit.  Peel it away from one end of the fabric, then peel it away from the few millimeters of polyimide tape.  Stick the end of the paper backing back onto the fabric's adhesive layer about a centimeter away from the end of the fabric, so you have a place to hold the fabric.  Straighten out the edge of the tape and fold it over the end of the fabric, onto the adhesive side of the fabric.

{{wiki:jitsbuild:bedins3.png?800}}

Peel the backing away from the rest of the fabric, and then away from the tape on the other end, and then stick it back near the end so you have another place to grab.  Fold the tape over as before.  Then remove the paper backing.  Both ends of the fabric have now been secured with tape so they won't fray, and the self-adhesive is fully exposed (except at the very end, where it is covered with a bit of tape).

Turn the fabric over and stick it down on the underside of the bed.  One edge should lie on the line between the screw holes.  Try to get the ends of the fabric the same distance from the edges of the bed.  Do it right the first time, as you really don't want to pull it off and try again.

Once it is stuck down, apply tape along both long edges:

{{wiki:jitsbuild:bedins4.png}}

Two long edges have now been secured with tape.

Do a second piece of fabric the same way:

{{wiki:jitsbuild:bedins5.png}}

A third long edge has been secured with tape.

A third piece:

{{wiki:jitsbuild:bedins6.png}}

Four long edges have now been secured with tape.

The last piece:

{{wiki:jitsbuild:bedins7.png}}

Five long edges have now been secured with tape.

There are two edges of the bed remaining that don't have lengths of tape along them.  Apply tape there, vertically, with the edge of the tape even with the edge of the bed (at its narrowest):

{{wiki:jitsbuild:bedins8.png}}

Two more strips of tape vertically, across the middle.  These strips are long enough to fold over the edge of the bed and wrap around the other side a few millimeters:

{{wiki:jitsbuild:bedins9.png}}

Three more strips of tape, horizontally, along the seams between the fabric strips.  These also fold over the edge a few millimeters:

{{wiki:jitsbuild:bedins10.png}}

The center screw hole at the top has been partly covered by tape.  Cut the tape away from the hole so the small flat-head screw will fit through.

Attach the bed to the platform.  The top of the bed still needs to be done.  If the bed had already been leveled, it needs to be leveled again.

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