A6 Heated Bed Insulation Retaining Clip

Clips to hold foam-board insulation to the bottom of the Anet A6 heated bed.

IMPORTANT: If you do this project, you will be putting potentially flammable and electrically conductive material near/on the electrically-powered heated print bed of your printer. VERY BAD THINGS could happen (such as electrical shorts and fire). I've been running this modification for a few months, printing PLA, PETG, and TPU at bed temperatures up to 70C without any problems. That said, please use common sense for your application. If you do not understand the risks and accept the sole responsibility for this modification, please DO NOT PROCEED. Thank you.

I wanted to insulate the heated bed on my A6 printer so it was easier to achieve and maintain the set temperature, and consequently, reduce the workload of the power supply. I liked the idea of a simple foam-board sheet as an insulator (with aluminum foil on it as a radiant heat reflector) because it's light-weight, inexpensive, and easy to make. I needed a way to hold it in place. I didn't want to use glue or something permanent. I also wanted a way to install and remove all of it without a lot of disassembly.

With this design, you only have to remove one of the spring-tensioned screws to put the insulation in position. The retaining clips go into place without any disassembly (assuming you have a reasonable gap between the bed and the carriage assembly.

DOES IT WORK? The foam-core insulation (with foil) works well. With no insulation and a room temperature of 26 C, the heated bed was "on" 45.8% of the time to maintain a 70 C bed temperature. Repeating the test with the insulation in place, the heated bed was only "on" 31.5% of the time.

Note: That data was collected by printing the same object twice. The heater "on" time was monitored/measured for a 12 minute period, starting at about 25% print completion. The heater-on time was divided by the elapsed time to get the percentage.

Notes:

I printed with PLA and it works fine. I think a higher temperature, more flexible/springier material like PETG might work better since the heat causes the PLA to lose some of it's spring. Print with supports, in the existing orientation of the STL file.

How I Designed This

What You Need

• Foam board (foam core), typical 5mm thick, at least 220mm x 220mm (for an A6 Printer). It's available at nearly any department store for about $3 for a 20 x 30 inch sheet.

• Aluminum foil. Check your kitchen.

• Spray adhesive. Available at hardware or department stores, but it can be as much as $10 for a can. You're only going to use about 10 cents worth, so if you don't already have some, ask a neighbor or a friend if they do.

• Kapton (or another non-conductive, high temp) tape. Regular electrical tape would probably work fine as well.

• Sharp knife, pencil and a straight-edge/ruler.

Step #1: Layout foam board sheet

• Using a straight edge and your measurements, draw the size of your cutout piece on the foam board. The A6 bed is 220mm x 220mm. The cutouts for the springs are 10mm x 10mm.

• Cut out the main 220mm x 220mm piece. Don't worry about removing the smaller cutouts yet. Glue on the foil first.

IMPORTANT You still need to determine where and how much to cut-out for the power connector. You DO NOT want to lay aluminum foil across the open solder contacts on the bottom of the heated bed. Additionally, I want to clear the area around the LED light and avoid contacting the temperature sensor in the middle of the bed. I will show you my dimensions later but verify your own dimensions and location for yourself.

Layout drawn on the foam board.

Step #2: Spray contact adhesive

Spray contact adhesive on the foam board and on the aluminum foil. Follow the directions and press them together when it's ready. Once it's all stuck together, cut off the excess foil.

I used this adhesive but there are many brands that will work just fine.

Spray the foil too. You want the shinny side exposed, so spray the adhesive on the more matt-looking side.

Put the foam on the foil

Step #3: Electrical Contact Cutout

• To avoid the electrical contacts, I removed an area that is approximately 15mm x 45mm, biased about 5mm to the right (looking from the non-foil side), along one of the edges. This will give me ample spacing around the wires, solder contacts, and power-on indication LED.

IMPORTANT: BE SAFE! Verify these dimensions for yourself before you power-up! Your heated bed may be different than mine.

I made a 45mm x 15mm cutout for the electrical contacts.

Step #4: Cutout the smaller cutout pieces. Apply tape.

• Using a sharp knife, remove the cutouts for the springs and the electrical connector.

• I applied Kapton tape around the electrical cutout as a bit of insurance.

• Also, compress the foam somewhat in the center of the piece and covered the area with Kapton tape. The temperature sensor is in that location and I didn't want the insulation lying directly on it, or possibly shorting any exposed contacts.

Step #5: Put the insulator into position

• Remove one of the spring-loaded screws and slide the insulated sheet (foil up) into place.

• Replace the screw, spring and wingnut

• Put the clips into the corners to hold the insulation up against the heated bed.

Remove the spring, screw and wingnut. Slide in the insulation.

Insulation into position. If you cut the notches the correct size, the insulation is held in position by the springs and will not move horizontally.

Replace the spring, screw, and wingnut. Install the clips

Clip in position. Do all four corners.

Final Step: Verify good clearance

• Look underneath and verify you have good clearance between the electrical connector/solder contacts and the insulation BEFORE powering up your printer.

(I took the heated bed and carriage assembly off the rods and flipped it over to get a good picture. You can also get a decent look by putting your cell phone into selfie mode and peeking underneath.)