how to make the filament extrude and stick to the hot bed w/ a i2 printer

1. Check if the distance between nozzle and hot bed is too close.

2. Raise the temperature of extruder.

3. Check if the nozzle is jammed.

4. Check if the extruder motor driver is fine.

5. Try to raise  the power of extruder.

6. Check if the extruder motor is fine.

7. Check if the motor wire  is fine.

   If you've tried step 1-7, but still make no sense, maybe the mainboard is not so good.

The bed on my printer is made from PEI (polyetherimide) thermoplastic probably made by Ultem. This bed material does not need any surface treatment to work.

When the bed is heated to 65 degrees, the printer plastic sticks to it with a strong bond. When the bed cools to room temperature the parts just come off with no force.

You can buy PEI in sheets and stick it or clamp it to your existing bed or possibly replace your existing bed.

There are also lots of other tricks you can try:

Reprap development and further adventures in DIY 3D printing: Stick with it... 3D Printing - Print Bed Coating Materials…

well, you need to check the distance and the temperature of the extruder and the motor driver if  is fine.  To get rid of these problems, you can choose the good quality Dual Extruder  from elecrow.

This is a Dual Extruder which is used on Makerbot 3D printers. The two print heads are conjoined with a piece of high hardness aluminum bar with good heat dispersion and high reliability. The main benefits of this Dual Extruder includes being able to print more complex objects with support structures and more aesthetically pleasing objects that feature multiple colors or multiple materials.

I've seen someone spray hairspray on the bed, and it really helps it stick!

You should definitely go through the checklist by Cheung Weng. Filament jamming is common. Based on the checklist, the following would be how I typically go about troubleshooting for my printer usually.

Just to build on the checklist for points 1-4:

1. Check if the distance between nozzle and hot bed is too close.

- Ensure your print bed is clean. Put a piece of A4 paper under the nozzle. Home Z. Once the nozzle comes down, move the A4 paper around a bit. Adjust the z-axis until the paper the paper and slide with minimum effort.

2. Raise the temperature of extruder.

- Extrude filament for 10mm. If it is extruding properly, then wait 5-10 mins. Try again. Then retract the filament to check if the end has more than 5mm which is still soft, the nozzle may be too hot. Having an extruder fan will help in this situation. Once you start printing, the temperature may need to be readjusted.

3. Check if the nozzle is jammed.

- If nozzle is jammed, if filament is pla, I would typically change the nozzle or us that nozzle for other higher temperature filament such as nylon. At high temperature, the pla would melt and be extruded together with nylon when I start the flushing process. For ABS, there are some chemicals which you can use to melt it away.

4. Check if the extruder motor driver is fine.

- There may be a case where due to insufficient cooling, either your motor is too hot or stepper driver is too hot.

For warping or filament not sticking to heatbed after everything else is remediated, I typically use glue stick and do without heatbed for low temperature materials. In somecases, I would use glue stick in combination with heatbed to increase the "sticking". if you still want to use heat bed, do ensure your power supply is sufficient as heatbed draws a lot of current.