Heatbeds

Preamble

Looking at heatbeds for 3D printers, in particular a 200 mm x 300 mm for a P3Steel v.4, although a heatbed of that size would also be suitable for a Wilson II, amongst others. One of the things that needs to be considered are the costs of the various configurations. It should be noted that, when compared to the usual 200 mm x 200 mm heatbed/build plates, there is an additional premium to be paid for the larger 200 mm x 300 mm build area.

Note: 300 mm = 11.811 inches, 200 mm = 7.87 inches.

Links

These links contained, what I found to be, some useful tips

See also:

Types of heatbed

There are a variety of heatbed formats to choose from, among which are:

  • PCB – the usual choice, recommended to have a glass plate, or aluminium tooling plate, to print upon, as the PCB may not be entirely flat
  • Aluminium – Does not require a glass plate, resulting in a lighter print bed
  • Silicone – Expensive, usually 110V/240V AC, although there are some 12V/24V versions.

Heatbeds should have a low resistance, of around 1 Ω, so be wary of cheap PCB heatbeds, with higher resistances, and their associated hotspots – see Heatbed driving me crazy, Silicon replacement?

PCB designs

The heatbed is heated by a printed circuit, thus:

PrintrBot heatbed PCB design
PrintrBot heatbed PCB design

There are a number of designs out there MK2A, MK2B, MK3, with many people preferring the Mk2B.

Dual Power

Some boards can be powered by 12 V or 24 V. Using 24 V enables thinner wires to be used, due to the lower current. Note that the wiring to the board will be different, depending on whether 12 V or 24 V is used.

Three point levelling

Some beds (MK2B, MK3) offer have an additional mounting hole in the middle of one side, to offer three point levelling, as opposed to four point. Three point levelling could be considered easier:

It’s like balancing a stool. Is it easier to balance a 4 legged stool or a 3?

[Source]

See Bed levelling springs section below.

Insulation

Having the heat bed backed by an insulation layer (cork) can enable faster heating, and higher temperatures to be achieved.

Configurations and costs

Among the many options available, there are two common configurations:

  • PCB heatbed and a borosilicate glass plate (see below fo aluminium tooling plate instead of the glass plate)
  • Aluminium heatbed and a PEI film sheet

A backing of thermal insulation is most advisable in the aluminium heatbed and optional, yet advisable, in the case of the PCB heatbed.

Aluminium heatbed

Note that some of these plates do not come with a thermistor, see section on thermistors below.

eBay

Amazon.co.uk

Amazon.com

There are cheaper options, but they do not ship to the UK

PCB heatbed

eBay

Amazon

There are cheaper options, but they do not ship to the UK

Silicon heatbed

Note that it is worth remembering that a silicon heatbed, much like a PCB heatbed, requires additional aluminium bed, or glass plate – so there is not much of an economical advantage to be gained.

eBay

Amazon.co.uk

Amazon.com

  • ???

Aluminium tooling plate

There is the alternative of using aluminium tooling plate, en lieu of the glass plate, for the PCB heatbed option. Aluminium tooling plate (also known as MIC-6 or Mic 6) has the advantage of being less prone to breakage, greater thermal conductivity and better at evening out hot-spots. An example is EcoCast at Alumimium Warehouse – UK, £10.10 ex. VAT (£12.12 including VAT) for a 200 mm x 300 mm x 5mm sheet.

From Third party 3D printer build logs, this answer to the question Would a steel, instead of an aluminum, plate be reasonable?, mentions MIC 6 aluminium plate. Aluminum Sheet Between Heater and Glass – interesting thread, that recommends not using aluminium and glass, and to use only an aluminium cast tooling plate instead.

Aluminium backing sheet

This is not tooling plate, but could be useful as a backing plate, from Is a cork board necessary under the heated bed?

Both of my printers have a couple of sheets of 2 mm thick cork sheet underneath the aluminium heatbed.

The sequence is, from the top: glass sheet, 3 mm aluminium heatbed (like this), 2 sheets of 2 mm cork (with the first one cut for clearance around the wires), then a 1.6 mm aluminium plate as a backing. I have washers as spacers between the heatbed and the aluminium plate, with single nylon washers against the heatbed (they press against tracks on the heatbed). The washers prevent any distortion that may be caused by the fixing screws.

This setup allows me to reach 110°C without problems, even though it takes a while. Insulation on top, while it’s heating up, helps a lot.

Borosilicate glass plate

eBay:

Amazon:

PEI Film

As used by the Prusa i3 MK2, and its MK42 heatbed, Polyetherimide (PEI) film (also known as Ultem) provides a superlative 3D printing build surface that requires no tape, slurry, or adhesive, for printing both PLA and ABS. ABS and PLA both stick extremely well to the surface, which eliminates the need for support rafts used for better adhesion. PEI sheets have a glossy and a matt side. The matt side has better adehsion, the glossy side gives a glassy finish to your prints. It helps to wipe the surface down with isopropyl alcohol, methyl alcohol, or soap in between prints. This will ensure the PEI is clean, and help adhesion. Light sanding with 2400 grit paper will also give the PEI sheet more life.

It can be secured to the heatbed using either bulldog clips (as one would do with a borosilicate glass plate (Pyrex)) or 3M 468MP adhesive tape.

Some examples on eBay:

Amazon:

Useful for inductive levelling as glass plate can not be used – see Mk3 Heated Bed:

I use one of those on my Prusa i3 – works very well with just kapton tape on it, as I use an inductive sensor for auto-levelling and therefore can’t use a sheet of glass.

See also PEI build surface – RepRapWiki.

For tips on fixing the PEI sheet to your heatbed/build plate, see PEI Board for 3D Printer.

Kapton sheets

An alternative to PEI is Kapton tape sheets, and again necessary for auto-levelling inductive sensors. Good for PLA, although I seemed to remember reading that it is not so good for ABS, but I may be mistaken (link/source?)

Amazon.co.uk

Back Insulation

There are a number of different materials that could be used for insulation, with cork at one end of the economic scale, and air gel (aerogel) at the other. Here is an instructable guide to using cork: Insulate your 3D Printers Heated Bed.

The actual amount of cork insulation required is debatable, see How much insulation do I really need? Also, there may be concern about the suitability of cork, with respect to flammability, see Has anyone experienced scorching or burning of cork heatbed insulation? However, as the ignition temperature of cork is over 300°C, the risk is minimal.

eBay

There are a lot of choices, the best being a 1 meter length roll, as you are getting, effectively, five (200 mm x 300 mm) sheets for the price of two. The excess sheets could be used as stepper motor gaskets:

Amazon.co.uk

Amazon.com

Thermistors

While it is possible to purchase the thermistors separately, to save time, I looked at options where they were already soldered to 1 m wires, namely NTC 3950 100K thermistors (these are the thermistors that come with some aluminium heatbeds from amazon.com (see section above)):

ebay

Some aluminium heated plates, such as the RepRap PCB Heatbed 200X300 mm (from RepRap.me for £18), come with solder pads for SMD thermistor 1206. However, these come in reels of 10 or 50 or more, and so cost more:

ebay

Be wary of pre-fitted SMD thermistors, as their heating curve maybe unknown, see Heat bed Mk3.  See also, Mk3 Heated Bed:

Initially I had a problem as I couldn’t find a suitable thermistor table to match the one that came with my heatbed – in the end I chose type 7 as that seemed to match the thermistor that the seller provided. Your mileage may vary…
… here’s the line from my configuration.h file (my comments added):

#define TEMP_SENSOR_BED 7 // best fit for thermocouple on RepRap-me aluminium heatbed

Bed levelling springs

eBay

Fixings

From Upgarde Kit 300x200mm Aluminum Heated Bed Buld Plate 3D Printer RepRap Prusa i3, there is a useful list of fitting required to secure the heatbed, and alumium printing plate to the Y carriage:

  • 4 x M3 x 25 Stainless socket head countersink screws.
  • 8 x M3 Washers.
  • 4 x M3 Locknuts.
  • 1 x ~50mm High temp silicone rubber tubing
Fittings for aluminium build plate and heatbed to Y carriage
Fittings for aluminium build plate and heatbed to Y carriage

Preparation of P3Steel frame parts

A couple of preparation points for the steel frame parts, prior to assembly:

  • Oil is often used on steel plate, during the manufacturing process, in order to prevent corrosion. Clean the steel with brake cleaner to remove oil deposits/coating of the steel. This tip is from Shed and Buried Series 2, episode 15 (Signs and Wonders).
  • Spray the steel parts with standard black spray paint:
    • Keep the nozzle equidistant from the steel;
    • Quick light sprays/strokes applying multiple light coats, and;
    • Spray in alternate orientations (horizontally and vertically) to reduce striping.

Aluminium Composite Y-plate

These Y plates, Prusa i3 Alucomp 200mm x 300mm Heated Bed Support, Y carriage Plate 6mm style 2,

Alucomp 200 mm x 300 mm Y-plate - style 2
Alucomp 200 mm x 300 mm Y-plate – style 2

and Prusa i3 Alucomp 200mm x 300mm Heated Bed Support, Y carriage Plate 6mm Reprap,

Alucomp 200 mm x 300 mm Y-plate - style 1
Alucomp 200 mm x 300 mm Y-plate – style 1

are cheap, $21.89 + $9.00 – cheaper than 6 mm aluminium Y-plates – and are made from Aluminium composite panel (ACP), also aluminium composite material (ACM). See also Wanhao i3 6mm Y carriage.

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