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Sold my first heated bed kit

This article is a detailed assembly and build manual for my heated bed kit for RapMan machine.

On the above picture, you can see everything included in the kit.
Additionally during the build you will need two pliers, one hex key and a slotted screwdriver. So almost nothing;-)

Step one: Pins
Mount the 5 pins. Also remove the protecting foil from the aluminium if you have any.
(precision plate usually has one).
On the below picture I highlighted the pins, but the foil is still on the aluminium (remove it!).

Step two: Terminals

Mount the terminals on the back of the bed (four in total):

Each terminal is mounted using an M3x35 bolt, 13 washers under the terminal, and one M3 nut.

The bed is pretty hot, so we need to leave some distance between the terminals and the bed, hence that many washers.

Step Three: Resistors

Prepare the resistors before mounting them.
(you may be able to skip this step if your kit arrived power resistors with wires already mounted)

For this step you need the two pliers. The leg of the power resistors can bend really easily, so you need to hold the leg with a plier while you are twisting the 1.5mm2 wire with the other pliers.
You cant avoid the use of two pliers, you risk to simply twist off the leg of the power resistor.

The use of the two pliers:

Usually 4-5 twist is enough, but make sure, the wire is not moving
(if it is not tight enough, then twist more).

Cut off the remaining wire:

And here is the final result:

Do this for all of the resistors, so 10 legs in total (5 resistors). It should take less then 10 minutes.

Step five: Resistors mounting

Mount all the five resistors using the shipped M3x6 hex bolts, dont overtighten it!.
The aluminium threads are not strong.

Should look like on this photo:

Also notice, that the wires are longer then they are needed to get to the terminals. Its on purpose, see next step.

Step six: Connect the resistors

I made in all wires an "S"-form when connecting to the terminals.
It has two goals:

  • easier connecting to the terminals
  • thermal stress/expansions does not loose the terminals' screws

Here is a picture of it:

It does not look beauty, but who cares?;-)

Here is a picture of the final wiring. All the resistors are connected parallel.

Step seven: Magnets

Caution: These are really strong magnets.
You need to handle them with extra caution. If you wear pacemaker, then ask somebody else to mount this bed.
Also you can easily injure yourself if your finger is pinched between two magnets.

Put some polyimide tape on the magnet:

And place all the 12 at the bottom of the bed, in a way that 3 at each edge of the steel sheet, and four in the middle.
Make sure none of the wires are touching them. Also may be a good idea to put one layer of polyimide tape between the magnet and the bed.

Here is one magnet mounted on the bed:

Step eight: Power supply

The power supply is a 200W 230/23.5V toroid transformers with integrated heat protection:

Clean off about 200mm from the end of the power supply's wire.
Cut into the wire watchfully to not cut into the inner insulations:

Here is cleaned off:

You should connect the power supply just like on this photo:

Step nine: Polyimide tape

Prepare the steel sheet with polyimide tape. The best way to cover it diagonally just like on this picture:

Step ten: Replace the bed

We are done. You only need to put this bed into the machine.

ps: This article may be updated in the future, as I want to keep it an up-to-date assembly instruction.

Also remember, this heated bed is available for sale.

If you are interested buying one, drop me an email to order (at) arcol (dot] hu

Hope you enjoyed this article.

Comments (2) Trackbacks (0)
  1. Why don’t you solder the wires? At these temperatures ordinary solder will be fine. Otherwise bare copper connections will tend to oxidise very quickly when heated.

  2. nophead: I can add solder even after I operate some weeks.
    I used bootlace on the first prototype, see this picture:

    Also if the wires are touching really hard against each other they cant oxidize there.

    I dont think extra soldering is necessary here. Also all high voltage applications use copper-copper contact without any soldering. (like circuit breakers, contactors, etc, etc).

    So I think it is just fine that way. But if I see sparks, I will definietly solder it, and update you.


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