Hesine M-505 3D printer mods

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I have a Hesine M-505 3D printer which is one of the Chinese Prusa i3 clones that came onto the market around 2015. The frame appears to be exactly the same as the Anet A8, however this is a distinct printer. The Anet A8 has developed a reputation for catching fire, and after going over most of the reasons for this, the Hesine printer seems to be much safer out of the box. There are several reasons the A8’s catch fire:

  • Firstly: thermal runaway detection was disabled in their Marlin-based firmware
  • Faulty connectors with wires at the heated bed induce failure of the connectors
  • Poor cable management allows bed wires to break off and short out
  • Because of the above issues, the custom Anet driver board is prone to overheating and burns out, or also catching fire

The Hesine M-505 does not have these issues:

  • Uses the standard and well proven Melzi driver board running Repetier-based firmware
  • State of thermal runaway detection code is unknown as the M-505 firmware is not released as far as I know
  • Heated bed wires come from the factory soldered directly to the heated bed, prevents thermal failure of a connector

All this being said, the Hesine M-505 still has some deficiencies. Namely, the routing of the heated bed wiring is prone to breaking loose due to very poor cable management. There are other smaller issues, but that is the biggest. The acrylic frames on these printers also gets a bad rap, so reducing wobble, namely in the Z axis is also a priority.

Next up is firmware updates for the board. Initially neither the Marlin or Repetier code bases supported the display and 5-button controls on either of these printers. This meant that anyone wanting to update firmware or guarantee thermal runaway protection was in place lost the use of these components. However, 2 years on, this has been resolved in both Marlin and Repetier code bases. Sadly, despite both code bases being GPL V3, often the Chinese printer manufacturers are out of compliance by not releasing the full code which caused this control panel situation for some time. On the up-shot, it's China, and about anything can be had if you know who to ask, which is how I assume the display code finally was obtained and integrated.

Since long print times are the name of the game, i decided I wanted to make my printer as safe as possible. I’ve assembled a number of upgrades to improve safety and also reliability.


Printed upgrades

Todo yet:

Notes for printed parts

  • Anet_A8_Y_Chain_Remix

I found that the Anet_A8_Y_Chain_Remix had some minor sizing issues which could be inherit defects no one has bothered to fix or differences between the A8 and M-505. The block that attaches to the main printer frame has a notch for one of the thread-rods to run over top of it. This notch is off enough that some of the printed part has to be broken off to allow the rod to seat back into place on the frame. It's not a show stopper, but the problem exists. Next, the screw holes that allow the other end of the chain to attach to the bed are about one screw-hole diameter off. Again, not a show stopper, but it could be improved. Maby there is an improved version already out there and I've missed it.

Purchased Upgrades

Some of these parts match up with printed parts above, so be mindful if you interchange some of these (like the power switch). The power supply and MOSFET upgrades I deemed fairly important. The thermal fuse is maby a little overkill, but better safe than sorry. After those, everything is a reliability or usability upgrade.

Other upgrades

For the main power wiring it's wise to use crimp connectors on the wires. These are the most important:

  • Power supply to main board (12V and ground)
  • Heated bed wires where they attach to the main board using screw-terminals
  • Hot-end wires where they attach to the main board using screw-terminals

The issue is that on high-current wires like for the heated bed, bad connections heat up and corrode over time which can also lead to a fire. Screw terminals on bare-wire usually looses about half the surface area for connection when compared to a crimp connector. I've seen ferrules recommended, but both the connectors and the crimping tools required are fairly uncommon and expensive. I use crimp spade-terminals and just grind the spade down to a size that will fit the screw terminal. It's cheap, the parts are very common, and it works just as well.

Hesine M-505 Firmware Updates

I have not yet done this, but I plan to soon. This is an online configuration tool for Repetier firmware which the M-505 uses on it's included Melzi board. The board mine came with was a Melzi V2.0 board, this was in late 2015. It allows you to point-n-click a new firmware binary which can be loaded via the usual Arduino update. I've read that Repetier now includes support for the LCD display and 5-button input used on this printer.

There's quite a bit configuration required, I plan to add an update with the options needed once I get time to work on this.

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