Share your hardware improvements for your HIC i3, the good and the bad!
- Chip Luck
- Posts: 191
- Joined: February 11th, 2016, 9:12 am
- Location: Central Florida
- 3D Printer(s): HICTOP Reprap Prusa I3
Years of experience, you are spot on as tinned ends on all wire connections are vital. We use crimped ferrules on military and flight applications.
- Posts: 121
- Joined: March 15th, 2017, 8:46 pm
- Location: Oregon
- 3D Printer(s): HICTOP 3DP-17
Just a note, I bought the 3DP-17 on Amazon a couple of weeks ago (March 6th), and mine came with a 24v power supply and 12awg wire. So they do take customer feedback to heart apparently. I'm sure you can still buy the printers with the lower rated wire and power supply, but I would guess that is existing inventory at Amazon or elsewhere.
You seem very knowledgeable and I would like to ask you if Chip Luck's idea can somehow make the printer worse. I realize that if you're savy enough you might not need to spend the extra $20. I'm not so could his upgrade hurt?Chip_M wrote: ↑June 28th, 2016, 5:52 pmI too noticed that the fan speed dropped whenever the bed heating clicked in on our HIC i3 (acrylic frame model) with the stock power supply and wiring. I also noticed that the wiring from the power supply to the RAMPS board was getting HOT, so it was clear that the wire from the power supply to the RAMPS board was undersized. I swapped out the OEM wiring with some 12 gauge cable, and the overheated on that wire was gone...but another problem developed: the wiring from the RAMPS board to the heated bed was overheating even worse than before, and it actually melted the connectors on the RAMPS board itself!
Looking at the current draw specs for the heated bed, I decided that I wasn't comfortable drawing that much current through the FETs on the RAMPS board or through those wimpy connectors. I purchased a generic automotive control relay rated at 40 amps and drove the control coil of the relay from the RAMPS board heated bed connection; you need to include a reversed diode across the control coil to snubber the voltage spike you get when you switch the coil on and off, there are details on the .net. I then wired the heated bed through the relay contacts directly to the power supply using some more of the 12 gauge cable, and I included an in-line fuse (automotive blade fuse) just for some extra protection.
The result is no more cable overheating, faster hot end warmup, faster heated bed warmup, stable hot end and bed temperatures. One consequence of using the relay is that you can't used PID control of the bed heating, but I don't find that to be necessary. I wouldn't use a relay for the extruder hot end, since it's current draw is pretty small compared to the heated bed. I haven't checked the voltage levels at the board as the heated bed cuts in and out, but I think they are pretty stable. No detectable change in fan speed.
Here's the fried control board:
Fried Control Board - Bed Heater Connection.JPG
The board connections were so munged up that I just added some pigtail leads and bullet connectors to that I could attach to the control relay. Still using the original power supply; it seems to handle the load just fine.
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