Thursday, July 9, 2015

CTC (makerbot) to Reprap (RAMPS/Marlin) conversion, day one

This is day one of replacing the horrible Makerbot (clone) firmware with a RAMPS board running Marlin.

I wish Marlin would run on the Mightyboard, it's a very nice piece of hardware. Shame about the horrible, 2009 feeling firmware. If it were running Arduino I might take a stab at it but I don't think it is. It is an ATMega chip and I suppose I could probably cram an Arduino bootloader on it. Might be worth a play once I get the RAMPS board going. Right now I don't want to potentially wind up with a completely bricked printer. Even if I get a bootloader running I'd have a lot of fooling around in pins.h to get all the I/O running on this thing. It is an open design though so it's not reverse engineering, just time.

Anyway, I was just poking around today, looking for pitfalls I'm going to encounter. I really don't want to cut any wires and make this irreversible. First challenge was that the stepper motor connectors are using large connectors about the size of molex connectors. I found that 14 gauge solid copper wire, removed from Romex cable, goes in just fine so I can make an adapter. Also the last two pins on the endstops can be wedged in, though since the X and Y are max stops and the Z is a min stop, I may not be able to fit the Z in very well.

Today I just got the firmware compiling, the LCD is working, I hooked up to a bench power supply and just attached the X motor and endstop and made it home that axis.  Worked fine first time.




Next up is to pull the print head and install thermistors instead of thermocouples, since the RAMPS electronics does not have thermocouple amplifiers like the Mightyboard does, and I don't really want to pay $30 for a pair of amplifier boards for no good reason - there's nothing wrong with thermistors.

15 comments:

Anonymous said...

Greetings, I am attempting the same conversion and would like to inquire on the procedure. In the image a smart adapter board is used to connect the RAMPS board to the LCD Display; did the 5 input buttons and SD card reader work when you got the LCD display to function. If so, how did you go about this process. Do you still have the config file you used and would you be willing to share it?

John Ridley said...

No, I was completely bypassing the built in control system. If I do ever revisit this project I will probably attempt to port Marlin to the electronics rather than replace the electronics.

However at this point I think it more likely that if I ever do something else I'll just build a new printer. I honestly could have tossed together another printer in less time than I wasted on this project, and for not much more money.

Jonathan Luna said...

Please don't trash it... Keep the project alive or atleast pass it down.. I just spend hrs researching to see if this conversion is possible and this was the first ray of light I came by. I have a friend who has a fried might board and we are looking to convert port the hardware over to reprap style electronics.. Any help will be greatly appreciated.

John Ridley said...

Well, there's no "it" to trash. I just soldered up a few adapters and crammed a RAMPS board in there, poked at it for a while and gave up. The RAMPS board has already been incorporated into another printer.

The biggest problem with this whole thing is that the CTC runs on a 24 volt supply and RAMPS is really geared to 12V. Running off 24V requires the linear regulator in the Arduino to work too hard, so you have to pre-regulate that.

The use of thermocouples instead of thermistors is another huge pain in the butt.

The ideal solution is to just port Marlin to run on the Mightyboard. There's already some work done on that.

Really, IMO, it's easier to just build a new printer than to convert this one. It'd be cheaper and far less time involved, and I think you'd have a better printer at the end of the day.

The thing that irritates me most about the CTC as it stands is the atrocious temperature control. It's unforgiveable that they're still using bang bang and not PID. It's just horrible.

If I do decide to attack this again, I'll probably go farther with it and completely strip the electronics, leave the 24v supply just to run the heated bed and perhaps the hotends, and add a 12v supply to run everything else, probably build a new base for the printer to boost it up 4 inches to give room for a completely new set of RAMPS electronics and go with a rotary encoder, which is a WAY better control system than pokey buttons.

Anonymous said...

Greetings once again. I agree that these CTC printers are a not that great to use, however I have 5 machines that are some type of Chinese knockoff MakerBot. All have experienced issues at one time or another, so when a board recently failed on one of the CTCs I started looking into a RAMPS conversion rather than pay for another board replacement.

For the issue of running the Mega board on 24V: I found a derivative mega board meant to handle native 24V, The Taurino Power Board (http://reprap.org/wiki/Taurino).

I would have preferred to keep the original interface but I the more I look into other RAMPS builds the more I find that very few have keypad interfaces (with little documentation) and most have stuck with the rotary encoder interface. Do you have a preferred Display/Encoder/SDcard slot to recommend?

Additionally, which firmware do you prefer?

John Ridley said...

I just buy whatever's cheap. I haven't had any trouble with any of the Display/encoder/SD slot boards. There's not much to them, and they operate at very low speeds.

For 12/24V, the power requirements are very low, less than an amp. A $2 buck regulator board will make any 12V RAMPS board work just fine. It's just one more thing you need to deal with. If the Taurino is cheaper than a $12 Mega and a $2 buck regulator, that's fine.

matt batt said...

I have finally just finished this conversion and all has gone well and all is working the way it should. A lot of settings to be amended. I have gone for a complete conversion including heated bed to 12v. I thought I would drop my details here if any body wanted some help as there is not a lot of detail available for this conversion.

John Ridley said...

That would be cool. I don't know why you'd convert the heated bed to 12v though - 12v heated beds are miserable. I'm sort of considering redoing this conversion as a complete gutting and just using the mechanical parts, but even so I would save the 24v supply for the heated bed.

matt batt said...

I am slowly learning this. 12 does take its time. Maybe some decent SSR's are needed. I will just have to rewire for a 24v PSU then. The control with Merlin compared is amazing.

John Ridley said...

The math just doesn't work very well for 12V. You only need half the amps at 24 volts to get the same heating power as you do at 12V, and voltage is a lot easier to get than amps (a 24v 15 amp power supply is a lot cheaper and easier than a 12v 30 amp supply.

Also the standard heating boards are usually 1.2 ohm, which at 12 volts draws 10 amps, which is 120 watts of heating. You can't force it to draw more current, Ohm's law dictates the heating value.

But the same board at 24 volts draws 20 amps, which is then 480 watts, so you get 4x the heat (assuming the board can take 20 amps without melting).

matt batt said...

New plan 24v PSu Solid state relay and 24V bed. The default print quality from Cura over makerware is amazing. I very happy I have made this conversion

John Ridley said...

*sigh* Now you're really making me want to do the conversion again. The quality of print I get out of this machine is really not great, and I am pretty sure it's the firmware doing it, because the old RepRap did much better with the same slicing software.

matt batt said...

I would. Simple things like breakaway support and rafts. In makerware I had so much clean up to do after my prints and I spent months trying out different configs. In Cura the supports and rafts just break away and i have not touched a setting. I also moved to a bowden and the stringy blobs drove me mad and retraction im sure did nothing now it just works.

John Ridley said...

I've never needed to use a raft, and I generally just design my stuff to not need support. However, you should be able to use Cura with the original firmware as far as that goes. I never used Makerware, it's a horrible, wretched pile of junk. I use Slic3r with Sailfish on my CTC.

But I still would like to go back to Marlin. I may just sell this thing and build another RepRap though, it would be less work. I'm sort of thinking about building a Prusa variant around a welded steel frame and 12mm fully supported rod with split linear bearings.

Marc Vicente said...

I have also doing a CTC to Ramps 1.4 but I am stuck configuring Marlin, any chance to anybody upload a preconfigured CTC Ramps Version of Marlin or maybe all the main settings On configuration.h, etc... Thanks in advanced