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Introduction

Please check this before installing the heated bed:

05-06-16 Incorrect ground wiring

Also, please only use shielded wires for the heated bed harness or any wires coming for the heater outputs to avoid EMI.

  1. Disconnect the power cable from the machine when doing any modifications to the electronics Locate leads 1 and 3 on your heated board. Solder the positive terminal to 1 and the negative terminal to 3. Do this so the other side of the board remains perfectly flat. Cover the other side with a piece of electrical tape to keep it from shorting against the metal platform. VERY IMPORTANT. If you short these wires against the metal body or platform it will damage the Arduino, it's an easy fix, but nobody likes down time!
    • Disconnect the power cable from the machine when doing any modifications to the electronics

    • Locate leads 1 and 3 on your heated board. Solder the positive terminal to 1 and the negative terminal to 3. Do this so the other side of the board remains perfectly flat.

    • Cover the other side with a piece of electrical tape to keep it from shorting against the metal platform. VERY IMPORTANT. If you short these wires against the metal body or platform it will damage the Arduino, it's an easy fix, but nobody likes down time!

    • This wiring setup allows you to only run half of the heated board. Since the board is 8.5" square, and uses more power than necessary (at 19V vs 12V) or than we have available. We're now able to heat a 8.5" x 4.5" area with the correct wattage. The thick aluminum platform will conduct the heat and allow for good thermal distribution.

    • Solder your NTC 3950 thermistor to two long wires. Shown here I used a broken harness so I would be able to disconnect the bed when I wanted to mill.

  2. Mark a spot on your platform where you would like to take the temperature from. Drill a hole. I drilled mine about 1/2" deep. Drill a hole. I drilled mine about 1/2" deep.
    • Mark a spot on your platform where you would like to take the temperature from.

    • Drill a hole. I drilled mine about 1/2" deep.

  3. Trim the top corners of the board. Be careful not to cut into the circuit. You can see where the circuit exists. You'll want these style wire clippers shown here. Clip a V in the bottom center. Be very careful not to clip the circuit. Clip a V in the bottom center. Be very careful not to clip the circuit.
    • Trim the top corners of the board. Be careful not to cut into the circuit. You can see where the circuit exists. You'll want these style wire clippers shown here.

    • Clip a V in the bottom center. Be very careful not to clip the circuit.

  4. Place a strip of 2" Kapton tape all the way around the perimeter of the platform. Place a strip of 2" Painters tape around the perimeter over the kapton tape. Fold the tape down on both sides of the platform. This works to keep the aluminum from conducting too much heat into the air. It's basically insulation.
    • Place a strip of 2" Kapton tape all the way around the perimeter of the platform.

    • Place a strip of 2" Painters tape around the perimeter over the kapton tape.

    • Fold the tape down on both sides of the platform. This works to keep the aluminum from conducting too much heat into the air. It's basically insulation.

    • Lay the heated bed over the center of the underside of the platform so all registration holes in the magnets are free from any coverage.

    • Trace the outline in the tape and trim way anything that would sit between the heated bed and metal platform.

  5. Use binder clips to secure the heated bed to the UNDERSIDE of the aluminum bed, making sure you are not covering the magnets. Use heatsink plaster to cover over the thermistor and put some inside the hole you drilled earlier. Install thermistor deep into the hole being careful not to allow a short between the wires and the aluminum
    • Use binder clips to secure the heated bed to the UNDERSIDE of the aluminum bed, making sure you are not covering the magnets.

    • Use heatsink plaster to cover over the thermistor and put some inside the hole you drilled earlier.

    • Install thermistor deep into the hole being careful not to allow a short between the wires and the aluminum

    • Let cure

    • You should drill a hole through the thickness of the platform and run a wire tie through and around the wires to support the wires and keep the thermistor from being able to be pulled out during printing (not shown here)

  6. Unscrew the cover bolts a few turns, don't remove them. Lift upwards slightly and pull back a little. Disconnect top fan plug if necessary for more available movement. Slide cover to the side carefully
    • Unscrew the cover bolts a few turns, don't remove them. Lift upwards slightly and pull back a little.

    • Disconnect top fan plug if necessary for more available movement.

    • Slide cover to the side carefully

  7. Locate the hole that allows the bottom limit switch wires to come through. Feed your heated bed wires through In my case I used a damaged plug given to me by the BoXZY team. I recommend this approach as it will be very simple to remove my heated bed when needed. In my case I used a damaged plug given to me by the BoXZY team. I recommend this approach as it will be very simple to remove my heated bed when needed.
    • Locate the hole that allows the bottom limit switch wires to come through. Feed your heated bed wires through

    • In my case I used a damaged plug given to me by the BoXZY team. I recommend this approach as it will be very simple to remove my heated bed when needed.

  8. Locate heated bed input at the bottom of the board. It's the only one without wires installed. Install Positive wire to the far edge and negative wire to the inside. Unscrew the flathead screw and place wire into the slot, tighten down Check that the connection is secure and does not pull out. Verify there are no loose or free wires shorting between the positive and negative terminals.
    • Locate heated bed input at the bottom of the board. It's the only one without wires installed.

    • Install Positive wire to the far edge and negative wire to the inside. Unscrew the flathead screw and place wire into the slot, tighten down

    • Check that the connection is secure and does not pull out. Verify there are no loose or free wires shorting between the positive and negative terminals.

  9. Locate thermistor plug for heated bed. It's the top plug and the only one without  a plug installed Install your connector or leads into the plug. The middle pin isn't used. Connect the two wires to the top and bottom pin. Order doesn't matter, there is not positive or negative.
    • Locate thermistor plug for heated bed. It's the top plug and the only one without a plug installed

    • Install your connector or leads into the plug. The middle pin isn't used. Connect the two wires to the top and bottom pin. Order doesn't matter, there is not positive or negative.

    • You can hijack the second plugs connector if you'd like (the actual wires and plug not the spot on the board). It's for the #2 extruder thermistor which doesn't exist yet.

  10. Reinstall your back cover. Place the bottom to the machine first and plug the top fan plug back in that we removed earlier. Visually inspect your heatsinks and make sure they are installed and not hanging off or missing. Use your fingers to push the wires to the sides as you bring the top towards the machine. This will keep them from getting caught between the fans and the heatsinks and blocking airflow. Place the cover holes over the bolt heads and slide down. Careful about the filament drive harness, you must make sure it's in its own groove.
    • Reinstall your back cover. Place the bottom to the machine first and plug the top fan plug back in that we removed earlier. Visually inspect your heatsinks and make sure they are installed and not hanging off or missing.

    • Use your fingers to push the wires to the sides as you bring the top towards the machine. This will keep them from getting caught between the fans and the heatsinks and blocking airflow.

    • Place the cover holes over the bolt heads and slide down. Careful about the filament drive harness, you must make sure it's in its own groove.

    • Screw down cover.

    • Turn on power to verify there are no wires hitting the fan blades making a scratching noise.

  11. Tape the top of the platform with a layer of Kapton tape and then a layer of harbor freight quality painters tape. Zip tie the wires so that they will not get caught between the bottom of the ballnut and the base.
    • Tape the top of the platform with a layer of Kapton tape and then a layer of harbor freight quality painters tape.

    • Zip tie the wires so that they will not get caught between the bottom of the ballnut and the base.

  12. The power cable should be disconnected but the USB cable should be installed in the computer and BoXZY for this step. Open the Arduino software and load the firmware file found in "Files" here. Locate and click the Configuration.h tab
    • The power cable should be disconnected but the USB cable should be installed in the computer and BoXZY for this step.

    • Open the Arduino software and load the firmware file found in "Files" here.

    • Locate and click the Configuration.h tab

    • Click Contrl+F and search for "Have_heated_bed"

    • Adjust the numbers to match what is shown on the third image.

    • Load the edited firmware files to the board. You should see a "done uploading" at the bottom when this is completed correctly. Use the link below for instructions, follow steps 2-3. Updating Your Firmware

  13. In the interface go to your printer settings. Under the "Extruder" tab enter 120 as your max bed temperature. Go to the config selection at the top of the interface while connected to your machine. Click "Firmware EEPROM configuration". Adjust the "Extr 1 PID Drive Max" to 150. Adjust the "Bed PID Drive Max" and PID Drive Min" to 255.
    • In the interface go to your printer settings. Under the "Extruder" tab enter 120 as your max bed temperature.

    • Go to the config selection at the top of the interface while connected to your machine. Click "Firmware EEPROM configuration". Adjust the "Extr 1 PID Drive Max" to 150. Adjust the "Bed PID Drive Max" and PID Drive Min" to 255.

    • Click OK at the bottom. Close and reload the EERPOM settings to verify it saved.

  14. The temperature can be controlled and viewed in the manual control window. You will see a new bar appear. Print away! Print away!
    • The temperature can be controlled and viewed in the manual control window. You will see a new bar appear.

    • Print away!

Conclusion

First I want to thank the BoXZY team for letting me prototype and problem solve this setup on one of their testings units. I can't believe how easy it was. It's all there for you; coding, output, inputs, and control.

I highly recommend having a spare Arduino Mega for this installation. Though I did not damage mine, a wiring mistake can easily do so. They are around $20 and are easy to replace.

This system will allow you to get to 100C in about 25 minutes, 35 for 110C and 40 for 115C. It has no problem maintaining it. We are using nearly every ounce of BoXZY's excess power here, so some of the PID max tuning may need to be done for certain situations. However these settings have been 100% reliable for me so far. If you do end up pulling too much power your power supply will shut off (it will not harm it). You must disconnect the plug from the machine and the wall for it to reset. Let me know what you think and feel free to ask questions. I'll continue to improve the manual as times goes on.

Just Helping

Member since: 03/08/2016

6,858 Reputation

6 Guides authored

57 Comments

Awesome guide! Thank you, greatly appreciated. I still will likely start with this because of the low cost, but in the end the heat times aren't something I will want to deal with in the longer term. If we upgrade to an additional 24V PSU, how long do you think it would take to heat fully? How would you wire this with 24V supply, but still controlled by the Arduino? Thanks again for your contribution!

Jakrey Myers - Reply

Thank you so much! I will be adding that process soon: You wire the thermistor as normal. For the two power wires coming from the machine they get wired to a relay. They control the on and off for the relay, your power wires from your power supply go to the input of the relay, the output goes to the heated bed. When I do the write up I'll likely go with a 110V direct powered "oil pan" style heater as these don't require an additional power supply, just a relay. But I haven't decided anything at this point. You can fairly easily get heating times down to a matter of 5-10 minutes with enough power. However, higher power systems scare me a little. Mainly because the temperature can run away very quickly and it's such a large surface area. I'll keep everyone updated as I do more tests. If you see oven mitts in my photos, you'll know why :)

Just Helping -

You can significantly speed up heating times on this setup by truly insulating the bottom of the platform and any excess surface area on top. You could easily cut it by a 1/3rd.

Just Helping - Reply

When you say truly insulating the bottom of the platform, what do you mean exactly?

James Nutter -

Thank you so much for this! I have learned so much from you already.

Ken Gross - Reply

Thank you for the guide!

For those of us who can't help but have the heat pad over-nighted, would this one work just as well? http://amzn.com/B015369X80 (Anycubic Reprap 3MM MK3 Aluminum Board PCB 12/24V Heatbed)

Thanks again!

Matthew Smith - Reply

It should, yes. However there can be slight differences in circuit resistance between manufacturers. If it's a little lower it's no problem, too much higher and it will draw more power than mine did. This isn't a big issue, I can direct you to change some settings to reduce the power use. Just let me know if that's the case and I'll help you solve it.

Just Helping - Reply

I've got it ordered! Will let you know how it turns out!

Matthew Smith - Reply

I think you have the resistance and power turned around. A lower resistance will take more current and thus draw more power. You mentioned only heating half of the board. Does the heat radiate that much throughout the aluminum bed to keep even heat across it? Or the elements/ PCB traces are interleaved and cover the entire space. How much "spare" power does the BoXZY have? Assuming 100% drive on its standard single print head. (My BoXZY gets delivered later today!)

Great Guide.

Renaissance Tinker - Reply

Thank you @darian_k, that's an error in my comment. It heats the area I outlined in red on one side of the board. The temperature is surprisingly even across the aluminum platform and near perfect inside the build area (because it's smaller than the size of the overall print platform). From my experiments, the machine uses under 80 Watts even while running all 3 axes, the filament drive, the nozzle heater, and all fans at 100% simultaneously.

Just Helping - Reply

This is based on successfully using an 80 Watt power supply for 48 hours of non-stop printing. There is also some creative power use leaving excess power available for the heated bed. BoXZY uses PWM to control the power draw for many of its component which allows them to be driven at perceivable identical times, even though the power is provided intermittently between them. This is the only reason I can run a heated bed that has a resistance of 2.4ohms with 19V on only 200 Watts for the entire machine.

Just Helping - Reply

Would it be possible to update the BOM list with an item number and the quantity, as well as a working link (I am having trouble locating wires/plugs). Item numbers could be indicated in the main profile photo (preferably w/ balloons).

I am not sure if application of Kapton tape is appropriate (as shown above). Kapton serves as an insulator.

Since we are covering it with painters tape (not printing directly on it), a better approach might be to use Kapton on the other side (covering bottom heating element) ....

But I am new to 3D printing, so what you have might be perfectly correct.

Master Yoda - Reply

I'll definitely try to get a more detailed bill of materials put up. You're right on, Kapton is an isulator, a pretty good one. I definitely recommend covering the bottom as well with some type of insulation. The idea with the Kapton tape on top is to slow down the heat transfer through the air. Plastic conducts heat much slower than air or aluminum, so this way the speed at which your platform can conduct heat externally is better matched to the plastic you're printing with and you won't lose as much heat to the atmosphere (the whole path of least resistance, heat storage thing). Although, at this point it may just be preference, there's no real scientific method behind it, just a half-baked observation on my part :)

Just Helping -

I followed the instructions and now have a heated print bed for BoXZY! Thanks so much for the walk through!

Matthew Smith - Reply

Strangely the extruder temperature is showing -26ºC. I disconnected and reconnected but seem to have the problem still. Any ideas?

Update: When the system is idle the temperature shows at 243.5ºC. I set it to 210ºC and click Print. The extruder temp bounces back for a moment then shows -26ºC. It attempts to print but of course since the extruder isn't hot the filament can't be pushed through.

Matthew Smith - Reply

This is very easy to trace. There's a very partial short in the extruder thermistor circuit. It's most likely where it connects to the board since you just had the cover off and added a plug in that general area. There is a little red wire that is piggybacked into the thermistor plug for the hotend (extruder). Unplug the lowest thermistor plug on the main board and make sure no strands from the independent red wire are shorting between the the top and bottom pin (it has happened), or the middle pin which can be clipped away entirely. To reinstall twist the end of the independent red wire very well and insert it into the socket of the thermistor plug (red random wire to WHITE wire on the plug), then set the plug in as normal, making sure the red wire is tightly in place and has a good connection to the white wire side of the plug. Hopefully my description wasn't confusing. Its fairly likely that's the issue. Let me know if you need more information or details or it doesn't solve it.

Just Helping -

I followed your troubleshooting instructions but haven't had any luck. To avoid hijacking your guide I made a new question here: Installed heated bed, Extruder no longer working..

Matthew Smith -

This looks great! I got my bed and thermistor, any suggestion on where to look, and what to look for in terms of the plugs and wires if we don't have something lying around?

Thanks for putting this together!

James Nutter - Reply

Definitely! Any auto-parts store. A 4 pin trailer harness should work perfectly.

Just Helping -

Just make sure you wire the covered ends of the plug to power, and the exposed ends to the heated bed. That way you will avoid a power short, as only the end that does not produce power is exposed when they're not connected.

Just Helping -

And I was thinking it couldn't be that simple haha, thanks for the reply!

James Nutter -

Secondary question, I didn't have the heatsink plaster on hand so I ordered, but it looks like it will take a while to get here for some reason, is there a difference between this and something labeled heatsink compound that is sold at electronics stores for mounting cpus? Its unfortunately the one thing holding me up.

James Nutter -

In my experience, heat sink -plaster- is a material that cures to a semi-hard rubbery state. Most thermal compound that I have seen has a greasy base, and does not harden. I would put some kapton tape over either material, just to make sure that the thermistor stays in place.

Irving -

@Irving Thank you, that was the impression I got from reading the description, but it is always hard to tell without having handled something personally. I will just have to be patient.

James Nutter -

Some boards have a built in thermistor. Are these appropriate instead of the installation into the edge of the plate? I am looking at a 500 watt AC heater to be switched by a relay. It has a built in thermistor and comes with 3M adhesive to glue it to the bottom of the build plate. What do you think?

http://www.amazon.com/thermistor-KEENOVO...

James Osborn - Reply

That's the exact system I want to play with. Let me know how it goes! It looks like it uses the same type of thermistor as BoXZY so it should be perfect. My only concern would be reading the temp from the heater and not from the aluminum because their temperature may differ slightly during initial heat-up. Nothing to worry about if you let the temperature settle for a minute or so after initial heating.

Just Helping -

The pad arrived from China. The fit is good. I cleaned the bottom of the build plate using denatured alcohol and applied the pad using the included 3M self-adhesive. I warmed it with a heat gun and burnished it down - hopefully it will stay stuck. I drilled a small hole on the edge of the build plate so that I could use a zip tie to hold the wires firmly after installing some cable sleeve and shrink tubing. Installed on the BoXZY, I drilled another small hole in the bottom plexiglass so I could use another zip tie to hold the other end in the correct location and threaded the bundle through the same hole used for the Z motor cabling. I have an appropriate relay so the next steps will be to hook it up and modify the firmware. A few photos are linked below.

http://www-eng.lbl.gov/~jrosborn/BoXZY/K...

http://www-eng.lbl.gov/~jrosborn/BoXZY/p...

James Osborn -

That is beautiful! I received some new information about the heated bed install and some feedback from other users. Please go here to fix an issue before using the bed heater: 05-06-16 Incorrect ground wiring

Also, make sure you are using shielded wire for all heater wires coming from the main board even if they are just for switching. Can't wait to see the system up and working!!

Just Helping -

OK got the AC heater working. I didn't see the warning about incorrect ground wiring or shielded wire, but I don't seem to be having any issues. I did twist the wires from the bead heat terminals out to my relay and the AC line to the heater pad and relay are all outside of the BoXZY electronics enclosure. It heats very quickly. The build plate temperature seems to lag the silicone pad/thermistor reading by about 5 to 10 seconds, not bad at all. I found during testing while not printing that it cycled on for about 2 seconds every 7 seconds to maintain 100 C on the bed (normal room temperature environment). I used a polarized AC cord and switched the hot wire with the relay.

James Osborn -

When I actually tried a test print for PLA the BoXZY interface went with 70 C bed temp and 188 C extruder temp which is fine so I gave it a whirl. Seems to be printing nicely at this point. However, I hear my relay clacking on and off a lot. Usually it is quiet for a second or so, then clacks on and off 3 or 4 times in a row at about 3 or 4 Hz. I think this is unneccessary (and good thing I bought a couple relays because it can't last long doing that). What firmware settings should I adjust to tone it down? Basically if the thermistor reading is not off by more than a degree, I would prefer it to NOT cycle.

James Osborn -

A couple photos. The first shows my connections. I did it all up with the cover off and tested it first. I didn't snap a photo, but after buttoning it up, I just coiled the excess wire bundle with relay outside of the enclosure and secured with zip ties. The second photo shows some printing in action.

http://www-eng.lbl.gov/~jrosborn/BoXZY/A...

http://www-eng.lbl.gov/~jrosborn/BoXZY/A...

James Osborn -

I can see from my wiring photo that my thermistor signal/ground wires are backwards. Not sure why it is not causing me problems. I will reverse them next time I open my BoXZY back up.

James Osborn -

Hey Just Helping - did you seem my query asking about how to change the duty cycle on the heat control? It seems to cycle my relay far more than I want. Also something happened and my extruder is no longer heating properly. Does something burn out in the Mega with the backwards ground that can cause this?

James Osborn -

I just saw it! I'm sorry I missed it before. Can you post a question to me in the main answers area? It will be easy to go over with you that way.

Just Helping -

Ok, because i'm impatient to get you up and working properly, I'll go ahead and get started here. To change the duty cycle go into your EEPROM settings and look under "Bed". Change the "Heat manager" to 3 (it's currently 0). This makes your heated bed run under what's called a dead time controller. Still under Bed locate the "P-gain" setting. Here's how to tune that number: https://www.repetier.com/dead-time-contr...

Just Helping -

Once you've gone through that, you'll still need to fix the wiring on the thermistor and make sure you're using a good, relatively short, USB cable with shielding and ferrites. The extra EMI from the switching heater output has been known to cause some temperature reading issues for the other thermistor inputs. Doing these fixes and using shielded wire should resolve the issues.

Just Helping -

OK I am back in business with a new ATMega board and swapped extruder wires. I also detached the extra wire (Gary's mod) though I have not fixed my laser yet. I verified that my extruder is heating again. Then I set about tuning the bed heater. I am a little confused by your statement to change the heat manager to 3 because we already did that for the heated bed in the first place (so I didn't need to make that change). Then following the reference page you gave, it talks about measuring the dead time, but there does not seem to be a parameter in Configuration.h or in the EEPROM settings in the BoXZY interface to set this. You mentioned the PID gain setting, but the article doesn't mention this. It does talk about lowering the drive max to 140 versus 255 in my Configuration.h. I'm not sure which values to adjust or how to predict good changes to make. Suggestions?

James Osborn -

I tried playing with the values. Firstly I found that lowering the Drive Max values caused my relay to clack on/off more rapidly which is what I am trying to stop. It seems like this is kind of a duty cycle. For the relay, I want a 100% duty cycle, either ON or OFF, not switching back and forth. Then I started fiddling with the bed PID gains. I found it was better by drastically lowering them. I eventually settled on the values in the EEPROM for the bed of 2.5, .5, 10. It is definitely better than the stock settings (196,33,290). I notice that the interface calls the Extruder P value "P-gain/dead-time" and uses a value of 5, presumably meaning 5 seconds. My dead-time as measured by the procedure in the link you referenced is about 2.5 seconds so that is where I got that value to plug into the P-gain for the bed even though it is not labeled as "P-gain/dead-time".

James Osborn -

For reference to anybody interested, the 500 Watt AC silicone pad I have is able to go from room temperature to 100 C in about 3 minutes! This is a pretty nice upgrade.

James Osborn -

Awesome! Looks like you figured it out. Yes, the P- gain setting for the bed is the dead time setting. The PID drive settings adjust what frequency your output is. 255 is the highest frequency, 1 the lowest. Max settings is with fans running, Min is without. For the bed they should be the same. You can actually adjust which frequency it's using to vary, but that is a little more complicated. I'll try to get more into it at another time.

Just Helping -

for 24v i would recommend replacing the entire setup with this ($40) it will take the unmodified BoXYZ firmware i believe. (My daughter has one in her very small Mini Kossel Pro it replaces the UM2 board AND the Arduino Mega2650. It has better MOSFETS WITH heat sinks. Better/More PWM and will handle 24v input, and Mixed 24v extruder/bed/motor and 12v fan power if desired. its better cooled and more reliable in my opinion. if i pick up a spare i may do a guide. yours is excellent. thanks!

Michael Shievitz - Reply

Finally got everything I needed and worked through the guide and have a working heated bed! Thank you!!

James Nutter - Reply

I was running a print yesterday and after about 7-8 hours (and within only a few minutes of completing) the power supply shut down. I am now assuming that the heated bed drew too much power. Is there a way to limit the power draw marginally to avoid this happening again in the future? I would be more inclined to have the hot bed not heating at maximum, and have my program finish, than to have everything shut down and effectively ruin a print before it is finished.

I happened to sit down just before it happened, and did make a mental note that the cooling fan in the 3d print head had come on just prior. It was working heavily on the last little area of the top, so I am guessing the hotend needed a higher rate of consistent power to stay at temperature. Relative to the first prints I made using the bed where I had no issues, the surface area the printer was working on at this point was much more focused. Is there a way to automate having the heated bed turn off if the nozzle requires peak power?

Thanks!

James Nutter - Reply

Or could it have something to do with the cooling fan turning on? Any insight or fixes are appreciated much!!

James Nutter -

This definitely sounds like a situation with too much power draw. It's possible to write in code that would eliminate such an issue, but it would be very complicated (the BoXZY team is working on something to that effect). You can reduce the power draw by adjusting the Extr 1 PID drive Max. Since when the fan comes on the heater requires more power, this setting allows you to adjust how much the power increase is in that case. If you followed the guide it's set to 150. I would reduce it to 100 and test if that solves the issues you're having. Also, the fan is way overpowered, so reducing the max fan in your prints to be below 30% would reduce the need for your machine to bump that power as much. You'll also want to make sure you adjust the fan power setting for bridges as well. It's a separate line.

Just Helping -

Great, thank you! I will try that.

James Nutter -

It looks as though some implementations of this heated bed may overload the Boxzy power supply, causing it to shut down. The extra current draw may be too much for the existing power supply. I would recommend an AC powered heater instead. I used the following Keenovo kit with excellent results and no extra load on the power supply.

http://www.ebay.com/itm/281676789120

Gary - Reply

Or go with the Keenovo pad I spec'ed out, and a relay to use the BoXZY to control it:

http://www.amazon.com/thermistor-KEENOVO...

http://www-eng.lbl.gov/~jrosborn/BoXZY/K...

http://www.amazon.com/HM78-12A-S-DC12V-G...

http://www-eng.lbl.gov/~jrosborn/BoXZY/A...

Bed PID values:

P=2.5, I=0.5, D=10.0

It is kind of nice to be able to use the BoXZY interface to control the heating. My pad is twice the wattage at half the cost. It should be able to heat faster and respond more quickly and it's cheaper! It looks like with Gary's setup (above) you would be controlling the temperature with the heating pad control box, completely distinct from the BoXZY control and printing interface. Correct me if I am wrong Gary!

James Osborn -

Thanks for this, Gary. Exactly what I was looking for so as not to overload the power supply.

Noel -

So I have been encountering an issue today, I have tried a print repeatedly, and after a couple of layers it keeps giving me this error:

17:43:15.560 : extruder 0: working

17:43:15.564 : heated bed: temp sensor defect

17:43:15.568 : Error:Printer set into dry run mode until restart!

And continues with the program but turns off the extruder and no longer recognizes the heated bed. I checked connections, and everything seems to be unchanged. Any idea why it is doing this?

James Nutter - Reply

Your printer is entering into protection mode, this most likely means there is a short in the wiring for your heated bed thermistor. When the machine does not measure a resistance from the thermistor that translates to between 0C and 115C it will do this. It could also be that you've set the bed above 115C which is the safety limit in the firmware. I would start by going through your heated bed thermistor wiring and looking for defects.

Just Helping -

I have had the bed set at 50C, so not that. I checked all of the wiring for a third time to be safe, and resecured all of the connections in the thermistor circuit did not see anything out of place, and it didn't solve the issue. It actually seems to have gotten worse, it goes straight to protection mode now, whereas I was previously able to turn it on and have it get to temp and even start printing before the error popped up.

Could this be caused by the thermistor coming into contact with the aluminum bed? I thought I did a good job of coating it when I installed, but if somehow it became dislodged since and was able to make contact could that cause this error? If so, is it possible to just pull it out carefully and reapply the plaster and reinstall it?

Thanks!

James Nutter -

It could definitely be the thermistor touching the aluminum and causing a short. It could also just as easily be a defective thermistor. Personally, I would pull it out and replace it entirely, but you could also try to remove it and re-install it. There's no reason why that should harm anything.

Just Helping -

Hi everyone... I decided that I wanted to add a heated bed to my Boxzy and have found this guide super helpful. I do have a few questions that I would like to have answered before I go ordering any parts. I would also like to create a guide myself after completing my heated bed to share with the community.

1. Where is the Arduino Mega 2560 needed in this setup?

(then is there an advantage to using the GT2560 3D printer controller board as Michael Shievitz mentioned?)

2. If going with the Keenovo pad that James Osborn speced out above what 500 W heater was used or recommended?

It seems like having a dedicated power supply and the Boxzy controlling the heated bed is the best way to go.

Sorry if these have pretty obvious answers. I am trying to understand so I have everything I need when I order.

Thank you,

Matthew

mtr - Reply

Success! Finally!

mtr - Reply

Hi dere, First of all I want thank you for the really good guide. I have some advantages to share with you. In my case I have a power supply with 230V-24V an 5A because in Europe we havent 110V. The board works with 16V - 24V DC. If you have to less power supportet you want heat up the heating bed up to 90° or higher. Over my heating bed i have also a glass plate. I tried a lot of stuff to get the best bonding. and its also easier to clean.

The parameters like in step 13 works with my heating plate not so fine. I had to change the Bed Heat Manager to 1 and Extr. Heat Manager to 1.

With PLA i print with 202°C, flow of 96%, Heating bed on 65°C. Without Cooling. If you want to get better performance with Cooling turn the Cooler in the Extruder to 180° so that the flow goes from the Extruder head to the top.

Karl-Heinz Pichler - Reply

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