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V2 Bed Over 80C??

Discussion in 'General Questions' started by adikted2astro, Apr 29, 2020.

  1. adikted2astro

    adikted2astro Active Member

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    Hey guys, so about 2 years ago (maybe), I was printing with ABS or maybe TPU; something that required a lot of heat on the bed (V2). I took it to 100 C and it worked for a while, then the bed heater cable fried - quite literally - along with part of the main board, and of course, the bed itself. So I called Robo and they told me to never take the bed over 80C, that in reality, it shouldn't go above 70C because a lot of the beds were doing this. That kinda sucks because it's supposed to be able to do 110C. Anyways, I am in need of a bed that can go to at least 100C. Does anyone know of a way to do this with the V2 bed at all? Or, would I be better off designing and building my own bed with a reliable heater that can achieve high temps?
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Probably (much like the R1 series) if you want a strong and reliable heater you need to go after-market and install your own (which you can drive with a relay/MOSFET from the signal the Robo control board is using to turn the bed on/off).

    There are some really nice silicon pad heaters that will do the job (and I would suggest you get one that is 110 volt A/C driven rather than any DC driven heater). Those are nice and they heat REALLY quick and maintain it well.

    So, it would be a bit of a project :) But not a huge one.


    I am NOT saying to use this one, but it is an example of what I mean (you might find one sized better if you look around). One of the bed heaters on an R1 is out of commision and this is the sort of heater I am going to replace it with.

    https://smile.amazon.com/Silicone-310x310mmx1-5mm-Creality-Printers-Adhesive/dp/B07FB1TZ25
     
  3. tkoco

    tkoco - -.- --- -.-. ---
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    If the sensing thermistor is different from the stock thermistor, you probably will need to make a change in the firmware to account for the difference. Another member of this forum wrote up a posting detailing the thermistor issue.
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The thermistor on that pad I linked is NTC 100K thermistor ( Beta 25/50 3950K)

    So -- type 1 in Marlin (which is same as stock for the R1 series -- not sure on the R2)
     
  5. tkoco

    tkoco - -.- --- -.-. ---
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    @Lance Weston might be able to answer the R2 thermistor question.
     
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  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Looking back at some of his emails I am certain that the thermistor is the 3950
     
  7. Lance Weston

    Lance Weston Active Member

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    The type 1 is an epcos/TDK B57540G1104+000 The table is for a 100K thermistor with a Beta of 4092 @ 25C/100C. The curve is very close to a 3950 and more than likely a 3950 is installed. A 3950 is a 100K thermistor with a Beta of 3950 @ 25C/50C. I think that the wrong curves are used on both the bed and the hotend, I believe both have 3950's installed. If you would like I can generate a hex code for you to load with the 3950 table used for both bed and hotend.
     
  8. Lance Weston

    Lance Weston Active Member

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    The type 12 for the bed is listed as a Vishay NTCS0603E3104FXT but the type 12 curve is for a Murata NCP__WL04 and I think what is installed is a 3950. The curve deviates from the 3950 making the bed 8C @ a setting of 70C
     
  9. Lance Weston

    Lance Weston Active Member

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    Here is the problem. The connector used has contactacs rated at 3 amps. Three contacts are used and the bed draws 6.7 amps. The contacts are generally rated for a 10C rise. The connector is directly mounted to the bed. That means the connector temp has it's own temp rise plus the temp of the bed. The 10C rise goes up as the connector gets hotter. At 80C the connector is probably rising 15C for a total of 95C. At that temp the contacts oxidize with the moisture in the air, raising the resistance of the contacts raising the temp of the contact and eventually one gets to hot transferring the current to the remaining two which now get real hot and the connector fails.

    The solution I have taken is to purchase computer extension cables I cut off a couple of inches of the female ( with the male pins ) and solder the red and yellow to the bed heater and the two blacks to the thermistor. I now take the remaining length of cable and install the two connectors bed and thermistor to the cut wires. Use it instead of the original cable. The connectors are 9 amps and not sitting at the bed temperature. The upper limit of the bed temperature now is the thermal fuse soldered to the bed, which you can bypass if it blows.

    I got tired of replacing the bed and cable connectors.


    https://www.ebay.com/itm/36-4-Pin-M...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
     
  10. adikted2astro

    adikted2astro Active Member

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    Thanks for all the replies, I appreciate it. I'm going to try and modify one of my extra beds with a more reliable heater that can reach at least 110C and sustain that temp for as long as I want it to. I have an old V1 and an extra V2 - the one I fried. However, I may have to build my own bed and just make sure I can add the magnets in like the Robo beds have because I do like that feature. I don't need the heat most of the time, but for flexibles and Nylon I definitely need it, or a heated chamber. I haven't tried ABS in a while, so I'll see how that goes this weekend. This past weekend I printed an adapter for a doctor at my local hospital who wants to use it to install a filter on a snorkeling mask (the new ones, not the old design). I wanted to print it out of nGEN Flex so it would fit universally over any of the brands of snorkel masks out there. I was most definitely successful, but only after a couple of failed prints. I had to brim the s..t out of the part on the first layer, raise bed temp to 80C, and use a liberal amount of glue stick. Ended up working well though and the part was gorgeous, nearly flawless.
     
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  11. adikted2astro

    adikted2astro Active Member

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    That's extremely useful information, thank you! Ima gonna do this for sure. You just used those Molex connectors? I have a ton of those ready to go. I would like to ask a favor though.....do you have a tutorial up on the forum for this mod? I won't run my bed that high again until I do this.
     
  12. Lance Weston

    Lance Weston Active Member

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    I will post with pictures tomorrow.
     
  13. adikted2astro

    adikted2astro Active Member

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    Awesome, thank you!
     
  14. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    I have modified all of my R1 style printers to use Anderson powerpoles.
    The wimpiest version of those is 15 amps. (we used them all the time in robotics applications)
     
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  15. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    one of our deltas uses deans connectors -- similar in concept and they work good as well in high current DC circuits.
     
  16. adikted2astro

    adikted2astro Active Member

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    I use power poles in my R2 for a lot of things, but not the bed. I wasn't aware of the oxidation issue at all. Now that I know, it makes perfect sense.
     
  17. Lance Weston

    Lance Weston Active Member

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    Here is the procedure in pictures. I clipped a piece of plastic off the bed frame to pass the cable because the connector is well fixed to the bed and soldering to it is safer than just soldering to pads on the bed. I used heat shrink tubing to keep things neat. I drilled a hole for the tywrap. The bed draws a max of 6.7 amps which is important for connectors but the wire only cares about average current. The cable I am using appears to be about 20 gauge and is fine.

    Your bed that died probably has an open thermal fuse ( pictured on the bottom of the bed). Just short it out and you should be back in business. It was probably put there to protect the connectors.
     

    Attached Files:

  18. Lance Weston

    Lance Weston Active Member

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    This is the original R2 code modified to use a table that I generated (3950) for both the hotend and the bed. This gives me good results always within a few degrees of measured. I figure it must be right on because all of the component tolerances and still within a few degrees. The actual parts used are probably 3950's.

    https://drive.google.com/open?id=1qfY8-dQpO4ppbUjqpoGBrPa_-3rGwnPj

    In the Marlin folder you will find "Marlin.ino.mega.hex". Load the hex file onto a USB drive formatted with FAT32. Plug in the USB drive and on the LCD go to FILES -> USB. Select "Marlin.ino.mega.hex" and run it. In a minute you will be running with the new tables.

    I included the code so that using Marlin 1.8.9 you can go into the configuration.h file and change back the temp tables for the hotend and the bed. The original values are in the comments. Download Marlin 1.8.9, which is what I have be compiling with, click on Marlin.ino in the Marlin folder and open configuration.h. Make the changes. Now goto SKETCH -> EXPORT COMPILED BINARY. When it is done compiling you will have the original code to load back into the R2.

    #if RBV(R2)
    #define TEMP_SENSOR_0 14 // 1
    #define TEMP_SENSOR_1 0
    #define TEMP_SENSOR_2 0
    #define TEMP_SENSOR_3 0
    #define TEMP_SENSOR_4 0
    #define TEMP_SENSOR_BED 14 //12
    #endif
     
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  19. Lance Weston

    Lance Weston Active Member

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    I looked and the Marlin Arduino is not all that easy to find. Here is a link:
    https://drive.google.com/open?id=1IyeNEKdW3KH3-SoI0Oe_LZBBG-V0agYO
     
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  20. adikted2astro

    adikted2astro Active Member

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    Awesome, thanks for all the info. I am going to try changing out the wires first and see if I can get my bed up to 100 C.
     

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