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Heated Bed Heater Size R1 Plus

Discussion in 'General Questions' started by Lee, Feb 6, 2016.

  1. Lee

    Lee Member

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    I have noticed that the shipping R1Plus heated bed shows the following. With temperature set to 100, the center of the bed show 100 but out where the small squares are in each corner, the temp is around 40. I am trying to get ABS to stick to the bed better and it appears that a different heater would be a good idea. I understand that the existing heater is 100w. I am looking at either a 200 x 200mm or 200x300mm silicone pad at around 150 watts. So, my questions are:

    1. What is the size of the existing heater? I haven't pulled the cork off yet. Still using the printer.
    2. Is the existing heater a silicone pad?
    3. Will 150 watts be enough to get the heat more even out further?
    4. Can the Ramps support 150 watt without pushing it too hard or do I need a solid state relay and grab power off the power supply?
    5 Will 200x200 work okay or do I need 200x300?

    Any other thoughts you might have are welcome.
    Thanks
     
  2. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Input on the RAMPS v 1.4 board for heater bed is only 11A. It can only reach that if sufficiently cooled, 100W = 8.3A at 12V, so if you go to a 150W heater you should use an SSR as 12.5A max will routinely exceed the RAMPS power rating.
     
    Lee likes this.
  3. KTMDirtFace

    KTMDirtFace Well-Known Member

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    You could try Buld Tak on your bed, i have had pretty good success with ABS on it. But ABS likes to peel up regardless on big prints. ( even on my other printer that the heater covers the entire thing )

    [​IMG]
     
    #3 KTMDirtFace, Feb 6, 2016
    Last edited: Feb 6, 2016
  4. Lee

    Lee Member

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    Thanks for the input. I have some Build Tak. It does help but I want to do more. Right now I am mounting a 60mm cooling fan to blow air over the Ramps board. The next task will be to get the heater to be as good as it can be (will use SSR as suggested above). Then I'll add a heater to the enclosure (Mike's enclosure) to get the enclosure to around 50C. Between Build Tak, more uniform heating, and a heated chamber, I hope to get the printer to print ABS (and nylon) easier. The main question is what wattage and size heating pad is best.
     
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  5. KTMDirtFace

    KTMDirtFace Well-Known Member

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    Cool good luck, I don't know the answer to your wattage and heating pad question sorry.
     
  6. Mike Kelly

    Mike Kelly Volunteer

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    The existing heater is 8.2"x8.2" so around 208mm.

    You can go bigger, say 254x254+. Since the bed is only 254mm wide you can't go wider but you can go longers. Say 300ish

    You'd want at least 220 on the X otherwise what's the point.

    The stock heater is ~150W. Or 1.4ohms. This is pushing the current rating of the RAMPS polyfuses and you should use an external board like this: http://www.makerfarm.com/index.php/heat-beds/heat-bed-relay.html

    If you can find a larger heater at that wattage you could use it, but most likely the best you'll find is 200W
     
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  7. Lee

    Lee Member

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    Hi Mike,
    I measured the bed with an Infrared thermometer. The center around the R gets to proper temp say 100C. The 4 corners where the flames are gets to about 40C. This tells me that 1. the heater is too small a wattage or 2. the heater does not distribute its heat throughout its pad. Using a 200x200 is fine if I can get the same area to be evenly heated. Jerry says it is a 100 watt. Do you know if it is a silicon pad? I was thinking that if I go to 150 watts as a silicon heating pad then I might be able to get the entire bed to a more even temperature. If I could find someone who says "Our Pads will deliver an even temp throughout" then I might even be able to go with 100 watts. The main reason for all this is to be able to print larger ABS items without the corners breaking loose or warping. After taking care of the bed problem, then I'll look at heating the enclosure (your enclosure). I am hoping that cleaning up the bed problem will generate enough heat that a heater will not be necessary. I am using ABS slurry and it sticks very well as long as the bed is hot.

    The relay you indicated looks good. Will it handle 150 - 200 watts? The page does not indicate. Is it a SSR? I believe you were using an SSR that you got from Amazon. Is this better.

    FYI. I installed an extra fan blowing on the Ramps board. Not needed but want everything to be cool

    Thanks
     
  8. Mike Kelly

    Mike Kelly Volunteer

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    You can calculate the heater power yourself if want by measuring the resistance.

    I typically measure around 1.1-1.2 ohms of resistance. At 12v that's ~120-130W. Which a seller would probably call 150W. I did the math once and you'd need around 130W just to reach 100C, which makes sense because the resistance across the bed would drop at high temperatures, increasing the supplied power.

    A while ago someone posted pictures of various heated beds temperature distribution, and the Robo was the worst of them all. Very large distribution in the heated area. Then naturally as you left the heated area it dropped off rapidly.

    If you're measuring 40C off the heater that makes sense, but you would not see a 60C differential. Don't confuse the markings on the bed with actual heater dimensions :) YOu can see clearly where the heated area is by applying slurry to the bed hot.

    The heater will work well enough to heat your enclosure. Around 40-50C depending on your ambient temperatures. Which is enough for ABS

    The reason I went with a SSR was because I upgraded to 24V thus the supplied power on my heater was something crazy like 450W. I ended up doing some chopping in the firmware to reduce that, but it can still pull enough power

    I don't think that one is a SSR but maybe just a relay. You don't really need a SSR unless you have a really fast acting control circuit, which the stock robo uses Bang-Bang so you wouldn't. They claim it works with their 200W beds. You can zoom in on the relay and get the Omron part number and look that up
     
    Lee likes this.
  9. Lee

    Lee Member

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    Thank you. That was very helpful.
     
  10. Mike Kelly

    Mike Kelly Volunteer

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  11. Lee

    Lee Member

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    Thanks. I called the author and he said I should use a silicon heating pad. He did not say what little tricks he used to ensure more even heating. I got the impression that he was thinking that the Robo does not use a silicon heating pad. Or maybe he was implying that they use an inferior heating pad. Do you happen to know what they are using?
     
  12. Mike Kelly

    Mike Kelly Volunteer

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  13. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The good news ABS is the only one out there that picky and tricky to print with.
    Given all the other choices for filament now available it will soon be the Red-headed step-child of filaments (and already is for us).

    Even the steep drop off in bed temps doesn't affect my nylon, PET, TPE, TPU or most of the other filament types I tried. PC was the next most needy in terms of bed heat. Most are happy with as little as a ball-park 40-50c on the bed area.

    So if you materials requirements can be met with something else you can avoid the hassles.

    If you really need ABS for some reason then Mike is right you can beef up the heater bed a good amount.
     
  14. Lee

    Lee Member

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    Mike - Thanks for the info. I don't need another picture. Just knowing it is Kapton is good enough. I couldn't find anything that says one is better than the other. But, I'll try the silicone heater and see how that goes. I'll also order one of the relays you indicated.

    Thanks again for your help.

    Mark - Thanks for the info. I do need to print ABS for some parts (shop and field use). I was thinking about going to Taulman's crossover material when I no longer need ABS specifically.


    Thanks again
     
  15. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Spec sheet on the Omron relay used in that board: http://www.datasheet4u.com/html/G/8/Q/G8QN_Omron.pdf.html, I am not sure why they claiim it is a good relay, it only has a continuous current rating of 5A. I would never use that for a bed heater. You are better off staying connected to the RAMPS.

    re: heaters, While ABS would clearly benefit, anything that you heat the bed for, even PLA can warp if the outsides are cold. I have one model that I have printed several times that I can only print in PLA that will warp on the outside ends as I am near the limits of the build platform. The model is about 210 x 245 x150 mm, the large size means a very long print time and that doesn't help either.

    The other thing that inhibits heating on the Robo is one of it's main features, using a borosilicate glass bed. Glass is a natural heat insulator and as such has poor thermal conductivity. So going to a 240 or 250 mm square heater will at least be better than the current setup,

    Silicone heater is fine as a replacement
     
  16. Lee

    Lee Member

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    Update --

    I decided fix up the bed first and see what effect that had. Basically, I added Fiberglass and cork to the underside of the bed on top of the existing cork. It made a heck of a difference. The heat is now fairly evenly distributed across the bed. Here are the instructions (courtesy of a friend - thanks Gregg)

    I ordered a 12 X 12 sheet of McMaster Carr p/n 8549K42, 1/16 ridge fiberglass, under $6.00. Cut this down to 7 1/2 X 10 1/2, you will have to add a slot for the ribbon cable. From Lowes, a roll of 1/8 thick cork, $10.00. You will need a roll of aluminum tape, also from Lowes. Glue the cork to the fiberglass. Cut a slot for the flat ribbon cable. Attach this panel directly over the top of the cork that is on the build plate. Make sure it is well centered.

    Next, is the hard part. The two 8m bolts for the y axis tensioner will need to be removed. First, put a mark on the Philips screw drive that comes with the RoBo. Next, unscrew the belt tensioner on the front left side of the build plate support. Rotate the screwdriver 3 turns counter clockwise. This will be enough to remove the bolts. When the bolts are out 1/8 .125 inch is machined off of each hex bolt head. Reassemble the idlers and tighten the belt tensioner the 3 turns. You are done!!

    With this done, I do not see the need to replace the heater with a bigger heater. the reason for cutting down the cork-fiberglass combo is to avoid having to machine down the Phillips screws on either side of the bed.
     
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  17. regor

    regor Member

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  18. regor

    regor Member

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    What is the reason for machining 0.125" off the hex bolts? Is it for clearance? I haven't looked under the build plate and would also like to do your idea, but wondering about possible problems.
    I was considering trying to install one of the AC silicon pads on Amazon in place of the current Robo R1 pad with an SSR DC/AC relay, but if doing your mod is sufficient I'll try you're method.
     
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  19. Lee

    Lee Member

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    Hi,
    Yes. Machining the heads is for clearance. So, far everything is working great. I am printing ABS now and it sure is better. Note that I am using Mike's enclosure. I am printing a modified strain relief for the flat ribbon cable under the bed. It will get rid of the U bend in the ribbon cable. I will post it as soon as I install it. I will be trying a big ABS box in the next few days. If it can do that, then that is good enough. Don't forget to cut the slot for the ribbon cable.
     

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