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Advices about improvements

Discussion in 'General Questions' started by tiagomaricate, Sep 6, 2020.

  1. tiagomaricate

    tiagomaricate Member

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    Hi people!
    I'd like some advice and tips about an idea.
    I like the printer area, the visual, and the overall structure from R2.
    But as the boards are "limited", I was thinking on replace the mainboard for a Duet 3 and change the stepper motor by a servo-motor.
    I confess I'm new on printing hardware and still reading a lot and making some experiments with my machine.
    My intention is to convert it to high-end equipment.
    Further, the changes will include the hotend and so on.

    So... is this too much overkill? Waste of money/time? Good choice?

    I would be very grateful for some tips and advice on how to improve the printer.
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    You could likely make it work, @Lance Weston would be a better resource for alternative approaches.
     
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  3. Lance Weston

    Lance Weston Active Member

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    I need a clearer idea of your goals.

    The hardware (plastic case, hotend plastic, and bed) are the limiting factor in the quality. A minor improvement can be had by changing the steppers from 42mm long to 48mm long steppers (part number ending in 02 for current compatibility). Why would a servo motor on x and y improve your output? A stepper with it's non cumulative error is critical to having vertical walls that are straight and smooth.

    I built an "R2" with a 3030 extruded aluminum frame and 4 12mm posts and 2 z steppers. It has a better output and by that I mean if the aluminum frame is a 100% on finish the R2 is a 95% on finish.
     
  4. tiagomaricate

    tiagomaricate Member

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    Actually I disassembled the entire printer. It had a very strong metal structure on the base and on the back, to hold all the stuff.
    I'm not sure where the plastic case can interfere with quality once the metallic structure is holding everything else.
    Actually the plastic case, for me, is an advantage.
    I'm replacing all the electronics.
    Putting an SKR Turbo with 2208 drivers and several others extensions for SKR to keep the print save when the power goes off and others control features.
    Also, I'm thinking of using the RR firmware instead of marlin.
    The same with the heatbed. Disassembling, redoing the connections and replace for an AC heat bed under the R2 bed.
    Reworking the power supply and putting some RGB LEDs for internal illumination.
    Also working on support for a 7-inch display and finally replacing the hotend and putting together the second extruder.
    Basically I'm keeping the visual of R2 put changing and improving everything else.
     
  5. Lance Weston

    Lance Weston Active Member

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    The carriage has no connection to the metal frame, it is plastic on plastic. The critical dimensions on the x and y rods is all plastic and flexible. The height of the bed comes down through the plastic case and connects to the metal frame at the bottom of the case. All of the electronic changes will not improve the quality of the print output.
     
  6. tiagomaricate

    tiagomaricate Member

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    Indeed some parts are connected using plastic but so far I don't face any problem with print quality (at least related to the mechanic parts).

    But you have to take on account the new board is faster and can use silent drivers with 256 micro-steps. Also is 32 bits.

    The new heat bed is faster and more stable (the same for the new hotend).

    This is one or another way will improve quality. Maybe not a huge difference but for sure will improve.

    Sure the best solution is (maybe) upgrade it for a core xy and a more solid structure (I have some workarounds).

    After finish this first part I will make a vibration test to compare the difference and if this is affecting the process of printing.
     
  7. Lance Weston

    Lance Weston Active Member

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    Are you replacing the bed and the hotend? If not then then heat up speed will not change because 24v is 24v and that determines the rate of temp rise. I have made the hotend faster by going to a 40w heater. If you go to the new Partsbuilt.com board there is really no limit to the heater power except the power supply. Right now the hotend and the bed are regulated to +/- 0.5C, I am not sure better regulation will make a visible difference.

    The mechanics are what limits print quality not the electronics, where fast enough to keep up is all that is needed. You need to go through the numbers to see what the resolution difference is between micro step resolutions. The real limitation is the belt, look at how many micro steps there are to 1 tooth on the belt and what a reasonable tolerance of the accuracy and hysteresis tooth to tooth on the belt.
     
  8. tiagomaricate

    tiagomaricate Member

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    Good appointment!
    About the heat bed, I will use a relay to be possible connect it to the power supply.
    In case of hotend is more limited due space limitation. It has to fit in the place from the original.
    Do you know if 40w heater needs a specific block?
    I completely forgot the belts. Maybe using a new one with steel inside could help. I have to check it.
     
    #8 tiagomaricate, Sep 16, 2020 at 4:02 AM
    Last edited: Sep 16, 2020 at 4:01 PM
  9. Lance Weston

    Lance Weston Active Member

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    A 40w heater is the same size. The FETS driving the bed have a 30a capability and the power supply is only good for 6.5a. Going to a relay means going to bang bang regulation which is nowhere near as good.

    Steel belts are stiffer and will bring new problems. Fiberglass reinforced are the best all round belts.

    I think you are not being realistic in your expectations. Robo did a real good design, for the materials used, which define the limitations on quality. No electronics will get around the mechanical limitations. I have posted info on using the E3D J5 and J6 hotends where you just need to print a new shroud and adjust the printer eeprom settings. These hotends can handle more heat.
     
  10. tiagomaricate

    tiagomaricate Member

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    But is there other way to use ac bed without relays? I though both ac an dc beds use bang bang regulation.

    Actually I don't expect a huge improvement. The main improvement would have silent drivers. So I have to change the main board. So why not skr turbo? Why not a new screen more responsive? Why not this... and so on lol

    In the end is almost a new printer... A custom printer.

    The main gain is for sure all learning process.
     
  11. Lance Weston

    Lance Weston Active Member

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    As a learning experience, great. I knew nothing and Mark and Geoff walked me through so much in the beginning. I would not have gotten off the ground without them. I have a simple machine shop and a little software experience so I was able to make a machine. I would recommend that you do that. I could post all of the printed parts to make a "Robo R2" with 3030 extrusions and a 12" bed. That way you can play without risking your working R2.
     
  12. tiagomaricate

    tiagomaricate Member

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    Wow! This would be amazing!
    If possible I'd like to have access to your project.
    Usually, where do you buy electronic/printer parts?
     
  13. Lance Weston

    Lance Weston Active Member

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    I order from China. Give me three days and I will include a spreadsheet of where I purchased all of the parts. I attached a picture of the printer I built. I am assembling parts for my next printer build and I have almost all of the parts. It has taken six months. The plastic parts will take about 3 rolls of plastic and 3 weeks to print. I printed most all of the parts on an R2. The housing for the electronics was too big for the R2 and I printed it on the the newly assembled printer. As you can see it thinks it is an R2. It uses 4 12mm posts and 2 z steppers. The Partsbuilt.com board is perfect for it or you can go with your new electronics. This printer gives better finishes than the R2. Picture attached.

    Link to all of my files, it is a lot to go through. If you want to pursue it I can go through it file by file to make sure it is the latest and greatest.

    https://drive.google.com/file/d/1Af_f6OpP-5CZxHVrhI-82TZKMq2Mz7rX/view?usp=sharing

    printer.jpg
     
    #13 Lance Weston, Sep 17, 2020 at 7:20 PM
    Last edited by a moderator: Sep 18, 2020 at 7:06 AM
  14. Lance Weston

    Lance Weston Active Member

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    The attached jpg is the regulation and speed with an R2 bed, an E3D J5 hotend and a replacement power supply of 15 amps. The R2 bed is 160w which defines the temp rise time. I slow the process down by bringing the bed to 70C first. This allows time for the flexplate system with a glass bed to achieve desired temp. If you are going to use a flexplate system and a glass plate using a faster heater will not allow the glass plate to be at temperature when you start printing.
     

    Attached Files:

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  15. tiagomaricate

    tiagomaricate Member

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    Is there a way to "convert" the dc bed to work with ac? I imagine the main problem is the velocity of heating. It will burn instantly.


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  16. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    You would need to replace the bed heater element with an A/C one and then use a relay from the control board to turn it on/off.
    Not complicated, although ripping off and replacing the old one may be a bit of a pain.
    I like the A/C heaters since they really get to temp and stabilize a lot faster.
     
  17. tiagomaricate

    tiagomaricate Member

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    I'm thinking of simply put a new heater under the original bed.


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  18. Lance Weston

    Lance Weston Active Member

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    Heaters are just resistors and they do not care whether you are driving them with AC or DC. Instead of worrying about AC/DC you need to determine the power of the bed. My 12" square bed is 240W @ 24v but I use 26v making it 280w. Once in regulation the power use would be the same, but I needed more power for the PID tuner to work.

    The R2 is 160w @24v, add another 24v heater below and put the two in parallel. Pick up a cheap external driver board ( in my spread sheet) and feed the bed voltage from the main board to the signal input and use an external 24v. You can get 24v 15a supplies from Amazon for around $20. Use this supply to power the bed. This should be easy to implement and has the advantage of not being a bang bang regulator.
     
  19. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    If you feed 110v A/C to a heater rated for 24v it will fail :)
    A/C or D/C doesn't much matter I agree, but the heaters rated for 110v A/C are what you would want to use if you want a 700w A/C heater. There are a number of ways (some of which you have already pointed out) to "skin that cat" if you want faster heating / stabilization of the bed.
     
  20. Lance Weston

    Lance Weston Active Member

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    Yes a 24v heater will fail if applying 110v, Marlin does allow for a maximum duty cycle which "might" limit the power well enough if limited to 5% max duty cycle. I would not try it with my stuff though. The AC/DC does not matter.
    700w is a lot of power for a bed designed for 160w. What happens during the initial heat up? Will it warp the bed? I do not have a feel for it but would be leery of it. If you go to AC relay drive it will be bang bang regulation. Once in bang bang bang there is a minimum of heat delivered every time the relay turns on. What type of ripple in the temperature can be expected on the plate from the minimum heat pulse? The bed is mounted on a steel plate, how much attraction to the plate is there when the current is on? Can it pull the bed down far enough to be visible in the print? It would be good to have a response from someone who has used a 700w heater.

    The temp sensor is on the bottom of the bed; it takes time for the temp to travel bottom to top of the bed. Faster heating of the bottom does not translate to faster heating of the top. Once the bottom is at temp you still have to wait the thermal lag time for the top to get up to temp. I had to set an initial temp of 70C and then let the bottom cool to set 45C to 55C printing surface temp to reduce the thermal lag time. I use a flexplate with microporous glass, this has a long thermal lag time. Since my finished prints go to the freezer for print removal, the bed is very cold when returned to the printer. I think the ideal heater power is one that delivers identical rise and fall times of print temp at the print surface. That would allow the PID to regulate with the smallest amount of ripple in temp. I do not know what that power is.
     

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