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Ballscrew Style Delta 3d Printer

Discussion in '3D printers' started by Jason Moyer, Mar 12, 2015.

  1. Jason Moyer

    Jason Moyer Well-Known
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    Jason Moyer published a new build:

    Read more about this build...
     
  2. hax0red

    hax0red Journeyman
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    Cool looking design. I've been considering a big openbuilds delta with ball screws and Igus T linear rails for rigidity and precision. With the linear rails though I'd need to use 20x60 extrusion on the 3 vertical towers.

    What size build plate are you considering? Can't wait for more details but luckily I'm just starting a C-Bot build which should give me time to decide on a delta six or your ballscrews design...maybe a hybrid combination of both :cool:
     
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  3. Jason Moyer

    Jason Moyer Well-Known
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    My build plate will be 14" diameter. the ball screws are 16mm OD so for this application they are huge and overkill. the columns are 1.5" PVC and the only reason for the guides is to take out any deflection in the screws in the center. This whole printer is around 38" tall or so.
     
  4. Terry Peterson

    Terry Peterson Well-Known
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    That's some massive hardware there Jason.... I like the idea of using PVC uprights supports. I built an 8' tall delta frame for a hot wire cutting project years ago using 6" PVC pipe for the uprights. Used toilet bowl flanges for the ceiling and floor mounting plates and made my own galvanized steel clamping plates for the fixture holders. Shot everything in to sec. degrees with a theodolite instrument I rented from a local survey supply shop. The foam part I cut was used to make a fiberglass mold for a large architectural dome project I contracted for. The finished glass parts had to be very precise because they all bolted together like giant flower petals to create a 30' dome structure for a new building. The PVC jig worked perfectly. Should do the same for your project. Good luck.
     
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  5. Jason Moyer

    Jason Moyer Well-Known
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    Yea i know i went a bit overkill for the size of the machine. i have it about 2/3 built now i just haven't posted the pics. i am waiting for the ball screws to come back from the machine shop before i can put the upper frame together. i built it heavy because my biggest complaint with the Makerbot Replicator 2x that I have access too is just built too flimsy. I've been a machine designer for the past 10 yrs or so and i can and have run machine tools myself. if you are trying to calibrate a machine to run a layer pass of .1 or 2mm (appx .010") how can you expect that kind of accuracy from a machine that will have the carriage flex or the bed flex over .030" just by looking at it wrong?! the concept of that just seems absurd to me. The ball screws are 16mm and will be plenty rigid for what im doing but i have the column pucks on a single bearing to help with screw flex as its trying to push the end effector around the build area.

    If its too slow i will change the drive configuration and do a 1:2 belt drive on the screws. thats the beauty of ball screws. no backlash and will take the higher speeds. I've been told over on the RepRap forum that my electronics will be borderline for controlling this machine. So i'm pretty much planning that as the first upgrade after I get it up and running. Then I will re-purpose the Arduino/Ramps setup for something else. maybe another printer...maybe a scanner...not sure yet.

    Domes are no joke. I've built dome style fire-pits using my cnc plasma table and they are fun to figure out that's for sure.
     
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  6. DarkAlchemist

    DarkAlchemist Veteran
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    Yes, I hate to say this but Deltas are the one type of 3d printer that you will see the most gain from by going to an ARM based system. Something like a Smoothieboard, Azteeg X5, etc... I am not much into Delta printers as my thing is SCARA based bots but if one was cheap to build I would gladly ditch my I3 rework for it as any future printer I ever get, or make, MUST have a non moveable build platform regardless which kind it is. I learned a lot about inherent weaknesses from this I3 rework and a moving bed, outside of an elevator type, is just not Kosher.
     
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  7. chris kelly

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    do u have a link to download the 3d printed files and the motor plates?
     
  8. Jason Moyer

    Jason Moyer Well-Known
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    Not as of yet. i have not completed the build. I want to make sure that it works properly before i release any files. I am hoping to have my ball screws sometime before the weekend so i can start getting some real motion out of it.
     
  9. laurie

    laurie New
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    Hi, I am also just starting the planning to build a ball screw type Delta printer....I was just curious are you planning on using Nema 17 Motor's to drive those ballscrews ?
     
  10. Jason Moyer

    Jason Moyer Well-Known
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    no... im using 200oz/in NEMA 23's for the screws and a Nema 17 for the extruder
     
    #10 Jason Moyer, May 17, 2015
    Last edited: May 17, 2015
  11. laurie

    laurie New
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    Thanks I figured as much...I was working towards the NEMA 23 as well, crossing my fingers the they will work with the 2AMP motor controller's I have without getting too hot... Any good luck with it looking forward to seeing how your machine turns out...looks great so far....cheer
     
  12. Jason Moyer

    Jason Moyer Well-Known
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    thanks. eventually i want to go to a higher amp stepper but for now i am going to try and keep the speeds down to try and minimize the amp spike. im not sure if i can bypass the on-board steppers with the duet board im using now.
     
  13. DarkAlchemist

    DarkAlchemist Veteran
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    What I do not get is that ball screws are made for, and work best in, the horizontal position not vertical so nice to see that this works well.
     
  14. Jason Moyer

    Jason Moyer Well-Known
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    not necessarily. ball screws will work in any orientation. the benefit is the zero backlash which is what you need for this type of printer. the weight of the head and arms will keep tension in one direction but switching it will induce backlash. using acme or std thread could cause the print to not be correct. they are also made for heavy loads...which i wont even come close to loading up the screws to even 1/4 their capacity.
     
  15. DarkAlchemist

    DarkAlchemist Veteran
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    I was just saying what a ball screw manufacturer was saying on an instructional video I was watching.
     
  16. Jason Moyer

    Jason Moyer Well-Known
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    thats interesting...which manufacturer were you looking at?
     
  17. DarkAlchemist

    DarkAlchemist Veteran
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    Was on Youtube when I was doing a search for something like Leadscrew vs Ballscrew. Where I read that a ballscrew was not as good vertically I do not know but here is the video anyway -
     
  18. Jason Moyer

    Jason Moyer Well-Known
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    That's a great video from Thompson (one of the largest names in linear motion and bearings in general) but after watching that video he doesn't say anything about positional application of screws. yea he shows the difference between different styles of screws and the holding force of different pitches but that doesn't mean that it is not good for a vertical application. The unspoken meaning there is that there is a compromise between the load vs speed. A high load on a screw meant for high speed means that the holding torque of your motor and the resting position of your assembly become more important though out your design. You would need a motor that either has a built in brake or has the enough holding torque to keep your assembly where its positioned. Also means that your un-energized position needs to be at the end of the travel where the moving part is sitting on something solid and not hanging in the air.

    In this case the entire assembly is light. I am using pre-loaded screws and they don't drift like the high helix one in the video. My challenge to overcome will be how fast i need the screws to spin to get the desired print speed. the nice thing about the ball screws is they will take the higher speed with no issue. I might need to add a 1:2 ratio belt drive to double the speeds of my screws, but until i get them and try out the printer i wont really know. The machine shop has had them for 3 weeks now. I was hoping them to be done in 1 unfortunately, but I can't complain too badly as its not costing me anything (owner is doing it as a personal favor).

    I have the rest of the machine built and ready to go. I started doing some testing with using Pronterface and the Duet board to spin the motors as well as turn the hot end off and on and run the extruder to make sure the thermistors were reading correctly. I have to replace the thermistor on my heated bed. I think it may have been bad out of the box...new one should be here today. I know I have been slow to upload this build but I am working though some design iterations and don't want to clutter it up too badly.
     
  19. DarkAlchemist

    DarkAlchemist Veteran
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    As I said where I read about horiz vs vert I can't remember. As far as brakes I agree because if you have any weight on Z (a CNC router/drill/Nema motor) it will fall right down very fast once the motor(s) disengage, and if you noticed that ball screw that has the exposed bearings (I guess easier to grease) it fell fast like a lead balloon. I saw another video of a CNC router once turned off and the router did fall but slowly (was a belt driven type Z) at about the speed of those leadscrews in that video.

    Yep, Thompson is a well known, and highly respected, company and you pay $$$$$$$$$$ for their stuff but if you can afford it the item(s) will out last you for our purposes and not unheard of for 7-20 years in a production environment.
     
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  20. Jason Moyer

    Jason Moyer Well-Known
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    It all has to do with the screw pitch. A finer screw and it wont do that. My plasmacam cnc plasma cutter has a screw to run the Z-axis and it doesn't move on its own when its not powered (granted there isnt much weight there). The exposed bearings are still a sealed system. that just means they have a ball return tube on the outside of the bearing nut. I believe that this style typically has a higher load capacity. they can use a larger ball because they dont have to account for a return passage within the body of the nut itself.

    The angle of the screw pitch really is the key to it all. its the difference between rolling a car down a 1 deg incline vs down a 20 deg incline. with the belt drive system there is nothing to help the mechanical advantage of the motor and its 100% up to the motor to keep the carriage in its position. and most motors when turned off will free wheel. I am not sure how the belt driven delta bots stay up when powered down...or if they do at all. I cant imagine they just crash down but its possible that due to the friction in the slides they will drift down to the build plate.
     
  21. DarkAlchemist

    DarkAlchemist Veteran
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    Ahhh, that makes sense about the size of the bearings and why the return path is on the outside. The delta bots I have seen drift down and the head (nozzle) rests on the build platform. They do make brakes for these things where they disengage when powered and engage when they do not have power but really no need. Sort of like the original hard drives for computers (back in the stone age) you had to manually park them before shutting down your PC so on a Delta just park the nozzle ESPECIALLY if you have a delta with a direct drive on it regardless what size motor that is it is weight and the weight will make it come down fast enough to crack glass or at least chip it or screw up a soft brass nozzle.
     
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  22. Jason Moyer

    Jason Moyer Well-Known
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    yea that would be my concern.... mine has a glass build plate. i know my mechanism wont walk but I've thought if the screws are too problematic i would re-purpose them and go to belts but the drift wasn't something i thought about until now. you would need some sort of brake that would be locked when the power is off. or manually drop it to the deck when done. last thing i would want to do is shatter a $60 piece of tempered glass [email protected]!
     
  23. DarkAlchemist

    DarkAlchemist Veteran
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    I chipped my 25 dollar boro glass with a M3 screw on my extruder I had off. I knew when I did it too and it was not dropped or pressured it just chipped it (I guess like a Diamond if it hits precisely at the right spot it will shatter the diamond).
     
  24. Jason Moyer

    Jason Moyer Well-Known
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    well i have the electronics hooked up and had the motors turning... number of issues... first and the most damning to this project is the screws are not straight. they are bowed considerably which after removing the bearings that ride up and down the column its very apparent that I need to remove them and try to straighten them out. this may be the part that damns the ball screw idea...

    I also am realizing that should have used a regular bearing on the bottom of the screws instead of a thrust bearing... I re-wired my 6 wire motors to half coil to help with torque issues but the duet board is still not able to feed the Nema 23's enough current to reliable turn them. they will spin for awhile and any little resistance they stall and sound really angry LOL.

    I am not sure the rod ends on the delta rods were such a good idea. even after adding some spacers I am not sure they have enough movement in the ball joint to allow full movement of the delta configuration. I m working on trying to flash the arduino mega that I have with marlin or repetier since it has removable stepper drivers and maybe go that route for the electronics.

    if i ditch the ball screw idea i might as well ditch the pvc columns and go to a better guide setup as well. ive been playing around in CAD the past 2 days and have a frame that will work with the makerslide extrusion and their v-guided wheels. However, when i start to look at the costs to rebuild this delta differently for belts and nema 17's, I am coming close to what it would cost to build the XY style printer I have been working on in CAD... so I am not sure what I want to do now...
     
  25. DarkAlchemist

    DarkAlchemist Veteran
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    You are right where I have been for the last 6 months with my I3 Rework. I have given up on 3d printers as the cost to fix the issues this printer has would be the cost of another printer.

    How in the world did the ball screw get warped/bowed?
     
  26. Jason Moyer

    Jason Moyer Well-Known
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    cheap Chinese screws.... im guessing they came bent.
     
  27. DarkAlchemist

    DarkAlchemist Veteran
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    A majority of my issues have been **** Chinese <bleep> and price had nothing to do with it. Rods I got from Misumi were fantastic just 8mm which is junk for a printer the size of the I3 Rework but that isn't their fault. I just had a switch on my Z endstop crap the bed and it fell apart in my hands. Sainsmart Chinese junk. Sorry, but I am at my limit with the Chinese. Sure sure they could make wonderful stuff, so I am told, but I haven't seen any. Hell, even their SCUD missile from the 1990's was junk and they haven't gotten any better either. I could go on and on but you get the gist.

    Sorry about your issues but many others are in the same boat and it is too heavy so is sinking. :(
     
  28. Jason Moyer

    Jason Moyer Well-Known
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    part of my issue is im working away from home most of the time so i dont have access to my shop. i can straighten the screws once i get home again... but the motor issue is a bigger fish.
     
  29. DarkAlchemist

    DarkAlchemist Veteran
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    Yes, coulda woulda shoulda but in reality you should not have to. Chinese junk is junk and is so much aggravation. For instance I need some tools and if I would have purchased them 7 years ago I would have had an okay tool but now they are made in China of plastic and pure junk. All made to sell not to any sort of precision or to last.
     
  30. chris kelly

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    Hi Jason how is the 3d printer coming are you giving using ball screws I would like to know if you could email me the plans

    thanks
    chris
     

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