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Discussion in '3D printers' started by Carl Feniak, Sep 29, 2014.

  1. Elmo Clarity

    Elmo Clarity Journeyman
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    I started with two motors wired in series. This keeps the power draw on the driver down so it thinks it is only running one motor. I ran some experiments with my bed where I ran it up and down fixed distances each way. Then variable distances but would still finish where it started. I put a level on the bed and after running this for awhile, I could see a slight tilt to the bed. Saw this after every run. So I have switched to the single motor and belt. Either way will work.

    I started off using 24v, mainly for the bed. Had problems getting the bed up to temperature using the 24v connection. The heater supported 12 and 24 and by running the 24 on the 12, it heated up a lot faster, but the power draw through the cables worried me. I could feel them getting warm (using 16 gauge wire). On my Printrbot Simple, I switched to using an AC powered silicon heater. That thing heats up fast. I switched to an AC one on the C-Bot and glad I did. I have switched back to 12v for now since I don't need the 24v for the heater anymore.

    I will be interested in finding out how that Flex3Drive works out. I like the idea but the cost is a bit out of the budget for now. Was thinking I might use one on a delta printer I am working on.
     
  2. Matt Mathias

    Matt Mathias Well-Known
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    I couldn't find an AC one that was 12x12 lol, at least not anywhere within a month of me. I am super excited about the Flex3, its going to be several weeks before I get it tho, he has a long lead time. I will keep you in the loop on how it works.

    I may look at belt driven Z, I am really trying to make this printer as repeatable as freaking possible.

    Well here goes another plate of parts, crossing my fingers that this spool makes it through.
     
  3. Chris Roadfeldt

    Chris Roadfeldt Journeyman
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    I'm on spool #3 and will probably hit #4 before I finish this thing. But then again, I'm going for the slowest build time ever. :)
     
  4. Elmo Clarity

    Elmo Clarity Journeyman
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    Yeah. They all come out of China it seems. I got mine from Keenovo. Took about 2 1/2 weeks for it to arrive. If you do go that route, check prices on both eBay and Amazon. The one I bought for my Printrbot was half the price on eBay vs Amazon. But the one for the C-Bot was cheaper on Amazon than eBay. All the listings were from Keenovo too. Guess the price fluctuates based on the day they list it. :)
     
  5. Matt Mathias

    Matt Mathias Well-Known
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    Holy hell how have you used that much plastic? I am at least 2/3 of the way done and I've not even killed one spool yet. Printing at .2 with 70% infill.
     
  6. Carl Feniak

    Carl Feniak Journeyman
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    That's a good one as long as you are happy with the height. Obviously you will need a 5mm to 5mm coupler instead of a 5mm to 8mm. You can see how much "extra" length I left sticking out the top in the rework assembly file.
    I went and did that for ya:
    Capture.JPG
    Less conservative, but less wastage then the original C-Bot. I roughly modelled an E3D v6 in there so if you are using a shorter hotend will need to adjust as it looks like the top of your lead screw is turned down for a bearing.
    As for the number of starts you are fine. You have more torque due to the better mechanical advantage and will be more resistant to self turning when off and under weight. The only sacrifice you are making is speed, which isn't really important for the Z axis.
     
  7. Carl Feniak

    Carl Feniak Journeyman
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    He didn't say what size of spools he was using ;) I hope they are not 1 kg spools though! The Rework parts are beefed up (as was the goal), so they will take a bunch more plastic than the original.
     
  8. Chris Roadfeldt

    Chris Roadfeldt Journeyman
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    Ha! They're indeed 1kg spools! I burned up a lot testing the generator, making parts for my i3, now printing a metric ton of wire chain links. Plus I like my infill for structural parts. :)
     
  9. Matt Mathias

    Matt Mathias Well-Known
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    I am estimating that I will use almost 1 kg dead on. I started printing individual parts but once I was confident that my new extruder was killing it and I had the settings locked in I started dumping whole plates of them on there. Right now I am printing 4 brackets for the Z-axis, two lead screw captures, 2 corners for the bed and an XY endstop mount.
     

    Attached Files:

  10. Matt Mathias

    Matt Mathias Well-Known
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    I started using Nylon for structural parts, I swear once you get it working its unreal. I was going to do all these in nylon but I couldn't source enough and didn't want to wait. Plus nylon is an order of magnitude more expensive than the PLA I get from Microcenter.
     
  11. Matt Mathias

    Matt Mathias Well-Known
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    You are a gentleman and a scholar. Thank you for the information. I have these lovely 5x8 couplers lying around but the 5x5 ones are already on their way. I could not find the spider ones in 5x5 but oh well.

    How are YOU syncing the Z-motors?
     
  12. Chris Roadfeldt

    Chris Roadfeldt Journeyman
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    I do enjoy a good PLA, but for structural PETG is my favorite now that I've got it dialed in. Would try nylon except I don't have a thermocouple in my v6 blocks nor in the volcano.
     
  13. Matt Mathias

    Matt Mathias Well-Known
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    I love PET+ from MadeSolid but decided against it for this build since I plan on slowly replacing the PLA with Nylon anyways.

    I don't have a thermocouple in my E3D either, although I may go to one since the especially since the Azteeg has the hookups ready to go. I print Taulman 910 @ 245 but I have to go pretty slow.
     
  14. Carl Feniak

    Carl Feniak Journeyman
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    Basically at the start of a print I always do either a few loops or a brim. If there is a left/right imbalance then I adjust the stepper a "notch" while it is moving. The left to right discrepancy is never large unless a lead screw misses steps due to lack of oil or dust build up, which can occur when homing after a tall print.
    I don't find it a big enough of an issue as I always watch this first bit of the print and adjust both together if I don't like the amount of squish. I would probably approach it by leaving the motors as is and adding a pulley at the bottom of each lead screw and locking them together with a belt. If the right belt length couldn't be found then an idler might be required to take up the slack.
     
  15. Chris Roadfeldt

    Chris Roadfeldt Journeyman
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    Any openscad experts want to help me fix my awful awful fan duct in the generator?

    I am thinking about half or quarter circles around the nozzles. Currently I have just a rectangle pointing 5mm below the nozzle and offset 18mm from the nozzle tip. Works great for the side the fan is on, but completely misses the back and it shows in the prints.

    I need ideas and perhaps some help with the trig.
     
  16. Matt Mathias

    Matt Mathias Well-Known
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    So you would leave both motors driving the axis (serial or parallel?) and then lock them together so that if one turns, the other turns.
     
  17. AK Eric

    AK Eric Journeyman
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    The only downside I encountered when swapping to the front\back leadscrew option was that for whatever reason, that front leadscrew\acme nut would really squeak when the bed was raised. Was... odd.

    What's interesting is, now that I've switched to the RADDS/Repetier, the squeak is gone. Didn't do anything different to my bed setup in any way.
    Now that I think about it though, the only other difference was that I was using (via the Rumba/Marlin) two DRV8825 drivers to power my dual-z steppers separately. With RADDS, I'm using a single SD6128 driver to power them both. Food for thought.

    I personally like the front\back setup because it requires nearly no new hardware: just a cutoff you probably already have to run across the front of the cantilevered bed, plus some corner brackets (I 3d printed them) to hold it in place. So if you'd already built your bot, you can make that change without having to invest any extra cash or wait on shipping. If you're building the bot from scratch you have more options of course, but I'd probably do it the same way again if I built another one.
     
  18. Matt Mathias

    Matt Mathias Well-Known
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    I am going to be using SD6128s as well, and I was leaning towards Repetier, I really liked that firmware but I was using it at a time when I didn't know how to calibrate my printer and so I switched to a version of Marlin that was a lot closer to being dialed in, now I am running Marlin because almost everyone else that has this printer is and helping them with config settings and what not is a lot easier when its what I use.


    I am also looking at Sailfish since ... well..since I can.
     
  19. Mark Carew

    Mark Carew OpenBuilds Team
    Staff Member Moderator Builder Resident Builder

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    Hi @Carl Feniak
    This is great feedback! We are adding a new developer to the team here of OpenBuilds.com that we know will bring on lots of exciting new changes to the board.
    I will be ear marking your suggestions to make sure that in time they become a part of the new changes.
    Thank you again Carl
    Mark
     
    Muh_3d, adamcooks and Carl Feniak like this.
  20. Carl Feniak

    Carl Feniak Journeyman
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    Yes, I drive both Z motors from a single DRV8825 with parallel connections off the Ramps shield. The main concern here is that the steppers have the potential to get out of sync and cause the bed to become out of level. I am a mechanical and not an electrical engineer so I don't understand why this would happen other than missed steps as both motors have the same step count and receive the same signal pulses. If they didn't respond identically then wouldn't put that put the viability of open loop stepper control into question?
    However, mine do need a slight adjustment every now and then and I suspect it is due to the missed steps while homing a tall print or slight movement when the printer isn't powered. My thoughts are that physically connecting them together will prevent a desync. If one misses steps then so must the other. The disadvantage is you can only send so many amps with a single driver, plus you can't add the gear ratio that AdamCooks & CapnBry did with the 3 lead screw and one motor setup. A good way to counter these issues would be to use a lower pitch lead screw ;)
     
  21. Matt Mathias

    Matt Mathias Well-Known
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    If I was to make a guess I would go with a firmware problem here, otherwise I totally agree with you.

    The nice thing is that I have the motors and the screws, so I can get it set up and then figure out if/how I want to change it.

    One thing that seems interesting to me is the idea of using a single stepper to drive a drive shaft that in turn drives 2 worm gears. I am NOT a mechanical engineer, I am a software engineer. So why wouldn't this work / why hasn't it been done?
     
  22. Matt Mathias

    Matt Mathias Well-Known
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    Like basically linking two of these, but connected to a stepper. Its actually basically what we are doing now, except we are turning the power transmission 90 degrees which would allow us to connect two lifts with a physical steel shaft (or even a flexible one?)

    ActionJac MJ-20-UR 5:1 | Nook Industries
     
  23. Carl Feniak

    Carl Feniak Journeyman
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    Yeah, that would work great with a through shaft stepper in between. I think it comes down to complexity and cost.
     
  24. Matt Mathias

    Matt Mathias Well-Known
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  25. Carl Feniak

    Carl Feniak Journeyman
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  26. Matt Mathias

    Matt Mathias Well-Known
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    I am looking, but havent seen that yet. The offset wouldn't be that much depending on how I drive the leadscrews. Still looking for some 90 degree power transmission stuff that will work.

    125oz/in? I was like...yah...that should work.
     
  27. Spiffcow

    Spiffcow Well-Known
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    So it looks like the BOM was updated yesterday with new calculations. I'm about to bite the bullet and place an order, but I *really* want to get this right since shipping is not cheap. For a 12x12 bed with 500mm lead screws mounted on the side, this is what I got from the spreadsheet:

    X4 480 mm <-- front/back, top/bottom horizontal stationary pieces (2x 1m extrusions)
    X1 466 mm <-- the back/Z moving piece
    X1 506 mm <-- the top/XY moving piece (1x 1m extrusion cut with piece above)
    X2 480 mm <-- top sides (1x 1m extrusion)
    X2 460 mm <-- bottom sides (1x 1m extrusion)
    X4 650 mm <-- legs, gives some flexibility for hotend length and mounting (2x 1.5m extrusions)
    X2 445 mm <-- bed support
    x1 520 mm <--offset motor mount option (1x 1.5m extrusion cut with piece above)

    So it looks like 5 1m extrusions and 3 1.5m extrusions, plus probably an extra 1.5 in case I screw up. Does this look right? Have I missed anything? Should I go with a smaller lead screw?
     
  28. Matt Mathias

    Matt Mathias Well-Known
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    Give me a minute, I will update my cut calculator with the new dimensions, it does a pretty good job getting the right lengths
     
  29. Spiffcow

    Spiffcow Well-Known
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    Are your calculations different than the BOM? If so, what accounts for the difference?
     
  30. Matt Mathias

    Matt Mathias Well-Known
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    Spiff, check this out.
    C-Bot Cut Calc

    You put in your dimensions and it finds the most efficient way to cut the pieces given your desired extrusion length. What I have not done yet is figured out how to make it mix extrusion lengths to get the MOST efficient solution. That is going to require some linear math that I just haven't had the time to write yet (I just started this yesterday) but I am working on it!

    According to this you can go by with 6 x 1500 and 1x500 and end up with about 700mm of slack, if you wanted a bit more slack then make the last one a 1000 and you get 1200mm of slack and it would be long enough to cut any of the pieces again if needed.

    Just another tool to help you, I had similar questions so I wrote myself a solution :)
     
    RacerBo and AK Eric like this.

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