I made another MP3DP…..kinda

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This topic contains 167 replies, has 15 voices, and was last updated by  Ryan 1 month, 3 weeks ago.

Viewing 30 posts - 91 through 120 (of 168 total)
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  • #51329

    Craig
    Participant

    I can get the whole thing on a 24 x 24 piece!  I could get 8 out of a 4×8 sheet. I’m gonna have to make more printers.

    #51331

    Ryan
    Keymaster

    With room to spare!

     

    I like this, I know what I will be doing tonight. https://printedsolid.com/blogs/news/a-solid-foundation-for-high-quality-corners found the link in the SeeMeCNC forums.

    #51335

    Bill
    Participant

    I can get the whole thing on a 24 x 24 piece! I could get 8 out of a 4×8 sheet. I’m gonna have to make more printers.

    Ooo, I want the file for that. 🙂

    #51339

    Ubaldo
    Participant

    Awesome work on the design of this, alted!

    Couple of questions if I might?

    F

    Does this machine share all the same spacing between smooth rods on x axis?

    Is there any particular rseason for the spacing on the x axis to be different from the prusa printers?

     

    I’m assuming it has to do with better stability? Just something I’ve always been curious about.

     

    I’m very excited to start building one of these. Thanks for your hard work!

    #51342

    Barry
    Participant
    100%, tuning is getting very exciting on this one for some reason. I can’t find any really good info so I will have to sit down and come up a good system to tune with. Part, speed, quantifiable tests. To tune a fast 120mm/s part you have to have a large part and it just takes longer. So I figure tune at 50ish and then speed up when I think it is dialed and I have a firm grasp on what effect each setting is doing.

    There needs to be a better way to visualize it, or at least get some feedback as to what the jerk/accel are doing. The slicers do a good job of illustrating speed in the preview, but they don’t show the trapezoid. Do they show colors for speed if you load up a gcode file? Maybe a script that edits the F speeds in the gcode file based on some parameters could change the F speeds, and then slic3r could display the output?

    Mattercontrol will show print speed by color.

    #51343

    Ryan
    Keymaster

    Ubaldo, I just made the spacing work for what I was doing. Making it work with Prusa’s parts also means his belt and belt spacing. It is much easier to just do a fresh build. If I was going to make it work for his stuff I would just end up making a frame to fit his parts…that’s no fun, on second thought that actually might be kinda cool.

     

    Mattercontrol will show print speed by color.

    I have to look, now that you mention it S3D does but it doesn’t/can’t account for accel and jerk, but would be awesome if it could!

    Been cutting parts on the RowRider for a few hours….Updates come to mind…

    #51364

    Barry
    Participant

    I like how you added your logo into the parts.

    #51365

    Ryan
    Keymaster

    Thanks, as much as I love to see it I am sure most don’t so I tried to make them inconspicuous.

    #51370

    Ryan
    Keymaster

    Inconclusive? A few hours later I learned a lot. I disabled all slicer enhancements, coast, min layer time, so this should be raw plain gcode. The test was only 90° corners so I would assume no jerk came into play it was set a 4=X and 2=Y (never changed them forgot to make them equal just in case). Same printer, same gcode, same filament, same room temp, same speed 50mm/s. To do the tests I only changed XY DEFAULT_MAX_ACCELERATION and Default Accel all three numbers where always equal. I ran them alternating fast and slow zeroing in on a speed that sounded good and looked good. 500mm/s/s to 5000mm/s/s.

    MVIMG_20180119_2106172
    Sat parallel with the Yaxis (bed), should show X axis ghosting.

     

    MVIMG_20180119_2104282
    Sat parallel with the Xaxis (extruder), should show Y axis ghosting.

     

    MVIMG_20180119_2105322
    X again, with accels labeled.

     

    So now the odd thing…the clean one was at 75mm/s! 100mm/s failed as the time between layers was too short and it just squished but was looking great before it died horribly. Once the accelerations are where they should be I think you can really crank up the speed.  It all makes so much more sense now. I could go a step further and tweak the two axis separately but I think a little belt tension experiment is up next. Then figure out how best to set the jerk.

    I mean I have been very happy printing at 35mm/s forever, this made 50 look simple and 75 was really not that bad. At those high of speeds though first layer time and minimum layer time need to be dialed in or it fails fast. I only ever bothered to tune the MPCNC ( I will be revisiting it very soon), Why did I never tune a printer…..Dang!

    #51376

    Ryan
    Keymaster

    The printer starts to sound a little rough at 1500 and 3000 sounds pretty harsh. The first pic shows why I honed in on 1500, could go either way a few hundred depending on how you where planning on printing, fast-less acceleration, slow- a little more, so 1500 seems like a sweet spot. I know it might sound a little sluggish but it is not.

    accel1
    It is getting to full speed in about 0.8mm.

    With this and coasting enabled I think the corners would be perfect and it would be smoking fast.

    Attachments:
    #51384

    Barry
    Participant

    Man, these parts are pretty!  I forgot how nice pla prints.

    #51391

    Bill
    Participant

    Great job! What is the model you are using? I’d like to see how my bowden setup compares. I should be able to use higher acceleration number for the same result, since I don’t have the weight of the motor to deal with. I’ll have to check to see what I have accel and jerk set to now, I remember tweaking them to match some random web page suggestion… 😉

    #51393

    Ryan
    Keymaster

    Here is a direct comparison. 50, 75, 100mm/s.

    I want to keep testing but Marlin 2.0 isn’t playing nice right now. I have been at it for a while.

     

    #51403

    Craig
    Participant

    Got my frame put together. I would up using MDF. Ryan said it would work – and it’s much cheaper. I put the bottom on and it seems pretty ridged. Ryan you are a great engineer. You could teach Ikea a thing or to. It was a joy to assemble . Got a ways to go but so far so good.

    #51406

    Craig
    Participant

    Hey Ryan, I wanted to add your “V1” sticker at the too but it’s a tad big. Would any of your other stickers fit? Also That would be a cool name for your printer I think “The V1” has a nice ring to it.

    #51407

    Craig
    Participant

    I’m having issues typing on my phone today . I was trying to say I wanted to add the sticker to the too of the printer.

    #51408

    Craig
    Participant

    TOP! Dang phone.

    #51409

    Craig
    Participant

    I need a little help, On my Y and X axis I had assumed the 608 bearing in the BOM ware for the belts oposite  the motor end, -They Don’t seem to fit there. Help please, I must be missing something. Thanks

    #51420

    Jeffeb3
    Participant

    W.r.t. jerk. I don’t think I agree with what it does.

    What I understand is that it is the speed where acceleration “short cuts” and doesn’t limit speeds.

    So if jerk is 10mm/s, max speed is 100mm/s and Accel is 1000mm/s/s. Going in a straight line, from stop through the line to stop, the speed would go from zero, immediately to 10mm/s (the jerk), then follow the acceleration to 100mm/s. Then at a computer point, it will decelerate at 1000mm/s/s, until it reaches 10mm/s second. At the exact end of the line, and it will stop immediately.

    If you take a 90degree turn, I think it treats it just like that, completely stopping in X and completely starting in Y. With the numbers above, it will slow down to 10mm/s and take the turn at that speed. That is a big impact on the printer though, because it has to apply enough force to stop the carriage from 10mm/s in X to zero, instantly, and go from nothing to 10mm/s in Y, in the same instant.

    I think max speed is meant to limit things like too many steps/second or an extruder that can’t possibly hear fast enough. Acceleration is more the critical piece, because it’s going to be very sensitive to mass and rigidity.

    If they didn’t use jerk, or the jerk was 0.0, the math for acceleration would mean that the printer would go very slow any time it stopped, started or took a turn. The reason there is jerk is because any impact under 1mm/s is bacisally no big deal, right? So why bother slowing down from 1 to 0 in this smooth, acceleration? It’s an optimization, really.

    I would try to tune like this:
    – Set the jerk to zero or very close to zero.
    – Set the max speed to huge.
    – Make the model small enough that you aren’t getting under extrusion problems. You won’t reach max speed.
    – Adjust the acceleration until you get an acceptably low amount of ringing. Keep this Accel. You might want try this twice, once for perfect and once for ok.
    – adjust the jerk up, a little at a time, until you notice some problems in a corner. Back it down a little.
    – Adjust the model to be bigger, and reduce the max speed until you can print a big side without extruder, belt, stepper problems. You can probably determine a good print speed and travel speed separately in this step.

    This way, the acceleration should keep things smooth in even the worst situations. The jerk will be optimizing as much as possible, without affecting your prints, and you won’t ever exceed your top speed for extrusions and steps.

    #51425

    Bill
    Participant

    I need a little help, On my Y and X axis I had assumed the 608 bearing in the BOM ware for the belts opposite the motor end, -They Don’t seem to fit there. Help please, I must be missing something. Thanks

    They are the pulleys in the original MP3DP. In the new MP3DP V2 there are actual idler pulleys. Which parts did you print? If you did the original parts then the pulley should fit between the two bosses embossed around the hole.

    #51427

    Craig
    Participant

    I printed the new version . I had a couple idler pulleys and they worked. What threw me off was the new bill of materials doesn’t show the pulleys.its cool though I’m about ready to fire the printer up. Thanks.

    #51443

    Ryan
    Keymaster

    I have it in the notes about the idlers, mine died real fast lube them up. Bill hasn’t had an issue so I am on the hunt for better pulleys.

    #51444

    Ryan
    Keymaster

    Heffe, I have been looking to the motion equations in marlin and can’t find them. I am still tweaking settings but with the equations I really feel like I am poking around in the dark, the notes in the firmware are far to vague. I printed some parts yesterday and they had ringing even with the slower accelerations. Maybe even worse.

    #51462

    Jeffeb3
    Participant

    Try setting the jerk really small. Like 1mm/s.

    #51468

    Ryan
    Keymaster

    I have tried 2 and 4, I will go lower but the dam LCD doesn’t work right on the mini for some reason with Marlin 2 all the other boards are fine…Hours trying to fix it.

    #51501

    Ryan
    Keymaster

    Progress, I think. Here is a better test showing the issues I saw in the real print.

    75mm/s accel 1500mm/s/s test part is smooth to 5° STL conversion.

    Jerk x=4 Y=2 still

    Showing horrible bulges at 5 degree increments heavier on the left which was ramping into x axis parallel so super shallow Y moves.

    MVIMG_20180121_2025352

    Jerk both 2…. both sides bad, needs to go higher! You can see the emboss ghosting differences.

    MVIMG_20180121_2041142

    Jerk both 4 @ 75mm/s and 50mm/s

    MVIMG_20180121_2104492

     

     

     

    #51506

    Ryan
    Keymaster
    #51508

    Jeffeb3
    Participant

    Let me guess at what’s going on. I think those are being printed as line segments, so with lower jerk, it is be trying to reduce the speed at each point. The higher jerk is making it take the curve at a smoother speed. I really wish there was a way to display what speed it would actually take there…

    I think you’ve made a better test print, in just worried it won’t translate well to another radius part. It looks like this artifact isn’t ringing at all though, right? It’s just over and then under extruding. The filament flow isn’t dynamic enough to match the dynamics of the x/y motion.

    I wonder what it would do with an arc.

    Very interesting though.

    #51509

    Ryan
    Keymaster

    You can hear it in the big round corners too low of a jerk and it sounds obviously wrong. Still haven’t found the equations. Not sure this was a big deal or not…

    #51542

    Ryan
    Keymaster

    Finally found the equations, seems obvious now…Marlin/src/module/planner, duh. 4 planner files and some in the 2 stepper files Jerk is mostly in planner.cpp and the trapezoid is in planner.h (starts at entry speed).

    How I am reading it. It calculates the speed trapezoid (basic straight line) starting at whatever jerk is set to as the minimum speed (entry speed), this sets both ends of the ramp up and ramp down. Smooth velocity is checked to see if the change in velocity is higher then the jerk to trigger accel or not (curves).

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