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Discussion in '3D printers' started by Adam Filipowicz, Sep 21, 2015.
Super Rigid CoreXY 3D Printer
Adam Filipowicz published a new build:
Read more about this build...
Wow. Great modeling and render.
Overall the belt system seems too complex, but what do I know.
The Z Belt definately needs some love and simplification. perhaps I should remove the Cbeams on the Y Axis. and replace with something else.. i have seem other more elegant CoreXY belt layouts. but i want to avoid printed brackets if possible. also I think i should go to Nema 17s. not sure if one Nema 17s could run all 4 Z screws
I'm not sure about that either. Maybe the right 17 or an additional slaved one in the mix. Sounds like some math is involved in that decision.
How do you level a drawbridge like that?
Really like your design. I would go for a bigger build plate. I have an 18" x 18" heated bed in mine and its awesome to have all that room.
going 18"x 18" is a good idea (in the long run) I have a 12" build plate that I can salvage from the Makerfarm i3v 12" for the short term.. I have also added spool holders and turned it around.
id like to enclose it in acrylic. and and use the extrusion channels to hold the panels. but i need to rejig to make this happen.
Do you think I need to have the top framed off.. i like having just the posts, I feel it would be rigid enough this way.
Build plate is 6mm Alum + Heater, + 6mm Borsilicate glass plus PEI
Id like to use the idea of Piezio disks to do auto bed leveling. under the build plate
using C beam on the Y. takes up alot of room. I need to revise.
How about something super simple. Sorry for my sloppy drawing.
I want to avoid multiple steppers per axis. for sync issues. with this config you are driving 5 steppers vs 3.
You can drive the 2 motors of the Z and the Y on 1 stepper driver each. Then the X alone. We do this all the time on 3D Printers. You could also do auto bed leveling with this. I do this on my big printer.
yes but if one stepper misses a step. it will be out of sync, and will need calibration and will bind. keeping it to one stepper adds complexity with the belts but will stay synced. My makerfarm i3v has dual Z steppers running off the same driver but everytime i calibrate it they are out of sync from each other by a slight amount
Wow. My machine is never out of sync
Here is a thread on the subject
I do like this setup.
Is this still CoreXY?
Here is another version. where there is a belt loop on top and bottom. no cross over. but does this still qualify as CoreXY with its advantages or Hbot?
Here is an update. after playing around for several hours on an alternate belt config for corexy I ended up staying where I started. but im not more confident in my choice. I also ended up going to a Hybrid Direct drive for the extruder.. there is a very short bowden tube. 50mm between them. this adds weight to the gantry but should get rid of the typical bowden issues. I am hoping that since im using Nema 23's and GT3 Belt and 40x40 extrusion the added weight wont be so bad.
I also pushed the XY Steppers in to the frame so they dont stick out the back anymore
Did you figure out the Generic cost of this in Open Build parts yet ???
not yet. im going to try and revise so extrusions are 500mm or less
You can use one geared Nema17 for your z-axis. That's what I'm using for my Samson build. 5:1 reduction ratio should be plenty of torque, but you could go up a little bit. I get geared steppers from phidgets.com.
Yeah, we do this all the time thanks to Josef Prusa but it has been found out that a 2 motor Z drive on one driver DOES lose sync. I was telling people about this years ago but only recently (look around reprap.org's forum) has people actually measured it. This quote is from another thread for another printer but it too was trying to use 2 motors with 1 driver so I thought I would post Mr. Davis' reply the pertains to this issue:
Even Josef Prusa finally saw the error in his ways with 2 motors 1 driver.
My design will not use two motors due to what I know, what I have seen on my own boat weight i3 rework, and what I have read. What some are doing is using a belt to drive two leadscrews/acme screws with one motor and the reports are that doesn't lose any amount of sync at all. Since this is for Z the loss of resolution by using a GT2 belt wouldn't matter.
Oh, one thing on this printer's design I would be cautious about is the open air design on those 4 legs especially with tall prints and trying to go fast or have rapid accelerations.
Was reading up and spotted this. /High five and you are spot on. This is one reason so many printers have to have Z recalibrated before every print after long print runs or at least once a day or two. Just a bad, no a terrible, design to have two motors on one driver and to have two motors on two drivers requires some feed back of some sort or at least two end stops and go from there (that is if neither loses a single step if one does look out).
Here is an update. feed back appreciated.
I really want to make the build plate solid. with no movement at all.
belt layout is rough and should be able to be tighter to the sides. so it doesnt eat up the X Travel as much.
Revised Z belt layout
$125.20 (Silver or 1 dollar more for black) for each leg made me sick. I love the design but it really is very costly when all said and done even though very few parts are being used.
Unfortunately your right. I wish some of the parts were cheaper. I calculate aprox $100 each, they are 420mm long
Know a good place for closed Gt2 belts?
100 dollars each for what? The price I quoted was for the 500mm version of the c-beam linear actuator which is an absolutely hideous price and is the only negative thing I now see.
Yep I priced it based on buying longer extrusions and cutting down. but really its the plates, bearings, rods, block and other small parts that really make it add up. I Wish they had a smaller C Channel linear extrusion and smaller Gantry plate for it
You might check here.
They also offer Bundle Packs at 500mm for $99
Yep, this morning that was listed at the price I said but last month they were around 100 so I figured inflation or something. One hundred is about the limit I would go (though 70-80 is a more realistic price imo) for 500mm.
I see now I went to here http://openbuildspartstore.com/v-slot-linear-actuator-bundle-lead-screw/ this morning and last month to the link you posted, LOL. I was having sticker shock with about a 30% increase in price in a month.