Newbie to CoreXY with DBOT build

Hi all,

Having owned an I3 clone for the last 2 years, I am about to embark on a DBOT build. The main reason I am swapping platforms is the COREXY looks to be more stable and will enable me to use a more substantial bed that I could on the I3.

I have am already printing the parts as we speak but I looking at the following spec..

300x200 D-bot with 4 Z gantries instead of 2 and some aluminium parts instead of printed
Duet Wifi running @ 24V
0.9 steppers on Z and XY - not sure about extruder as I'm not sure if I should go Bowden or Titan
Closed belt between 2 Z steppers to keep position when the machine is off.
6mm MIC-6 aluminium bed with 300w 24v silicone heater
600w 24v 25A PSU.

I am hopefully also going to enclose it aswell with Perspex/acrylic in the slots but not reasearched that yet!

Most of the parts are on order as I type so I will update the thread with photos/question etc ASAP!

Thanks,
Shaun

Edited 1 time(s). Last edit at 01/23/2017 09:33AM by prawnabie.

Welcome to the forum! CoreXY is a good choice for a new printer.

Quote
prawnabie

300x200 D-bot with 4 Z gantries instead of 2 and some aluminium parts instead of printed. Do you mean 4 screws instead of 2? You might find that 4 is overkill. 3 is a good number, as 3 points define a plane and so you can actually level your bed with 3 (Firmware update incoming for the duetwifi where you can use 3 steppers to level it). Alternatively, you may find 2 well supported gantries/screws works just as well. Quality over quantity.
Duet Wifi running @ 24V
0.9 steppers on Z and XY - not sure about extruder as I'm not sure if I should go Bowden or Titan 0.9 stepper isn't really needed on the Z axis, you might find 1.8 with a good gear ratio to work better as it has a bit more power for the weight. 0.9 could well be adequate though.
Closed belt between 2 Z steppers to keep position when the machine is off. A closed belt between 2 motors will fight each other. You're better off using 1 motor with a closed loop belt to power x number of screws. (EDIT - or is it a belt providing linear motion to the bed??)
6mm MIC-6 aluminium bed with 300w 24v silicone heater Sounds decent. CoreXY is a good candidate for mains voltage beds as well using a relay. It's arguably overkill, but heating times less than 30 seconds to get to 120c and you're laughing.
600w 24v 25A PSU.

I am hopefully also going to enclose it aswell with Perspex/acrylic in the slots but not reasearched that yet!

Most of the parts are on order as I type so I will update the thread with photos/question etc ASAP!

Thanks,
Shaun

Edited 1 time(s). Last edit at 01/23/2017 02:36PM by Origamib.

Spiffcow's "Spiffbot: [www.thingiverse.com]
and JonnayLin's "J-Bot": [www.thingiverse.com]
are remixes of the famous D-Bot, that use 4x guides on the Z rails.

Problem with the roller guides is they obscure the possibility of an easy enclosure, you need to add another box outside the bot

Good luck on your CoreXY build

Hi all,

Thanks for the replies!

By 4 gantries on the Z Axis I meant having 4 rails for the Z assembly rather than having it cantilevered from 2. The J-bot seems to have the same setup as I am looking to implement - the 2 Z steppers connected via a closed belt - is this not a good idea?

Regards to the Z steppers, I was looking at these... 0.9 Stepper but do you think I shouls be using these on the Z instead?

Thanks

Trying to lock two motors together with a belt is a bad idea and completely unnecessary.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

What DD said.

Threaded rod, leadscrews, and especially ballscrews, have more than enough mechanical advantage to drive a 3d printer bed.
The 3 belted screw approach is probably the best for support and balance, and provides leveling while the set screws on the pulleys are loose. Set it, and forget it.

The big disadvantage of multiple motors is they are not guaranteed to be 100% in Z-synch after each power up, something to do with powering down stationary but mid step.
Only reason to go to more than one motor is if you're planning on doing CNC milling/drilling. All the same, belting together is a waste of a belt and probably a few toasted stepper drivers.

BTW, unsupported screws are a bad idea, though cheap. Unsupported screws wip and will cause Z banding. Motor or pulley at the drive end, and a bearing that "floats" on the screw/shaft on the other.
Yea "it's the Z and hardly ever moves, and very little when it does", unless you're rapiding, or your acceleration is set mid to high. Just a personal pet-peeve, ignore if you like.

Edited 1 time(s). Last edit at 01/24/2017 04:46PM by prot0typ1cal.

Thanks for the info! I will ditch the belt idea then and just run with the 2 Z steppers to start with, then once it is printing I will look into the 1 motor and 3 lead screw idea.