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Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

Doboz 2 (H-Bot 3D printer)

by ckaos, published

Doboz 2 (H-Bot 3D printer) by ckaos Aug 2, 2012

Description

UPDATE : 31/08/2012
- Finished basic version of x_carriage
- Finished basic version of Z axis elements
- Added updated main .scad file (doboz_v2 0.1.scad)
- Added pictures and video of Z axis
- Please see the github repository for more up to date information

Descriptions
This is preliminary work for an h-bot configuration based reprap, with a rather large build volume.

The main advantage of this kind of setup is its mechanical simplicity, so with that in mind, I plan to make this very easy to build and hopefully just as easy to calibrate etc.

This is of course fully parametric!

Dependencies
-Requires the MCad library

Specifications
- H-bot design
- Maximum build size (not set in stone): 220*350*400 mm

Media
- first X/Y movement test of prototype (running Marlin firmware with CoreX/Y support enabled)
youtube.com/watch?v=a4HLpNbQznU&feature=g-upl

-first Z platform movement test:
youtube.com/watch?v=IwWGr_ky8B0

More info
github.com/kaosat-dev/Doboz-2

Recent Comments

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I used 2 gt 20 tooth synchronous wheel inner hole 8 mm.
Built-in bearings and bushings to activities.
H - bot transmission system is great.
I also designed a bot h - all metal parts.
item.taobao.com/item.htm?id=39952829876
With a large build area (i.e. potentially large/heavy objects being printed) and a canterlevered build platform, do you suffer from Z banding or sticking/jamming on the Z axis? Is it using a regular threaded rod, or acme style? I am currently designing an H-bot style printer now and was planning on putting guide rods/linear bearings for the Z axis on the sides at the front and one in the middle or the rear to distribute the load evenly, but my Solidoodle 2 is like yours and only has a single drive with 2 smooth rods at the back (and suffers from banding I believe because of this). Good luck with getting the kinks worked out, I am still at the very early stages of my build!

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Instructions

For now this is still in the very early prototyping phase, so almost nothing is in a 100% usable state, but I hope to have a fully working prototype by September.
Until then, expect the files to change a lot !
(and feedback is always welcome)

I will update files here regularly , but you can always find the latest version here github.com/kaosat-dev/Doboz-2

Things that are finalized:
- X ends
- X carriage
- Z axis elements

Next to be finalized:
Extruder, hot end holder etc

Not done at all:
- "box" structure angle elements : not

Bom:(totally incomplete for now)
- 8mm smooth rods (4X for X/Y axis, 2x for Z axis)
- lm8UU linear bearings X10
- 5mm wood plank (used for build platform)
- 4mm dia nuts & bolts (12mm long) X6 for x_ends
I used 2 gt 20 tooth synchronous wheel inner hole 8 mm.
Built-in bearings and bushings to activities.
H - bot transmission system is great.
I also designed a bot h - all metal parts.
item.taobao.com/item.htm?id=39952829876
With a large build area (i.e. potentially large/heavy objects being printed) and a canterlevered build platform, do you suffer from Z banding or sticking/jamming on the Z axis? Is it using a regular threaded rod, or acme style? I am currently designing an H-bot style printer now and was planning on putting guide rods/linear bearings for the Z axis on the sides at the front and one in the middle or the rear to distribute the load evenly, but my Solidoodle 2 is like yours and only has a single drive with 2 smooth rods at the back (and suffers from banding I believe because of this). Good luck with getting the kinks worked out, I am still at the very early stages of my build!
hello sorry if this has already been asked, is there firmware that may be downloaded?
ckaos - in reply to BV3D
Hello !

No worries: as said earlier, it is just using Marlin firmware, with the corexy option enabled :)
BV3D - in reply to ckaos
Very cool I didn't understand that thank you.
I notice your moving gantry does not have the typical three bearing setup, opting instead to use only two linear bearings, one on each side, and with the smaller bars set up one on top of the other. Doesn't this allow the gantry to skew out of square when you are quickly moving the head left/right or moving diagonally?
That is actually something I was a bit afraid of, but the structure was sufficiently rigid to make skewing non noticeable.
With really high speeds it could be an issue , but that would need to be re-checked: a few people did some derivatives of this design and/ or close enough designs and they have not reported such problems, however.
Nice design, one question, ther firmware that you use is? how to modify to work with parametric mechanic?
ckaos - in reply to bgc_e6
hello ! 

Sorry for the late reply:I am currently using it with the Marlin firmware, with the corexy option (just uncomment the corexy line in the configuration file & compile/upload it).
Thanks for the comeback, What about the gcode? does that require special rework?
No problem.
I am not sure I understand your question though?

All the parts in the pictures were sliced using Skeinforge, at 0.28 layer thickness, no special settings or precautions required normally.

A big warning though: this is still a prototype, and I have lots of cleanup , clarification , and changes coming up :)
I noticed that the x-end elements have provisions for a 3mm screw as bearing shafts. What type of bearings do you propose to use? What size and type of belting?
Hello Librav, sorry for the late reply!
Actually , it is 4mm screws for bearing shafts.
Bearings:
- Currently I use two 624 ZZ bearing on top of each other for each "corner" on the x-ends.

For the belting:
- tricky question : for the prototype I use 2X Gt2 belts attached together : so 6 mm wide, and 2x 131 cm long
 (and corresponding pulleys I got from http://techpaladin.com/store/#ecwid:category=1941327&mode=product&product=9001827 )

But, as longer GT2 belts are impossible to obtain, the final version will likely use T2.5 , also , you can use different belts if you wish (A friend is building a variant of this machine using MXL belts), just be sure to specify the correct belt_width param to the x ends.
Very neat design !

What is the build volume of the small and big versions?

Also I am curious, what speeds do you manage to attain ?
hehe yes, there is no such thing as "too much h-bots" ! ;)
yay for more h-bots !
Been working on the Hbot for a while now

youtube.com/watch?v=Hc0ADpQ6FBg
Really Nice !

Did you manage to move forward with the plans to open source it ?
Thanks ckaos yours looks awesome too!

The idea is to release the plans once they are completed. We are still in the testing phase and working out a few issues with calibration.

We have two of them now. One is a mini version :) That I am testing and the other is the larger version a friend is testing.

Couple pics of the mini the lights are too cool

8-)

The code (written by my friend) we figured out simply rotates the output gcode @ 45 degrees!
Since there is no specific x-axis and y-axis steppers,what modification is required for the gcode?
Awesome! I was at IKEA the other day when a random "I wonder if I can use this stuff to make a 3D printer". Glad to see someone actually do it!
haha :) well , I actually made the original repstrap to fit Ikea shelving , but it does not actually use the ikea shelves themselves as structural element or otherwise! ;)
I like the H configuration a lot. I was leaning very strongly towards this for my own repstrap (in strap-age until further notice) and only abandoned it because of it not conforming to the budget I had in mind. This bot is fussy about the materials you use, but should have Ultimaker-like performance with much less rod...

You can really see the Gada prize contenders crawling out of the woodwork now...
Yeah, H-bots are so elegant in their simplicity (seriously, I never thought I would have something working so soon), and as you say, uses less rods and vitamins overall but still should give good performance ...

This prototype is still too early in the development process to push it to max speeds, will see how that goes!

Funny thing is, I had forgotten about the Gada prize, this was just done because I really want to build a reprap that is "simpler", more reliable, faster, and has better volume usage than standard repraps:)
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