Mondrian build thread January 14, 2014 01:39PM |
Registered: 11 years ago Posts: 553 |
Re: Mondrian build thread January 15, 2014 01:32PM |
Registered: 11 years ago Posts: 553 |
Re: Mondrian build thread February 02, 2014 04:02PM |
Registered: 11 years ago Posts: 12 |
Re: Mondrian build thread February 03, 2014 09:50AM |
Registered: 11 years ago Posts: 553 |
Quote
cakeslob
I followed the Foldarap2 from the beginning of the project till the last Hbot revision where he went over to the rack and pinion. At the point I started doing my own fork of the foldarap2 hbot. I could never get them to work the greatest. Too much drag, binding, and deflection to make the hbot work properly. I really liked the corner brackets and the belt inside the channels of the Tslots but the brackets just flexed to much for me and the belt had way to much resistance. I started using rod and bearings and eventually just redid my whole Hbot from scratch.
I dont mean to put down the foldarap hbot revisions at all, because they were a large inspiration for my current hbot. I can see why he abandoned the hbot for now
Re: Mondrian build thread February 04, 2014 06:53PM |
Registered: 14 years ago Posts: 615 |
Re: Mondrian build thread February 05, 2014 09:22AM |
Registered: 11 years ago Posts: 553 |
Quote
Emmanuel
Yes, if you can use the CoreXY layout, it will avoid the biding problem with a simple H-layout (or for an H you'll need an expensive frame to make it work). I'de be curious to see your variation if you keep some parts of the Mondrian but manage to use a coreXY.
I built an H bot also to understand how it works, and after that I realized why Ilan made his CoreXY like that
Re: Mondrian build thread February 05, 2014 04:23PM |
Registered: 11 years ago Posts: 12 |
which is what I opted to do. I took out the corner brackets and made more rigid metal brackets.Quote
Emmanuel
(or for an H you'll need an expensive frame to make it work).
Re: Mondrian build thread February 07, 2014 04:37PM |
Registered: 11 years ago Posts: 553 |
Re: Mondrian build thread February 09, 2014 11:35PM |
Registered: 11 years ago Posts: 162 |
Quote
gmh39
Quote
cakeslob
I followed the Foldarap2 from the beginning of the project till the last Hbot revision where he went over to the rack and pinion. At the point I started doing my own fork of the foldarap2 hbot. I could never get them to work the greatest. Too much drag, binding, and deflection to make the hbot work properly. I really liked the corner brackets and the belt inside the channels of the Tslots but the brackets just flexed to much for me and the belt had way to much resistance. I started using rod and bearings and eventually just redid my whole Hbot from scratch.
I dont mean to put down the foldarap hbot revisions at all, because they were a large inspiration for my current hbot. I can see why he abandoned the hbot for now
Thanks for the input!
Yea, I am doing a redesign of some of the parts, specifically the corners (intergrating motors completely) and making it a corexy, or at least I am going to try to. I have heard that the H bot configuration is prone to binding because of the uneven forces (I think that was it), and I am really looking for something that wont have that problem.
Re: Mondrian build thread February 10, 2014 08:37AM |
Registered: 11 years ago Posts: 553 |
Quote
iquizzle
Quote
gmh39
Quote
cakeslob
I followed the Foldarap2 from the beginning of the project till the last Hbot revision where he went over to the rack and pinion. At the point I started doing my own fork of the foldarap2 hbot. I could never get them to work the greatest. Too much drag, binding, and deflection to make the hbot work properly. I really liked the corner brackets and the belt inside the channels of the Tslots but the brackets just flexed to much for me and the belt had way to much resistance. I started using rod and bearings and eventually just redid my whole Hbot from scratch.
I dont mean to put down the foldarap hbot revisions at all, because they were a large inspiration for my current hbot. I can see why he abandoned the hbot for now
Thanks for the input!
Yea, I am doing a redesign of some of the parts, specifically the corners (intergrating motors completely) and making it a corexy, or at least I am going to try to. I have heard that the H bot configuration is prone to binding because of the uneven forces (I think that was it), and I am really looking for something that wont have that problem.
The problem isn't necessarily binding (although it could be if it was reeeeaallly bad). The problem is that the force balance in the h-bot configuration results in torque on the gantry. Here is an image I made a few months ago to describe it.
This mainly manifests itself in small angle rotation of the linear rods permitted by the clearance of the bearings. The resulting distortion is easiest seen by elliptical shapes along the 45 degree directions when printing circles.
I have *mostly* eliminated h-bot distortion on the UConduit h-bot by:
- spacing the outside bearings farther apart
- using LME8UU adjustable bearings and applying tension on them to reduce clearance to the rods
- replacing LM8UUs with LML8UUs
Anything you do to reduce the angles by which the linear rod can go through the bearings will help. It is manageable without expensive linear rails. I am getting good prints without noticeable distortion, but in the end, I think corexy is physically a superior drive system. When I produce my second version, it will probably be a dual option h-bot/corexy... though I expect to be switching to corexy myself.
*Also, https://groups.google.com/forum/#!forum/h-bot-and-corexy-3d-printers might have some helpful information for those thinking about h-bot/corexy printers.
Re: Mondrian build thread February 10, 2014 05:16PM |
Registered: 11 years ago Posts: 12 |
Quote
iquizzle
The problem isn't necessarily binding (although it could be if it was reeeeaallly bad). The problem is that the force balance in the h-bot configuration results in torque on the gantry. Here is an image I made a few months ago to describe it.
This mainly manifests itself in small angle rotation of the linear rods permitted by the clearance of the bearings. The resulting distortion is easiest seen by elliptical shapes along the 45 degree directions when printing circles.
I have *mostly* eliminated h-bot distortion on the UConduit h-bot by:
- spacing the outside bearings farther apart
- using LME8UU adjustable bearings and applying tension on them to reduce clearance to the rods
- replacing LM8UUs with LML8UUs
Anything you do to reduce the angles by which the linear rod can go through the bearings will help. It is manageable without expensive linear rails. I am getting good prints without noticeable distortion, but in the end, I think corexy is physically a superior drive system. When I produce my second version, it will probably be a dual option h-bot/corexy... though I expect to be switching to corexy myself.
*Also, https://groups.google.com/forum/#!forum/h-bot-and-corexy-3d-printers might have some helpful information for those thinking about h-bot/corexy printers.
Re: Mondrian build thread February 16, 2014 05:01PM |
Registered: 14 years ago Posts: 615 |
Re: Mondrian build thread February 17, 2014 08:47AM |
Registered: 11 years ago Posts: 553 |
Quote
Emmanuel
Thanks for sharing, it's always interesting to see
gmh39, your drawing could be possible, if you add panels on the frame (wood, acrylic, etc) you can remove one Y extrusion of the frame