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Building a 3d printer - looking for some suggestions

Posted by Cougar281 
Building a 3d printer - looking for some suggestions
January 31, 2019 11:56AM
After a year of printing with the CBot kit I got last year, I decided I want to build my own, larger printer. What I'm building is going to be similar in design to a Flying Bear P902, just bigger.

I have a good idea what I want to do with the Z-axis, but the X & Y axis is where I'm floundering a bit. I was originally thinking of using linear rods, at least 8mm, for all. I had been thinking of using two rods on either side for the Y axis, but that may be overkill and one on each side would probably be plenty, but then I was considering linear rails. For the X Axis, I'm thinking of something like the Flying bear, where the rods sit side by side and the print head drops down in between them.

That brings me to the other part I'm trying to figure out - the hot end. Of the hot ends out there, the E3D V6 seems to be pretty highly regarded, so I was originally thinking of that, but as I want it to be a dual extruder setup, trying to find something that would mount two E3D V6's was pretty much non-existent other than one setup meant for a delta printer. Then I noticed E3D's chimera hot end. I rather like it and I think that will probably be the way I want to go, but again, finding the appropriate carriage has been a bit of a challenge.

Ideally, I'd like to stay with pre-manufactured parts, and metal wherever possible. While I could 3d print parts, I'm not really sure the precision is there with the printer I have.

Does anyone have any thoughts or suggestions for the pieces I'm having trouble with?
Re: Building a 3d printer - looking for some suggestions
January 31, 2019 03:34PM
Dual nozzle hot ends such as Chimera have the problem that the non-printing nozzle leaves a mark on the print whenever it passes over freshly-printed filament that hasn't cooled completely. So for dual extrusion I recommend either a mixing extruder (e.g. Diamond), IDEX machine (two or more independent carriages moving along the X axis), or tool changing. Prusa's MMU is another possibility, but I know less about that.

What is your budget? If it's large enough, you might want to consider an E3D tool changer kit, which is currently in beta.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Building a 3d printer - looking for some suggestions
February 01, 2019 10:33AM
Well, I currently have a dual extruder setup, although I haven't moved into actually doing dual extrusion and the second extruder is raised up higher than the first one since I haven't been using it. As far as leaving marks, I actually have an issue where when the carriage is moving from one location to another over the print, it tends to drag across the print, so I'm guessing a second nozzle wouldn't change too much. The problem with single nozzle multi filament not ends is materials - you wouldn't really be able to run two different materials in the same print, such as your main material and a support material.

I don't really have a particular budget in mind - I don't expect to be finishing this overnight, and the hot ends will probably be one of the last things I get. That E3d Tool Changer kit looks neat, but the issue I potentially see is heatup time - if the parked heads get shut down, I would think the time required to get to temp could potentially be an issue.Unless they were brought to temp before the carriage went to switch, but that wouldn't work too good if they go to the pogo pin connections I saw mentioned in a video.
Re: Building a 3d printer - looking for some suggestions
February 01, 2019 03:09PM
Flyingbear p902 has huge bed cantalever
they even dicontinued it with p905 that supports bed on two ends

Consider linear rails

read thru:

[reprap.org]

a lot of good build techniques there

The digital dentist knows how to build a printer

[drmrehorst.blogspot.com]

confused smiley
Re: Building a 3d printer - looking for some suggestions
February 01, 2019 04:51PM
Quote
Cougar281
That E3d Tool Changer kit looks neat, but the issue I potentially see is heatup time - if the parked heads get shut down, I would think the time required to get to temp could potentially be an issue.Unless they were brought to temp before the carriage went to switch, but that wouldn't work too good if they go to the pogo pin connections I saw mentioned in a video.

Parked heads are run at standby temperature, just as you should run any multiple nozzle setup. You set the standby temperature low enough to avoid oozing and prevent the filament hydrolysing if it is PLA, but high enough that you can bring the tool up to printing temperature quickly.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Building a 3d printer - looking for some suggestions
February 04, 2019 03:44PM
Quote
Cougar281
After a year of printing with the CBot kit I got last year, I decided I want to build my own, larger printer. What I'm building is going to be similar in design to a Flying Bear P902, just bigger.

I have a good idea what I want to do with the Z-axis, but the X & Y axis is where I'm floundering a bit. I was originally thinking of using linear rods, at least 8mm, for all. I had been thinking of using two rods on either side for the Y axis, but that may be overkill and one on each side would probably be plenty, but then I was considering linear rails. For the X Axis, I'm thinking of something like the Flying bear, where the rods sit side by side and the print head drops down in between them.

How big is bigger? If you have large spans, 8mm round rods have low moment of inertia, or resistance to bowing, compared to 2020 extrusion. Almost all larger machines use extrusion of some sort for the XY, with the extrusion as the rail, or ground linear rails on top of the extrusion.
Re: Building a 3d printer - looking for some suggestions
February 06, 2019 12:14PM
Quote
cozmicray
Flyingbear p902 has huge bed cantalever
they even dicontinued it with p905 that supports bed on two ends

Consider linear rails

read thru:

[reprap.org]

a lot of good build techniques there

The digital dentist knows how to build a printer

[drmrehorst.blogspot.com]

confused smiley

Yes, the 902 actually is a poor example with regards to the build plate - I was planning to have the build plate supported on two sides more like the 905H, but in terms of the X/Y axis, the 902 and 905 are pretty similar.

Quote
gmedlicott
How big is bigger? If you have large spans, 8mm round rods have low moment of inertia, or resistance to bowing, compared to 2020 extrusion. Almost all larger machines use extrusion of some sort for the XY, with the extrusion as the rail, or ground linear rails on top of the extrusion.

The outer dimensions of the frame are about 64cm wide and deep and about 49.5cm tall. I'm planning my initial build plate to be probably something in the area of a 310mm x 310mm plate, give or take. I may or may not eventually want to move to an even larger build plate, but I opted to make the frame as big as it is to allow for such an upgrade without having to totally rebuild the whole thing should I want an even larger build plate, and to make sure I can use the entire usable surface of the build plate with dual nozzles - that's one problem with my current printer and dual nozzles - I lose a pretty decent amount of usable surface due to the nozzle offset. One thought I had was linear rails attached to the frame for one axis and 8mm or 10mm rods for the print head to ride on, but if a piece or extrusion with one or more linear rails would be better (lighter/stiffer/etc), I'm open to that idea as well.
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