3D Printer Build (Napier - NZ)

Hi, I'm starting to build a printer in Napier, NZ. I've made a few designs and started gathering parts together.

I've posted it on a blog,

[rappronz.blogspot.com]

After people's opinions of what works, what they think etc. Be critical



Regards,

Nigel.

I don't think your feeder system is going to be strong enough, the PLA or ABS is really quite viscous. All working extruders have some sort of gear that cuts into the plastic to drag it threw. Eg a hobbed bolt

Other than that it looks nice.

I have a Sells mendel and now I'm building a Prusa so that I can work out how much it costs as I keep getting asked where to buy one complete the build so far can be found [picasaweb.google.com]

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Experimenting in 3D in New Zealand

Hi, thanks for the replies. Every little bit of input helps. I've designed the drive roller setup to be easily changed to knurled rollers or whatever is needed. It's something that I'll sort out when it's up and working so I can test it out.

From what I've been told atleast 80N force is required at the filament drive rollers. I only have about 54N with the current setup. Changing to a Nema 23 stepper with 0.746 holding torque will give me a calculated 259N - more than enough.

What are the advantages / disadvantages or running 3.0mm or 1.75m filament? Is there a preferred size or due to availability in different plastics? I can't seem to find much information on this.



Cheers,

Nigel.

I don't know much about stepper motors but according to kthx, the bot in the #reprap IRC channel:

Quote
kthx
ideal motors are NEMA17 size, rated 1 to 4 volts, 1.5A, 3 to 8 mH, 62oz.in (44Ncm, 4.4kg.cm) or more of torque, 1.8 or 0.9 degrees per step (200/400 steps/rev respectively) such as the kysan 1124090/42BYGH4803 for example

So I NEMA 23 with 0.746 Nm of holding torque sounds pretty low when the recommended holding torque is 4400 Nm. The Prusa page on reprap.org says something similar:

Quote

Be sure to get ones with at least 20mm of shaft length. Shorter shafts require modifications to the X pulley assembly and Z motor couplers. One of the five motors, for use with the extruder, should be capable of creating a holding torque of at least 40Ncm, at the very least.

Does the larger NEMA 23 size increase the torque considerably?

Regarding your filament diameter question - 1.75mm is good if you're aiming for really high quality prints when combined with a tiny nozzle (i.e. 0.25 - 0.4). This is because you're feeding in a lot less plastic at a time and can more finely control the flow. However 3mm is almost half the price of 1.75mm (in PLA from Vik anyway) and NelsonRap has said in another thread that it is stronger on the roll so can be easier to handle. I say go for 3mm until you're at the stage where you need to improve your print quality.

Hi, thanks for your reply. The information on filament sizes is exactly what I wanted to know.

You might want to check your maths on the torques above, 4400Nm seems a wee bit high! I have a Mitsubishi Triton with about 420Nm of torque, don't think a Nema 17 stepper motor is greater than that 44N.cm is 0.44Nm.



Cheers,

Nigel.

Wow you're right, I have no idea how I got that so wrong!

Update: I tracked my mistake down to this conversion page:

[www.convertunits.com]

The description at the bottom ("How many N/cm in 1 N/m? The answer is 0.01") is correct but the actual converter is backwards.

Edited 1 time(s). Last edit at 10/05/2011 05:57AM by grokbeer.

I've never seen anything justifying the additional expense of 1.75mm plastic unless you're building a very small machine and just want everything to be tiny. I've certainly not been shown any before/after pics of a RepRap 1.75mm build so I couldn't say for sure though. I have huge stocks and sell relatively little of it.

If you need buckets of torque from a wimpy motor, use a Wade extruder design.

Vik :v)

Hi, thanks for the input Vik. A lot more work has been done on the machine, most of the base and frame are completed just waiting for linear rails and parts from eBay. Photos are up on my blog.

What I really need to figure out now is what's the best options for heating the filament and the table. Is using a resistor the best heater or are there more specific heating solutions which can be better? And what type of power supply is required for this? Also what type of interface is needed to control the heating resistors and thermocouples? This is the side of the project I'm least familiar with so any help is appreciated

I plan to use a stepper motor controller of this type http://www.trademe.co.nz/business-farming-industry/industrial/manufacturing-metalwork/lathes-accessories/auction-423929070.htm to run the steppers, with a 15A 24V power supply which I have purchased of eBay.

Any advice regarding the electrical side of the machine is greatly appreciated.




Cheers,

Nigel.

People have tried to use this particular controller before, with no success..

see [www.reprap.org]

Also you still need a controller board, this provides the real time control that a pc with parallel port cant do.
Ie if a milling machine (what these boards are for) pauses, no issue, the head just spins doing nothing, if you pause a reprap plastic will still flow, causing blobs.

Edited 1 time(s). Last edit at 11/15/2011 04:50AM by Dust.

I use J head hotends that are heated by resistor and I use 4 2.2ohm housed resistors for my heated beds and they can easily get the aluminium bed up to 55-60C needed for PLA to stick.

I make my own heated beds

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Experimenting in 3D in New Zealand

Hi, thanks for the replies. I'll have some more pictures of the machine up over the weekend with all the rails, X-Z Saddle, Extruder Body and bed mounted.

Regarding the controller boards, if the board I mentioned above isn't a good option, what is recommended and where can I purchase the boards from? I would rather buy a complete assembled board rather than a kit as machining is my speciality not electronics

NelsonRap - are you able to provide me with more information about the heated bed and hot end assembly? And any idea where I could source the parts from?


Cheers.

Looking into it a bit more, is this what I should be using?

RAMPS Pre-Assembled Kit Complete
[ultimachine.com]

The stepper motors I have a are rated at 3.0A / phase so I don't think they will work with the stepper drivers that included with the kit -they are rated at 2A per coil. [ultimachine.com] Is it possible to use a different stepper or what should I use?

What other parts will I need? Any recommendations are greatly appreciated.


It seems the more I look into it the more confusing it gets but that's what I'm here to learn.



Cheers.

Nigel_NZ Wrote:
-------------------------------------------------------
> Hi, thanks for the replies. I'll have some more
> pictures of the machine up over the weekend with
> all the rails, X-Z Saddle, Extruder Body and bed
> mounted.
>
> Regarding the controller boards, if the board I
> mentioned above isn't a good option, what is
> recommended and where can I purchase the boards
> from? I would rather buy a complete assembled
> board rather than a kit as machining is my
> speciality not electronics
>
> NelsonRap - are you able to provide me with more
> information about the heated bed and hot end
> assembly? And any idea where I could source the
> parts from?
>
>
> Cheers.

I made my own heated bed with some aluminium housed resistors Prusa and I use these hot ends here

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Experimenting in 3D in New Zealand

I use the heated bed PCB from [ultimachine.com]
But if you have upsized your build area, this wont work.

I really like makergear hot ends [www.makergear.com]

Ramps is good as is Sanguinololu for the main controller.

You should take a look at www.emakershop.com and or www.lulzbot.com cheaper prices...

comment from Prusa today re jhead " weve had j-heads but each nozzle was different, a lot, and few of them were not usable :-((("

So I cant recommend j-head at this time.

Hey Nelson,

I liek your heated bed, but you don't seem to have the tradition bed on stalks, is that a new thing for linear bearings, do you have any issues with levelling it? Are you worried about the wood getting too hot?

korban Wrote:
-------------------------------------------------------
> Hey Nelson,
>
> I liek your heated bed, but you don't seem to have
> the tradition bed on stalks, is that a new thing
> for linear bearings, do you have any issues with
> levelling it? Are you worried about the wood
> getting too hot?


It's MDF and for PLA it's fine as you only need to get up to 55-60C for that. I would not use it if printing ABS though as it could burn at the higher temperature. With linear bearings and a nice thick 5mm alu bed it stays nice and flat so I just set the nozzle height and forget

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Experimenting in 3D in New Zealand

A lot of work done, here's a short video of the machine:

[www.youtube.com]