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Prusa i3 kit from Aliexpress, help!

Posted by squinter 
Prusa i3 kit from Aliexpress, help!
December 07, 2014 01:50AM
Hi all,

I'm thinking of building a Prusa i3 by getting a kit from Aliexpress Prusa i3 kit

I never build any 3D printer before. I need some help on what to watch out for when buying a kit like that one on Aliexpress.

Or is there an easier way to start out building a RepRap in NZ, like a local community? I'm based in Levin.
Re: Prusa i3 kit from Aliexpress, help!
December 07, 2014 02:52AM
Fist thing, stay away from acrylic printers, they crack with any stress.
Re: Prusa i3 kit from Aliexpress, help!
December 07, 2014 02:54AM
Hey, I am also looking to build an I3, just down in Wellington. smiling smiley At the moment I am trying to decide whether to go with a kit or source all the parts myself and build it over the Christmas break. I have started a thread to try work out where to get everything. I know clogs51 bought a kit (see his thread here : mendel 90 thread ), and he ran into a few problems. So its a risk if you try order a kit- you may find yourself replacing parts. Hence why I am more tempted to source the parts myself.

In the end it depends whether you want the ease of a kit build or a bit more security in the knowledge of what you get yourself, that you are happy with the quality of the build. And how comfortable you are in doing the dirty work yourself.smiling bouncing smiley
Re: Prusa i3 kit from Aliexpress, help!
December 07, 2014 03:06AM
Thank you for the quick responses

I mainly want to get started. I can improve/upgrade the printer later on. So I'm looking for a kit so I can get cracking and build a 3D printer quickly and see all the parts working together. Then as I understand more, I can work on each part and upgrade as necessary with better quality materials.

"Fist thing, stay away from acrylic printers, they crack with any stress."

Are you referring to the acrylic frame? What kind of stress? heat / weight?

I'm thinking I can replace/upgrade the frame later after I get the hang of it, or would it be too hard to replace the frame?
Re: Prusa i3 kit from Aliexpress, help!
December 07, 2014 12:03PM
The ad. doesn't say what thickness the acrylic is,but mine being 8mm,I have had no problems with the frame.
Unfortunately,they don't show the control board,which probably means it's a Melzi,which is what gave me problems.
I'd say it's a good starting point,but budget for $150-200 for Ramps electronics .The extruder looks to be a direct drive,and might work for now.
My printer was slightly different ,having rods in the front in stead of the acrylic piece.
Oh,don't forget you'll probably be pinged by customs for GST and customs fees.$80-200,depending on the customs officer's mood.
Re: Prusa i3 kit from Aliexpress, help!
December 09, 2014 11:15PM
I've been thinking about this. I think I'll take time to understand the blueprint first before potentially blowing a couple hundred bucks smiling smiley

Thanks all
Re: Prusa i3 kit from Aliexpress, help!
December 13, 2014 12:40AM
I just purchased one of these as it seemed a good way to get a starter pack with all the bits, will arrive in 3 days , so ill let you know how well build it is and ill put up a list of the parts , PCB''s, stepper motors etc etc
Re: Prusa i3 kit from Aliexpress, help!
December 16, 2014 12:03AM
OK the printer arrived today,

Took about 3 hours to assemble the hardware , everything fitted perfectly, there was only 1 washer missing, and I added 3 extra washers under the screws that hold the stepper motor on the x axis to spread the load on the printed parts.

The kit came with tools to assemble it , Cutters , screw driver and tweezers, heat shrink and extra screws nuts and tyraps ( cable ties) . The kit also had some spare belt clamps ( just in case you break them).

The Wiring took another 4 hours to complete and I used cable ferules on the ends of each cable before going into the terminal blocks.

The Acrylic is very stiff and is all 8mm, the only thing I may add is a all thread rod to keep apart the Y stepper motor from the Pulley when you put on the belt tension the Acrylic bends in about 1mm on both ends , I guess this would happen with wood and the all thread type,

The Power supply is 12V 15A, with a Melzi controller .
Re: Prusa i3 kit from Aliexpress, help!
December 16, 2014 04:36PM
Quote
moth4017
The Acrylic is very stiff and is all 8mm, the only thing I may add is a all thread rod to keep apart the Y stepper motor from the Pulley when you put on the belt tension the Acrylic bends in about 1mm on both ends , I guess this would happen with wood and the all thread type,

The Power supply is 12V 15A, with a Melzi controller .

First Hi Moth4017, your user name is familiar, have you used this on the coarse fishing forums in NZ?

Second, do you mean that the Acrylic sheets at each end of the Y axis? that's not so good, it will cause the smooth rods to not be parallel.
if the Y axis rides smoothly from Ymin to Y Max by hand and you don't feel an increase in friction on the bearings then this might not be too big of an issue, the treaded rods on my Y frame do not flex when I tension the Y Belt.

Edited 1 time(s). Last edit at 12/16/2014 04:37PM by Zerker.
Re: Prusa i3 kit from Aliexpress, help!
December 16, 2014 05:27PM
yep ,Same guy from the fishing site.

the front and back Acrylic parts are held apart by the threaded rod, but the stepper motor and belt pulley are in the middle of these, so as you apply belt tension then bend slightly in the middle.
So my solution for this was to put a threaded rod between them as a support. the bed moves very easy on the guide rails so it must be square smiling smiley.

First print in PLA came out very well , so I guess its quite a good starter kit for the Price..
Re: Prusa i3 kit from Aliexpress, help!
December 16, 2014 06:17PM
Hi Moth4017,

Thank you for sharing your experience with the kit!

"my solution for this was to put a threaded rod between them as a support."

Would you be able to upload a photo of it?
Re: Prusa i3 kit from Aliexpress, help!
December 16, 2014 06:48PM
Will do, ill take a photo tomorrow and put it up, I also changed the type of cable from the heater plate as the product supplied was very stiff and I could see it flexing the hot plate connections, but out the box with no fine adjustment yet , gives a pretty good result, if you do go and by the Kit I would suggest buying a can of compressed Air, Because the parts are Acrylic the polystyrene packaging is statically attracted to the Acrylic , the best way of getting it off was blasting with Air smiling smiley
Re: Prusa i3 kit from Aliexpress, help!
December 26, 2014 06:08PM
Just a Final update on this Prusa I3 Acrylic from Omni from Aliexpress...

Some of the mods I made to give me made a beneficial increase to the quality of the prints. ( I have to say out the box the prints are quite acceptable )

300.Jpg Photo
I added a support bar between the Y stepper motor and the pulley, not only does this maintain the belt tension, but stopped some the miss aligned layers at high speed.

443 & 955 mod made to the extruder so that I could print flexible PLA, I got the tube from the makeshop in Auckland, I had to drill the Aluminium block out to 4mm Dia to a depth of 3mm so not to interfere with the tube from the hot end.

742.jpg
Wobble on Z axis , this was because on the coupling is 8mm and the threaded bar is only 7.8mm I used some thin walled heatshrink on the treaded rod to take up the play, this stopped the wobble from the coupling. the rest of the wobble came from the bent in the threaded rod.

Note Blue tape .. guide rod holes were 0.2 mm over size so fixed that at the same time..

758.jpg
To remove the last bit of wobble from the threaded rod, I made the Nut in the Z housing slightly thinner ( about .2mm) and remove about .5mm from across the 2 Flats on the nut allowing it to move from side to side .

All wobble has gone and Prints even better smiling smiley

Edited 1 time(s). Last edit at 12/26/2014 06:51PM by moth4017.
Attachments:
open | download - 20141222_120300.jpg (288.9 KB)
open | download - 20141226_114443.jpg (173.4 KB)
open | download - 20141226_130955.jpg (238.8 KB)
open | download - 20141227_143742.jpg (226.1 KB)
open | download - 20141227_143758.jpg (203.1 KB)
Re: Prusa i3 kit from Aliexpress, help!
December 27, 2014 11:17PM
Update

started to Print ABS with this printer and the spring tension needs to be increased as there is no adjustment on this extruder head it has to be achieved by adding a washer under the spring , which increases the tension just right smiling smiley
Re: Prusa i3 kit from Aliexpress, help!
January 09, 2015 04:58PM
Just thought I would update some info regarding the 13 Prusa from Alliexpress

I did some X,Y and Z calibration checks and heat bed expansion check

the distant check was from the home position and 120 mm in the X y z travel, I used a vernier calliper attached to each access and used the Repetier software to do the stepping

error in each axis :-
x 0.2mm
y 0.76mm
z 0.47 mm

not sure why the y axis was so bad.. will look into this later smiling smiley

Heat bed check... was the amount of deflection up or down from room temperature 25 Deg C to 100 Deg C . at 100 Deg C the deflection in the middle of the bed was 1.06mm up, and while I was doing this check a took a Thermocouple measurement at the centre just to check how accurate this was my recorded temperature was 91.6 C.

Note the thermocouple was under a 25mm x 25mm x 8 mm thick PLA block , this was trying to replicate a printed object.
Re: Prusa i3 kit from Aliexpress, help!
January 10, 2015 02:32AM
was the Y over or under by that amount?
I'd assume it is potentially some backlash in there that is being effected by the larger mass of the bed.
are you sure they have used the same number toothed pulley for X and Y?

steps_per_mm = (motor_steps_per_rev * driver_microstep) / (belt_pitch * pulley_number_of_teeth)
[reprap.org]
Re: Prusa i3 kit from Aliexpress, help!
January 10, 2015 12:19PM
Hi Zerker

All errors were under travel .

the number toothed pulley for X and Y are the same ..
Re: Prusa i3 kit from Aliexpress, help!
July 27, 2015 02:14AM
Just an update to my i3 from aliexpress.. I have just added a e3d Lite .. wow !! for the cost (direct form the UK) well worth it.. I have been using the 3dbenchy test print and with the e3d hotend I can almost read the name on the stern of the print.
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