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new prusa, a bit bigger

Posted by jf pion 
new prusa, a bit bigger
July 14, 2012 08:45AM
As I found the prusa on the small side, specially on z, I designed one, slightly bigger with part from the local hardware shop: aluminium square tube 20*20 mm, 4 threaded rod 10 mm, smooth rod 10 mm 3lm10UU bearing and abs printed parts

the picture of the project is joined

the frame parts are mostly printed

the frame is secure to the plastic parts with 3.9 parker screw

the x axis get a vertical topology to allow easy change of extruder and easy fan setting

the frame is wide enough to allow double extruder in the future

do you have some comment/suggestion ?

thank you
Attachments:
open | download - projet.JPG (107.2 KB)
Re: new prusa, a bit bigger
July 14, 2012 09:28AM
Makes sense. I wouldn't call it a Prusa though, seems like a new machine descended from Mendel.

I have tried suspending a Wades from a right angle printed bracket. I found it changed the Y position of the nozzle during the first few layers as the heated bed caused the bottom of the bracket to expand more than the top and hence curl it slightly. One of the reasons I stuck with a horizontal axis on Mendel90. I think you need an extruder with vertical mounting points.


[www.hydraraptor.blogspot.com]
Re: new prusa, a bit bigger
July 14, 2012 10:24AM
yes you're right more a new mendel, I looked on big mendel but I can't find the extruded aluminum part, and I want to use very common stuff.

for the X carriage I want to add a small fan to cool the upper part of the hotend (get some pb with PLA and Budaschnozzle, so even if the jhead mk4 doesn't really need it ....) do you think it will cool the carriage enough ?

I want to make it strong I thought of 8 mm infill 60% ABS dou you think it will be enough ?

otherwise I can make a part to fix the upper side of the extruder to the vertical wall of the x carriage with the upper motor screw

and I planned to have the motor through the wall to get a better balanced carriage (see the pic)

thank you for the advice I haven't thought of the thermic curl effect
Attachments:
open | download - x carriage.JPG (139 KB)
Re: new prusa, a bit bigger
July 15, 2012 04:58AM
jf pion Wrote:
-------------------------------------------------------
> yes you're right more a new mendel, I looked on
> big mendel but I can't find the extruded aluminum
> part, and I want to use very common stuff.
>
> for the X carriage I want to add a small fan to
> cool the upper part of the hotend (get some pb
> with PLA and Budaschnozzle, so even if the jhead
> mk4 doesn't really need it ....) do you think it
> will cool the carriage enough ?

Maybe. I don't really know without experimenting. I don't use fans because I find a draught causes ABS parts to warp and lift off the bed. People seem to state the opposite with PLA.

>
> I want to make it strong I thought of 8 mm infill
> 60% ABS dou you think it will be enough ?

That would be plenty strong enough to hold the weight I think. Thermal stability is the issue. With the typical length of a nozzle the angle of the base only has to change a minute amount to cause a significant offset of the nozzle. Something like 0.05mm is going to be noticeable.

The effect I noticed was the nozzle moved one way during the first few layers as the bracket warmed up close to the hot bed. It then slowly moved back over subsequent layers as the carriage moved away from the bed and the bed also cooled after the first layer.


[www.hydraraptor.blogspot.com]
Re: new prusa, a bit bigger
July 18, 2012 06:34PM
nophead Wrote:

>
> Maybe. I don't really know without experimenting.
> I don't use fans because I find a draught causes
> ABS parts to warp and lift off the bed. People
> seem to state the opposite with PLA.

i'm thinking about 2 fans: one for the upper part of the hotend to cool the cold side of the hot end which could be always on also with the abs with a duct to avoid blowing on the part
an an another for the part when using pla specially small part with thin wall ( and yes it increase the reliability of the print work, it's easier to get the good result the first try)

for the wrapping effect I found the brim in skeinforge or slic3r not strong enough for the big parts. I use build in design pad quit big ones of 2 layer of 0.25 mm high ) perpendiculary cross and found it quite effective and easy to remove with cutter, a lot of easier than raft in fact

see the joined stl

and also some picture of the frame
Attachments:
open | download - structure.jpg (564.5 KB)
open | download - coin bas.jpg (332.8 KB)
open | download - support mot.jpg (370 KB)
open | download - support moteur z a.stl (130.9 KB)
Re: new prusa, a bit bigger
July 22, 2012 11:23AM
I have been printing PLA exclusively for over 2 years now (with a heated bed the last year) and do not need any fan.


Bob Morrison
W├Ârth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
Re: new prusa, a bit bigger
July 22, 2012 12:40PM
rhmorrison Wrote:
-------------------------------------------------------
> I have been printing PLA exclusively for over 2
> years now (with a heated bed the last year) and do
> not need any fan.

it's depend what you print and with which PLA

I found very difficult without fan to print one width wall quite high or very small bits

with the fan it's ok on the first try, so why taking the hard way ?

you don't need fan ? great some other need it, so it's better to design the thing with the possibility in mind
Re: new prusa, a bit bigger
July 22, 2012 02:28PM
rhmorrison Wrote:
-------------------------------------------------------
> I have been printing PLA exclusively for over 2
> years now (with a heated bed the last year) and do
> not need any fan.

With the PLA that I have, sharp overhangs start to curl up, even on larger prints, if I do not use a fan. The result is that the curling is eventually severe enough that the hot end either knocks the print off the bed, or the motors skip steps running into the curled part.

I think it does depend on the specific PLA that you have. I have been printing exclusively with PLA for four years now, and in the past have been able to print PLA without a fan.


Cameron

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Re: new prusa, a bit bigger
August 25, 2012 06:34AM
Can someone point me in the right direction on where to find the stl files for this build? Thank you
Re: new prusa, a bit bigger
August 25, 2012 09:03AM
what software do you use to draw that?

jf pion Wrote:
-------------------------------------------------------
> As I found the prusa on the small side, specially
> on z, I designed one, slightly bigger with part
> from the local hardware shop: aluminium square
> tube 20*20 mm, 4 threaded rod 10 mm, smooth rod 10
> mm 3lm10UU bearing and abs printed parts
>
> the picture of the project is joined
>
> the frame parts are mostly printed
>
> the frame is secure to the plastic parts with 3.9
> parker screw
>
> the x axis get a vertical topology to allow easy
> change of extruder and easy fan setting
>
> the frame is wide enough to allow double extruder
> in the future
>
> do you have some comment/suggestion ?
>
> thank you
Re: new prusa, a bit bigger
August 25, 2012 12:58PM
the files are here:
[www.thingiverse.com]

new add the x carriage with transverse wade extruder in one piece , sliced in 2 parts for easy printing

the others parts will follow (it is nearly completed, need only the small part like x belt fixation ant tensioner, end course switch support)

and i have to make the bed ant its fixation

I'm doing that [www.thingiverse.com] for the electronic
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