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3D Printing. How to (And not to)

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ParCan:
Hi all

I'm fairly new here but here goes for my first post !
I'll add more info in further posts.....

So what is this 3D Printing lark all about ?
Well there are several technologies out there ranging from tape and cutters to powder and solvent as well as some sintering and UV processes.
I'm going to talk here about "Home Brew" 3D printers that print form a palstic filament.

About 2 years ago I was looking around for a crazy project to attempt. I had a budget (500) and a desire to do something totally out of my comfort zone.

The RepRap Project at http://www.reprap.org seemed to fit all criteria except for the budget.
Oh well, in at the deep end.

BEFORE you ask: "Can I 3d print with my Mill ?"
Can your mill move at 100 mm / sec, change direction, move back at 100mm/sec, rinse and repeat for hours on end ?
A Mill is built to be precise with speed and agility as a secondary factor. A 3D printer needs to be fast and agile.

A set of low cost parts was bought from eBay. They were Cast from polyester resin and needed to be drilled.
That really required a Pillar drill so off to Wick es I went.
TBH The parts I bought were total and utter Rubbish.
They were Brittle, warped and very very poorly cast with the cheapest resins available no doubt.

The Frame was assembled over a weekend.
The next stage was the Y axis ( Bed Plate ) which took another entire weekend because of the poor parts.
The X axis eventually became reality, followed by some Stepper motors and Drive belts.


Whilst the Budget caught up I got everything working well and borrowed a friends lathe to make the Print Nozzle.
I'd not used a lathe in 20 odd years but it all came back to me and got what i thought would be a workable nozzle at the 2nd attempt. (More on that another day )

I hacked together a power supply from an old PC. 


Bought the electronics and finally almost 4 months later the axis moved under their own power.

http://parcansreprap.blogspot.co.uk/2010/09/images-of-final-build.html

Total Cost, just under 1000

I think that'll do for tonight.
I'll do another post in a day or 3.

Alex.

Brass_Machine:
Thanks for that Alex...

I haven't done much research, so forgive any naive questions.

The plate that is printed on. anything special with that? I seem to recall seeing a video (I believe it was the UP printer), that they painted something on the plate? I also believe I have heard it called a hot plate? Am I crazy?

Eric

ParCan:
Hi Eric

The Bed (Hot) plate in those images is pespex.

Today i'm using am aluminium plate. I built my own heater for the plate ( more on that in a later post ).
It's coated in blue 3M Painters tape.

Alex.

ParCan:
Part 2

3D Printing Concepts:

We are all familiar with 2D printers.
We feed them paper and ink on a Ribbon, as a powder, or as a liquid. The text/image is placed onto the paper and we have a printed page that is flat.

Imagine if that ink had substance that you could build up in layers, then remove the paper.
My 3D printers print using PLA (Polylactic acid) Plastic.
The PLA starts as a 3mm dia filament which we force under pressure through a heater to melt it then out through a tiny hole (between 0.3 and 0.5 mm).
We call this extruding.
Using X and Y control we draw a copy of the image we want to print.
We then move up 1 layer (around 0.4mm) and draw the image again, and again, and again, sometimes several hundred times.
The result when you have peeled it from the base plate (removed it from the paper) is a solid physical object.

It could also be referred to the exact opposite of machining.
3D printing starts with a filament and builds the object rather than start with an object and remove material.

The next stage for my 3D printer build is the electronics to control it.

The Reprap Commuity has designd and built it's own electronics for a while now.
I Chose a brand new offering from a guy in Holand. The electronics is named Gen 6

Can I use a mill control board ?
Probably, but we also need to control 2 heating elements and 3 end stops.
It also needs to be compatible with RepRap software.

The electronics were installed and powered up late one Friday evening. The magic somoke stayed contained :)


I loaded up some software (repsnapper) and it (to my total amazement) moved under it's own power with nothing nasty happening.

Calibrating the movement took a while. Move an axis 100 mm and measure tha actual travel.
Adjust the motor steps per mm in firmware and uplaod it to the Board. Rinse and repeat.

My Extruder Nozzle was a bit of M7 threaded brass rod tapped into PTFE.
PTFE being soft then heating it up to 200 C making it softer ment that the brass was pushed out of the PTFE heat Shield.


Eventually I did manage my first "Print" - I was chuffed to bits but a reality check told me that things were not quite as they should be.


Tying to get more filament from the nozzle only resulted in it pushing the Brass out of the Nozzle again so i decided to design and make my own.

and The actual item completed.
http://3.bp.blogspot.com/_2q-oc2Sya40/TMMNS5laHEI/AAAAAAAAAEk/wGEyzf5-2Sw/s1600/P1010078.JPG

This design printed really well, but because the Heated section was rather long it dribbled moulten plastic everywhere resulting in rather untidy and stringy prints.

I also noticed that the teeth were chipping off the gear and belt drive cogs. These were reprinted with my new nozzle.
Then other parts started to crack and fail under the stresses of printing.
It really was a case of printing parts before the next bit broke.

Today most of the origonal Plastic parts on my machine have been reprinted and replaced.
 
Some of my more recent prints are not far from perfict for 3D prints made using this technology.
You will always have ridged sides becauss the plastic is built in layers.
With Fine tuning and carafull twealing you can get a rellay nice top finnish, but often a perfect finnish is at the cost of strength. The base layer is always nice and flat because it's printed onto the base plate.

That's enough for tonight.
Next time I'll cover my Heated bed plate and the actual printing process.

Alex.

raynerd:
Nice one Alex....

You now know what my next project is...  :headbang:

Keep them coming...I`m learning but my head is getting very sore!

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