3D Printing. How to (And not to)

[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... 

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

[yorkie_chris]

I'm really interested in this.

How does it rate in terms of mechanical strength? What about if you wanted to machine some accurate features onto a part afterwards?

Chris

[ParCan]

Hi Yorkie_chris

The 2 plastics that Print well are ABS and PLA.

ABS is softer and more forgiving than PLA but is not as strong.
PLA is fairly hard and more brittle than ABS.

How strong. Well most repRap printers are printed in PLA and it's more than strong enough to survive.
I have Coat Hooks that I printed many months ago and none have broken.

Both plastics are machinable with care. PLA gets hot very fast and can melt as you machine it.

Alex.

[buffalow bill]

Alex,

I’m interested, and this looks like a project.     

What is the surface finish like, What’s of  interest to me is using the printer for production of patterns for casting. But I suspect the surface would require finishing, is this correct?

Bill

[ParCan]

Hi Bill

The Bottom is always flat and smooth.
The sides will have micro ridges as it builds up the layers. They are good but not smooth.
The top is usually fairly good. 

This technology builds up the part in ~0.4mm layers.
Can you cast using the printed part at the template ? probably.
People have used PVA glue to improve the sides.
You can sand and machine the plastic or maybe you could reflow the surface.

I'll try and do some high res pictures of some parts for you.

Alex.

[buffalow bill]

Hi Alex,
Thanks for the quick reply – but it has given me more questions !!!

Presumably you can print onto a rotating (along a horizontal axis) cylinder held in a rotating table set vertically. Thereby printing all the detail on a wooden core, or have got to far ahead with the wooden core?


 Bill

[Divided he ad]

Very interesting stuff Alex 


Keep it coming... It's all getting stored away    (and I can come back and read it again too  )







Ralph.

[ParCan]

Part 3

So how much does all this cost ?

I said in part 1 that my 1st machine cost me around £1000.
The design of the machine has since moved on significantly.
 
The Current full size machine known as the Prusa 2 will cost you around £500 to build.
The full size machine has a Print area of about 200mm X 200mm X 160mm high

Another option is a smaller machine known as the Huxley.
The print area will come out at around 140mm X 140 mm X  100mm High.
You should get that together for around £400

Prices are as always dependent on what you already have kicking around or can scavenge.

Expect a good parts set to cost you around £75.
Rods, fasteners, Bearings and Sundaries around £100.
Belts and Pulleys around £25.
Electronics around £150.
Motors around £50
Nozzle around £50
Plastic to print with and all the rest will bring it up to £500

There are various speciallist suppliers around the world. I'm not going to pass comment on any of them here.
You could try Ebay - there is always plenty on there but usually at a price.
Another good place is a community site http://www.emakershop.com


The Printing platform

SAFETY:
Please be aware that we are talking about more than enough power here to burn your house / workshop / Shed down. It may only be 12 volts but we are talking about 10 - 15 amps.
Use appropriately rated connections and wiring.
A bed plate can easily get up to around 150 C. More than enough to burn you!


One thing that helps to keep prints both Flat and stuck to the bed plate is the printing surface, also known as the Bed Plate or Y axis.

The Biggest and most important upgrade for your printer has to be a heated bed plate.
There are several designs out there, a Circuit board being the most popular option.
http://reprap.org/wiki/PCB_Heatbed
On top of that you need a Glass or Aluminium plate for the actual print surface.

If you print with PLA Use 3M Scotch Blue painters tape. (No the brown stuff will not work)
It's a few £/$/euro a roll from any DIY / hardware store and available world wide.
Some people have tried a variety of other surfaces with mixed results.

For ABS you need to use heated kapton Tape.
kapton tape is expensive and you will have to look around to get it.
Trying to print ABS without a heated bed simply won't work. The prints won't stick and curled up.

PLA did work but I had several prints come loose during the print. I solved that by warming my bit of MDF with a hair dryer first.

I made my own Heated Bed from a 4mm thick Ally plate I got from a skip and some constantin resistance wire from Maplin in the UK.
I insulated the ally plate with kapton tape. I then taped the constantin wire in sets of 3 loops all over the bed.
Another layer of kapton and the heater was secured firmly and stuck down.
Connecting it up was fun. I was aiming for about 1 Ohm @ 12 V
With the help of: http://www.the12volt.com/ohm/ohmslawcalculators.asp and http://www.sengpielaudio.com/calculator-paralresist.htm
I soldered it all together and connected it up.
You can solder constantin wire. You can not solder Nichrome wire.

It warmed up and is still working to this day.
The bad news is I don't have a Photo of it and I'm not going to pull the bed apart just to do that !

The Gen 6 electronics has no provision to control a heated bed so a got a thermostat kit from Maplin. All of the modern electronics have provision for a heated bed that is controlled by the software.

You will find some of my experiments with Heated bed plates at:
http://parcansreprap.blogspot.co.uk/2010_09_01_archive.html

Alex.

[ParCan]

Hi Alex,
Thanks for the quick reply – but it has given me more questions !!!

Presumably you can print onto a rotating (along a horizontal axis) cylinder held in a rotating table set vertically. Thereby printing all the detail on a wooden core, or have got to far ahead with the wooden core?


 Bill

Now that is an interesting concept.
I can see no reason why that would not work I have to say.
I'm also told that this has been done during the early development of the reprap Project.

You'd need something to control the rotation of the cylinder in software.

Alex.

[buffalow bill]

Hi Alex,
How about using the same stepper motor that drives the Y axis to drive the rotary table/device. Providing the gearing is all set up correctly, the software/print head won’t know the difference (possibly).

This is sounding like a project !!!           


Bill

[buffalow bill]

Hi Alex,
The heated table and different types of tape, are used presumably so the printed item can be removed from the base. Therefore if it was required to print detail onto an item that is no the table, there would be no requirement for heating or tapes, or am I a barking mad modder?


Next question, in a previous post you indicated that the filament was forced through the heater. Is this force applied by forcing the cold filament into the heater or more like an injection moulding machine where the molten material is forced out via a heated screw???


Am I running ahead of your tutorials?

Sorry 

Bill

[ParCan]

Hi Bill

The tapes give a good surface for the print plastic to stick to and also be removed.
The warmth keeps the plastic just below it's transition temp so that it won't warp as it cools and also aids the sticking process.

If you wish to make a cylinder printer you have a few things that I see to consider.
You can use the existing Y Motor and mountings to drive the cylinder with the Y belt.
Attaching the cylinder is going to be interesting with current machine designs.
The the cylinder must be accurately calibrated to give the correct revolution. That is going to be easy to do using the Y axis calibration in Firmware.

The real fun will be to extrude more as the Dia of the print increases.
I'm not aware that any of our software can handle this at the moment.

We control the extrusion rate in the Slicer software we use to take a 3D object and cut it in to layers for printing.

I'll talk more about the software toolchains in a later post.

I missed the 2nd part of your Q thismorning. It was rather early !

The extruder drives solid filament which is then fead into a heated chamber to melt it.
If you use a screw you get air bubbles in it.

Alex.

[ParCan]

Part 4

Electronics and Software.

Once you have your hardware together you can start to make it move and do stuff.
The Reprap printers are Belt driven from stepper motors (X & Y) and a pair of lead screws for Z.
T5 Belts have been superceeded by T2.5 belts.

We use NEMA 17 Motors. Must have Good Holding torque.
Something like SY42STH47-1684B  from Zapp Automation in the UK are ideal.
DO NOT scrimp on the X, Y and Extruder stepper motors. You can howeve use lower power motors for the Z.

The RepRap Community (and others) have developed their own electronics and it is a minefiled out there.
Most RepRap stuff is based around the AT Mega chips and Arduino boards. i'll try and summerise the options here.

Gen3: Obsolite and will not work with current firmware.
Gen3+: Obsolite but will (with some work) Work with current firmware.   
All the Gen 3 Series requires separate Motor Drives and End Stop Boards.

Gen 4 and 5 never took off.

Gen 6: developed by Mendel-parts.com is a really nice attempt at a 1 board solution.
It's stepper drives will only do 1/8 stepping. This makes your printer noisy as hell.
It has no Heated Bed support.
Current Firmware will run with some work.
I have one of these boards gathering dust, it's simply far far to noisy.

Gen7: A well respected low cost and full featured DIY solution. Well worth looking at but still being developed.

RAMPS: The most popular current electronics. It's a shield that plugs into an Arduino Mega board.
Works with all current software and Firmware.
Uses 4 separate 1/16 stepping Polulu Drivers
Has support for 3 end stops, 2 Heaters (Nozzle + Bed) and 1 fan.
A very good choice.

Sanguinolulu: My Preferred Choice.
Missing the Fan controller that RAMPS Has. That's about all.
It's a stand alone 1 board solution.
Easy PTH Soldering (except for the FTDI chip).
Image attached from my Reprap mendel.

There are Other Electronics solutions out there that may or may not perfom well. I have not seen used or tested anyning not in this list so am unable to pass comment.

You then need 3 End stops for X, Y and Z.
Many People use Micro switches. They are low cost and easy to buy.
I prefer Opto End stops. They seem to be more repeatable than the switches, especially for Z.

Nozzle Heater:
Aim for 22 - 30 W of power.
@ 12 volts that's between 5 and 7 ohms
I use 6.8 Ohm 3 watt wire wound resistors.

Bed Plate Heater: Aim for 100 - 150 watts.
@ 12 Volts that about 1 Ohm.

Power Supply.
Minimum 300 watts @ 12 volts.
You can hack about an old PC Supply but put a load on the 5V rail or the 12 V supply will drop causing Brown outs.
Without a Heated bed 100 W will happily run the printer.

Software tool Chain.

To drive a reprap you need 3 things.
Firmware to:
Tell the motors what to do.
Control the Temps of you Bed Plate and Nozzle.
Look after end stops etc.
Look after Calibration (Steps per mm)

There are 2 Current Firmware tool chains, Marlin and Sprinter, that are worth looking at.
I prefer Sprinter myself. Config / Calibration is quick and easy and I get some really nice prints from it.
Marlin is also very popular but i have not used it myself.

The firmware is uploaded to your board using the arduino software from www.arduino.cc

Slicer:
The Slicer software eats your .stl Object files and converts them to g-code files that your Firmware can convert to movement and Filament feed
Again several choices here.
Slic3r is considered to be the best around at the moment but I have not used this myself.
I Use SFACT, which is no longer being developped.
It works just fine for everything that I have ever wanted to print.
Repsnapper is great but very limited. I suggest you avoid it.

Control Interface.
This one is easy. Pronterface is by far the leader here.
It's full featured and well put together.
This is where you start your print jobs from and do things like Home it and set Temperatures.

Again, theer are other Software and Firmware packages available. No doubt some are very very good but i'm writing this from my own personal experiences.

All the Soft / firm ware will run on Mac, PC or Linux.
Full Details of all the products can be found on the Reprap Wiki at http://www.reprap.org

Alex.

[ParCan]

Part 5

Exrtruding the Plastic.

The hardest bit to get right is extruding the plastic.

There are 2 extruders worth looking at, both very similar in design.
Wade and Gregs extruders use an M8 Bolt with a Hobb cut in to it with a tap.
I have attached an image of a Hobbed Bolt.

The bolt is held in 608 skate bearings.
A 3rd 608 skate bearing is used to force (with springs) the Plastic Filament against the hob.
The Large cog drives the 13mm hex head of the bolt.

This arrangement is low cost and works extremely well.

The next part is the Thermal Insulator or heat shield.
This prevents the heat from the Nozzle form melting your extruder drive.

PEEK, a high performace plastic is used as the heat shield in most modern hot end designes.
PTFE can also be used but it is not suitable as a structural part of the Hot end and must be supported.

ABS and PLA stick rather to well to PEEK, so the heat shield must be lined with PTFE or your filament will jam up.
Most modern hot end designes use PTFE Tube.
The PTFE Tube also needs to be fixed in place to stop it form moving when you retract your filament.

The next part is the heat chamber and Nozzle.
Most hot ends have an intergral nozzle.
Some do have an interchangable nozzle but the additional thermal Junction can cause issues.

The melt chamber does exactly what it says on the tin.
It Melts the filament before being extruded through the nozzle.

Nozzles are available in a range of sizes from 0.25mm up to 0.75 mm.
Start with a 0.5mm Nozzle.
A 0.5 mm nozzle is a great compromise betewwn print speed, detail and surface finish.

Most modern heaters use a block of Brass or Aluminium drilled and tapped to fit the nozzle.
The heater is a 3W 5.6 or 6.8 ohm Wire Wound resistor.
The Sensor is a 100K glass bead thermistor.

These Hot ends are well respected within the Reprap community.
Arcol: http://shop.arcol.hu/
Budaschnozzle: http://www.lulzbot.com/en/5-hot-ends
J-Head: http://hotends.com/ & http://www.emakershop.com/Seller=784
Makergear: http://www.makergear.com/products/operators-pack
Parcan: http://www.emakershop.com/Seller=59

Which one is the best one ?
That is cause for much debate amongst the community. None of those listed abouve are bad and would be a vrey good choice.

You will also notice my name in the list.
I make and sell RepRap Hot end kits, Hobbed Bolts and other related items.
That is also how come I have a Lathe.....


That's all for now.
I have 1 more tutorial to add to this, and may do it as a Video.
It's the actual printing process.

Alex.

[ChrisC]

Hi I've been lurking here for a while, so I thought it was about time I made a post!  I built a Prusa Mendel about a year ago and have been using it quite a bit.  In general I'd say it works surprisingly well.  I have found that the design of the extruder and hot end nozzle makes a big difference to the quality of the print you produce.  I initially used the simple hot end from the Reprap site, similar to the one shown by ParCan in an earlier post.  I currently use a slightly simplified version of the Budaschnozzle, which I find works very much better and has greatly improved the quality of my prints.  I use a Wade extruder but have found that knurling the M8 bolt seems to work just as well as the hobbed bolt, and is much easier to make.  You need to turn off a few thou in the area to be knurled, so that the completed knurled bolt will fit through the bearings.  I used a medium diamond knurl which seems to grip the fibre very well.  Some commercial machines use rubber coated rollers rather than knurling or hobbing.

I agree with ParCan's summary of the electronics.  I have been using a Gen 6 board, but as he says it is noisy and also has a couple design problems.  The thermal management of the stepper driver chips is poor, I've added tiny heatsinks to the chips, but it is not ideal.  The thermistor input circuit for the hot end is also wrong on my version of the board, it results in a poor calibration and a very noisy signal. I'm building a Sanginololu at the moment.

I found a Reprap machine was very handy when I was doing my CNC conversion of a Sieg X3.  I used it to make opto limit switch brackets and flags (use black PLA for the flags, other colours are too transparent for the opto switch to work!).  Numerous brackets for holding cable chains and covers were made, entirely suitable and much quicker than machining.

I'm in the process of building up a couple of other designs of Reprap machines to try out a few design ideas... I'll post photos and results as I progress if people are interested.

Chris

[tumutbound]

Has anyone built a printer utilising and existing  CNC device i.e.a CNC router?

All you should need, hardware wise, would be  the hotplate and the extruder head.

[ParCan]

Hi tumutbound

In my first post I said:

"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."

If your mill / Router can do this then go ahead and give 3D Printing a go.
If it's got a Lead screw drive, somehow I think that you will not get very far.

I have no desire to stifle ideas and development, but experience of many others who have tried and failed is often the best way to learn.

ParCan

[yorkie_chris]

I went to see Chris/Nophead yesterday, I was well impressed with his Mendel90 machine and think I'm going to have a go at making one very similar but slightly upscaled to hopefully give a 250x250 build area.

[yorkie_chris]

Decided not to bother with the enlarged build area, got parts set and wood for a mendel90/sturdy config with the standard build area.

There's a place in peterborough does the complete set, sanguinlolu electronics, steppers, heated build platform for £170 ish, the wood was £1.50 and the printed parts £70 from nophead.

Should be just a hot end to buy then

[sshire]

I had been seriously considering the RepRap build on then I saw this at a trade show.
0.3mm resolution, 150mmx150mmx150mm build area. Runs out of the box. About 300 GBP
May be the next purchase from the tooling fund.

http://store.solidoodle.com/index.php?route=product/product&path=59&product_id=56

Best
Stan