When we surf the web we pick up trends in discussions. One of the trends is keeping your print to stick to the printing surface. If you dig even deeper you start getting discussions like which print surface is the best between aluminium and glass.
Today’s discussion will be about aluminium print surfaces with some comparisons to glass print surfaces. This is not an article trying to persuade you to use aluminium; it is just for you to make a better decision. This is my experience with aluminium.
Although this plate looks like it seen its days, one of my future blogs will show how to restore this plate to its former glory.
a. It is durable and can withstand quite a bit of rough handling.
b. You can repair the surface to its original state with a glass panel and some sanding paper.
c. Aluminium is light at 2.7g/cm³ and almost the same as glass 2.4g/cm³.
d. Inductive probes work out of the box. Nothing else needed.
e. Even temperature distribution. Thermal conductivity.
a. Fractional expansion per degree.
i. Aluminium – 0.0024 @ 100°C
ii. Glass – 0.0004 @ 100°C
b. Some plastics are harder to get stuck on the surface than other plastics.
c. Aluminium may warp under some heat stress.
I will try to explain each of the points above as precisely as possible. I may here and there compare to glass but it is only to get my point into perspective.
As you can imagine, aluminium can withstand quite a bit of hammering i.e. normal pressure and sudden blows. Glass on the other hand does not like too much pressure, especially sudden blows. The only thing that may happen to aluminium is that it could get scraped or gashed.
Fortunately aluminium is quite a soft metal and can be repaired to its former state by just sanding it with sandpaper. Just be careful with the sanding. Do not sand in the same place the whole time. Sand the whole plate in a figure eight movement so that you can keep it as flat as possible. In one of my next blogs I will discuss the sanding methods to get your aluminium plate as smooth and flat as possible.
Aluminium is light compared to other metals, when compared to glass there is a very small difference between the two. For a 300mm x 300mm x 3mm plate the weight is only 729g. For glass it is 648g, a mere 81g which is quite surprising for a metal to be almost as light as glass. This means that the forces needed to move the bed at almost the same and therefore the glass bed is able to be moved fractionally faster with the same amount of energy. For various reasons which I will explain later, I recommend a 4mm plate, rather than a 3mm plate.
This is a no-brainer as it is an inductive metal and therefore the inductive probes work on the aluminium plates as is. This is one reason I did not move to glass since you would need a separate mechanical device modification to your extruder to level the glass bed. And mechanical devices are inherently much less accurate and the repeatability is not that good either.
Temperature distribution is measured in Thermal conductivity i.e. Watt per meter Kelvin.
(W.M¯1.K-1). Another way of understanding this is with this definition from Wikipedia - The heat transfer coefficient is also known as thermal admittance in the sense that the material may be seen as admitting heat to flow.
The Thermal conductivity for aluminium is 120 W.M¯1.K-1 @ 373K and that of (Borosilicate) Pyrex Glass is 1.14 W.M¯1.K-1@ 300K. The difference of temperature between glass and aluminium when this was measured does not change the comparison much. This is one reason why aluminium is used as heat sinks. Aluminium conducts temperature roughly about 105 times better than glass. Therefore you get a better distribution of temperature over the whole plate.
Aluminium expands quite a bit with the temperature rising. This would immediately lead someone to believe that it is bad for your first layer, as the height would differ from when you calibrated and levelled your print surface.
Expansion can be measured as Fractional expansion per degree Celsius.
a) Aluminium - 24 x 10 ¯⁶ mm per degree Celsius.
b) Pyrex Glass - 4x10¯⁶ mm per degree Celsius.
If we calculate the actual expansion for 3mm glass and aluminium at 100°C we get the following:
a) Aluminium – 0.0024mm – rounded to 0.01 mm
b) Glass – 0.0004mm
The 0.01mm starts to have an effect on 3D printing as we usually print between 0.1mm to 0.3mm layer heights. I have some ways to easily overcome this problem with aluminium. First of all, I do my calibration and bed levelling at the temperature I am going to print at. That way the aluminium is already expanded and your calibration would be correct. But even with glass it is better to do your calibration at working temperature.
I do my calibration always at the same temperature, in my case 100°C because I print a lot with ABS. By now I have a very good idea as to what I must set my z-axis offset to, if I want to print at say 60°C. So I do not have to re-calibrate every time I change filament type.
I am printing on my aluminium bed from the beginning and here are some of my tricks:
a. ABS – just use plain ABS juice on the plate and it will stick with no problem. Just make sure you do not use too much juice and if it has a powdery white layer on top, just take a brush with a bit of acetone and brush over it until it has a see through plastic look. There is enough material on this for another blog.
b. PLA – The hairspray method works for me. I bake a layer of the hairspray at 100°C for about 30min. And then before each print just give it a quick spray.
c. PETG – This is where blue painters tape would come in handy. I just cannot get it to stick on bare aluminium. I have a cheaper way than painters tape. Come back for one of my new blog to see what I use.
Warping of the plate can be a big problem if you are using thin plates. For this reason I would like to use 4mm thick print surfaces. The thicker the plate would tend to warp less under the temperature stresses we are working at. Just remember the thicker has more mass.
I am using a 3mm plate at this stage and have now after a year found the warping to be a problem. So I am looking to replace it with a 4mm plate.
Well after writing this blog, I am even more convinced that the aluminium plate is going to stay on my printer. The only change I would like to make is to get a 4mm plate instead of 3mm, as it is even more resistant to warping. It will hold temperature better so that my heater does not have to work that hard and it does not have significantly more mass than a 3mm plate. It does have more expansion than the 3mm at the same temperature, but as I said in a previous paragraph, it is easy to overcome the expansion problem.
Just a word of caution, I use bare aluminium, so that I can sand it when needed and it does not look bad after a time of use. Anodized or coloured aluminium will look bad after a few uses because of the scraping on the bed with the scraper.
First and foremost
You have determined your budget and decided you want to explore the 3D printing world, but you are still not sure where to begin. So here is my experience up to now, and what would I have done differently when I started out. I am not trying to scare you off, as a matter of fact; I am trying to make the experience as pleasurable as possible. Lot of the first-timers gets scared off and give up because they were either not prepared for the dedication the 3D world asks of you or they did not make the right choices in the beginning, like me. But I am a hard ass and just kept going when the going got tough. No, really it is not that daunting, as a matter of fact it is a very pleasurable path you are going to walk with your printer and you are going to discover a whole new world.
That is why I call it the 3D revolution. This is going to be as big as the computer revolution if not bigger. Entrepreneurs and engineers and builders are now able to test their proto-types at home and not fork out millions of dollars just to get a prototype working and tested. It means that anyone can now start inventing and building their ideas at home at a fraction of the cost it usually would be.
Prepare yourself for a tough time in the first few weeks but it will then start to get easier as you begin to gain experience with your printing. Join user groups and make friends with the people, they are usually very friendly and want to help. Yes, there is that one guy or three that just joined to bully the new-comers, but ignore their posts and do not let them put you off and talk to the friendly people.
Enough of the blabber let's start
Types of printers
There are already a lot of printers out there and they may or may not be in your budget. Fortunately you do not need a lot of money to start in the 3D world. Luckily most of these cheaper options can be easily upgraded and as your experience builds, you may need to upgrade your printer, to solve a problem. Believe it or not most of the upgrades you can print with your own machine. Just make sure in your budget that you have some money left for upgrades when buying the printer. Even some of the expensive printers would need upgrades later but then you have to buy their parts to upgrade your machine, so leave some space in your budget for that.
From the printers above, this article will cover the FDM printers because they are the most widely used and are the most affordable out there. They can also build the prototypes you need without any post-processing but the model may need a bit of a clean-up afterwards. For a description of each of these printers you can get a on the web. One good article I downloaded is: https://www.3dhubs.com/talk/thread/3d-printer-types. This is out of the scope of this document.
Most of the other printers are pretty expensive and may or may not need post processing before it can be used.
The FDM printers also have a few sub types i.e.
1. The x-y printer -
The x-y printer typically has an x,y and z-axis and the printing surface bed is doing the y print moves, the printer head is doing the x and z printer moves. Here is a sample picture of the Prusa I3. This printer is where the 3D printer technology basically became affordable for the person at home. The x-y printer in, its usual configuration, are much slower than its counterparts because it makes use of direct extruders. This means the print head is much heavier than that of a bowden extruder and therefore cannot reach the accelerations and speed that the bowden extruders do. I will give a better explanation below of the differences between the bowden and direct extruders.
2. The Cartesian printer -
The Cartesian printer uses the z-axis to move the bed of the printer up and down and the print head of the printer moves in the x and y direction. The thinking around this is that the print head is very stable and it is light because it uses bowden extruders (which will be explained below). These are situated in a distance from the print head and therefore it can reach faster speeds than the other printers.
3. The delta printer
The delta printer of which there is a picture below, uses three stepper motors which are placed in a triangular orientation to each other and these stepper motors use a mathematical algorithm to move the print head in the x,y and z-direction. Usually the x-y printing surface of these printers is not very big and circular. But the print height of the printer is usually much higher than its counterparts the x-y printer and the Cartesian printer. This printer also makes use of bowden extruders, but the speed is determined by the controller, as the calculations put some significant strain on the controller to move the print head.
The biggest issue with 3D printers evolves from the frames. The frame must be sturdy and should not be able to shift in any direction under stress and/or vibration. I know that was a mouth full, just look at what I mean in the picture below. One of the big issues with the original Prusa was that the z-frame was not sturdy enough and a print height of 0.2 mm was the smallest you could go without problems. The forces that the print head generates would make the z-frame go forward and backward, changing the print height considerably. You usually work in tenths or hundreds of a millimetre when printing, so you can imagine what happens if the frame is not sturdy enough to hold its stature.
Make sure the frame you buy has at least a boxed x-y frame and the frame has enough support on the corners to prevent it moving around. You will find most of the cheaper printers do not have this supports. Although some of the frames really needs a bit of work to make it sturdy, prints will still be of relatively reasonable quality. It is a matter of your budget.
Controllers are one of the easier decisions. Make sure you get a controller that can run a decent readily available firmware, and for which you can get spare parts around the corner.
Firmware is the software that is loaded onto the controller so that it can understand the files sent to it, and that it then converts these files into the moves on the printer.
The obvious choice for me is the Ramps 1.4 controller shield on top of the Arduino Mega 2560. These two boards make up the controller. It is the most widely used controller and you would most definitely get them around the corner. The second thing I like about this controller is that you use a freely available open source firmware on it that has a lot of support and active development done on it. There are proprietary printers out there with their own firmware and controllers, but then you may be locked in with that printer and have to buy their parts the whole time. My choice is the Ramps 1.4 controller.
These days you get hundreds of extruders out there; you can download the models from thingiverse for free and build your own. You can buy most of the spares you need from my siteJ Here is some very good advice: buy a single extruder for your printer and leave some money to later upgrade to a dual extruder. A dual extruder adds too much complexity to the learning curve. It is better to have a single extruder and just have to concentrate on a few things before printing your first print.
Dual extruders has a very tedious and precise setup that must be done before printing. The setup of the software is also much harder with a dual extruder if you are not familiar with your printer and your software.
I used the CharlStruder, in the picture below, for the first six months and I never had a problem with it, except when I did a stupid thing to make it clog. It prints flexible filament with no problem. It is another kit I have for sale on http://www.Xanics.com.
There are basically two types of extruders and both have its own pro’s and con’s.
1) The bowden extruder
2) The direct extruder
There are a lot of filament materials out there, and new plastics get added to the list every day. But for a beginner there is only a choice between two filaments.
ABS would be everybody’s choice if it was not for all the problems you may or may not have using it to print with. It curls up from the printer bed, especially in bigger prints. It delaminates if the temperatures are not correct and it is difficult to stick it to the bed of the printer. ABS definitely needs a heated bed to print on and there should be no sudden temperature changes when printing. The pro of this filament is that it is strong, you get better precision and therefore you can use it for printer parts and engineering proto-types. The following is my personal experience: I chose ABS as my starter filament because I wanted to print printer parts and prototypes. That was by far the wrong decision to make, I should have started with PLA because it is much more forgiving and I have heard of people printing on cold beds.
PLA would have given me the opportunity to concentrate on the printer and not on the filament. I would have gotten quicker results and it would have given me that “Eureka” feeling much earlier in my 3d discovery. PLA is a very hard but brittle material and therefore not as strong. PLA is also not suited for printer parts as its melting point is too low. I should have bought one roll of PLA, and get my printing experience going till my expertise level was on a point where I could start experimenting with ABS and the exotic filaments out there. Take my word for it. One or two rolls would give you enough printing to really get up and running. When printing smallish models you will get a lot of prints out of one roll of filament.
Read up on printing experiences of other people to setup and calibrate your printer to get a decent print.
Printer bed surface
Here I am a bit lost as I have an aluminium bed with a heater stuck to the bottom of the aluminium. I cannot give an opinion on this as I have not worked with a glass bed yet. I had my fare share of problems with my aluminium bed, but unfortunately cannot compare it. One thing I might say, it does not matter what surface you print on, make sure your heater is adequate to quickly get your bed to the correct temperature and be able to hold that temperature. A lot of the heaters out there are just adequate enough to do what it must but the time wasted for the heated bed to get to temperature and electricity wasted to keep it at that temperature is maybe worth looking for a better heater i.e. a silicon heater. If you know what you are doing, you can even go for a 220V heater which is very quick and keep the temperature easily. On the other hand, the right 12V or 24V silicon heater would work as good or maybe even better. I have a 12V Kapton heater on my aluminium bed and it definitely does not have enough power to do the job adequately.
Heated or Not
Definitely go for a heated bed. Most of the filaments need the bed to be heated. All plastics tend to curl up as they cool down, some just more than others, like ABS. The heated bed goes a long way to helping with this problem. Especially ABS needs a heated bed of a 100°C or higher. Even PLA that sticks to a cold plate would benefit from a 60°C hot bed. So this is a no brainer, get a heated bed.
Slicing software is the software that cuts up your model in layers and then converts each layer in G-Code that the printer controller understands. There are quite a few slicing packages out there and each has its own pro’s and con’s. Unfortunately the software makes a big difference in the quality of the prints. I used certain slicing software for a long time and really got frustrated with it when I saw the near perfect prints the people on the web produced and my prints looked like a donkey’s as compared to theirs. I then read an article on the web, comparing the different slicers, which by the way was not very scientific, and I saw this software called Craftware. I immediately downloaded their software which is in beta at the time of writing and tried it out. I could not believe the improvement in print quality I got from that slicer. Both the slicers were open-source at the time of writing and were basically free. Even Craftware unfortunately had some con’s, which is very irritating but my prints looked great and keep in mind it is still in Beta version. I am now putting money away to buy Simplify-3D to see if I am going to improve my prints even more. So if you have the budget, go for Simplify3D or just download Craftware to start out with. And please do not get stuck with one piece of software, change every now and then and see if there are not any improvements on the software you already used or new software on the market.
Most of the above is my own experience, and I have told you what I would have done differently the second time around. The areas to concentrate on are the frame, filament and software. Remember to keep space in your budget for upgrades; you would most definitely want to upgrade key areas of your printer afterwards. Have a happy 3D experience.
Unfortunately I swotted a fly lounging on my keyboard. He was pestering me for a while now and the opportunity presented itself and I took advantage. Needless to say my keyboard stand did not like that and here is the outcome:
Well what was a man to do other than design a stand. The stl fiile can be downloaded here
This was the outcome:
3D printing is not as uneventful as you may think. I had a bit of a slip this morning with my sharp scraper, trying to get my prints of the bed. Yes, they were stuck pretty good.
The not so lucky:
Hi , have you ever sat and thought about what you can do with a 3D printer at home, well I did the other day and came up with some interesting stuff you can print and fix. I will add to this blog as I go on.
The other day I sat and looked at my sad expensive CampMaster camping chair while sitting at my printer, waiting to change the colors for my print. Sadly one, or should I not expand on this, person sat on the chair and the two back feet just gave away. Here is the result of that incident:
I designed this new foot which is much stronger in design and has been printed at 100% infill with ABS of course:
And eureka, the missus enjoys the chair again and are out of my hair about repairing the chair. Not that I do have any hair, lets say it just feels like she is in my hair :-)
The ciclop scanner is a neat little scanner that is inexpensive and would do the trick in and around your 3D printer at home. It is not the most sophisticated scanner on the market but with a bit of tweaking and calibration you can get fairly decent scans to print or build on. Regards building, configuring, scanning and post-processing of the scans, I have put together this blog to supply some references to videos and instructables to make life easier. The videos and instructables are not my own and I give credit below each part to the person who deserves the ovation.
Another building instructable can be seen at the following URL. It is in a sense better than the video because it is a written instructable that covers hardware, software, electronics and drivers.
dtrewren - instructables.com
3)Calibration through the Calibration WorkBench:
The stl files for the printed parts are available on thingiverse - http://www.thingiverse.com/thing:454584. Unfortunately I had to take the filament width sensor of my site as their is licensing issues with this. I endaviour to design my own or get another design that does not have licensing issues. In the mean time I still have four or five full kits available at 5% discount and a few pc-boards, I am sure flipper would not mind us getting rid of the existing stock. Please email us at firstname.lastname@example.org if you are interested.
The pc-board and circuit diagram and the stl files can be downloaded from thingiverse and can be viewed and or printed from Eagle CAD. I am using the lite version which is for free. Download a copy from their web-site to be able to manipulate the files. It is a very small board with very fine traces and unless you are a professional in making pc-boards, either get them made or buy them from us.
Here is a video of reflowing your pcb with a skillet. I used basically the same set-up but have made mine Arduino controlled as the cheap skillets does not have very good temperature control, but that is for another blog I am planning to write. The person in the video uses a hot plate but it is the same principle for a skillet.
And last but not least, the filament sensor calibration.
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First of all you get the HC-06 module here:
This module is a slave module and is not capable of acting as a master. With this application your computer or cellphone will act as the master. There is some people that claim they have flashed the firmware of this module to be the same as the HC-05 module which can act either as a master or a slave. But we are getting of the point, we only need it to be a slave.
The datasheet for this module is can be downloaded here:
As you will see in the datasheet, the hc-06 is a 3.3V module and the Arduino signal is 5V, you would therefore need a 2 Channel Logic Level Converter 3.3V to 5V TTL Module to be able to communicate with the RAMPS board. THe supply voltage however is 5V and can be coupled directly to the RAMPS board. Another way to do it is to use a voltage divider as depicted in the following video:
by Charles Werbick - youtube
If you have a FTDI module that you can connect directly from the computer to the HC-06 to set up the HC-06 to run on a 11500 bitrate to get faster communication from your computer or cellphone you can watch the next video to help you set it up:
by Charles Werbick - youtube
The other way to change or setup the HC-06 is with an Arduino as depicted in the following instructable:
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