Category Archives: Musings

3D Printing – Getting What You Need Now

From need to product in less than one hour

From need to product in less than one hour

When people find out that I have a 3D printer the question that I am often asked is ‘why do you own one?’. Usually I tell them that it started as a hobby and to be able to make my own cases for my electronics projects (I have never been very good at buying a box and making it look good by drilling out holes etc!). However over the couple of years I have now owned a 3D Printer for I have evolved that thought. It was personified yesterday while I was cleaning my desk at home…

Yes, I am untidy! My desk often looks like an explosion at some weird combination engineering, computer and plastics factory. On the odd occasion even I get miffed and have a tidy up. While I was cleaning I kept finding SD cards. Having got loads for my camera and RapsberryPi, I needed a way to store them tidily and I turned to the ‘net. Sure I could have brought any number of card cases, but then I looked over at my Huxley which I was sure was bouncing there shouting “USE ME YOU IMBECILE!”. So I hit up Thingiverse and found a parametric SD card holder. Perfect for my needs. I got the Huxley up and running while I carried on cleaning. 30 minutes later it was printed and I was able to store my cards nice and neatly.

So now when I am asked why I own a 3D printer I’ll tell them that story. After all it would have cost me much more to buy a holder that probably wouldn’t have fitted my needs so well and it would have taken me days to receive it. As it stands the print cost me about £1 and took no more than an hour from investigation to final product.

Parametric SD Card Holder

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Setting Up Megatronics

Steps per mm

Possibly the most exciting thing for me when building a 3D printer is the electronics. I have built 2 kits (a Huxley from eMaker and a Mendel from RepRapPro) and am now building my own design. Until any printer gets attached to its electronics it is a mere metal doorstop. What I wanted to write up about was how I calculated the steps per millimetre for the DSF.

While in my usual ‘I’m bored lets search the net’ mood, I stumbled across the excellent RepRap Calculator3  by Josef Prusa. If you are building a printer from scratch this will greatly simplify figuring out what number the steps per millimetres should be.

Like many of the printers out there my DSF uses belts for the X and Y axis’ (T5) and a lead screw for the Z (M5). For the belt drives all I needed to change was the belt preset to 5mm – or the T5 belt. The pulley I was using was already 8 teeth and 1/16th stepping. As a result this would give me 80 steps per millimetre or a 0.0125mm resolution.

The Z axis uses an M5 threaded rod as its drive so again all I needed to change was the preset to M5. This means a step of 4000 steps per millimetre or 0.00025mm resolution. Obviously that is much finer then any of the prints I would ever do, the finest I have done was 0.1mm/layer. In reality I could set the stepper to full steps and still retain a resolution of 0.004mm.

So thanks to the calculators I have a 80 steps/mm for X and Y and 4000 for Z. Ignore the 800 for the extruder above. I have not yet got an extruder so that is just place holding!

One last thing; I have limited the feedrate of the Z axis to a low 2mm per second. Any faster and the motors stall. I need to oil the threaded rod to try and get some extra speed out of it, but I am not holding my breath.

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Simple Cooling Fan for RepRapPro Mendel

Simple but very effective

At the school I work at we have a RRP Mendel. I was trying to print some students work but it kept failing. Eventually I discovered that the problem was down to curling from some overhangs on one piece. As the part had 45degree angle and only 5mm thick, the printer was catching on the curled ands and eventually cause the printer to miss some steps. I needed a way of cooling the plastic faster.

I then found an 80mm computer case fan that was being recycled. As I needed to get the part printed I simply cable-tied the fan onto the smooth rods of the X-Axis. Amazingly these are about 80mm apart and the fan fitted beautifully behind the X-Axis endstop. Now I was able to get the print to finish and have a great look as well.

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Playing with Strimmer Wire

Image

Print was good, finish was rubbish!

So there I was wandering around Wilkinsons (a hardware/homeware store for those outside the UK) when I came across some strimmer wire. “Hmmm,” my mind went, “that looks awfully like filament for my Huxley, ooo look, 1.6mm so close the the 1.75mm I use”. So I brought some. £2 for 20 meters, not cheap, but some fun for the weekend!

Getting home I have a quick look online to see if I can find out which plastic it actually is, it doesn’t say on the pack. As far as I can figure out it should be nylon. Another search points me to the RepRap site as I look for the best way to use it (http://reprap.org/wiki/Taulman3D_618_Nylon). First issue, it doesn’t bond to glass or aluminium. However the Wiki suggests glue sticks which I don’t have around the house. I do have some PVA woood glue though, should be good enough. A light coat over the glass bed and then off we go!

Packet sitting on the bed at 50C. There was a largish hole on the bottom and I have drilled ho

Packet sitting on the bed at 50C. There was a largish hole on the bottom and I have drilled holes into the top for the air to escape out of

Issue two quickly shows its head, moisture. Darn its spitting like a Cobra. Still my test piece comes out looking reasonably okay and it was stuck to the bed like you wouldn’t believe. Some warm water dissolve the glue and off came the part. To solve the moisture problem I have to dry out the filament. Now I could do this in an oven at about 50C or so for a few hours, but the filament came in a nice little package. So I made a couple of holes in the top of the packet, place it on the bed of my printer and set the bed to 50C. Again this is an experiment and will be interesting to see if this will help dry out the filament. I’ll leave it on my printer for a few hours and see how it goes.

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A Year of Printing

Has it really been a year – already? Well according to my first tweet on this day last year it is!

I remember being introduced to the RepRap project a few years ago. The printer at the time was Darwin. I absolutely loved the idea of it – but the machine was a bit of a monster. Not only did it look huge and complicated – it also had a bit of a ‘bodge job’ electronics solution. When I read up on making the printer the electronics were the most confusing – seeming to take several different boards and then modify them for this application. A far cry from the need single board solutions we have at the moment.

The second iteration of the RapRap was Mendel – a far less cumbersome looking machine. This was then modified further into the Prusa Mendel. This basically looked like the Mendel but was easier to build. Since then there has been the Huxley, Prusa Air, Mendel Max and the Wallace to name a few. That doesn’t even take into account the other more commercial machines like the Thing-O-Matic or the UP!.

So in this year I have gone through over 4kg of filament (although about 750g is waiting for the Filabot so I can recycle it) – I’ve had to repair the printer several times (3 times for the heated bed!) and changed or upgraded several parts of the machine.

Overall it has been a great experience and being able to have an idea and a few hours later have the item in my hand is great.

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My Huxley

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Poll – Stand Alone Printing

I was wondering how many people have their printer connected to a computer to print or with it stand alone. Have a go with this poll – just for a bit of fun.

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Store Your Filament – Well

Okay – so I may have forgotten that I had some filament (Bling Bling Gold from Faberdashery) that had fallen down and I had forgotten about it. On doing a clear-out I discovered said filament and thought I would use it in my latest adventure – stands to display my Game Boy cartridges. Unfortunately that wasn’t to be.

Conditioner

Anyone will tell you to store your filament correctly – that is in a bag and maybe with some desiccant. Don’t store it randomly behind the unit your printer is on! Not entierly sure what has happened but when I went to insert the filament into the printer a section snapped off. Strange I thought – carry on and try again. It done it again. Hmm. I then looked at the filament and saw this.

If you look at the top of the filament you can see that there are really small ‘cracks’ in it. This is the point where is breaks. I am assuming that the filament has reacted with the air or moisture to have resulted in this defect. Although it looks more like the filament has dried out.

My Fault not Yours

I must say that this is the only time I have ever seen this from filament from Faberdshery. This is also some of the oldest filament I have as well. Had I stored it in a bag would it have faired better – I can’t say. However storing it outside of a bag will not help keep it in top condition either.

Let this be a lesson for everyone at my expense . Care for your filament and you will get some long life out of it. This is also a positive for Faberdashery’s ethos of only buying what you need when you need it, don’t try and store/horde it. I cannot blame anyone but myself for this – I should have put it away when I had last used it – now I have to bin it. Well – put it into recycling ready for my Filabot! (When I get one that is!)

Links

Faberdashery

Filabot

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