Adventures in waterproofing 3D prints

I’ve started printing 3D vases which look really nice in metal filaments.

3D prints are prepared by making the shape in software and then ‘slicing’ it into layers which can be understood by the printer. Usually this means that several layers are placed on the bottom, the side walls are built up by multiple passes of the print head, the top is a repeat of the bottom and the middle bits which are not seen are filled by ‘infill’ in special patterns. All this makes for strong objects.

There is a special mode of slicing which ensures that the print head never lifts off the work being printed, and never ‘retracts’ the filament nor moves backwards. This is sometimes called ‘vase’ mode and makes the print into a long spiral all the way to the top. There are few objects for which this works properly since it makes the sides only one layer thick and there is no infill. On vases or drinking glasses, cups this is ideal however and with the proper sized nozzle and good filament the results are great.

One issue is that usually these are not waterproof. Filament and deposition manufacturing by their nature leave microscopic holes in the print and while tuning the slicing parameters and the printer can have some effect, generally it is just luck when things hold water.  I’ve decided to look into lining the inside of objects to see if their water-tightness can be improved and so far I’ve read or seen of a few ideas:

  1. A wax or waxy substance rubbed into the surface then allowed to dry,
  2. liquid latex, of the type used for face painting,
  3. PVA wood glues of different types,
  4. general purpose epoxy resin, sometimes used in the fibreglass manufacturing industries. One I have found is called ‘Epolam,
  5. acrylic conformal coating used in the electronic industry for coating PCBs,
  6. … or general spray paint coatings.

Of these, the conformal coating sounds good but is very expensive. I’m going to try some of the other ones first to see if they are effective and attractive, starting with the cheapest which seems to be the wood glue and liquid latex. I wouldn’t want to mar the appearance of a beautiful vase by having a thick visible coating, but I also don’t want that vase to leak.

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Power

I wish power cords and wall warts came with labels showing which things they were meant for; it’d save everyone a whole lot of headache!

Redemption

The roots of the word ‘mortgage’ mean something which is paid until complete. Some macabre definitions float around the internet including those which take the old French or Latin and read them in English, which is always a dodgy way to interpret languages. I saw ‘death-pledge’ being touted as one due to ‘mort’=death and ‘gage’=pledge, which sounds too simplistic.

Different countries also have other expectations about how to finance buying a house – I was surprised to learn in Turkey that colleagues of mine there would take a loan from the property developer, and repay in a matter of years rather than decades. I’ve always lived in countries where the loans are taken through financial organisations and paid over decades with low interest rates that compound because of the extreme length of time involved.

The process of removing this debt is called ‘redemption’ and is removal of the pledge-until-payment and release of the deeds which show title in ownership. While that is nice, it feels a little medieval and reminds me of the long history of land title and ownership. Real land reform is quite rare and has mixed outcomes, not always helping either the rural poor nor the lower classes. I do admire the land reforms in Scotland which include returning tracts of land to common or community ownership.

It is nice as I redeem my own house to learn of the different ways that governments and rulers – some quite surprising – have redistributed land and tried to encourage greater wealth and ownership.

Pruning grapes

I have a grape arbour over my back patio. My father loved grapes and grew them for many years in Australia and I’ve inherited his love of the grapevine, if not yet his skill in keeping them pruned.

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Grapes have the advantage of growing very well in early spring and covering an area in shade leaves, while dropping during the winter and allowing light to come through. This is good for our north-facing house as we don’t get a lot of light during the winter months. However, it brings with it a couple of issues: the first is the sweeping necessary to clear away the fallen leaves which for a few weeks each year adds a little burden. The second is more tedious and involves dropping and dead grapes littering the patio and becoming squashed underfoot. The yellow jacket wasps which at this time of the year are missing the hatched grubs feeding them (look it up!) and searching for sweet material, infest the bunches and make a real nuisance as they buzz around drunkenly.

We can’t yet use the grapes as they are largely sour. This is because I haven’t mastered the art of pruning grapes to bring out the best flavour. Hopefully, with the vine trained over the large pergola which forms the arbour, I will now have the space and time to create some sweeter grapes!

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I cleared away approximately three bags full of  solid grapes – last week when I took the other half of the arbour to the recycling centre I think the staff wanted to try them! I advised against it, but have no idea what happened when I left…

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The tidy-up has produced a large mound of grape trimmings which awaits a trip to the green waste bin at the local recycling centre, and then on to actually pruning using the rod and spur (also called the cordon) system. Hopefully this will produce better tasting grapes next year, along with a covering over our outdoor patio during the summer months.

Parametric modelling

I’ve been using a number of programs to design 3D parts. While there are a number of very good commercial offerings these are very costly and my budget does not stretch that far. Autodesk is a particular favourite as they seem to provide quite a number of tools in this space including photogrammetry, mesh modelling and parametric CAD. Their TinkerCAD is pretty good. I’d love to use their stable of tools but as a maker and hobbyist they remain largely out of reach.

Instead I’ve been trying the free and opensource tools and they very in ability and usefulness. While Blender is perfect in the mesh modelling space and my son is pretty good with it, like a lot of comprehensive tools you need to devote the time to make it become familiar. For a while I’ve use FreeCAD and some of it is pretty amazing, but as there is many ‘ways’ to accomplish the same thing it can get confusing at times. I’ve made a few models using it.

Support

Recently I’ve started using OpenSCAD and are really enjoying it. OpenSCAD is a little unusual as it is a programming language of sorts and you do not operate in a WYSIWYG mode – instead creating the model in your mind and then translating this into distances and objects. A great tutorial on OpenSCAD is over here. Its power comes from using geometry in a Cartesian reference space to combine, intersect, and subtract objects to create your model. I find it very powerful and easy to use as I can easily visualise 3D objects.

I’m building an enclosure for my 3D printer and will keep a record here, while making the objects available on Thingiverse for others to use.

3D prints everywhere…

dav

I’ve started printing lots of things with my 3D printer, maybe too many things! There were the normal table top figurines, busts of film characters, and printer test prints but then the bug really caught hold and I am in the midst of building a veritable mini-factory of sorts. Here’s my project list:

Projects

During the build of the 3D scanner, and while waiting for the parts to arrive from China, the US, and Europe I started another and began to get confused which project was which. Time to focus, methinks. The scanner is almost finished in its first incarnation and I’ll be able to use it for my future activities.

The end point of all this is to set up a mini-process line where I can produce small trinkets and sell them in my church’s Christmas fair in late November. We’re fund raising for a new building which involves mortgages, loans and long term commitment to a large community building, hence the fund raising.

How do you rotate a PDF?

Searching the internet for information on how to manually rotate a PDF finds lots of frustration. The reason I have done is this that my scanner produces pages rotated 90 degrees, and the times I have searched the internet over previous decade the answers have depressed me:

  1. Buy Adobe Acrobat Pro,
  2. Send your document off to an online service – dodgy if you value the information on that PDF,
  3. Download a program to do it, again suspect as you cannot examine the source code or understand the provenance of some programs,
  4. Buy a Mac, as the Preview preview on a Mac can do permanent rotation, and save the rotated document.

A lot of those ideas are bad for different reasons. Acrobat Pro is expensive for simply rotating a PDF; online services, even those that promise not to peek at your document, do have control of it; running strange programs isn’t recommended at all; and the world of Macs are wonderful and expensive.

There is a simpler way.

Some of the raw material in a PDF is in a format which describes the document in plain text, while some is in a binary format. The binary bits are best left alone, but the plain text parts are easy to edit in a good editor. I used Notepad++ but there are others such as Sublime Text or Atom. I realise that this is “download a program from the internet…” dressed up in different words, but these well-known editors main job is to faithfully edit things and save them without collateral damage. I also use them frequently for playing with programs that I write, so I trust them.

Within the first few lines of a PDF you will likely find a line like this:

/Rotate 0

Save a copy of the document first, then edit this line to some other multiple of 90 such as ‘180’ or ‘270’ then save the document. Multiple pages will have their own rotate declarative, so find those as well and change. On viewing the document now the page(s) will be rotated clockwise that amount of degrees. Job done!

Day Zero

Today is an amazing milestone in my life. Today, I am worth nothing. Not worthless – just nothing. If I add up all the liquid assets in my accounts they offset completely the debts I owe.

That is a good thing.

Debt is easily available in the UK and leveraging that availability leads to indebtedness. As an Indian colleague said to me as he moved back to India years ago: “most people here in England are on the tick” – which means that most people live on credit cards and other domestic loans for a long portion of their lives.

Once understood, it can be controlled and I found a program called You Need A Budget particularly helpful, a bit like a row of cookie jars into which you put your allowance each week and when a jar is empty then you stop spending. Their four basic principles are awesome. Using it for 5 years gave me a good appreciation of where my income was being spent, and that enabled me to accurately estimate how much I’d need when I retired.

Of course I am worth more than nothing – liquidate all the assets I have (investments, car, house, family …) then they would add to more than nothing but at least in liquid terms I am breaking even right now. That’s a great sense of relief, and allowed me to retire early. I’ve joined the FIRE movement big-time. Having started paying down all personal loans in my 40’s and moving to the YNAB budgeting system has given me the data needed to accomplish this and see life beyond the payslip.

Rage against the machine

I was expecting a delivery of a mattress today from a large retail chain.

When I ordered from the store I requested a specific day for the delivery and noted the time in my calendars. I kept telling my family that it would be delivered today and even prepared the space by taking out the old furniture to be ready. Lots of emails from the retailer including earlier today an invoice, and I noted that the money had moved from my bank account today as well. I was prepped and ready to receive!

Cue waiting at my window at the appointed time. With a sore back from an earlier exertion I had my son on hand to help with the lifting and shifting. Towards the end of the delivery window a large truck pirouetted around on the street and pulled just past my driveway. Woo hoo! son alerted, I opened the front door and put on my best delivery man smile … only to watch as they took out an mattress and walked around the corner and into someone else’s driveway! What, I thought, perhaps they have the wrong address – and my anger was confounded when they appeared with plastic in hand from unwrapping the mattress somewhere else!

I watched them drive off, any slower and I’d have been over the road accosting them and asking to see the delivery invoice. Back into the house and searching Google for things like “can I keep an item if it is misdelivered to me?”. Ready to stalk around the corner and ask a neighbour “have you got my stuff?” On the phone to the store asking what was happening, spouting off to my son and beginning to feel really passive-aggressive! Finally got through to the store and gave them my order number.

My delivery wasn’t today.

Apparently in the 10 or so emails which they’d sent through they’d moved it back 4 days. I’d skim read all of them including the three or so PDFs and missed the one where 14 ==> 18, at the same delivery time.

I was the one who was wrong, but I had plenty of ammunition to prove I was right!

It shows me how often incidents are caused by self-righteous people who think they are right, and perhaps even are right on occasion, but for whom that ‘rightness’ justifies all types of reactions. I’m glad I didn’t tell the delivery guys they were idiots, or bang on the door of my neighbour (although I might have met a new one that way!). I’m glad that I didn’t prove to be a fool to a greater extent than merely watching them and then calling the store, but I wonder how many other people around me today are encountering misunderstandings which escalate into angry words or deeds rather than being clear up?

Creality Ender 3 bed leveling

I’ve brought a Creality Ender 3. This is one of the cheapest 3D printers available and as many people were giving it good reviews on YouTube, decided to take the plunge at £165 on eBay. It was shipped locally from the UK and arrived quickly.

First impressions on unpacking were very favourable. All the parts came neatly labelled and I especially liked the small plastic bags with extra spare parts for screws, washers and other attachments. They also supplied a full set of tools including side cutters, hex spanners, zip ties and even a platen scraper to free models from the bed. This is a quality product and is very complete for the price.

But the bed levelling is a disaster.  Full disclosure – I may not know the slightest what I am doing, and all this could be a noob’s series of mistakes.

As I understand it, bed levelling is either done automatically with presence or induction sensors on higher-end machines, and manually on lower-end machines such as the Ender 3. While there is an after-market 3rd add-on available, I only have the stock machine. The whole idea of levelling is to make the plane of the print head x-y axis’s parallel to the plane of the printed material – more correctly known as ‘tramming‘ by machine operators. This is done by adjusting the bed to within a paper’s width of the print head, by moving the print head to the four corners and moving the bed up or down.

I did this, and could not ever get it level. There was never enough play length on the bed screws to adjust the amount needed. The issue seems to be that the side z-stop sensor is too high – even the installation instructions mention that it should be “~32mm” from the bracket bottom to the underside of the machine – however there was a lug on the printed bracket which would not let it descend to that level and held it at 35mm height.

  1. I removed the lug and set the z-stop to the suggested 32mm above base level. The bed was now too high and the auto-home feature would have broken the glass platen if I had not switched off the machine. IMG_20180809_110853
  2. Still not enough play, so move the z-stop higher. I can adjust the front thumb-screw enough and I am hopeful (- and this would work with the stock epoxy bed cover, not the glass one which is thicker). Still not enough play in the back thumb screws, especially the left rear. Heated bed electrics are in way. That spring is at the tightest depression while the nozzle is touching the glass. InkedIMG_20180809_110940_LI (2)
  3. So I removed the rear heated bed bracket, remounted without the bracket and now I get a lot more travel in the height at the rear. That leaves the heated bed electric exposed but I can live with that for a while.sdr

Much better. Now on to levelling the bed with the paper shim and manually moving the print head to the four corners.

I can either build a new support for the 24V electric line using Sugru or more likely, once I come up to speed with TinkerCAD and Cura or whatever software I start using, I can 3D print a new one.

It is a superb machine and very worthy of the kudos being given it on the internet – just be prepared to do a little work with it to get it running at its best.