Prusa Control

In the third post of the month/night after a cabinet and a Google hat I wanted to quickly talk about Prusa Control. Prusa Control, for the uninitiated, is a cut down version of the, very useful and powerful, Slic3r software for the Prusa printers.

Prusa love Slic3r and there is no reason to doubt it. They build a custom profile for the software and make sure it is shipped and linked across their brand. however they note that it can be over-whelming for beginners. That’s where Prusa Control comes in.

Prusa Control is aimed at ease and speed and with just settings for the Prusa 3D printers and there is something lovely about that. I have installed the beta and used it for a first print in my new cabinet.

It worked really well.

In fact I would say close to perfect. I printed with a brim and with loose settings (.2 at 15% infil for speed and ease) and I got a near perfect print with good bridging and detail and a wonderful layer height that is regular with no breaks or interrupts. The brim was light and they clearly had taken care to make sure it was a well printed but easy to remove printing support.

So for new users and for experienced users wanting to cut out the interface and get straight to the printing then it is worthwhile having Prusa Control next to Slic3r in your toolkit.

I also liked how smooth the layer height display worked after generating which is very quick and efficient.

A very clean and easy to understand interface greets you on opening, seriously the controls on the side are all you have to deal with, this is minimal and almost perfect

 

Easy to understand layer height control

 

One of the prettiest and nicely printed brims I have ever worked with

Building the Google AIY

The second blog post of September, and actually the second of this evening, concerns a recent build of an electronic item I did with my son (#1Son, Ben).

I managed to pick up the Google AIY Hat for the Raspberry Pi with MagPi for a very affordable £5 and Ben and I decided to build it together and to video it for our YouTube channel.

The build was complemented by printing a box from a design on Thingiverse instead of using the cardboard one. Rather than say too much more I have copied the video link* (and you can also play the video below) so you can view it without leaving this page.

If you like the video please give us a thumbs up, and if you have constructive criticism then please feel free to comment.**

The build was super easy to do and they are accepting advance requests for contact if they release a future version of the hat, I recommend you get one as they are well built and fun to play with and have a lot more applications than the standard one we put it to.

As always I wouldn’t be doing this if I didn’t have so much support and encouragement from my LAMM peeps, thanks guys, and especially, as always, to TBSliver who is always there with advice and support. He gets a big shout out and lots of free dinners at my house ;P.

* https://www.youtube.com/watch?v=ewaQNu_3Mys&t=38s

** A part of me says that if you have negative or destructive personal criticism then I should probably know what it is or alternatively you can write it on a piece of paper and place it under a rock on Mars for me to find when I decide to be a Spaceman in some alternate reality :). I really would like to hear any good criticism, positive or negative that helps me in the future.***

*** Obviously, and I shouldn’t need to say this but a small part of me realises this goes to YT and Twitter as well so has to add this caveat, if you have any criticism of Ben then do the decent thing and keep it to yourself, children have far more impressionable egos :P.

3D Printing Cabinet

I haven’t managed to get to the Space much in the last couple of months (again! – though at least I did my duties as a director, such as making some posters (see another blog to come soon) and attending meetings doing admin etc.) mostly due to summer holidays and the pressures of family life. However home projects haven’t stopped and I have a couple of blogs to talk about what I have been up to on the home front.

The first of these is all about my 3D printing cabinet. I was gifted a 3D printer (Prusa i3 Mk2 that I constructed with the affable TBSliver) detailed in a video to come soon. It has been working well but I often have prints that lift on one side.

After some discussion, with the amiable (and affable and affordable) TBSliver we decided it could be the drafts in the room. So again from a suggestion by the amazing TBSliver I decided to build a cabinet to hold my printer. To do this I used:

  • Two tables from IKEA – the well known LACK tables at £5 each (£10)
  • Two packs of cabinet hinges from B&Q at £4 each (£8)
  • One pack of straight braces from B&Q at £4 (£4)
  • One small knob from Wilkinsons (£2)
  • Some grip surface – spare piece that I had in my workshop
  • Screws, Superglue – all from other projects
  • Two magnets recovered from a hard drive that was dismantled
  • One 4 bar extension from Wilkinsons (£3)
  • Cut sheets of 3mm clear perspex with holes in three pieces for fixing (£60 including all cutting and delivery from the Plastic Man).
  • Total cost: £87

This might seem like a high sum, especially the perspex, but they are large sheets at 890mm by 550mm x 4 – and close to £12 for delivery. The actual sheets were £12 or so each and were delivered on time and well cut and transported so a bargain if compared to similar online retailers. I heartily recommend the service.

Construction was simple:

  1. Glue down some non-slip matting
  2. Align the two tables and fix together with straight braces (2 on each leg)
  3. Align the pre-drilled screw holes of the perspex and carefully screw down (do not over-tighten as perspex will crack
  4. Glue hinges to the perspex door and leave to cure for 24 hours
  5. Screw door to frame.
  6. Forget that you need a hole for the knob!**

My only issue is that the tables were a little flimsy and not very accurately made (a <1mm difference in legs from the cut and glazing process) which coupled with some slight inacuracies of the angle of screw holes can give ever so slight deviance in the build. However for £5 it is a small price and easily correctable once we bolted the whole frame together.

The finished box is quite pretty (IMO) and site nicely on the side dresser where I have my specialist tools and electronic knick knacks. in the utility room of the house.

Once again a big thanks to the wonderful chap who is TBSliver for all of his help, advice, support and praise, greatly appreciated. LAMM members are wonderful creatures.

Pictures below.

(** I solved this issue with the careful use of a soldering iron)

 

Lining up with a steel ruler and drilling holes with my drill
Non slip matting in place and using a quick template for the mounting of the internal power strip
Close up of non-slip matting
Here’s that template again, who needs expensive tools when a pencil and paper trick is shown to you
EU made card tables that are firmer than the price warrants
The bracing of the legs
Fitting the power internally so the cabinet has internal source.
Carefully tighten down the corners – so brightly reflective
Close up of the fit – nice and snug
The finished cabinet – I should be able to fit some tool and equipment bays at the top next

RFID Entry System

The new RFID system is almost fully operational, so now is the time to get your RFID key sorted!

We should be turning it on this Wednesday (26th July) So after this date you will need an RFID key to get in the upstairs door.

‘But I dont have one yet!’ I hear you cry. Well, if you come along this Wednesday Open Evening, we will be setting up anyone who does not have a key yet, with one!

If you are unable to make it down on Wednesday, then let us know! I (Tom) work only round the corner and so during office hours will be available to let you in and sort out your RFID Key.

If you are unable to do it during Office hours, let us know and we can organise a time to let you in and sort out a key.

To contact us, either message us on Facebook, in Telegram, or email the board at board@lamm.space and we will get back to you!

Making DIY dessicant from plaster of Paris

For a while now, I have been trying to make a dry box for storing 3D printer filament, having had problems with a reel of ASA filament becoming damp and the prints made from it coming out pitted and fragile. The first idea I tried was to use silica crystal cat litter as a dessicant in a sealed box. I bought a transparent storage box with a rubber seal and a packet of silica cat litter, as well as a cheap digital hygrometer / thermometer. Then I burned some holes in the lid of a plastic fast food tray with a heated skewer, and put the cat litter in the tray. Finally I put the tray, the hygrometer and the filament into the storage box and sealed the lid.

I left the cat litter in the box for a full day, and the humidity reading actually increased slightly from 55% Relative Humidity (RH) to 59% RH. This was at a nearly constant temperature varying from 24 °C to 23.7°C. The increase was within the error range of the meter but not the significant drop I had been hoping for.

The next thing I tried was to crush the crystals using the somewhat crude method of wrapping them in a strong piece of cloth and bashing them with the end of a brick, to see if this would increase the surface area of the crystals and make them absorb water better. This didn’t work so well as silica crystals are quite hard, and it also didn’t make them any better at drying the air in the box.

I suspect that the reason the cat litter didn’t work is that even though silica does absorb water, the granules you get in the sachets that come with electronic devices are prepared in a way that makes them highly porous and able to absorb atmospheric moisture, whereas the silica that is used as cat litter is designed to absorb liquid water so they make it out of solid crystals.

At this point I did a bit of research online and found this web page about drying mushrooms. It has a pretty good summary of the three main substances used as dessicants, how effective they are, and how to use them. In order of increasing effectiveness, they are silica gel, which will bring the humidity down to about 40% RH, calcium chloride, which is what is found in home dehumidifiers and can bring the humidity down to below 25% RH, and calcium sulphate, which is the strongest of the three and according to that page can lower the humidity to a few percent RH.

As it says on that page, calcium sulphate is the same chemical substance as plaster of Paris. This is a substance which attracts water strongly into its crystal structure, and can come in several forms depending on how much water it has absorbed: hydrated (fully saturated with water), hemi-hydrated (partly saturated), and anhydrated (no water at all). Plaster of Paris is the hemi-hydrated form and can be bought quite cheaply from craft shops.

The simplest way to make powdered plaster of Paris into a dessicant would be just to heat it in an oven to drive the water out of it, let it cool in a sealed heatproof container, and then put it into the dry box. This would probably work okay, but it would have the problem that air wouldn’t be able to percolate through the powder easily so it might take a long time to dry the air in the box.

I decided instead to try to make it into granules, thinking that they might absorb the water vapour better. The rest of this post describes how I did this.

Some of the equipment I used to make the granules.
Some of the equipment I used to make the granules.

The photo above shows some of the equipment I used to make the granules – two non stick baking trays, a bag of plaster of Paris, a mixing bowl and metal spoon, and a kitchen weighing scale. I also ended up using a couple of large glass jars, some rubber gloves, two plastic bags, a piece of heavy cloth about 40 cm square, some string, a pint glass of water, and a brick.

The first thing to do was to measure out enough plaster to fill the baking trays in a thin layer. You may want to wear rubber gloves for this as plaster is slightly irritant. I did this by just spreading it out in the trays to what looked like a reasonable depth to be able to break it easily once it had set.

Then I put the mixing bowl on the scales, zeroed them, poured the plaster into the bowl and wrote down the weight – 442 g.

 

Weighing the plaster of Paris
Weighing the plaster of Paris

You make up plaster by mixing it with water in a ratio of 100 : 69 by weight. This makes 305 g of water, which makes a total of 747 g in the bowl. I then made a bit of a hole in the middle of the plaster and poured water in until the weight was (about) 747 g. Then I mixed it with the spoon until it was smooth, and poured it into the two trays in roughly equal amounts.

Liquid plaster in baking trays
Liquid plaster in baking trays

I then allowed this to dry for a while (the instructions on the plaster say 6 – 10 minutes). The next thing was to take the plaster out of the trays and break it into granules.

To do this, I first put the trays inside a large plastic bag and turned out the sheets of plaster. These came out quite easily.

Turning the plaster out of the trays
Turning the plaster out of the trays

Having done that, I then put the bag inside another bag, broke up the plaster sheets a little bit by hand and then wrapped the bags inside the cloth square with a piece of string.

Plaster fragments inside bags
Plaster fragments inside bags

 

Plaster and bags wrapped in cloth
Plaster and bags wrapped in cloth

The next thing was to bash the bag with the end of a brick until it seemed like the plaster sheets were all broken up. Then I took the newly broken granules out of the bag, laid them out in the baking trays, and baked them in the oven at 230°C for two hours.

Plaster granules ready for baking
Plaster granules ready for baking

I left the trays on the hob for a couple of minutes to cool down a little, then poured the granules into the large glass jars to cool properly.

Plaster granules cooling in jar
Plaster granules cooling in jar

Once they were cool, I put them into the plastic tray with the holes in the lid and sealed this in the storage box with the hygrometer reading visible through the plastic sides.

Plaster granules, hygrometer and filament spools inside the dry box
Plaster granules, hygrometer and filament spools inside the dry box

 

The box sealed with the hygrometer reading showing
The box sealed with the hygrometer reading showing

Finally it was time to see if the granules were going to work. I wrote down the time and relative humidity for the next few hours, and watched the humidity fall from 62 % RH at 16:42 to 27 % RH at 23:04. It fell quite fast at first, going down to 38% by 18:03, and then slower after that. Whether it will get all the way down to the level of a few percent that the web page I referred to above says you can acheive using calcium sulphate, I’m not sure yet, but I’m pretty pleased with this result, as it is below the level that is supposed to be acheivable using silica gel.

One test I would like to do is to open the box again in a day or two, let the air mix, and then see if the humidity drops as fast the second time, to get an idea of how much drying capacity this amount of dessicant has. If I get around to this I’ll post an update in a comment.

Yarn On

So just after Yule I started a Crochet project, its big and uses a lot of part balls of yarn

IMG_20170621_165445

Yes its a big blanket which I finished at the weekend, when Britain hit a big heatwave.

For those of you out there that think this is very difficult, it is not. There is one stitch used for the entire thing and is just a standard Granny Square multiplied

IMG_20170621_170113

There are many tutorials and Youtube videos on how to make a granny square, so I won’t go into how to make one but the blanket consists of 176 small Granny squares sewed into blocks of nine and and 14 large ones. These were all stitched together into fours (2 blocks made of small ones and 2 larges ones). and then stitched all together. I then did one row of white and two rows of back all the way round to finish it off.  It is 157cm square so fits over a double bed.

IMG_20170621_165531

If you want to learn to crochet, want to sew something on a sewing machine or other textile crafts. why not join us in July for our Textile Hack day on 15th July.

Oh and while I have you, here is a sneak peak at another project I have on the go.

IMG_20170621_170344

3D design for 3D printing day

On the 17th of June from 12pm to 5pm we are organising a day of demos and talks on the subject of ‘3D design for 3D printing’. There will be several talks and demonstrations on the subject of how to use 3D design software to produce physical objects for manufacture, whether on a 3D printer, laser cutter, or CNC milling machine. If you are curious about 3D printing and other computer based manufacture techniques but don’t know where to start, or if you have experience but would like to share skills and ideas with others, this could be the event for you. All ages welcome but under 16s must be accompanied by an adult.

The talks / demos will be:

Tom Bloor – Introduction to Fusion360.
Ian Norton – Modelling in OpenSCAD.
Andrew Baxter – 3 ways to model a real object in FreeCAD.
— break —
Dave Leack – 3D Printing with Blender: Common errors and how to fix them.
Ian Jackson – Modelling in Vectric Aspire.

The talks will last between 30 to 40 minutes, with a 20 minute break in the middle.

If you would like to help publicise this event, please download and print out this poster, and put it up wherever you think people might be interested.

The Dolls House

I have been absent from the Space for a few months, only popping in for the occasional meeting and to grab a tool for a mini-project. Most of the reason for this is to do with a large home project.

This year my sister reached a half-century in years. All of her life she has stated she wanted a dolls house, and this desire did not decrease with age. So I decided that I would build her one.

Being a Maker I knew I wasn’t going to indulge in buying any old kit with instructions, so I bought a plan from online for twenty dollars with its 5 page A4 picture guide (which was less helpful than the three online pictures of a constructed house, and set to it.

Needless to say it was more work, some struggle and a lot of compromise more than what I wanted but I did get it done, it was in time and I duly delivered it on the birthday to a very surprised and elated sister.

Below is a video of the build, and I would like to formally thank all my fellow makers and family for their help, encouragement and support. I really would not have attempted this a few years ago, being a part of LAMM has really broadened the number of things I am willing to have a stab at.

Build Process

  • Bought plans and converted them for use on our laser system
  • Cut out the whole of the design
  • Try to work out which piece fits where (this took many hours)
  • Glue together each floor and all pieces
  • Use fillers and a lot of sanding for gaps
  • Apply base coat – Sprayed
  • Apply top coat(s) – Sprayed
  • Apply large area paint (brush)
  • Apply fine area brush (panic as there is only a few days left)
  • Buy model making extras, grass, vines and pavement
  • Apply grass, pavement and vines a day before
  • Carefully transport house to recipient

Thanks in specific

  • Tom Bloor: Help with Laser cutting and general tool advice and build suggestions;
  • Claire Jackson: Showing me the website with plans and lots of advice and moral support;
  • Ian Norton and Kay Kempers: Lots of Moral support and cheerleadering;
  • Leigh Keating: Painting, sticking and advice.

-mdk exeunt chased by a staircase

Controlling your dust extraction with a blast gate

Blast gates for controlling air flow are not a new thing but buying them off the shelf can be an expensive shopping experience, plus they’re only available in fixed sizes. I’m using 110mm UK drain pipe which there certainly isn’t a suitable gate for.

Clearly any self respecting woodworker has the skills to be able to build their own. I took some inspiration from Jay Bates and Marius Hornberger both of whom have brilliant YouTube channels that you should subscribe to.

But this is a hackspace blog post, so clearly that’d be a bit too straight forward… how about if we laser cut them?


blast-gate-on-laser-bed

That’s heading more in the right direction. That’s a pretty nice design as a starting point. I ended up having to tweak the design to account for a slightly different diameter pipe fitting (mainly because I forgot to measure it before going to the hackspace and guessed wrong). But neat trick if you happen to do this, cut another one the right size and then when it’s finished very carefully lift it out of the cutter without moving the board you cut it out of, now drop your badly sized one in the hole and re-cut. Obviously that only works if it’s too small, or you have a magic laser that glues bits back on… no, wait, that’s a 3d printer.

So our Blast Gate Mark 1 is available over on GitHub which looks a bit like this:


blast-gate-mk1

Parts list:

You’ll obviously need a laser cutter, we always recommend those awesome guys at Just Add Sharks because they rock!

Assembly notes:

  • The shorter bolts fix the handles to the gate
  • Squares with the larger hole go on the outside
  • The tricky bit is putting all your gate bolts in, adding the side strips, adding a washer and then adding your second set of gate pieces


blast-gate-washers

This is important, don’t over tighten this or your gate won’t side. I recommend the use of a cordless drill with torque setting that you can wind right down to low. As long as you can’t rotate them by hand, they are tight enough.

Having assembled your gates, you should have something that looks like the header picture above. Now we need to cut the pipe fitting in half and attach it to the gate. Safely cutting the plastic coupler in half without a big enough lathe is a hard thing to achieve, so having had a think about how to do this I came up with something that will undoubtedly make some people twitch like crazy:


2017-03-15 15.28.38-1

That’s a Dremel speedclic plastic cutting wheel on an arbor, in a pin vice, in a pillar drill, yes. I did warn you. A safer way to achieve this would be to use a lathe if you have one big enough (the pipe couplng for this goes around the chuck of my small lathe). This technique gives accuracy whilst being the safest I could think of with the equipment at hand.


2017-03-15 15.37.10

I cut mine to have the tabs on the end with the seal as that’s the one I plan to stick an extraction hose end into.

Once the coupling is cut, glue it in place on either side of the gate. I used Screwfix’s Pink Grip which hasn’t quite set right now but looks like it’s going to do the right thing.


blast-gate-mk1

So there we have it, Mark 1 blast gate. Stay tuned for Mark 2 which has electronics to control your extractor.

Presence sensors again!

In my previous two posts I’ve talked about hacking cheap presence sensors to work on 24v DC rather than mains.

As does happen with these things, we’ve ended up with another different style of sensor from the same supplier!

pir3-pcb

The design of this one is actually more complicated than we’ve seen previously making use of zenner diodes to drop the +24v DC to 5v for the front panel PCB.

pir3-2

Thanks once again to Malc who eventually gave up trying to make this design work and posted me three up to look at, I shall enjoy the beer on you mate 😉

Hack on!

Ian