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Archive for August, 2015


Kossel Power Supply

One of the things about the Kossel (not a mini version is mostly the sheer size of it. True it’s more compact than the usual Cartesian style box printers, but it still makes a fairly large foot print where ever you put it.

Then when you add the spool holder, it needs a little more room and finally there’s the power supply. Typical switching power supply, 12V 30A. 99% of the Kossels I’ve seen photos of just have the power supply under the table top or sitting off to the side.

One of the makers at our maker space showed me a couple of ideas he had for mounting the power supply on the top of the Kossel. Quite literally the only place left you could mount one. That provided the inspiration for me to give it a go.

I’d already designed a new front for the Geeetech LCD 2004 smart display and had added the cut out for the power switch so, in for a penny, in for some more designing and PLA printing.

After test fitting one of my spare 12V power supplies, I found the supply fit rather snugly in the top. So I designed a front hanger.

IMG 0381

The hanger fits behind the top front open beam. I used a couple of M3 screws with T-Nuts to mount it. I also made it 5MM over size in width and 2.5mm oversize for height. Why? There’s a fan in the power supply. Probably a reconditioned Boeing 737 engine from the sound of it. So I not only wanted to isolate that from transferring any vibrations to the open beams, I also wanted to isolate the open beams from the aluminum housing of the power supply.

Yep, all about the quiet.

Next I designed a rear bracket with the same over-size to it.

IMG 0382

The way you see that sitting in the photo is the way it prints too. Those are 30 degree angles and print just fine.

I mounted the two brackets roughly to see how they were going to work. Yep. It’s one thing to design all these cool things, it’s quite another to actually have them fit…

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This only left putting in the power supply to check for clearance.

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I’ll say one thing right now. If those open beams were any shorter, the power would NEVER fit. As it it there’s maybe 2mm of space so that it doesn’t touch either the front beam or the other two at the back. Although it would have been neater to mount the supply with connections at the back, there’s already a whack of wires running down the back of the Z tower.

Some unused 2.5mm rubber sheeting was cut up and made the bottoms of the brackets. Dense foam cut very thinly made the sides so the power supply is wedged in snugly. It doesn’t vibrate, nor does the tower vibrate it.

I was going to have to run 110VAC to the supply and rather than use a bunch of single 18 gauge wires I used one of those standard computer power supply cables. I cut the ends off, removed enough of the outer casing so I could run the wires down through the vertical open beam and out through the holes in the Kossel corner piece.

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If you check the photo, you can see a white power cable in the open beam and the wires coming out the corner piece. I wanted enough length on the bottom so I could run the wires all the way to the Z tower.

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Up top of the tower where the power supply is hanging I stayed in the open beam channel as much as possible.

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Time to design a receptacle plate for the AC plug to fit in. Standard EC variety.

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I made the plate fairly thick so when I’m plugging in or out the plate doesn’t give way. I did have to modify the AC outlet slightly. The distance between my beams on the Kossel is 19mm. The plug is 20mm. I used a rasp file to take every so little off the top and the bottom of the plug so if fit in between the beams without putting any stress on them.

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I run the wires from the bottom of the Y tower to the back where I have the AC plug in. You can just see the top of the plate holding the AC plug just past the bed holder.

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With the left over piece of power cable I cut it so that it would reach from the AC plug to my switch at the LCD front panel. I only needed two wires so I cut one of them off on each end. Just like wiring a light switch in your house.

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I plugged the wire terminals onto the rocker switch I have and pushed it into the LCD housing. Snug fit and it works flawlessly.

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The AC plate at the back accepts the standard computer cable power cord.

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Good idea to wrap your connections with electricians tape as well. Don’t want 110VAC leaking into one of those Kossel beams…

For the DC power from the power supply to the RAMPS board, I wanted to use some 16 gauge wire but the local building supply store didn’t have any. I ended up using some stranded 14 gauge wire. Heavy stuff to be sure but I still ran two sets of power wires from the power supply to the RAMPS board.

You can’t put four wires down the inside of an open beam, so I used both sides of the X tower to carry the four wires down and tried to hide it as best as I could. Where it was needed I used a couple of zip ties to hold the wire as well.

The finished job:

IMG 0396

An interesting side note to this. Before I started this modification I’d noticed that when the Kossel was printing honeycomb infill, the top of the tower would tend to vibrate enough so you could see it shimmy. This in spite of the fact that the hot end really doesn’t have much if any mass to it. Still, the steppers would start it moving when the right harmonic was hit I guess.

Once I added the power supply and wedged it with foam, the whole top of the tower suddenly no longer shook. Between the brackets and mass of the power supply it did dampen the vibration.

I was also concerned that with the AC close to the Arduino and RAMPS board that some electrical noise might cause some havoc. Happy to say that has not materialized.

Therefore I call the whole project a win-win…

Want to make your own? Here’s the link to the STL files for the brackets and AC adapter plate:

WabbitGuy Kossel Power Supply Mod


Kossel Display

My Kossel came with a full graphic display but in the real world that puts a fairly large load on the poor wee Arduino processor so I swapped it out long ago for a Geetech 4×20 LCD smart display. Truthfully, I’m not to sure how “smart” it is but it does work well and shows more information than I suspect one needs to know…

Geeetech LCDRAMPS1 4

Of course the Kossel also came with a really nice printed PLA box to house the full graphic display and that’s not going to fit the LCD 2004 display. I’d printed one for the 2004 LCD earlier when I was learning about the Kossel (like clamping the glass to the heater element) so I’d made a mess of that one.

While the previous messy one fit the display nicely, it was really meant for a MINI-Kossel and their open beams are a difference size. Matter of fact, if you search Thingiverse you’ll find most of the LCD units are designed for the smaller mini-Kossel. The Kossel I built is anything but “mini”…

I’ve been searching for a decent mounting system and I finally found one on Thingiverse. Or at least the basis for one. It was designed for a mini-Kossel as well so I imported it into Tinkercad and added some tweaks of my own.

Here’s the three parts that make up the mount.

IMG 0377

Enhanced left and right side are the changes I made. I used some left over open beam parts to mount the left and right sides to the front of the Kossel.

Starting with the left side, there is enough room for the SD slot. The holes in the mounts are designed for M3 screws and I used a tap on mine to thread them. Really they needed to be a little bit smaller for a snugger fit.

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The right side I change the original’s power switch for one that uses a press fit. I’m going to use it to turn the 110 power on and off eventually so for now it’s going to remain empty.

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From the front the minimalistic approach looks very nice.

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Is the design perfect? No. I think the front should be a little thicker than it is (only two layers) and the holes should be small in the left and right mounts so you can tap them with an M3 tap for better holding. But beyond that, it works very well and makes the panel look like it belongs there.

The next task will be to figure out where to hide the power supply. I’ve see guys put it everywhere from the side to the top. I thought about the top, but I don’t think the wires could be hidden as well. There’s two sets of 12Vdc lines and then the heavy power cord. On the other hand if I build a sort of “stand” for it, I can put some stuff in the bottom, but there’s always that 12VDC power supply fan and I don’t want that blowing up on the heated bed.

Eventually I’ll come up with something for the power supply…I hope…

If you want to print your own mounts, heres the link to the STL files:

WabbitGuy Geeetech LCD 2004 Kossel Mount


Kossel Lighting

After becoming more conversant with Tinkercad I’ve been designing little things that I need. And printing up a storm literally day and night.

Watching the printer during the daylight hours is no big deal, but when the sun goes down, even though the shop is well lit up, when printing a dark colour it’s darned hard to see what’s going on.

As the quip goes, necessity is the mother of invention. Or all screw ups. Depends on your view point.

The initial idea was to print up a couple of brackets to attach some 12V strip LED’s to and then mount those brackets across the front beam of the printer. Couple of things wrong with this idea though and the main one was that it was in the way when you wanted to reach into the printer area. The switch was okay.

LED Idea

This lead to version 2…2.1, 2.2 and finally 2.3 that I am using. What changed? I decided that I only needed the LED’s on when I was printing and I might was well have the Kossel control them.

LED Brackets Wiring

These brackets are designed to fit right in front of the X and Y towers. The LED strips are 12V strips of 5630 or 5730 SMD LED’s. Basically 1/2W LED’s and six of them in each strip.

I actually printed a channel for the LED strip to slide into. Although the LED’s come with a self adhesive backing my experience is that in time, it lets go. So why bother to start with.

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Using some left over hardware from my Kossel build I mounted the LED’s on the open beams.

LED Mounted

To turn the LED’s on and off, I wired them into the unused FAN terminal block on the RAMPs board (D9). It’s the pair of terminals between the bed heater and the hot end heater. I’m using since male Dupont pin connectors on mine.

LED FAN Wiring

I ran the power up to a four pin connector (top right corner in the photo) since the LED’s have two pins each (+ and -)…I did have to jump some terminals but it wasn’t a big deal.

There is also a reason I used the female connector. Remember there is 12V sitting on those terminals so we don’t want them touching any metal in the Kossel and causing problems.

IMG 0358

Next I wanted the GCode commands to turn the LED’s on and off. I use Slic3r so I modified the start and end codes:


That M106 command turns on the FAN, or in my case, the LED’s. The S255 is the “brightness” of the LED’s. S255 is FULL brightness, S127 would be 50% and so on. If you find the LED’s are too bright, easy fix.

The M107 turns off the fan/led’s at the end of the print job.

There is some slight LED flickering because of the MOSFET power changes with all those heaters on, but it’s minor in the great scheme of things. The LED’s run between 40c and 70c so they get warm too. Don’t be poking them unless you want a matching LED mark on your finger. The LED’s do not get hot enough to do any damage to the PLA mounts.

Here’s what the area looks like in a darkened room…


Turning on the room lights, which is a lot of light as I pointed out and letting in some outside daylight…

LED W Room Lighting

Yep, it still lights up the area nicely.

I was not using any flash on the camera when I took the shots either.

Yet another Kossel mod…here’s the STL download if you want to print your own. Note this is designed for the 5630 or 5730 LED’s.

WabbitGuy Kossel LED Mount


Filament Reel Holder

Addendum…free wheeling may not be such a great idea. I just replaced a reel of PLA and watched the extruder give it a good quick tug. About 4 feet of PLA instantly spooled off. Springy stuff that it is. Of course it wrapped itself around everything and had I not been watching…LOL So I cut a wedge piece of loose cell foam and added it between the base and the bottom of the spool so there’s some friction on the reel. Live and learn!

On my Kossel 3D printer the reel holder broke as I was moving it. So early on I printed up a temporary one. That was before I’d managed to calibrate the printer so you can imagine the kind of job I got. Yeah, suffice to say it wasn’t exactly perfect. More of a how not to.

While the peg sticking out the back works, I could see that the PLA doesn’t spool off very well. Especially when there’s some retraction going on.

I decided that if and when I learned how to design 3D dofunnies, I’d do just that. Today, as it turned out, was that day. I’ve been programming in OpenScad and with TinkerCad. Just for practice I thought I would see what I could turn out with TinkerCad.

After a couple of false starts it was easy to see that a single holder that fit the .5KG reels I use would be the most useful. From the two companies that I get PLA from, eSun via Hobby King and locally from MG Chemicals. And there’s a world of difference between the two besides the physical reels themselves. But that’s a topic for another post.

MG is short and fat, eSun is tall and thin. Of course there are no standards for spindle holes, so I designed a stepped spool hub.

Reel Empty

eSun uses the larger hub, MG uses the smaller one. If you’re wondering what the slots do, well, it’s called “Wiggle Room”. After designing a number of things I’ve come to the probably not so brilliant conclusion that making things fit perfect is best left to those with laser cutters or high end CNC. For my PLA squirter I’m quite happy to be close.

There’s four slots on each hub so what I did was deliberately under size the hub. I then took some rubber floor mat material (left over edging from my brothers truck when he cut in some new custom floor mats) and cut it to fit into the slot and stick out about 1.5mm.

Reel Plugged

You just screw the hub into the reel, it grabs and holds on very securely.

For the more astute, you might be wondering why I just didn’t print a cone. For a few reasons really. First, a cone takes a fair bit more material unless you’re spot on as to where the rubber hits the road (or the spool hits the cone shaft). Due to the cone shape, you have to lock the hubs into the spool or they just separate because of the weight. But, sure it could be done. I just found it easier with my edge ones, they don’t come apart.

If and when the rubber wears out, well, simple matter to pop out the piece and replace it.

For the axle I used a short piece of 3/16″ steel rod. Now I would have preferred to use 5mm rod but apparently for a country that’s supposedly metric, finding that at the local hardware stores is impossible. Weird….

I designed the side stands so they would hold a typical roller skate bearing. Here’s all the parts that went into the build:

Reel Holder All Pieces

Parts list:

  • 2 x hubs
  • 2 x side stands
  • 1 piece of floor mat rubber
  • 1 piece (4″) of 3/16 steel rod
  • 2 x skate bearings (5mm ID, 16mm OD)
  • 2 x 5mm collars (with set screws)
  • 1 x Pine wood 4 1/2″ x 6″ x 3/4″

Why the pine? I’ve seen a number of filament holders with PLA printed bases. Which makes them VERY light weight. When the reel gets down over half the extruder tends to drag the reel and the holder around. I wanted the weight of the wood to hold the reel in place as it empties.

With an empty MG Chemicals 1.75 .5KG reel:

Reel MG

Yep. That’s why I made it as wide as I did.

With a reel of eSun .5KG PLA:

Reel eSun

In either case the reel turns so easily it’s unreel. Er. unreal I mean…

If you want to build one of these for yourself, here’s a zip of the two files you can use.

WabbitGuys Weel Holder

As a closing note, after building and testing my new reel holder, I have to admit the bearings are overkill. The steel rod turns not the bearing. If it had been 5mm rod, it might be different. On the other hand, the bearing is going to last light years longer than a rod turning on a PLA bearing.


OpenSCAD Bezels

One of the things that got me interested in 3D printing was the ability to make faceplates or bezels for some of the Arduino projects that I construct.

I’d found some LCD 2004 bezels on Thingiverse and while they did print out, I could see there was room for improvement.

Thus, I decided I needed to learn how to design my own stuff. I downloaded a number of 3D drawing programs that advertise as being intuitive. Perhaps I’ve been in a 2D world too long, or been a programmer for too many years. Whatever the case, I found none to which I would even remotely attach the word intuitive. More like “steep” learning curve. Steep as in the case of a cliff.

What I wanted was something where I dropped an object, clicked on it, entered all the measurements and carried on to the next object. Apparently CAD has never been done that way. Not exactly out of the box thinkers I’m assuming. Hence if you never grew up with that mindset, trying to wrestle control of it would be frustrating. Exactly what I experienced.

There are some commercial software packages, SolidWorks was one that was suggested. Still, it didn’t appear to work the way I wanted it to. The remaining free ones I tried and tossed just about as fast.

One of the members of the FVMakers, while listening to my 3D lament, suggested I try something called OpenSCAD. Essentially it’s a programming environment where you use shapes to build what you want to design. The catch is, you need to understand programming.

Fortunately for me, I do understand programming. So I downloaded and took a look at it. At first glance it didn’t look any more “friendly” than the other GUI 3D design programs. I was a little disappointed by this. It did obviously plant a seed though because some of it made some sense and stuck with me. Over the next couple of days (about 3 or 4 hours) I found some examples, looked at a fair bit of code and suddenly the light went on. Dang. It made some sense.

Honestly in a bit of a goofy way though. They way they do it is not exactly straight forward but once you get about half dozen of the commands figured out and how the union/difference works, you can use it.

I have a current project that uses some seven segment digits. Typical size…20 x 27mm x 10mm.

Seven Segment

With openSCAD you build the design more or less the way it prints. In layers, starting with the bottom first. In each layer you position and then combine or subtract or whatever with the previous layer (or object). The numbers you use are mm so making stuff to size is a piece of cake.

Plus OpenSCAD does math. You can resize, scale, well, pretty much whatever you want.

My first design was basically three objects (or layers if you like to think of it in simple terms). The face with smaller cut out, a second face with a different size cut out (full size of segments) and then a box to hold the digits.

I hard coded everything first, which means I had numbers every where. Not a good way to do it but I was learning.

The outcome was pretty exciting! Here’s the first one with a single digit in it. There’s a lip so the digit can’t fall out the face.

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I was pretty excited at this point but I could see all the stuff I did wrong. Those digits were SQUEAKY tight. The reason is the segments are square but the 3D print isn’t exactly a perfect square corner. There’s some gusseting going on. I could file it out so it wasn’t wasted.

The other issue was that I didn’t have the border around the digits quite right. Cause I’m learning. Time for version 2…

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And the back:

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I made the frame (cube) to hold the digits 1mm wider and .5mm taller and they fit easily. To hold them in a dab of silicon and that’s all you need.

Of course as a programmer, I started to mull over how I’d get the code to do more than 2 digits. Say I wanted, 4 or 6? What would I have to change. Maybe I could create different versions of the code for different digit counts.

That’s the point the programmer in me returned. Variables. Let the code calculate the size based on the digits. Yeah. As it turned out, pretty darn easy to do. For me. Probably not for non-programmers.

I re-did the code like so:

OpenScad Code

Whip out the digits and a digital micrometer, edit the values, render and presto:

OpenScad 3D View

Export as an STL file, slice it, print it and for four digit counts:

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And six digits:

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The openScad code follows. Next up, I plan designing some bezels for push buttons and some TFT displays.

And this, is exactly what I got the 3D printer for.