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Some links about me. Many of my 3D designs are free. I also post on Google+ and in another blog, oz4.us

Tuesday, October 30, 2012

How to write a Cura / Skeinforge plugin

First, do you really really want to write a Skeinforge plugin ?


Preliminary notes: some sites such as wired link to this post, but you may like to read my less technical review about temperature gradients applied to wood first. Also, you could check this post if you just want to try it.

Now, read on if you are a programmer and want to write your own plugin for Skeinforge. Note also that Cura no more uses Skeinforge as it has a much easier plugin system (that cannot do as much as what can be done with Skeinforge though).

Indeed and contrary to what was being done so far, I did not want to manually insert the M104 temperatures changes in the file sent to the printer, nor stay close to the ulticontroller. So I designed a plugin for the Cura / Skeinforge software pair.

Since that was not trivial, I document the procedure here.


Wood filament becoming brittle after a while

Wood filament now brittle, lost all its needed flexibility !



When I started printing this morning with my wood filament (~2-3 week old), all kinds of filament issues appeared, while I had almost none before. I soon realized that the filament now is much more fragile than one week ago.

First I though I had temperature and clogging issues, since I was testing my plugin for simulating wood grain.

Update: seller answer, see end of post.

Shades of brown with wood filament, via varying temperature

Wood filament : changing temperature to get shades of brown, or tree-ring effects

Wood filament, temperatures from 205 to 240°, home made Skeinforge plugin

You probably want to check my first post about wood filament if you did not already.

This sequel shows how varying temperatures impacts the color of the filament (as advertised).

Monday, October 29, 2012

Robust bowden attachment with a blind rivet nut

Using a blind rivet nut to fix the bowden tube once for all

Blind rivets nuts give you a nut where you cannot reach the other side of the support.

How to clean the hotend and nozzle from the outside

How to remove clogged/molten filament in a V2 head?

Obviously you can disassemble the end, which is quite painful. It may also damage some items and threads in the long term.

Or you try whatever comes under you hand to remove the damn molten stuff in and around the PEEK. Of course, start by removing your bowden tube from the top quick coupling.

Thursday, October 25, 2012

Review : settings for Cura (3D printing front end and slicer)

What are the most important settings in Cura ?

I switched to Cura as the unique front end to print with my 3D printer. This excellent software from Daid is handling all the printing work for you: displaying and scaling the objects, slicing them into layers, sending them to the printer. It will not help you design or modify your object though.


This is called stringing (overfeeding, bad settings)
but it gives an usable part and an interesting piece of art in the end

Wednesday, October 24, 2012

Review : printing with wood filament

Printing with wood filament : a short review 

Twisted Gear Lamp by BenitoSanduchi, printed with Cura at 80mm/s, 0.2mm layers, Ultimaker

You may like to read also my post on wood shades though temperature changes.

What is a "wood filament"?

I bought an early batch directly from a small producer in Germany. The full reference was LAYWOO-D3 LOT F0142. It was not cheap, but it even got more expensive because everyone wanted some!

How it is made sounds trivial: just a mix of saw dust and plastic... But shaping this mix into a nice filament must be tricky otherwise all the major producers would have produced it before and would be already be selling kilometers of it...

There was no choice on the color yet.

What strikes me first is the surface, which is extremely rough compared to the other filament kinds. I think there is still air in this filament... The overall stiffness is much lower than PLA, and you almost feel like you could bend it without breaking it (even though it still breaks nicely with a sharp movement and pliers). Later, I had serious issues with the filament for some time which lost all of its flexibility, but the issue is gone thanks to a air dryer.

Unusual deep marks left by my hobbed bolt (with a medium tension on the feeder)

The filament diameter is not very constant, but it is not worse than the two kind of PLA filament I had. From 3.0 to 3.1 mm, which is totally fine for me. I never had any grinding issue (during the first week of the filament). Some people however report serious issues and varying diameters (read on from this post for example). Note that my bowden tube is non standard, and its inner diameter is 4mm (OD 6mm). This proved to help a lot obviously.

Printing wood (how weird does it sound!)


On my first print, I thought I was under extruding a bit because I heard bubbles popping out of the nozzle while printing, and the thin walls where not that smooth. I still should try with higher feed rate just to check how it behaves and if the result is smoother.

However the macros for horizontal filling (picture on the right) seems to tell it is pretty well tuned. See how the successive pass really fit each other better than with PLA (my nozzle is 0.4mm). Well, it may not be better, but since the material is rough, it really looks like it is.

The layers are harder to see than with PLA. At 0.1 height, it makes walls almost invisible. But much more interestingly to me, the horizontal filling is much nicer than with PLA.

Also, the extruding temperature really seems unimportant, really not like PLA. You just can set almost anything and it prints nicely, but you will get different colors. For this, you need to insert specific g-code manually in the generated file or use my forthcoming Cura/Skeinforge plugin.

Also, it looks instantly "dry" out of the nozzle. So much that I may significantly reduce the minimum time between layers so it prints faster. It really does not look like it is melting the previous layer top when the heads moves over (looks like wet cardboard more than plastic to me). However the layers still stick nicely to each other; may be because of the texture more than because they get welded ?

With surprise, I realized I could bend the following object where I could not with PLA. Hence, I suspect that this material will not stand the same amount of stress as with PLA nor ABS. It actually looks like something between cardboard and a springy MDF (it gets a bit stiffer with time, not much imho). The printed object also really can be painted, much more than with PLA or ABS.
It really gives a fine result, but not for all uses.

Printed at 222°, 60mm/s, 100% fill. The resulting object is quite elastic.

Printing at 80mm/s, I could probably go much faster

A closeup HD video that show the nice "thick" paths

Tips and issues with wooden filament

I would not leave the filament heating for long in the nozzle as it becomes really brown (and somehow crusty), so there may be a risk to obstruct the nozzle (update: good prediction since it just occurred to someone!). So I purge the head manually with regular PLA when a print is done (which now appear to me very "chemical/industrial" compared to the wood filament).

Purging : from much heated wood to pink PLA. Disgusting but safer.

I had no grinding at all when I checked carefully the feeder marks on the filament. May be that was thanks to my bowden tube replacement, or to my own feeder, or both. Actually, even though the filament surface is rough, since the material is smooth I can move it in the bowden tube as easily as with PLA (if not more).

Also make sure to keep it in a sealed bag and somewhere it will not degrade as mine did :(

Conclusion


As a final note, I think this material really rocks for artists and designers, and even though I am not an artist, I think I will always have a spool of wooden filament nearby :)

Check also how you can get different shades of brown (gradients) by varying the extruding temperature during print.

And then, now, I want to go and invest a bit in making my own filament. Winter is coming and I will have a pile of wood dust, together with a pile of broken PLA things. By the way, it even smells like a biscuit :p






This could be my new business card, but the clean up is more difficult than with PLA




Replace the bowden tube

Replace the Teflon / PTFE / bowden tube

I ordered more Teflon tubing before running out of the original two pieces I received with the printer.

They had to be shortened regularly because they were getting damaged by traction in the quick connectors, and instead of popping out, some even was torn apart in the filament feeder plug !

The replacement I bought was a "teflon tube 4mm inner 6mm" (well, there is only one way to read the diameters). I got 12 ft for $19 with shipping on eBay.

Homemade heated bed

Why add a heated bed ?

After I made mine, I never had an object pop off by itself because of cooling retraction. Way less issues also when a small plastic blob gets hit by the head while it prints the next layer (which occurs almost all the time with tall and thin structures).

Now there is an update: in this post I explain about how I print reliably, and it works probably even with Nylon and a cold bed!

For the heated bed, I used a single power supply setup, that I attached on the underside of the printer. I now have only the mains and USB cable getting out of the printer, and I carry no more bulky external power supply (that I sometimes forgot to bring with me!). It also reduces the failures due to the tired stock power plug when someone bends over the printer...




Tuesday, October 23, 2012

Review : which software for 3D printers?

A short review of 3D-printing softwares


Example: Cura as a smart front end to show, scale, slice and print

Presenting my eBay Ultimaker clone (part 2): the head

An improved hot head that looked like an official V2

You may want to check also the first part.

To the credit of my seller, the printer came with a few special improvements from the real machine. To his discredit though, freely using the name Ultimaker is illegal, and I am far from sure that he released these modifications under an open hardware licence, as required by the initial designers of the Ultimaker. As a general rule, consider also that your free support should come from your seller and especially not from the company that got abused in the first place!

Bevel the bowden tube ends

I use a very convenient tool to deburr/countersink/bevel the bowden tube ends. I found it by chance and it is very cheap. Now I use it everywhere (it also will deal with aluminium by the way).

There are two reasons to use it on bowden tube ends in my opinion :
  • it reduces friction of the filament on the tube square edges
  • it makes the tube softer so that it can be applied with progressive force against the PEEK for example, for a better seal
Before buying the tool I used my biggest drills, but it was much harder to do a proper job.


Monday, October 22, 2012

Printed filament feeder small gear

The small stock delrin gear on the feeder stepper motor got some freeplay with time. I first replaced it with one I found on thingiverse made by Chasmaker. You can download my derivative here.



Removable filament feeder : add a plug to the stepper motor cables

Add a plug to the extruder stepper motor cable !

The case slot design let me thought it would be easy to remove the filament feeder for transportation, good idea. But... did they forget that the stepper cables are going through the case with no way to unplug them ? Note that the unusual feeder itself is described here.

Lock the filament feeder in place

When I pushed the filament manually, I had to prevent the feeder from popping out of its attachment slots.

I designed this thing to make my life easier. Interestingly, it is also one quite popular object on thingiverse, so there must be a lot of people annoyed with this attachment (and because of failure with the hobbed bolt).

Actually I almost never had to push the filament manually anymore, but this is due to my new and own filament feeder design.

Heat sink on the stepper motors

Clean passive cooling on a stepper motor

Cool down your steppers : active or passing ?

For some time I was developing a new filament feeder, made out of PLA plastic, and finally, after a long print, I stumbled upon a feared issue : the motor gets hotter with work, and since it was over-extruding it got hot to the point it started to melt the pla around its screw mounts...

Replace the filament feeder big gear


I am not sure that the plywood I received was of top quality, because the wheel teeth started wear out pretty early.

Before it was too late, I designed and printed a drop in replacement. It is really working well, without any wear though I really made its life hard sometimes.

You may like also the small gear replacement.






Reduce friction on the rods and bearings

Reduce free play at the head rod ends

It gives a smoother movement and less noise when the directions changes forth and back.



I originally designed this to reduced a bit the useless friction that the standard plywood losanges were applying to the bearing and/or the X/Y rods.

This may not be significant. Also, a hole in the object would allow the bearing to be oiled also. To do so, you can also use the batman derived object on thingiverse(!), or as below:



Update: switched to these better end caps
Better, with a Nylon hub and free play adjustment (jwag55's excellent upgrade)
I printed the inside hub in Nylon to benefit from its nice properties (less friction, no wear, a bit of flexibility).

It is also a very good illustration why open licences such as Creative Commons are good, since this is a design by jwags55 inspired by mine (above). So I benefit from a free smart upgrade because I did not ask for money not prevented anyone from improving it.

Belt tensionier : the best so far

Tighten the printer belts

Update: before you cut you belts, you probably better try my banana XY blocks! They replace the ugly wooden block that try to both hold the head rod and to tighten belt (and they fail at both in my opinion).

Back to the old post: I tried many ways to better tension my long X/Y belts (the short belts are another fixed issue). All other (PLA) printed belt tensioners I tried just failed miserably after a while because they could not stand the stress in the long term. Or they were bulky and hit the sliding blocks.
So the best I found definitely were dumb zip tie tensioners !

Isolate the hot end with Kapton and fight plastic leaks

Simply use kapton on your hot end !

My head came pre-assembled but it had a small leak between the Peek isolation and the aluminium heating block, that appeared at high temperatures. This resulted in oxydized PLA liquid (the brown juice that becomes crusty when cold), and it dropped on my prints, leaving a dirty dark trace in the object.

I first wrapped the peek and heating element with aIn any case I see no reason to do otherwise now. paper towel. But I had to change it often, and it becomes so dry that I was fearing it could start burning with the smallest trigger. But the leak finally reduced on its own.


Sunday, October 21, 2012

Filament plug, hot head and the short bowden tube

Get rid of a plastic plug in an early Ultimaker V2-like hot end

Updated: check my alternate blind rivet nut setup, it is way more robust.

Shortly after I changed the small bowden tube between the two plates of my V2-like hot end, I made the mistake to cut it a bit too short. Well, I did not try to find a place that would specify this the length, given that my head was not designed by Ultimaker in the first place -- I think.

Re-drilled the top brass quick connector

My hot end has a quick bowden connector made of brass and directly screwed in the top plate plywood (huh).

I recently had my second filament failure, located between the top and bottom plates. Two failures in 6 months still are too often for me, especially with this metric screw in the plywood (a metallic nut really should be insertedthere)...

I found some way to improve a bit though. I drilled the brass quick connector round and a bit wider. It had a hexagonal inner shape which aperture was uselessly smaller than the inner section of the bowden tube.




Varnish your printer plywood before it is too late!


Paint or varnish your 3D printer plywood first ! 

Since I could not think of a good color to use, I applied transparent varnish on the raw lasercut plywood.

I diluted a bit the first application to get it deeper into the wood. After waiting a bit I applied a thicker layer, and started assembly before it was fully dry (as I could not wait).

In fact, it made the parts stick a bit on each other, which proved to be good for the overall robustness !

Considering other's Ultimakers, I think my varnish protects all the wood parts against dirt and oil, so I warmly recommend this. Even hot melted plastic probably can stick enough on unprotected plywood to damage the surface when you remove it later.

And moreover, it must be much harder to do afterwards, so do not rush to assemble yours... make it happy first!

Presenting my eBay Ultimaker clone (part 1)

The Ultimaker I bought proved to be a (nice) clone !

I bought what was abusively called an Ultimaker on eBay on March, 2012.
ultimaker
In fact the printer I got was an illegal clone of the "real" Ultimaker, made by a Chinese guy and sold on eBay, that he later renamed to a blue-painted clone name before he went out of business.

Still, there where a few differences with the original printer (mostly the head). So this post about my printer may help re-injected some tips into the open hardware community.  Moreover, he does not seem to be selling printers anymore, so I will probably not harm the real and only Ultimaker you should buy ! Seriously, do not come and ask for support from the "good guys" if ever you bought a clone, this is not fair at all. I am far from certain that you would get support with low-cost clones so you would better go with something reliable in the first place.

To make it clear: even though the seller proved to be reliable, talkative and he did know his stuff, I suggest you read the related ultimaker forum discussion. Until then I did not fully realized that "open hardware" does not mean you could legally reuse brand names like this !

About Me

My photo

If you know me and you cannot tell exactly what my real job is, then you probably found the right Jeremie. Check zax.fr for some pointers.

I am self-employed and I help start-ups, research centers, small companies with their needs related to computers, sensors, data processing and mechatronics. If you have a project and know what "R&D" is, then you already sparked my interest ;)