Saturday, 28 May 2011

Nozzles and blockages

A few weeks ago I managed to totally clog my 0.5 extruder nozzle.

What happened is I changed the filament colour from white to purple, after changing the filament the extrusion just started to turn purple then stopped dead.

What I suspect happened is that when I changed the filament I dislodged some of the fluff that was building up on the inside of the extruder intake.
This didn't melt, and clogged things.

I have now added a "filter" on the intake of the extruder, its just a wad of a chucks cleaning cloth.


After installing this filter I was really suprised to see just how much fluff was being collected. This fluff does not match my carpet, I suspect it is already on the PLA from the manufacturer, probably a remainder of the polishing process.


I already had a new 0.35 hot end pack from makergear
that I was planning to install sometime in the future, this blockage has moved that time table up to now.


This is the main parts, 0.35 bighead nozzle, heatcore and a V3 Hybrid GrooveMount base


To this a thermistor was added and taped to the bighead.


Finally this was wrapped in two layers of Rubber Coated Black Fiberglass Insulation.


This is the business end, as it where, as you can see the 0.35mm hole is really very small

This is attached to the wades extruder by their Grovemount system

One thing I have noticed is that there are two different wades extruder foot prints, this will only work on the older ones where the hot end is off center.
I found this out by accident. I was looking at how it fitted together on parts I had printed, and it just didn't fit. Lucky my working extruder is a older one and it fitted without issues.

You can see the grovemount sitting nicely between the wades extruder and the x-carriage.

The print quality of this nozzle is really nice, but the smaller nozzle has also come with its own issues.

Firstly the obvious, the extrusion rates have to be re-tuned for the smaller nozzle.
I have also dropped back to 30mm/s as I cant seem to extrude enough material threw the 0.35 to keep up with 60mm/s. I will try faster speed again later.


I also found that with this smaller nozzle the issue of warping was back big time.
The standard trick of printing onto Blue masking take is no longer sufficient. The extruded filament still sticks really well to the blue tape, but the blue tape is being pulled up from the build platform.
Presently I am trying green 3M painters tape, it has a lot stronger adhesive.
It seem to work.



Its all very green, but seems to work well.

A heated build platform would also help with the warping issue.. Ive found one online and the shipping isn't to bad, so I have orded one.

Wednesday, 11 May 2011

Upgrading parts and speed

Its been a busy time of late with the reprap.

I have upgraded the Z axis drive M8 thread from Zinc Plated steel to Stainless Steel, this runs so much smother. This has also enabled me to increase the Z axis speed to 3mm/s witch is a 50% improvement over 2mm/s. Now the limiting factor is the Stepper motors. The threads are directly driven by the stepper motors, it takes 320 steps per 1mm, so thats 960 steps per second!
When I upgraded the above threaded rods I made them longer with another idea in mind, I havent done that part yet and may not need to now. The longer rods clearly showed there was an issue with my Right side Z axis, so I replaced that also.
I have not had any Z-axis issue since.

Next I replaced both the X and Y 8 tooth pulley with a commercial 12 teeth ones from http://sdp-si.com/


After this change I had to update my machine settings to match. After doing this the positioning is noticeably more accurate. My circles are a lot more circular. It must be noted though that there is no way to attach these pulley to the spindle. I glued it on. If I had more patience I probably could have milled a nut slot and drilled a hole like the printed pulleys have. 

Ive also gotten my first spool of filament. The idea being so I don't have to look after it so much, ie it could feed itself.

I made a spool holder like http://www.thingiverse.com/thing:8137


But unfortunately the spool is to heavy to auto feed.

So instead I run it beside the Prusa and just keep a loose coil between the two.


This seems to work quite well. (Note the earthquake crack behind the spool...) 

After these changes I had a play with upping the speed of the machine. I normally print at 30mm/s
I doubled this to 60mm/s and the adjusted the extrusion rate also. I fully expected this to totally fail, It didnt!!

video

There is a notable difference in the way the plastic looks, but it works fine.


The left foot was printed at 30mm/s the right at 60mm/s 

I have also found a nice trick, you can set the perimeter speed to a percentage of the main speed, this means the perimeters are printed perfect at 30mm/s with high speed in fill.
Unfortunately there doesn't seem to be any way to do this on the bottom or upper surface. But its a good start, ill keep tweaking setting, to see if I can improve things.

Thursday, 5 May 2011

Ive joined the reprap breading program!

Firstly an update, The new Pulleys work brilliantly, im not saying all issues are solved, but its a lot closer.

I've been printing up a storm, well lots of Prusa parts.

I have started to make a second machine, the basic idea is to have two machines, one for printing and one to experiment with.

I got myself a angle grinder and and cutting frame, has made the job of cutting the M8 thread much easier than a dremel 

Ive Started printing out a second set of plastics for myself in purple!

But unfortunately I ran out of purple, and had to print the rest in white.

I assembled the purple parts


I've decided that this looks really good and and I am going to have to make a fully purple one.


I also recently found out about the reprap irc channel irc://freenode/Reprap
Lots of really clued up people all building or contributing to the on going development of the reprap.

There I met a guy also from Christchurch who was desperately after a set of plastics.

So I've completed the rest of the set in white, and sold it to him for probably far to cheap...


But there is a caveat, I can't print the pulleys well enough for my liking.
I'm fairly sure you just cant get the detail in these pulleys with an extruder nozzle of 0.5mm  It just needs something smaller.