Sunday, August 28, 2011

Extruder back in action...

Extruder back in action... and working better than before.

With the printer happily singing away again I though it a good time to give an update... I had snapped the wire on the heater resistor a while back, and without a spare it ground me to a halt for the best part of a week. There's a lesson there I'm sure! Carry spares if you want to get back on the road quickly. :-)

The resistor was easily replaced, and with the extruder out it was a good opportunity for improvement. I've always been puzzled by others' reported heat up times (time taken to reach target temperatures), and the seeming ease with which similar hot-ends could print consistently at higher speeds. I made three changes to improve my set-up.

Checking the supply voltage I found the reading from my second-hand PC power supply was actually only 11.5v, so I popped the lid, found the pot and adjusted that so it now reads 12v exactly. The second improvement was to wrap the heater block in a little box of Teflon, which I formed from baking tray liner (rated to 260Deg C). I also placed a heat-shield, using the same material, between the cold and hotends. It also neatly keeps the airflow from the fan around the heatsink and away from the hot-end.

(The brass nozzle could do with being a bit longer but that's for another day.)
The final change (for now) was to fit a more powerful fan to cool the heat-sink that surrounds the stainless steel downtube to the hot end. There was 'heat creep' rising along this tube and heating the filament too far from the hot-end. This was resulting in the occasional jam. I want that filament to be as cool as possible right until it enters the melt chamber.

Here's the new cooling fan...


(If you want to see the old fan you can find it on the second little video on this post http://numbersixreprap.blogspot.com/2011/07/first-print.html )

The other big change is I've moved from Skeinforge and RepSnapper to SFACT and Pronterface, but I'll save my write-up on that experience for another post. Suffice to say, it's all been positive!

Oh... one more thing...  I've also been introduced to this website which is excellent for beginners, like me... http://reprapfordummies.net/.

Keep it printing!

NumberSix

Sunday, August 14, 2011

Test printing continues...then stops! :-(

[This is a duplication of the update I just posted to the forum (forums.reprap.org) but I wanted to log my current status here on my blog also.]

Update: I removed the extruder drive shaft and re-hobbed it cleaner and deeper (M3x0.5  tap). I tightened the springs on the idler bearing also once re-assembled, and tigntened some other cold-end motor mounting bolts that had come slightly loose. The whole assembly grabbed and fed the filament much better. Deffinetly no slippage now.

I adjusted some Skeinforge  setttings also before re-commencing so test printing.
Speed – Feed and Flow Rates 15mm/s, With over Thickness (both) 1.5, Layer Thickness .35mm.

Looking at thinks now, I think my layer thickness should be reduced, given my nozzle hole is .4mm.

Extruder retraction changed from 1mm to 2mm and retraction speed from 20 to 30mm/sec. Cleaned up blobs a lot!

I re-checked my firmware flow setting (E0_STEPS_PER_MM) and increased it slightly – now set to 540.

I’ve lowered the temperature from 200Dec C to 195Deg C. That’s its Target Temperature set in RepSnapper and it hovers at an actual of about 185. (I don’t have a digital thermometer so I’m going on look/feel of extruded plastic. When I lowered the target even more the stepper had trouble pushing the filament, and started skipping steps. I could increase power slightly to the stepper, but I think that would risk increasing hot-end pressure – it’s a balancing act.

I’ve removed the blue tape from my Perspex platform and the PLA took to the Perspex very nicely. It separated easily when cold and gave a good finish to the base of every print, visible in photos.

Some new test prints:  (Ignore the little number tabs in the pictures. They are for my own notes only.)
Circuit board spacer (my square test piece) http://www.thingiverse.com/thing:3183
Underside

Topside

LM8UU Linear bearing holder http://www.thingiverse.com/image:65625
Bottom

General view of LM8UU holder


Top


Underside

Side

The infill on what should be a solid top surfaces needs improvement. It may be my layer height for my given nozzle diam (.35mm for a .4mm nozzle). I’m not sure. I’m going to change parameters slowly and continue my observations. A general remark is that these photos are very close-up and stepping back the items I’m printing are robust and very useable.
Oh… there’s a great bunch of test objects here and some interesting discussion with it also, which I must return to:  http://www.thingiverse.com/thing:5573

Late update: In removing the extruder earlier today to make some change, I snapped off the wire from the heat resistor. I don’t have a spare resistor so that puts me ‘dead in the water’! :-(

I’ll have to order one from somewhere tomorrow.

Thanks to all for observations and feedback on the forum. Hope all the photos and detail isn’t too monotonous folks. It’s been invaluable to me.

Regards,
No.6

Sunday, August 7, 2011

3D printing fun!

At some point over the weekend I decided it was time to step off the Skeinforge learning curve and have some fun with the printer! :) So...with the settings 'functional', if a little slow, I returned to Thingiverse.com and downloaded some items, and set the printer to work. Here are some of the results...


Be sure to read all the detail, where the guy says 100% infill, otherwise you just get a 'rattler' like mine!

The Hyperboloid Pencil Holder. http://www.thingiverse.com/thing:8433
This one got a big 'thumbs-up' in this house!

Here it is without the pencils in.

Enjoy! Thanks for viewing!

Wednesday, August 3, 2011

Test printing and Skeinforge settings...

Quick update: I returned to printing some test pieces in order to improve print quality. I tried printing a 10mm cube with dissappointing results, and am now learning quickly that printing smaller objects has it's own challenges. I though it was the larger ones that had challenges! :)


To seek help with my Skeingforge and other settings I posted some questions over on the forum (forums.reprap.org) and received some good suggestions already. Here's a link to that thread: http://forums.reprap.org/read.php?4,92740,92740#msg-92740

I'll continue to testing and the information exchange over on the forum, and then post a summary of what I learn back here.
No.6