Blew my extruder head

[Bogdan Kecman]

one suggestion .. do not keep the screws that tight. If you had your filament pressuring screws not that tight there would be no blob as the filament would skipped and would not be pushed down.

btw - this Z movement hazard is definetely related to the SD card reading issue where, for some reason the SD library read the wrong nubmer from the SD card  (a bit is inverted probably) and the Z go balistic. The new firmware (those who are unable to upgrade will have to contact bfb, I really have no idea how to help them) Tony is making will have, beside some checks for SD reads, additional option to block the Z movement in "wrong" direction by more then xyz units (for e.g. if firmware read it has to move 2mm down it will skip that command) so this will be additional prevention for such issues. This behaviour will of course be optional (as for the milling you might want to move your head up/down - to drill a hole for e.g.).

anyhow - what is fairly good point is that I encountered this error few times with my old SD card (in every single long lasting print). I swapped it with some other card (both 1G, both kingston) and since then I pushed few kilo's of filament trough my extruder (more then 5, less then 10)  and never ever experienced that problem again. I do however never delete files from the SD - just add new ones, and when the card is filled, I format and start from scratch (formatted only once, 1G is a lot of gcode). IMHO this is pretty good proof that it is related with reading the SD card (yes, when I use the old one I get the problem again), how to read it - I cannot say for sure, I have not spent enough time with the SD library from MC but let's wait to see what will Tony produce - in the meantime
 - loosen the pressure screws a bit
 - monitor the print process

[MarcusWolschon]

I´ll monitor the print process better and will format my SD-cards.
The screws will stay as they are at least until I finished the rest of the mendel parts.
(Never touch a running system.)

[Forrest Higgs]

We were supposed to NOT HAVE to monitor the print process.   

[Bogdan Kecman]

We were supposed to NOT HAVE to monitor the print process.   

not my fault .. really .. and - I do not monitor it ... as I haven't had a single problem for a loooooooooooong time .. I monitor it for 2-3 layers and that's it

[Forrest Higgs]

not my fault

Nobody said it was.  It's just how things are.   

[Bogdan Kecman]

anyhow the SD is for some reason making all this very very annoying .. for some reason the SD read is just not that "safe" (and impossible to test) ... donno if there's time to read every line twice and compare the results .. or if we can add a C value with some checksum (should be easily added in post-processing / netfabb / skeinforge) but it's really a pain in the ...

[Dave White]

pre-made heads?
Haven´t seen them yet in the List of all products.

just noticed that Iain has done some updating of the BfB website the  prebuilt hot end is available at 80GBP (25GBP for kit plus 55GBP for building) to find it you go to the "hot end kit" and select (built hot end)  as an option  http://bitsfrombytes.com/index.php?page=shop.product_details&flypage=flypage-ask.tpl&product_id=181&category_id=5&option=com_virtuemart&Itemid=1 ..... having replaced mine recently I can say that the pre built ones are very nice 

Dave

[Forrest Higgs]

LOL!  Looking at the price and remembering what he first guessed it would price at, I think that Iain has discovered just how unpleasant it is to assemble that extruder head.   

[MarcusWolschon]

LOL!  Looking at the price and remembering what he first guessed it would price at, I think that Iain has discovered just how unpleasant it is to assemble that extruder head.   

I hope (for them) they are not using that bloody fire cement.

[Bogdan Kecman]

The first time it was "touchy" and slow .. and I spend almost whole day building the hot end ... the second one was done in under an hour without any stress ...

what is interesting on those "blue hot ends" is they look like they are put in a mould and then covered by some blue silicone - they do look "fancy"

[Dave White]

what is interesting on those "blue hot ends" is they look like they are put in a mould and then covered by some blue silicone - they do look "fancy"

Not certain which version they are selling on the site.... there appear to be 2 different ones ... The fancy blue one as seen on pics of the RapMan Pro and there is a slim, reddish brown one like the one i just updated to (as seen on the BBC film).... see attached picture.

I think the blue one is for extra insulation ... possibly for the US market???.... burnt fingers, litigation etc

Dave

[MarcusWolschon]

.o0(or it was actually a red one and covered in a blue blob of plastic once. )

This blob actually had a good side effect.
My head is not permanently covered in black plastic, so I no longer
have to worry about bits of the fire cement breaking up and shortening the
burried heater-wire.

[john348]

I have just made a new hot end using the Kapton tape method.  What I did was put the first layer of fireproof cement on then used Kapton from them on.  It seemed to go very easily and took no time at all (after the first layer of cement drying time).  I have only doen one print so far but all looks good.  I have just ordered another from the BfB site and found you can only order a built one!  Not a problem as I was going to buy a built one but found the Kapton tape method so easy I am not bothered now which way it comes. 

[Szilard]

anyhow the SD is for some reason making all this very very annoying .. for some reason the SD read is just not that "safe" (and impossible to test)

I also had problems with the SD card. I just forget it to post how we dealed with the situtation. Sorry.

So, when I finished the RapMan it didnt wanned to read the SD card. Anything I did it wasnt good and just simply didnt read it, and the LED wasnt on. Therefore, I found on the internet some short video made by Batist Leman (I cant find now the link to the video) about his RapMan also had this problem and he found that one pin on the reader it wasnt well solded to the PCB. Parently, it was the same pin problem I had. Rapidly, we solded that pin and it was "working". "Working" means the LED was on when I had SD card plugged, but still no reading the card. Therefore, we went on this base and solded all the pins well to the PCB and after this SD card was accepted, and was reading it well. Never had problems with it since. It is true that till now I didnt printed too many objects and not big ones (the bigest one lasted 1.5 hours). But for us soldening the pins did the trick.

All the best,
Szily

[MarcusWolschon]

One note:
With 2 of the SD-cards I´m using I need to remove and re-insert the card before the list of files apears.
With the third one the list of files is there instantly.
(both after pressing "load file")

Marcus