-=( BullDog extruder review )=-

-=( Bulldog extruder - review )=-

This is the new bulldog extruder from ReprapDiscount.

-=( first impressions )=-

It's shiney and very well machined and it looks like the kind of extruder you would expect to find in a high end expensive 3d printer , judging by the last week and a half of trouble free non stop extruding with 3mm it's not going to surprise me to see it find its way into many of the existing printers already out there

-=( stepper motor )=-

The stepper motor is a shorter than usual nema17 requiring only 1 amp for full torque which is what most Pololus run at anyway it also runs warm and not burning hot,  the stepper motor drives a small planetary gearbox (black square thing) and delivers enough torque to push 3mm filament flawlessly.

-=( the business end )=-

The hotend mounting point is designed around the jhead mounting groove and clamps the jhead vertically resulting in a very reliable and rigid hotend, due to the clamping action on the top end, so even hotends like the E3d which doesn't have a jhead compatible groove should work as well,

-=( testing )=-
My testing consisted of:
- extruding 4kg of previously written off 3mm pla (written off due the brittleness and age)
- extruding 1kg of previously written off 3mm abs (written off due bad diameter variance)
- currently on a production machine running 1.75mm pla (stopping occasionally due to diameter of filament dropping below 1mm in diameter)

-=( Getting one )=-

keep and eye on www.Reprapdiscount.com and shortly after www.3dindustriesaustralia.com.au

Bulldog extruder

_DSC0117, a photo by thejollygrimreaper on Flickr.

-=( New nozzle geometry )=-

After i recieved my latest batch of nozzles with a better quality orifice which now has a very tiny chamfer on the inside of the 0.3mm hole it is still compatible with the up! extruders and makerbot extruders, 

on this one i have drilled out the back to 4mm and extended the ptfe liner down into the back of the nozzle, this mean not only does the hotend not have to be sealed but also that retraction is so much more effective, 

after a little more testing i will make these the standard nozzle on the Aluhotend,

the photo below is the nozzle at operating temperature 30mins after the filament was retracted back up 7mm this will essentially make it perfect for dual extrusion setups

-=( Tip of the day #1 - Evil Heater Cartridges )=-

Don't ever take it for granted that the $4 ceramic heater cartridge is electrically isolated from it's stainless steel shell, always buy them in multiples and test them first before using them,

if your thermistor isn't as insulated as it should be or you are using multiple cartridges in a bed like i am for instance you will find it can generate a dead short, and if you run cheap power supplies like i do then you can either damage the board or blow up the power supply,

needless to say all the cartridges i now sell are tested before sale.

-=( V9 JGR Extruder )=-

I have recently been reviewing the way hotends are mounted given the noticable difference in print quality between the plate version and the groovemount version of my hotend i worked out that the groovemount especially in 3mm while it may feel very rigid it inherantly isn't no matter which type of screw you put in there,

I figured that my directdrive extruder had been around long enough that i update it with a few of the changes i had been thinking for for a while and here's what i came up with:

the whole thing is generally more compact , it sits lower to down on the carriage with , there is now a tight groove clamp system in place of the dual screw setup and the hotend also now sits higher up than before so the filament path is shorter than before to the control over the retraction should be better.

The reason it's called V9 is because i have already named other variants of the previous extruder eg v5 v6 v7 v8 so logically this one is V9 it's just i decided to put it up on thingiverse and here

if you want to try it out i have it uploaded on thingiverse , use the thinigverse link on the left

-=( Plate Mount / mk7 / mk8 /qu-bd upgrade hotends [update] )=-

I have had a slight change to the previous plans with the plate version, the actual plates won't now be available for another month, however i now have all the

parts available in the online store to make up the qu-bd and mk7 hotend replacements, most people will just need the thermal barrier,

** currently out of stock of the dedicated mk7/qu-bd thermal barrier replacements , there are however different thermal barriers up there at the moment, however they aren't captive at the top so if you use one on the mk7 you may find that the ptfetube with try and push upward, however this can be glued in with loctite

-=( Plate Mount / mk7 / mk8 /qu-bd upgrade hotends )=-

After quite a few people asking "when" a plate mount version is going to be available i decided i may as well make one sooner rather than later as part of the mk7 style extruder hotend i was planning on doing,

it can be used in several configurations, either on it's own with the plate it comes with or as a drop in replacement for the mk7/mk8/qu-bd hotend which apparently aren't as reliable as they could be

i'm putting this hotend up on ebay and later up in the 3dindustries store so those who want one, those are the places to look, 

 

-=( Aluhotend- update )=-

The Aluhotend-3mm-LT is now up for sale,

Available here: www.3dindustriesaustralia.com.au

The "Aluhotend V2" family

I thought I might clear something up about the Aluhotends given the number of questions people keep asking me



originally i never intended to get into 3mm mainly because i prefer 1.75mm , i do however now run both,

the Aluhotend family now has 4 members to it

1.75mm Aluhotend-LT - this one has a ptfe liner inside and is specifically for printing with PLA and ABS the upper limit for temperature is about 245c *production version available

1.75mm aluhotend-HT - this one is nothing but straight aluminium stainless and brass and can reach temperatures up to 500c, *currently made on demand

3mm Aluhotend-LT - this one is has a ptfe liner like the 1.75mm version and is currently undergoing testing polishing techniques are looking to make this one obsolete *currently made on demand

3mm Aluhotend-HT -  this is all metal and is also known as the "MAGMA" sold by trinity labs currently available there for use with pla abs nylon and polycarbonate *in production

The up!: The truth

The up! 3d printer,

while it's true you can pull it out the box install the software and it will print pretty much whatever you can fit on the build table, it doesn't come without it's caveats, and things you simply aren't told before you buy one and really discover yourself the hardway

for a lot of people this printer seems to be fairly reliable, for us ... not even close to the kind of reliability we get on our prusa derivative which is built from nuts and bolts and printed parts,

in it's original form:

Software: aside from the occasional slicing bug where you have to rotate a part on the z axis to get it to print and crashing requiring a PC restart or loosing the usb connection to the printer, there are some serious safety and logic errors that haven't been fixed and even have been added:

- temperature in later versions have been changed to display as percentages
- temperature can only be seen in the maintenance window
- confusing nozzle height setup where it actually prints 1mm higher than the nozzle height you set it to
- no actual infil percentage is shown just pictures which you have to make a guess from
- you cannot turn off support material
- infill patterns are limited to 1

Firmware: I'm not sure i can have much confidence here, we experienced randoms freezes, stepper motors just stopping, random shutdowns, what i call the "death music" ( it plays a tune then requires being initialised again to get it to do anything) , and the long beep of death (needed power removed)


Hardware: for the price it's not a bad platform especially if you are going to do what i'm about to, however physically there are issue some of which in my opinion and many other have been designed into it,-

- the y axis has a cable which is clearly not built for flexing in the way that it is asked to, the cable itself is one of those all in one pieces where you have a plug on one end with the heater cartridge and thermistor on the other end, to replace it when it breaks is about $45 , the type of wire that has been used has this really thin insulation on it which the internal wiring goes straight through on failure and potentially do some serious damage if the wrong ones failed at the same time, possibly requiring you to replace a the main board which won't be cheap if the printer is out of warranty

- the z axis is belt driven although not a bad thing until a power cut happens or unless you get a random shutdown then it will slam itself into the bottom which i don't imagine is good for the stepper drivers,

- the x axis in more recent versions of this printer now have a rigid mount piece for the extruder to sit one, however this still uses only 1 screw previous versions like our old up! has a flimsey mounting tab which lets the extruder flop around a bit, i strinly recommend you purchase this piece or make one yourself

- the extruder is probably about the worst part of the whole thing,

1 - it ships with this fixed distance while nylon piece that contains a bearing and just clips on the front of the stepper motor, leaving you wondering what holds it on other than being against the heatsink,

2 - the wiring to the hotend is terrible and is more of the same type of wire that you find inside the y axis, not designed for any flexing and will not last very long at all especially if you have to frequently dismantle it, bottom line be very careful with this piece because it's $110 to replace it if it breaks, and you have to replace the whole hotend not just the cable with the heater and thermistor, apparently the heaters cartridges won't come out ... in reality it's held in with a grub-screw

3 - the way the hotend is mounted is a little weird, depending on how well each particular piece is machined this can leave you hotend to progressively be pushed out over a few prints and can cause damage to wiring if it comes out in the middle of a long print and you aren't there to stop it,

4 - the hotend has an internal hole in it of only 1.8mm (+/- 0.02mm) now when you consider that the advertised tollerance on even the oem filament is 1.75 +/-0.1mm and that this means the filament could be up to 1.84mm or down to 1.64mm and still be within tollerance, but according to my distributor it is all ok since the filament they sell doesn't go that big! to me this is false and misleading advertising plain and simple,

*the 1.8mm figure i mention above has been verified by my distributor,  it is not a fictional number i plucked out of thin air

5 - the drive gear and idler are a set distance thing, any variance in the filament diameter lower than 1.73mm  and it just becomes easier for the filament to be stripped,  the evidence suggests this whole extruder has been built to only extrude a very specific filament diameter which is the oem filament which by the way doesn't even measure 1.75mm instead a very consistent 1.73mm



While i could probably just get a new board and hotend and y axis cable from my distributor its only going to fix a few problems in the short term and probably leave me with them again in a few months of printing anyway ( if i get that far) and i don't believe that pp3dp or my distributor have any plans on making this platform any better or have set any priority towards fixing some of these issues, some of which wouldn't even be tolerated in the open-source community , this opinion is shared by a few ex-resellers of the up! and some current ones, 

the current state of the printer is that it is a statue, it cannot run long enough to print a bar clamp without something catastrophic happening, so i now have alternative plans to replace the board with a Smoothie-Board which so far hasn't produced a single problem in tests on my prusa derivative, and it's still in beta

chinese power supplies ... the bad ones,

This is a Chinese Powersupply




















believe it or not, under the nice aluminum cover lurks a few big problems consumers just don't know about,

1 - overload protection doesn't work
2 - short circuit protection doesn't work
3 - fan is mounted upside down so gravity wants to pull it apart
4 - if the fan fails casing can get hot enough to burn skin
5 - will burst into flames before failing

this particular one failed because of the fan, and i sported a small burn to my finger when i touched the casing of it, here's an autopsy

how the fan looks when the cover is off, this faces down and blow air out of the case - this is actually a brand new one i now turn the fans around to stop them from destroying themselves, it make no difference to the running temperatures though

 not much to see here,

this is what happens when the fan finally fails with this one i got lucky,  that it was just the fan, the previous one self destructed because somthing metalic came away from the fan and shorted somthing it shouldn't, and delivered and nice high voltage to all my stepper drivers and heaterbed, thankfully the drivers were unharmed however the printer had to be completely rewired

Thin Wall Engineering and the problem with classic infill

The structural issue with infill is that this kind of support structure doesn't really do much and to it's full potential, here's why:

this is what infill currently looks like,

in the image below you can see the contact points between the two layers of infill,  as can be seen there isn't much linking the two layers, this essentially leaves you with towers of dotted links from the bottom of the print to the top,


 the result is a parallelogram type of effect, while the object will feel solid and behave in a fairly rigid fashion under compression when under a shear type of load its no where near as string as it could be, this however depends on the part too

 the solution to this problem is simple, like in a lot of inject molded  parts ribs are usually added to make the part stronger and to a very successful effect in our case where we have the luxury of being able to print the whole object including internal cavities , with the up comming version of slic3r we can do this:

because the internal ribs are solid walls as opposed to a 3d mesh you can get a stronger object, the main advantage however is that you can customize and reinforce specific parts of the object like holes with extra ribs to make specific parts of the object strong

the cylinder in the above photo is the most successful, it's just as rigid if not more rigid than if it was fully infilled,  currently however slic3r has no infill settings for this just the classics so it's up to the designer to draw everything, internally,

Filament Drive Perfection

After producing a large number of my aluminum filament drives, I've been looking at my "reject pile":

when i make one of these things, i do things a little differently, every single one is done by hand on a small American built lathe , the aim is to produce a filament drive with both consistant roundness in the hobbed area and sharp well defined teeth , the actual diameter of the hobbed section can end up anywhere between 10mm and 11mm this is almost irrelavant since you have to go through the extruder steps/per mm calibration procedure anyway


looking at my reject pile, the main reason for rejection is that the hobbing goes too deep or the gear goes out of roundness. if it goes out of roundness they end up in the bin, the rest are generally get given away or used for testing, the irritation is that for every ten good ones i normally get at least 3 rejects
just due to the hobbing going smaller than 10.50mm however they are all still round to less than 0.05mm and realistically make little to no difference on most direct drive extruders anyway

Aluhotends V2 - the next generation

here is the next generation of ALUHOTENDS

from the left -  mk2 clone jhead for sizing  1.75 cartridge version 1.75 resistor version 3mm resistor version 3mm cartridge version experimental deltabot lightweight version

1.75mm and 3mm - i have bowed to pressure to produce both sizes, however certain features in the future for things like the ultra short meltzone might not be as easy to produce as the 1.75mm versions

resistor and heater cartridge versions - some of us prefer heater cartridges some of us prefer wire wound vitrious resistors, both have their place, there is now two different heater block styles to suit them both

cold side is now shorter and lighter - give about the same z height as a jhead

the experimental delta bot version - this is a very experimental hotend currently weighing only 19 grams I'm looking to reduce the weight even further, this one by default with have a pushfit connector in the entry hole and will only be for 1.75mm filament, the meltzone on these i am looking to reduce to less then 7mm and a 2mm diameter space all the way down to the bottom, this should allow near retractionless use which would be perfect for bowden tube setups, currently this one is not up for sale yet