Wednesday, 30 May 2012

Batteries. and a kick Arse PSU

I got an Email the other day about the auction of all the left over parts from the submarine project. today was the day, i took a day off work, as i had spied a very very nice TDK-Lambda Gen 1500Watt PSU on the website i thought i would like that. looking thru the rest of the offerings i took note of a list of lots that i was interested. $600 later i was a happy lad. I didn't win the bid for the PSU but had worked with the guy that did win the bid on three of them, I inquired if he wanted all three, he said i may buy one from him for what it cost him, works out to just under $500au.. SCORE!!!! i also came home with boxes of random parts most purchased at $10 a lot. the best score out of the random parts was the Li-ion batteries that i found. there is
32x 11ah cells
5x     5ah cells
4x  6.3ah cells
5x   17ah cells
20x   2ah cells

I also scored a Few reels of Mosfets and opto-Isolators not 100% sure on the quantity or specs just yet it was a lucky dip box :)

not too sure what i will do with them all but i will find something :) I guess i should probably start thinking of how to charge these guys up and use them, that alone will be a fun exercise, wonder if i can get them to charge in parallel and discharge in series, will probably take a lot of mosfets but i might be lucky the ones on the reels may do the job. i doubt i would be really lucky and find both P and N channel mosfets, there is a slim chance these mosfets are from the thruster controllers which used both N channel and P channel mosfets that can handle lots of power... time for me to take over the world approaches...

ARGH!!!! OS X update does me in.

Being a Mac user A pop up message told me i had updates to install. I thought i had better hit this it might make my virtual machine run better (it suffered in performance when i updated last time, maybe just a coincidence i dunno), but no it in actual fact broke MPLAB_X a net beans ide i use to program PIC MCU's.

I have so far tried every link suggesting anything that might help but no, I Wiped my hard drive re-installed a fresh copy of OSX Snow leopard then restored my virtual machine and installed a fresh copy of virtual box and MPLAB X. tested out how solid works runs, At this point i was happy i could rotate a model and not sit there and wait while it thinks about rotating it and showing me the result it was running smooth. so i then tried to program a PIC MCU for one of my many projects i have on the go, Only to discover that MPLAB could no longer contact my pickit3 so i went and grabbed my ICD3 and the same thing, when you try to access the programmer the IDE says that the previously selected programmer is no longer available, and to select one from the list. only problem is that the list is empty.

I loaded up the VM to test my hardware and it all checked out, so i thought maybe the new version of MPLAB X 1.10 was at fault so i downgraded this to v1.0 all to no avail, i loaded up v1.1 in windows VM and i could access both the programmers, i found a little utility that switches the drivers/firmware in the ICD3 to MPLAB X but that didn't help either, starting to get really pissed at this..

As i said above i have tried a fresh install of OSX and tested the functionality of the programmers at each step of the update process but they have never worked natively on OSX since they stopped working, but the thing i don't understand is how MPLAB X under OSX can't see the programmers but MPLAB X under a windows VM machine on the same OSX machine can use them.. this is very annoying..

recap :-
mac laptop 32bit OSX Snow Leopard
windows VM using MPLAB 8.73a and MPLAB X can access both the ICD3 and the Pickit3
OSX MPLAB X Cannot access either the ICD3 or the Pickit3.
i have accessed both programmers and updated the firmware to the latest but still no dice..

ARGH!!!!!!!! any suggestions?

Saturday, 19 May 2012

plastic in all the wrong places...

so i had a problem with plastic building up over the top of the nozzles, i think i have found a rather convoluted solution :)

I have a 4mm ID brass tube that i have stuffed a PTFE liner into that was 4.05mm OD and 3.2mm ID.
this is then pressed into the top of the nozzle, this was drilled out to 4.72mm the brass tube has a OD of 4.85mm so its supposed to be a tight fit. (this theory is great, execution was not so great the hole ended up too big and i had to cross drill and pin the brass to the nozzle the first one. this was done to so the hole only just hit the brass tube and did not Perice the ptfe liner (no i am not that good,i was lucky very lucky) .

 This brass tube that sticks up 20mm up from the nozzle was still getting hot enough to soften the ABS, and the problem is now 20mm higher, as i have a Aluminium carriage plate i thought that would make a bloody great heatsink, i already had a fan on it to keep the stepper motor cool, so the plate would be well below 105'c (the point where ABS gets soft). I made up a little brass lump that i pressed into the aluminium plate that has a hole to suit the brass tube, this now keeps the top of the nozzle at about 50'c when no fan is on and the unit has been soaking for an hour or so. with a fan i think this will be a viable solution.

Its 15mins since i typed the above line and it seems that a 0.25mm nozzle is just too small for my extruder.. I have come to this conclusion by drilling out the 0.25mm nozzle to 0.4mm and the plastic is flowing nicely again. i cleaned the nozzle before i drilled it but it didn't help. but a bigger hole fixed my stripping issue, i maybe able to re-visit the idea of 0.25mm bolt once i get all the other problems sorted out... I will be bench testing this setup for a while before i go and bolt it all back up and attempt a print, i wonder if slic3r supports 3 materials with 3 different nozzle sizes?

Saturday, 12 May 2012

Video of the Vavle nozzle bench test.

Last night and yesterday i was rather industrious and made some good headway with my extruder, i tore it down after using it for a little bit for some preliminary testing, i would get close but then decide to add or change something so i would have to start again. This morning i have done a first test on the first nozzle, it also the first time i have tested a 0.25mm nozzle, there is nothing like changing only 1 thing at a time :D.


in this video you can see the valve work as the filament is pushed by the extruder the nozzle moves down and the valve slides out of the way ready for printing, there is one little problem with this profile of nozzle the step in the tip has two problem, A) the valve gets caught on the edge, this can be solved by forming the edge of the valve more, this may require a thicker but narrower valve. And B) the valve (if watch carefully) is pushing the nozzle back up into the extruder, this may or may not be a problem. Either way i am very happy with the way this works for a first try this is Awesome..

each time you hear the stepper feed its going slowly at a rate of 100mm/min and feeding 5mm of stock each time, tests will prove how well this actually works out, these valves are very crude, if i had better tools i would have made them 8mm wide and possibly attempted to put a V grove in the end to see if that helps with the riding up on the nozzle, i can see this riding action causing a problem down the path when the nozzle becomes worn from repeated opening and closing, but for a first attempt i am happier than a pig in mud..

My Powered Dividig Head

I  need a powered Dividing head for the Mill so i can make gears and drive bolts for the printer, i found  something close on ebay.. and i have since made up an frame for it to attach a stepper motor to the chuck..
 here is the chuck there is a locking screw that holds the back to tighten the jaws and while milling.
 Have i mentioned i am a lazy bastard.. I want to make gears with nice fine teeth and drive bolts for my printer with out breaking a sweat, done that too much already.. so i have devised a way to attach a stepper motor to the back of it and still maintain the ability to mount it either vertically or horizontally.  

I took a 12mm 1.25mm pitch bolt and drilled a hole in the end to match the steppers shaft, then i made a flanged shaft to attach the back of the chuck, on this i have a hobbed section that the bolt will run in, as it does the chuck will turn, but alas my measurements we off by 0.5-1mm and the drive bolt does not make proper contact with the flanged shaft. so i am going to have to print (slowly) a new worm and spur gear that i can use in this frame to mill a metal one out that will be able to turn while milling. the plastic one will require me to lock off the chuck when i make a cutting pass, i should be able to make the spur gear i need and the worm on the lathe. so many projects on the go it will be good to get some finished...

Update 10.. Valves are so rich and warm :)

My last post was a mess was downloading all the photos from my iphone so i jammed pics in later and they only sorta suit the words.. Meh...

I had to take apart my Extruder as i had a problem with the plastic building up above the nozzle and coming out the sides (must have been a lot of force up top there). to fix this i added tube to the top of the nozzles, these poke up through the carriage plate. while i had it in bits i thought why not see about my valves? see if they can work, i was going to just try them out separately while i was printing but the blobs up top forced my hand, thanks to my mate at work Dave, i got my paws onto some spring steel that was 10mm wide and i dunno how thin 0.5 at a guess, and bent them in to a Z shape that hugged the ends of my heater blocks..

 here you can see the valve made from spring steel bent. you can also see the brass tube on the top of the nozzle on the up turned carriage. it slides up inside the peek and goes thru the plate.
 see it fits :)
 here i have installed all three heater blocks, with resistors, these are held in place by a split brass tube. the nozzles are free to move up and down about 5mm, as they do they push the spring steel down and the taper on the nozzles push it to the side.
as the tips push the valves to the side the valves ride and spring up above the height of the print layer.and don't clip the print job.

here you can just see the tips of the nozzle poking down past the vlaves just enough to clear the print job.

these Nozzles will have to be leveled, i plan to do this by slapping down some emery paper or wet and dry sand paper on the bed and gcode it to go back and forth and hope they all end up at the same level. you can see that each of the nozzles have a different profile to their tips this was a bit of machinist error and when i saw it i thought hey i can claim its a test, wanted to see the best shape to get the valves out of the way, i need to model (somehow) how they move so i can get it perfect.

Between you, me and the lamppost my third channel may not work too well, i have something out of alignment and this can only be fixed by a complete rebuild, one of my mates who has helped with the build is now really excited about the printer, before he wasnt totally commited now he has volunteered to build the next prototype, once i have finished poking at this one. so far i need to shrink the camshaft motor (nema17 is beyond "Steven Segal styles" overkill), from playing with this unit the camshaft rolls so nice (even without rolled edges) in the bearings i can use a PM-20 stepper and some gears. i have these sitting here from old ticket printers. i might need to increase the spring tension or the the ratio of the tension arms so i get more grip on the plastic and try out a hyena style drive bolt but i need my CNC mill and the dividing head to be finished for that.. if my brass tube upgrade works i will be set :) then i have firmware and gcode scripts to sort out.. time to buff up on my python.

Update 9.Victory is near....

Having received my new Arduino Mega and installed it i started to play around with my printer..

I got impatient waiting to finish the mill so i thought i would see what i can do about the grip issue.. i cleaned the hobbing on the bolt and gave it a whirl, and what do you know, i could feed filament at 140mm/min into the hotend, then the motor would stall..
Talking to the peeps on #reprap i decided to ignore what they were saying and install a stronger motor.
$30 later including postage i was waiting for a new 62oz stepper motor...  this arrived very promptly.. i cut the wires nice and short and installed  a header onto the motor and a socket on the loom, it was a pain to re-wire the whole carriage to replace a motor..

So i have been printing quite nicely YAY.. i still have a lot of little settings that i need to tweak with slic3r or Skeinforge to get some nice printouts but i keep adding things so i never actually get to a happy point where i can claim complete victory..  See the "Things I have printed" page for the results..

To stop the extruded plastic from curling up and deforming i have a heated bed this was not enough, i had to also add a fan, i made one fan shroud that was ugly but encouraging, so i made a new one and this one is sweet the holes where the air come out have been reduced to only where i want them, but opened up more so i get better air flow, as sweet as this one is i think i need a second fan on it, i do have a problem i have a the fan driven off the arduino mega's pin 11 according to the screen printing on the board, the documentation and numerous websites pin 11 is PWM capable, i have exactly the same mosfet driver circuit as my hot ends, which are optically isolated and driven from a separate 12V PSU, with the hot end resistors are 4r7 so if i drive them all at 100% at 12v i will take 7.5amps, currently i am only experimenting with one hot end, but will have to keep that in mind later, until then i have no idea how to get his fan to PWM, wont spin until i give it a S value of 255. so i cant slow it down.

ok so it not perfect but it does the job, have a plan to print a nicer one, cuz its so big i need to add some LEDS to it, i bought some from jaycar and paid to much for them if you ask me.
i found that my extruder being all Alu needs a fan to keep it cool so i just hotglued one on top to blow air on the frame. the intake for the air that gets blown on to the print job is drawn too close to the bed and is to warm i think. the middle shot is of the old shroud the new one covers the bearings, they both blow air past the smooth rods so i will have to make some socks up to cover them to keep dust out of my bearings while i am at it i will make some socks for the other smooth rods too.. velcro should do the job.

The new stepper on the extruder makes a big difference i could only retract the filament @2mm/s before the motor would stall.. and i noticed a strange thing, when i have 0.25mm of retract with the new stepper i get nice prints if i turn the retract up any farther it gets worse.. but i dont care about that for now i have other problems with the extruder..

my plastic was melting above the nozzle inside the peek block this area/void was to be where the nozzle was able to lift up so it was out of the way and the valve can close.. I made a mission to Kellets hobbies (they are nice guys as long as you dont get there right on closing) to see if they
 have some ptfe tubing, forgetting that i have some on the Mill as air lines for the piston, and i bought some brass tubes that range in diameters all around 3mm. some metric some imperial. got that home and pulled apart my printer, took the  extruder off the carriage and removed the hot end, had to first heat the hot end up to break the blob of plastic off, then use a hammer and knock out the plug of plastic that built up above the nozzle. i then cleaned out the nozzle the best i could and drilled 5mm into the top with a 3.5mm drill, cut a piece of brass tube that has a OD of 3.55mm and a ID of 3.05mm and hammered the tube into the top of the nozzle see the pics.

this should stop the plastic from building up in the area above the nozzle and allow the filament more grip on the brass to lift the nozzle up so the valves can close.. if i move the fan to the front of the extruder the thin tube will poke up above the aluminium plate that my carriage is made out of, and will get cooled a little and stop it melting too high up.. (i hope)

 here is the first decent print i have done. this was/is vodka tight. i thas a seam line up the back you can see in the pic, i have since been trying to get rid of that, came close but ended up changing stuff and have to re-tune the settings..