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  1. #21
    Super Moderator curious aardvark's Avatar
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    my latest sheet of pei arrived this morning.
    So before i put it 'somewhere safe' and it vanished into the black hole I've got somewhere in my workshop - I cut it to size and fitted it !

    The main reason I've done this is to cover the screw holes at the corners of the build plate.
    If it proves as good to print on as the adhesives - even better - but it doe now mean I can print on the entire build plate.
    And if it doesn't work that well - well there's always the adhesives - of which I have an abundance :-)

    First print on the pei looks good.
    Love the smooth base.

    Adhesion was excellent.
    My fault the top surface is a litle 'slumpy' - I had the infill a bit too sparse.
    But the first layer went down at 30mm/s and the rest was a solid 100mm/s.
    Dimensions are absolutely bang on !
    These are shopping trolley 'keys' - I set the 'thickness' at 2.8mm and all three are bang on 2.79.
    I'll take that every damn day !

    And now I've been able to compare printbite and pei - they are quite different.
    Printbite is a LOT harder.
    In the three years the printbite has been on the he3d k200, it's been used and abused way beyond reasonable expectations. Getting the mymat nylon off with a metal chisel and a hammer would have destroyed almost all other print surfaces - the Printbite just winked at me and said: 'is that ALL you got ? '

    So next task an actual 235x235 test print.

    And apart from an extruder that cna do flexibles at speed - I honestly can't think of anything else that needs doing.

    I even like the built in cooling ducts. One fan per side and a wide duct setup.
    Given how good the 150mm/s iris box is - cooling is definitely working well.

  2. #22
    Super Moderator curious aardvark's Avatar
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    now this is how you lay down a first layer !
    there are 592 seperate 'links'. It's not agreat picture but every single one of those 'crescents' is a seperate part. The gaps between them are very small - but there are gaps.



    So final verdict on the PEI - excellent !
    Adhesion for pla is damn near perfect. And it comes off easy once cool.
    Going to be interesting to see how long it lasts.
    I think the sheet I bought which was 250x250 with 3m adhesive sheet, cost about £7
    And hassle free printing from here on in :-)

    Be interesting to see if pet-g sticks to it - it is supposed to, but who knows.
    If it doesn't - no bigge I've got three different types of print adhexive that all claim pet-g works with them.
    So we'll see.

    The bracelet printed perfectly, and peeled off very easily. I'll take pics in better light tomorrow - but 4 layer plastic chainmail is a thing of wonder :-)

    There was one other thing I did during the build of the printer. Or rather did not so.

    It comes with a big metal baseplate, I did not fit that.
    As long as you tidy the cables up with some cable ties so that nothing drags on the ground - there is no point fitting the base plate and several reasons not to.

    1) much much better heat dissapation - all the plate does is to keep all the heat in there. Without it everything stays a lot cooler and there is plenty of air circulation.

    2) if you ever need access to the electronics and wires - all you need to do is tip the machine on it's side. No big awkward metal plate to remove.

    It's not needed, so I'd recommend you don't use it.

    Some of those little sticky anchor points would be useful.
    Last edited by curious aardvark; 09-14-2020 at 03:54 PM.

  3. #23
    Super Moderator curious aardvark's Avatar
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    One thing I haven't mentioned is how long it takes to get to temperature.
    The new firmware has a 'preheat' button - one for pla and one for abs - which I'll probably eventually use for pet-g.
    Because it heat the bed and printhead up at the same time. To go from ambient room temp to 65c bed and 200c hotend take exactly 2 minutes !

    That's bloody quick.

  4. #24
    Super Moderator curious aardvark's Avatar
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    So today I decided I'd have aplay with pet-g.

    I have aroll of creality white pet-g that I believe I bought by accident.
    Pretty sure it was really cheap and I was out of white pla and just clicked without checking.

    So bed temp 85c.
    Made a little model for testing purposes. It's a 7 minut print with one piece inside a larger version. Got some gentle underhangs and overhangs and the gap tests retractions.

    First print was 240c and 50mm/s.
    I've kept my retraction and fan settings from pla.
    First print - looks great, zero stringing stuck to the bed like a limpet and came off easily when cool.
    I am really liking this sheet of PEI.
    Actual strength of the print is not brilliant, about the same as pla- but you can peel layers as well.

    Second print up to 250c and two models a decent way apart on the build plate.
    still 50mm/s.

    Well ! colour me impressed.
    Zero stringing, really strong prints - much mangling with pliers and no layer seperation, just squashed plastic.
    Really clean sharp transition areas from one model to the other.

    Either this pet-g is not normal or it's really not as tricky to print as I've been led to believe :-0

    Let's see what it will do at 100mm/s :-)

  5. #25
    Super Moderator curious aardvark's Avatar
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    the 100mm/s pet-g looks pretty good.
    My cooling settings have been left - so 0% for first layer and 100%b for all subsequent layers.

    So I'm running the same print on the delta with white pla and same speed.

    Curious to see if fast pet-g is noticeably stronger than pla.
    No actual scientific tests here - just a pair of crushing pliers.

    ***

    well that was interesting - and children, before you destruction test pla - PUT ON SAFETY GOGGLES !
    Umm, yeah the pla thin walled shape did not deform it just exploded and a bit did bounce off one of my eyeballs.
    The solid pla piece was just totally non-deformable. The pliers won't touch it.
    The 100mm/s petg - was not only a better looking print than the pla. With no stringing and sharper lines and zero blobbing. But while it will crush, it does not shatter. The solid basically ends up looking like a piece of mangled chewing gum. So layer adhesion - excellent, actual strength - nowhere near the pla.

    Really interesting, as I've never done this kind of comparison test before.
    I'll stick some pics up in a bit.

    But this pet-g is really interesting stuff - not at all what i was expecting.
    I can see it being really good for things like boxes with tight fitting lids.

    I'll try a 75mm/s iris box next i think.
    Last edited by curious aardvark; 09-17-2020 at 09:20 AM.

  6. #26
    Super Moderator curious aardvark's Avatar
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    So what I actuallyn did was to make alittle scraper.
    At which point I discovered that pet-g adheres to the PEI a bit too well.
    Could not get it off in one piece.
    The other prints were small and knocked off fairly easy. Obviously the larger the amount of material in contact with the bed the stronger the adhesion.

    I tried it at ambient temp and no-stick.

    So now trying it at 60c printbed.

    well that worked surprisingly well.

    Now whether this particular pet-g has very different properties to everything I've ever read about it - or whether it simply loves being printed on this particular make PEI - I have no idea.

    But it's basically printing as easily as pla and almost as fast.

    So of course I went to see if I could buy any more creality pet-g.
    Of course not !
    What was I thinking.

    Nobody on ebay or amazon sells it - not even sure creality still make it - I bought this roll last year, from sovol on ebay, actually.
    Last edited by curious aardvark; 09-17-2020 at 11:05 AM.

  7. #27
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    PETG is nice to print with. It has opposite the adhesion issues of PLA. PLA comes off the bed nice and separates at the layers if dropped. PETG will break chunks of glass off of your bed and break right through the layers. I usually have my heated bed temp set a little lower around 70C and you can raise that z offset the 0.05 or 0.1 or so from where you print with the PLA. You just do not want as much squish.

  8. #28
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    PETG seems to like moisture so if there's lot's of stringing, drying the filament seems to be a good idea. I had quite dramatic improvement in quality after I dried couple of PETG rolls. The problem was actually worse with bigger nozzle, I had ugly gaps in seams where retractions had happened and of course stringing and it was mostly fixed with dry filament.

  9. #29
    Super Moderator curious aardvark's Avatar
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    well the roll I'm using has been hanging around in my workshop since last year.
    I did open the vacumn pouch.
    But I generally don't have mositure issues anyway. once it's been opened most of my filament is just stacked up on shelves. While it does rain alot in england - we don't tend to have high humidity that often.

    And yeah next time i play with it I'll put the z-gap right up.

    I'm also starting to suspect that this particular PEI is menat for printers without heated beds.

    I've started making some pasta extrusion plates for my hand cranked mincer/grinder.
    Even at at 50c the pet-g only came off the plate after heating the plate back up and eventually getting a metal scraper under one part.

    Ended up making the first one out of pla anyway.

    But absoilutely no stringing, prints fast, I've had the cooling fans full on from layer 2 on.
    So whether it's just this particular brand (whihc no longer appears to exist) I don't know.

    I do have some transparent pet (no glycol). So I'll have a play with that.

    I'm also thinking - maybe polycarbonate might stick to this stuff.
    So that's probably what I'll play with to0night.
    The hot end is supposed to be good for up to 260c - though I have noted the official config file has max set to 290c and the one I'm using has it set to 285.

    So we'll see - if it goes up in smoke - I'll know better for next time lol

  10. #30
    Super Moderator curious aardvark's Avatar
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    this is the script for the chainmail bracelet - I modified it slightly to remove the supports he had and make the clasp actually print properly and not bugger everything up :-)
    /* chainmail bracelet

    Gian Pablo Villamil
    March 2013

    Based on Zomboe's chainmail (http://www.thingiverse.com/thing:8724)

    Added clasp mechanism
    Printed two layers of chainmail to prevent link rotation
    Added (hacky) offset to allow horizontal bridges to clear

    Extra bonus bitchain() module allows for multi color printing

    v2 reduced clasp bump, added more support
    v3 added internal support to female end, opened up clearance on female end, thickened tongue
    v4 retightened clearance, removed internal support on female end

    */

    // Variables

    layer_thick = 0.27; //filament layer thickness
    line_width = 0.4; //filament line width, = layer thickness * width/thickness

    b_width = 2; //block width in lines
    b_height = 6; //block height in layers
    d_height = 2; //diagonals height in lines

    r_halfwidth = .95+1.5*line_width*b_width+0.45; //ring inner half width
    corner = tan(22.5)*line_width*b_width; //fills in corner between block and diagonal

    claspwidth = 38;
    claspheight = b_height * layer_thick * 2;
    claspthick = 2; // in layers
    clasptongue = 6; // in layers
    claspsides = 6;
    claspclearance = 0.2;

    offsetmod = 0.8;

    bitmap =
    [
    [ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
    [ 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1],
    [ 1, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1],
    [ 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1],
    [ 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1],
    [ 1, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1],
    [ 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1],
    [ 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1],
    [ 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1],
    [ 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1],
    [ 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1],
    [ 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1],
    [ 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1],
    [ 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1],
    [ 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1],
    [ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]];


    module ring(modifier)
    {
    module blocks() //four blocks
    {
    for (i = [0:3]){
    rotate([0,0,90*i])
    translate([-0.6001,r_halfwidth,0])
    cube([1.2002,line_width*b_width,layer_thick*b_height]); }
    }

    module diagonal() //thin diagonals
    {
    mirror([-1,1,0])
    translate([0.6,r_halfwidth,0])
    union() {
    cube([corner,line_width*b_width,layer_thick*d_height]);
    rotate([0,0,-45])
    translate([-corner,0,0])
    cube([corner,line_width*b_width,layer_thick*d_height]);
    }
    translate([0.6,r_halfwidth,0])
    union() {
    cube([corner,line_width*b_width,layer_thick*d_height]);
    rotate([0,0,-45])
    translate([-corner,0,0])
    cube([corner,line_width*b_width,layer_thick*d_height]);
    rotate([0,0,-45])
    cube([sqrt(2)*(r_halfwidth-0.6),line_width*b_width,layer_thick*d_height]);
    }
    }
    module 4_diagonals(mod) //all four diagonals
    {
    translate([0,0,0]) union(){
    diagonal();
    mirror([1,1,0]) diagonal();
    }
    translate([0,0,layer_thick*(b_height-d_height)*mod])
    union(){
    rotate([0,0,90]) diagonal();
    rotate([0,0,-90]) diagonal(); }
    }

    union(){
    blocks();
    4_diagonals(modifier);
    }
    }

    module chain(w,h,m) {

    module line() {
    for(i=[0:w-1]){
    translate([i*(2*r_halfwidth-.55),0,0])
    ring(m);
    }
    }

    for(j=[0:h-1]){
    translate([0,j*(2*r_halfwidth-.55),0])
    line();
    }
    }

    module bitchain(w,h,c,m) {
    for(i=[0:w-1]) {
    for(j=[0:h-1]) {
    translate([i*(2*r_halfwidth-.45),j*(2*r_halfwidth-.45),0])
    if(bitmap[i][j]==c) {
    ring(m);}
    }
    }
    }

    module clasp_male() {
    translate([8,0,0]){ //moves reduced clasp to chain
    cube([2,claspwidth,layer_thick*(b_height*2+1)]);

    translate([0,0,-0.8])union(){
    translate([-8,claspsides+0.25,(claspthick+1)*layer_thick])
    difference() {
    cube([8,claspwidth-(claspsides*2)-0.5,clasptongue*layer_thick]); // tongue

    translate([7,0,0]) cube([1,3,clasptongue*layer_thick]);
    translate([2,2,0]) cube([5,1,clasptongue*layer_thick]);

    translate([7,claspwidth-(claspsides*2)-3.5,0]) cube([1,3,clasptongue*layer_thick+1]);
    translate([2,claspwidth-(claspsides*2)-3.5,0]) cube([5,1,clasptongue*layer_thick]);


    }

    //bumps

    translate([-2.75,claspsides+0.5,(claspthick+1)*layer_thick]) cylinder(r=1.0,h=clasptongue*layer_thick,$fn=16);
    translate([-2.75,claspsides-0.5+(claspwidth-claspsides*2),(claspthick+1)*layer_thick]) cylinder(r=1.0,h=clasptongue*layer_thick,$fn=16);
    } // end union
    // supports

    //translate([-8,claspsides+0.25,0]) cube([0.4,claspwidth-(claspsides*2)-0.5,3*layer_thick-0.1]);
    //translate([-7,claspsides+0.25,0]) cube([0.4,claspwidth-(claspsides*2)-0.5,3*layer_thick-0.1]);
    //translate([-6,claspsides+0.25,0]) cube([0.4,claspwidth-(claspsides*2)-0.5,3*layer_thick-0.1]);

    //translate([-5,claspsides+0.25,0]) cube([0.4,claspwidth-(claspsides*2)-0.5,3*layer_thick-0.1]);
    //translate([-3,claspsides+0.25-2,0]) cube([0.4,claspwidth-(claspsides*2)+3,3*layer_thick-0.1]);

    //translate([-1.5,claspsides+0.25,0]) cube([0.4,claspwidth-(claspsides*2)-0.5,3*layer_thick-0.1]);
    } // end mod


    }

    module clasp_female() {
    cube([10,claspwidth,layer_thick*claspthick]); // bottom
    translate([0,0,claspheight-(layer_thick*claspthick)]) cube([10,claspwidth,layer_thick*(claspthick+1)]); // top

    translate([0,0,layer_thick*claspthick]) cube([2,claspwidth,claspheight-(layer_thick*claspthick)]); // back

    translate([0,0,layer_thick*claspthick])
    difference() {
    cube([10,claspsides-claspclearance,claspheight-(layer_thick*claspthick)]);
    translate([7,claspsides+0.5,0]) cylinder(r=2,h=claspheight-(layer_thick*claspthick)+1,$fn=16);
    }

    translate([0,claspwidth-claspsides+claspclearance,layer_thick*claspthick])
    difference() {
    cube([10,claspsides-claspclearance,claspheight-(layer_thick*claspthick)]);
    translate([7,-0.5,0]) cylinder(r=2,h=claspheight-(layer_thick*claspthick)+1,$fn=16);


    }
    // internal supports

    // translate([3,14,layer_thick*(claspthick+1)]) cube([7,0.8,1.8]);
    // translate([3,25,layer_thick*(claspthick+1)]) cube([7,0.8,1.8]);
    }

    module bracelet() {

    //usage: chain(w,h) gives w columns, h rows

    translate([-34*r_halfwidth,-7*r_halfwidth,0])
    chain(38,8,0.8);
    translate([-34*r_halfwidth,-7*r_halfwidth,b_height*layer_thick])
    chain(38,8,1.0);

    translate([170/2+1,-(claspwidth/2+2),0])
    clasp_female();

    translate([-170/2-16,-(claspwidth/2+2),0])
    clasp_male();

    //translate([-170/2,-(claspwidth/2+2),0])
    //cube([170,claspwidth,1]);

    }

    module colorchain() {


    translate([-15*r_halfwidth,-15*r_halfwidth,0]) {
    color ("blue") bitchain(16,16,0,0.8);
    color ("white") bitchain(16,16,1,0.8);}



    translate([-15*r_halfwidth,-15*r_halfwidth,b_height*layer_thick]) {
    color ("blue") bitchain(16,16,0,1.0);
    color ("white") bitchain(16,16,1,1.0);}

    }

    //
    bracelet();

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