Centurion Mk III Scratch build

This section is for builds that are not strictly Tamiya or Heng Long. For instance, replacing the electronics from a WSN or Matorro, or even a scratch-build.

Postby AlwynTurner » Sat Jun 16, 2018 8:19 am

Printed the first sprocket, it's substantially different in design to the Chieftain but the sprocket teeth/spacing are the same
Image
Image
Image

Here's the scad code

**************************************************
module sprocket_cover () {
$fn=100;
translate([0,0,27.5]) cylinder(r=3.25, h=3);
translate([0,0,30]) cylinder(r1=4,r2=3.5, h=1);
difference () {
translate([0,0,31]) cylinder(2,3.5,3.5);
translate([0,0,32.5]) cylinder(2,2.5,2.5);
}
translate ([-3.25,-1,32]) cube ([6.5,2,1.5]);
rotate ([0,0,0]) translate ([2.5,0,32.5])cylinder(1.5,0.6,0.6,$fn=6) ;
rotate ([0,0,0]) translate ([-2.5,0,32.5])cylinder(1.5,0.6,0.6,$fn=6) ;

}
sprocket_cover ();

module sprocket_hub () {
$fn=100;
translate([0,0,0]) sprocket ();
translate([0,0,25]) sprocket ();
difference () {
translate([0,0,0]) cylinder(r=6, h=20);
translate([0,0,-0.5]) cylinder(r=4.1, h=10.5);
translate([0,0,-0.5]) cylinder(r=2, h=24);
}
difference () {
translate([0,0,15]) cylinder(r1=6,r2=14, h=10);
translate([0,0,18.1]) cylinder(r1=6,r2=12, h=7);
translate([0,0,1.5]) cylinder(r=4.25, h=12.5);
translate([0,0,0.5]) cylinder(r=2, h=24);
}
difference () {
translate([0,0,2]) cylinder(r1=14,r2=6, h=10);
translate([0,0,1]) cylinder(r1=12,r2=6, h=7);
translate([0,0,1.5]) cylinder(r=4.25, h=12.5);
translate([0,0,0.5]) cylinder(r=2, h=24);
}
difference () {
translate([0,0,8]) cylinder(r=8, h=10);
translate([0,0,1.5]) cylinder(r=4.25, h=12.5);
translate([0,0,0.5]) cylinder(r=2, h=24);
}
difference () {
translate([0,0,27]) cylinder(r=17, h=1.5);
translate([0,0,26.5]) cylinder(r=16, h=3);
}
difference () {
translate([0,0,24]) cylinder(r=8.5, h=6.5);
translate([0,0,19.5]) cylinder(r=7.5, h=15);
}

difference () {
union () {
translate([0,0,24]) cylinder(r=12, h=1);
translate([0,0,20]) cylinder(r=5, h=5);
translate([0,0,24]) cylinder(r=8, h=5,5);
}
translate([0,0,19.5]) cylinder(r=3.5, h=15);
}
rotate ([0,0,0]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,22.5]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,45]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,67.5]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,90]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,112.5]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,135]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,157.5]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,180]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,202.5]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,225]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,247.5]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,270]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,292.5]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,315]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,337.5]) translate ([14,0,27])cylinder(1.5,0.8,0.8,$fn=6) ;


rotate ([0,0,0]) translate ([6,0,28.5])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,45]) translate ([6,0,28.5])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,90]) translate ([6,0,28.5])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,135]) translate ([6,0,28.5])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,180]) translate ([6,0,28.5])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,225]) translate ([6,0,28.5])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,270]) translate ([6,0,28.5])cylinder(1.5,0.8,0.8,$fn=6) ;
rotate ([0,0,315]) translate ([6,0,28.5])cylinder(1.5,0.8,0.8,$fn=6) ;

rotate ([0,25,0]) translate ([-5.5,-0.5,26]) cube ([6,1,4]);
rotate ([0,25,45]) translate ([-5.5,-0.5,26]) cube ([6,1,4]);
rotate ([0,25,90]) translate ([-5.5,-0.5,26]) cube ([6,1,4]);
rotate ([0,25,135]) translate ([-5.5,-0.5,26]) cube ([6,1,4]);
rotate ([0,25,180]) translate ([-5.5,-0.5,26]) cube ([6,1,4]);
rotate ([0,25,225]) translate ([-5.5,-0.5,26]) cube ([6,1,4]);
rotate ([0,25,270]) translate ([-5.5,-0.5,26]) cube ([6,1,4]);
rotate ([0,25,315]) translate ([-5.5,-0.5,26]) cube ([6,1,4]);

difference () {
union () {
translate([-12,-1,0]) cube ([24,2,3.3]);
translate([-1,-12,0]) cube ([2,24,3.3]);
translate([-11.5,-1,2]) cube ([23,2,2.5]);
translate([-1,-11.5,2]) cube ([2,23,2.5]);
}
translate([0,0,-0.1]) cylinder(r=4.25, h=12.5);
translate([0,0,0,5]) cylinder(r=2, h=24);
}
translate ([-3.5,-5.2,0]) cube ([7,2.2,10]);
}
sprocket_hub ();

module sprocket () {
$fn=100;
difference () {
translate([0,0,0]) cylinder(r=17, h=2.8);
translate([0,0,-0.5]) cylinder(r=12, h=4);
}
rotate ([0,0,0]) translate ([16.5,0,0]) tooth ();
rotate ([0,0,30]) translate ([16.5,0,0]) tooth ();
rotate ([0,0,60]) translate ([16.5,0,0]) tooth ();
rotate ([0,0,90]) translate ([16.5,0,0]) tooth ();
rotate ([0,0,120]) translate ([16.5,0,0]) tooth ();
rotate ([0,0,150]) translate ([16.5,0,0]) tooth ();
rotate ([0,0,180]) translate ([16.5,0,0]) tooth ();
rotate ([0,0,210]) translate ([16.5,0,0]) tooth ();
rotate ([0,0,240]) translate ([16.5,0,0]) tooth ();
rotate ([0,0,270]) translate ([16.5,0,0]) tooth ();
rotate ([0,0,300]) translate ([16.5,0,0]) tooth ();
rotate ([0,0,330]) translate ([16.5,0,0]) tooth ();
}

//sprocket ();

module tooth () {
$fn=100;
difference () {
translate ([0,-2.5,0]) cube ([5.5,5,2.8]);
translate ([0,2.5,-0.5]) rotate ([0,0,-16]) cube ([6,5,4]);
translate ([1.5,-7.5,-0.5]) rotate ([0,0,16]) cube ([6,5,4]);
}
}


module nut ()
{
translate([-0.6,-0.4,0]) cube ([1.2,0.8,0.5]);
rotate ([0,0,60])translate([-0.6,-0.4,0]) cube ([1.2,0.8,0.5]);
rotate ([0,0,120])translate([-0.6,-0.4,0]) cube ([1.2,0.8,0.5]);
}
//}
module nut_large ()
{
translate([-1.2,-0.8,0]) cube ([2.4,1.6,1]);
rotate ([0,0,60])translate([-1.2,-0.8,0]) cube ([2.4,1.6,1]);
rotate ([0,0,120])translate([-1.2,-0.8,0]) cube ([2.4,1.6,1]);
}

//copyright Alwyn Turner 2018

Alwyn :thumbup: :wave:
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Posts: 1902
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Postby midlife306 » Sat Jun 16, 2018 8:23 am

Looks brill Alwyn, can’t wait to get back & hit print


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Postby c.rainford73 » Sun Jun 17, 2018 3:16 am

Looks like you are well on your way to another masterpiece Mr Alwyn. From the suspension to the sprockets simply brilliant!
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Postby AlwynTurner » Sun Jun 17, 2018 9:39 am

Idlers and gearbox cover done
idler and idler adjuster
Image
Image
gearbox cover
Image

Here's the scads
Idler
****************************************
module idler () {
$fn=100;
difference () {
translate([0,0,0]) cylinder(r=19,h=5,5);
translate([0,0,-0.5]) cylinder(r=17,h=11);
}
difference () {
union () {
difference () {
translate([0,0,0]) cylinder(r=19,h=1.5);
translate([0,0,-0.5]) cylinder(r=17,h=11);
}
difference () {
translate([0,0,0]) cylinder(r1=13.5, r2=13, h=3.2);
translate([0,0,0]) cylinder(r=5.2,h=10);
}
translate([0,0,0]) cylinder(r=9,h=3);
}
translate([0,0,-4.5]) rotate ([0,0,0]) cylinder(r=7.2,5,h=7);
translate([0,0,0]) cylinder(r=5.2,h=10);
}
difference () {
translate([0,0,0]) cylinder(r=13, h=4);
translate([0,0,-0.50]) cylinder(r=12, h=5);
}
difference () {
translate([0,0,0]) cylinder(r=9, h=4);
translate([0,0,-0.50]) cylinder(r=8, h=5);
}



rotate ([0,-5,0]) translate ([12,-1,-1]) cube ([6,2,3]);
rotate ([0,-5,40]) translate ([12,-1,-1]) cube ([6,2,3]);
rotate ([0,-5,80]) translate ([12,-1,-1]) cube ([6,2,3]);
rotate ([0,-5,120]) translate ([12,-1,-1]) cube ([6,2,3]);
rotate ([0,-5,160]) translate ([12,-1,-1]) cube ([6,2,3]);
rotate ([0,-5,200]) translate ([12,-1,-1]) cube ([6,2,3]);
rotate ([0,-5,240]) translate ([12,-1,-1]) cube ([6,2,3]);
rotate ([0,-5,280]) translate ([12,-1,-1]) cube ([6,2,3]);
rotate ([0,-5,320]) translate ([12,-1,-1]) cube ([6,2,3]);

rotate ([0,0,0]) translate ([10.5,0,1.75]) cylinder (2,0.8,0.8,$fn=6);
rotate ([0,0,45]) translate ([10.5,0,1.75]) cylinder (2,0.8,0.8,$fn=6);
rotate ([0,0,90]) translate ([10.5,0,1.75]) cylinder (2,0.8,0.8,$fn=6);
rotate ([0,0,135]) translate ([10.5,0,1.75]) cylinder (2,0.8,0.8,$fn=6);
rotate ([0,0,180]) translate ([10.5,0,1.75]) cylinder (2,0.8,0.8,$fn=6);
rotate ([0,0,225]) translate ([10.5,0,1.75]) cylinder (2,0.8,0.8,$fn=6);
rotate ([0,0,270]) translate ([10.5,0,1.75]) cylinder (2,0.8,0.8,$fn=6);
rotate ([0,0,315]) translate ([10.5,0,1.75]) cylinder (2,0.8,0.8,$fn=6);
}

idler ();


module centre_spindle () {
$fn=100;

difference () {
union () {
translate([0,0,-14]) cylinder(r=4,h=20.5);
translate([0,0,-6]) cylinder(r=5,h=9.5);
translate([0,0,-7]) cylinder(r=5.5,h=2.5);
}
translate([0,0,2]) cylinder(r=3,h=5.1);
translate([0,0,-14.5]) cylinder(r=1.5,h=23);
}
}
centre_spindle ();

module centre_cap () {
$fn=100;
difference () {
translate([0,0,2])cylinder(r=6,h=3);
translate([0,0,1.9])cylinder(r=4.2,h=2);
}
translate([0,0,5])cylinder(r2=2.3, r1=3.8,h=2, $fn=80);
translate([0,0,7])cylinder(r2=1.8,r1=2.3,h=0.5, $fn=80);
translate([0,0,6.5]) sphere(r = 2, $fn=80);
rotate ([0,0,0]) translate ([5.25,0,5]) nut () ;
rotate ([0,0,60]) translate ([5.25,0,5]) nut () ;
rotate ([0,0,120]) translate ([5.25,0,5]) nut () ;
rotate ([0,0,180]) translate ([5.25,0,5]) nut () ;
rotate ([0,0,240]) translate ([5.25,0,5]) nut () ;
rotate ([0,0,300]) translate ([5.25,0,5]) nut () ;
}
centre_cap ();

module wheel_spacer () {
$fn=100;
difference () {
union () {
translate([0,0,-4.5]) rotate ([0,0,0]) cylinder(r=6.8,5,h=6);
translate([0,0,-2.5]) rotate ([0,0,0]) cylinder(r=9,5,h=2.5);
}
translate([0,0,-14]) rotate ([0,0,0]) cylinder(r=5.2,h=20);
}
}
wheel_spacer ();

module nut (){
translate([-0.6,-0.4,0]) cube ([1.2,0.8,0.5]);
rotate ([0,0,60])translate([-0.6,-0.4,0]) cube ([1.2,0.8,0.5]);
rotate ([0,0,120])translate([-0.6,-0.4,0]) cube ([1.2,0.8,0.5]);
}
module nut_large (){
translate([-1.2,-0.8,0]) cube ([2.4,1.6,1]);
rotate ([0,0,60])translate([-1.2,-0.8,0]) cube ([2.4,1.6,1]);
rotate ([0,0,120])translate([-1.2,-0.8,0]) cube ([2.4,1.6,1]);
translate([0,0,0]) cylinder(r=0.75,h=1.5);
}
//copyright Alwyn Turner 2018

********************************
You need to print 2 idlers, one spindle, one spacer, one cap per side


Idler adjuster - needs to be mirrored for the other side
********************************************
module idler_adjust () {
$fn=100;
difference () {
union () {
translate([0,0,0]) rotate ([-6,0,-10]) cylinder(r=3,h=18);
translate([0,0,-0.5]) rotate ([-6,0,-10]) cylinder(r=5,h=16.5);
rotate ([0,0,20]) translate ( [1,-21,0] ) cube ([17,18,3]);
translate ( [1.5,-4,0] ) cube ([14,8,7]);
}
rotate ([0,0,0]) translate ( [-6,-10,-3] ) cube ([17,18,3]);
translate([0,0,-1]) rotate ([-6,0,-10]) cylinder(r=1.51,h=30);
translate([0,0,-0.5]) rotate ([0,0,0]) nut () ;
translate([0,0,1.5]) rotate ([0,0,0]) nut () ;

}
translate([15,0,0]) cylinder(r=6,h=7);
translate([15,0,0]) cylinder(r=5,h=8.5);
difference () {
rotate ([0,0,20]) translate ( [1,-14,0] ) cube ([3,12.5,12]);
rotate ([45,0,20]) translate ( [0.3,-8,12] ) cube ([4,16,9]);
translate([0,0,-0.1])rotate ([0,0,0]) nut () ;
translate([0,0,1.9]) rotate ([0,0,0]) nut () ;
}
}
idler_adjust () ;
module nut ()
{
translate([-3,-2,0]) cube ([6,4,2.5]);
rotate ([0,0,60])translate([-3,-2,0]) cube ([6,4,2.5]);
rotate ([0,0,120])translate([-3,-2,0]) cube ([6,4,2.5]);
}

//copyright Alwyn Turner 2018

Gearbox cover
***********************************************
module gearbox () {
$fn=100;
difference () {
union () {
hull () {
translate ([0,10,19]) rotate ([90,0,0]) cylinder ( h=3, r=19);
translate ([20,10,10]) rotate ([90,0,0]) cylinder ( h=3, r=10);
}
hull () {
translate ([0,13,19]) rotate ([90,0,0]) cylinder ( h=10, r=14);
translate ([0,11,19]) rotate ([90,0,0]) cylinder ( h=5, r=16);
translate ([18,13,11]) rotate ([90,0,0]) cylinder ( h=10, r=6);
translate ([18,11,11]) rotate ([90,0,0]) cylinder ( h=5, r=8);
}
}

translate ([-16,-7,2]) rotate ([-6,0,0]) cube ([ 60,10,35]);
translate ([0,20,19]) rotate ([90,0,0]) cylinder ( h=20, r=8);
}
translate ([8.5,11,34.25]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([-6.5,11,35]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([0.5,11,36.5]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([8.5,11,34.25]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([14,11,29.5]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([18.5,11,24.5]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([23.5,11,19]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([27.5,11,7]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([23.5,11,3]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([27.5,11,13]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([18.5,11,1.5]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([12.5,11,1.5]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([6.5,11,1.5]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([0.5,11,1.5]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([-5.5,11,2.5]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([-11.5,11,5.5]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([-15.5,11,11]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([-17.5,11,17.5]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([-16.5,11,25]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
translate ([-12.5,11,31.5]) rotate ([90,0,0]) cylinder ( 5,0.8,0.8,$fn=6);
}
gearbox () ;


// copyright Alwyn Turner 2018
*******************************************
You need to mirror the gearbox cover for the other side

Alwyn :thumbup: :wave:
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Warrant Officer 1st Class
 
Posts: 1902
Joined: Thu Oct 23, 2014 10:47 am
Location: Chapel-en-le-Frith, Derbyshire

Postby midlife306 » Sun Jun 17, 2018 10:50 am

Bloody hell Alwyn, you’ve been busy
What gearboxes & tracks are you planning on using?
Cheers
Wayne


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Postby AlwynTurner » Sun Jun 17, 2018 10:52 am

Well here's a right todo and no mistake. I've just started putting the return rollers on and the roller mountings are 5mm too low. This means that the road wheels will hit the return rollers....

Oh B%^^#r!!! :crazy: 8O :'(

That means a strip, redesign and reprint of the four suspension units that have return rollers in them. Wayne I do hope you haven't attached them to your hull yet!

Here is the modified design and scad

Image

module suspension () {
$fn=100;
difference () {
union () {
difference () { //back plate

translate ([-24,0,0]) rotate ([-6,0,0]) cube ([ 48,1.5,32]);
translate ([30,0,11]) rotate ([0,-14,0]) cube ([ 10,10,25]);
translate ([-39.8,0,13.5]) rotate ([0,14,0]) cube ([ 10,10,25]);
translate ([-32.7,0,-5]) rotate ([0,-28,0]) cube ([ 10,8,16]);
translate ([24,0,0]) rotate ([0,29,0]) cube ([ 10,8,16]);
} // end back plate


translate ([-22.5,2.5,16]) cube ([ 45,14,6]);
translate ([-22.5,2.5,22]) cube ([ 45,10,5]);
translate ([-22.5,11.5,22]) rotate ([0,90,0]) cylinder ( h=45, r=5);
translate ([-22.5,2.5,16]) cube ([ 2,15,15]);
translate ([20.5,2.5,16]) cube ([ 2,15,15]);
translate ([-3,2.5,16]) cube ([ 6,15,7]);
translate ([-3,11.5,22]) rotate ([0,90,0]) cylinder ( h=6, r=6);
translate ([-3,2.5,23]) cube ([ 6,10,5]);


translate ([-22.5,15.5,7]) cube ([ 45,2,9.5]);
translate ([-13,15.5,-2]) cube ([ 26,2,10]);
translate ([-6,15.5,-9]) cube ([ 12,2,10]);
translate ([-7,17.5,-3]) rotate ([90,0,0]) cylinder ( h=2, r=6);
translate ([7,17.5,-3]) rotate ([90,0,0]) cylinder ( h=2, r=6);
translate ([-13,0,-2]) cube ([ 26,3.5,12]);
translate ([-6,0,-9]) cube ([ 12,3.5,10]);
translate ([-7,3.5,-3]) rotate ([90,0,0]) cylinder ( h=3.5, r=6);
translate ([7,3.5,-3]) rotate ([90,0,0]) cylinder ( h=3.5, r=6);
translate ([0,18,32]) rotate ([90,0,0]) cylinder ( h=16, r=5);//return roller mount
translate ([0,23.5,32]) rotate ([90,0,0]) cylinder ( h=5.5, r2=5, r1=4.5);//return roller mount
translate ([-1,2,-9]) cube ([ 2,15,11]);
translate ([-18.5,5.5,29]) rotate ([90,0,0]) cylinder ( h=2, r=0.8,$fn=6);
translate ([-7.5,5.5,29]) rotate ([90,0,0]) cylinder ( h=2, r=0.8,$fn=6);
translate ([18.5,5.5,29]) rotate ([90,0,0]) cylinder ( h=2, r=0.8,$fn=6);
translate ([7.5,5.5,29]) rotate ([90,0,0]) cylinder ( h=2, r=0.8,$fn=6);


}
translate ([-30,-6.25,1]) rotate ([-6,0,0]) cube ([ 60,6.5,42]); //clean back plate
translate ([-28.5,15,11]) rotate ([0,45,0]) cube ([ 14,3,8]);
translate ([18.7,15,1.2]) rotate ([0,-45,0]) cube ([ 14,3,8]);
translate ([-7,17.6,-3]) rotate ([90,0,0]) cylinder ( h=3, r=1.5);
translate ([7,17.6,-3]) rotate ([90,0,0]) cylinder ( h=3, r=1.5);
translate ([-7,4,-2.5]) rotate ([90,0,0]) cylinder ( h=6, r=1.5);
translate ([7,4,-3]) rotate ([90,0,0]) cylinder ( h=6, r=1.5);
translate ([0,24.5,32]) rotate ([90,0,0]) cylinder ( h=22, r=1.5);

}

}
suspension () ;
//Copyright Alwyn Turner 2018

Oh well back to stripping and rebuilding!

Alwyn :wave: :wave:
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Postby midlife306 » Sun Jun 17, 2018 10:58 am

Hehe, no worries Alwyn, I do love a good scratch build, don’t get frustrated Alwyn
Cheers
Wayne


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Postby AlwynTurner » Sun Jun 17, 2018 11:22 am

Thanks Wayne. The problem did not become apparent until I attached the return rollers on either side of the centre suspension. Of course with the front and rear suspension it wouldn't have been a problem as the return rollers sit between the road wheels as on the Chieftain, but the Centurion has, believe it or not 6 return rollers on each side as opposed to the chieftains 3.

Bother and Damnation, I hate redoing work and especially the 6 hours of reprinting that will now be required for the modified suspension. At least I managed to remove the old suspension without damaging the hull by careful use of a large blade and a couple of thin screwdrivers.

Ho hum the joys of scratchbuilding!

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Postby midlife306 » Sun Jun 17, 2018 11:25 am

Hehe, oh Alwyn you sound as hot and bothered as I am sat next to this pool lol
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Postby Raminator » Mon Jun 18, 2018 6:51 am

Another beauty taking shape quickly, Alwyn. I was interested to read about how you orient the print for strength, I've wondered how strong and durable the printed running gear would be (particularly if they're not completely solid). Looking forward to seeing more!
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Postby AlwynTurner » Mon Jun 18, 2018 9:00 am

Thanks for the good words guys. Regarding the durability of the components I have been obsessive about the thickness of the components and the direction of deposition when printing. Whenever there is going to be lateral stress I have tried to design so the component is strengthened by a bolt, for example in the swing arms of the suspension. Only time will tell, but on the Chieftains outing at the LAD meet I ran it for about 10 minutes with absolutely no problems. I am confident the the sprockets in particular will hold up as they are heavily over-designed.

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Postby AlwynTurner » Mon Jun 18, 2018 5:52 pm

Hi Wayne, sorry I didn't pick up on the tracks/gearbox question. I am using the KV1 track
https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1
same as the Chieftain with the edge wings trimmed off and the gearbox from Forgebear is the standard Heng Long long shaft gearbox
https://www.forgebeartanks.com/store/p5 ... _Tank.html

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Postby midlife306 » Mon Jun 18, 2018 6:24 pm

Thanks Alwyn, I’ll get them ordered
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Postby AlwynTurner » Mon Jun 18, 2018 6:28 pm

I'm just assembling the suspension and the wheel spacing is all wrong, I think I'll have to shorten the swing arms on the suspension by 3mm to give the correct wheel spacing. I'll experiment and post pics when I've finished printing the tyres.

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Postby AlwynTurner » Mon Jun 18, 2018 7:08 pm

Here is a photo of a Centurion
Image
and here is what the current set up looks like
Image

The wheels are too far apart on the suspension unit and too close together between the suspension units. The only solution is going to be to shorten the swing arms to get the gaps corect. It's a straightforward fix, it just requires more printing!! :crazy: :crazy:

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Postby midlife306 » Mon Jun 18, 2018 7:36 pm

Hi Alwyn, could you not just move the hole positions closer together on the suspension units?
Cheers
Wayne

Edit, I think it’s quite important to keep the arms as long as poss to maximise suspension travel

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Postby AlwynTurner » Mon Jun 18, 2018 7:41 pm

HHi Wayne, no there is no space between the pivot points to allow that
Image
To make the space bigger would require making the swing arms thinner, which would weaken them too much. Better just o shorten them by 3mm. It's an easy retrofit, just means reprinting the arms.

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Postby midlife306 » Mon Jun 18, 2018 7:45 pm

No worries Alwyn, it’s all part of the entertainment
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Postby AlwynTurner » Mon Jun 18, 2018 8:06 pm

I've just checked against the 1/35 model and if I shorten the arm by 3mm it will be exactly to scale. It just shows that the suspension design changed subtly between the Centurion and the Chieftain :crazy:

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Postby AlwynTurner » Wed Jun 20, 2018 11:18 am

Modified the scad and reprinted
Image
The spacing is now correct on the right hand side pair of wheels. Here is the scad

module suspension_arm () {
$fn=100;
difference () {
union () {
translate ([10,15,-3]) rotate ([90,0,0]) cylinder ( h=11, r=5);
translate ([31,17,-3]) rotate ([90,0,0]) cylinder ( h=13, r=6);
translate ([31,22.5,-3]) rotate ([90,0,0]) cylinder ( h=6, r=5);
translate ([28,6,0]) rotate ([0,-25,0]) cube ([3,8,12]);
translate ([23,6,0]) rotate ([0,0,0]) cube ([4,8,12.5]);
translate ([10,4,-8]) cube ([ 21,11,10]);
translate ([23,14,10]) rotate ([90,0,0]) cylinder ( h=8, r=2.5);
}
translate ([10,15.5,-3]) rotate ([90,0,0]) cylinder ( h=12, r=1.5);
translate ([31,23.5,-3]) rotate ([90,0,0]) cylinder ( h=20, r=1.5);
translate ([23,14.5,10]) rotate ([90,0,0]) cylinder ( h=10, r=1);
translate ([23,11.5,10]) rotate ([90,0,0]) cylinder ( h=3, r=3.3);
translate ([31,6.4,-3]) rotate ([90,0,0]) nut ();
}

}
suspension_arm ();

Now I just have to print another 5 sets. This reminds me of the Red Queens Race from Alice in Wonderland, running as fast as you can to stay in the same place! (or in this case printing as fast as I can) :crazy: :crazy:

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