RC Tank Warfare community hobby forum

Having decided I wanted to build a Diamond T, after exhaustive research I could not find tyres to fit, so decided to try making my own using my 3d printer.

I did the design

and printed off a test



The next stage is to test printing flexible PLA filament which may or may not work on my printer. I've ordered a test sample from rigidink to try.

To those who want to try printing, here is the openscad code
tyre ();

module tyre() {
$fn=100;
difference () {
union () {
translate ([0,0,-1.5])cylinder(15,34,34);
rotate_extrude (angle=45, convexity = 9) translate ([32,-0.5,-2.75]) circle (r=2);
rotate_extrude (angle=45, convexity = 9) translate ([32,12.5,-2.75]) circle (r=2);
difference () {
union () {
translate ([0,0,-2.5])cylinder(17,32,32);
translate ([0,0,-3])cylinder(18,27,27);
}
//translate ([0,0,-3.5])cylinder(20,25,25);
translate ([0,0,13.6])cylinder(1.5,20,25);
translate ([0,0,-3.1])cylinder(1.5,25,20);
}
}
translate ([0,0,-3])cylinder(18,17,17);
for (z = [0:12:360])rotate(a=(0)+z,v=[0,0,1])translate([28.8,0,-3]) cube ([6,3.5,8]);

for (z = [0:12:360])rotate(a=(30)+z,v=[0,0,1])translate([28.8,0,7]) cube ([6,3.5,8]);

}
difference () {
union () {
translate ([0,0,-0.5])cylinder(13,32,32);
rotate_extrude (angle=45, convexity = 9) translate ([30,0.5,-2.75]) circle (r=2);
rotate_extrude (angle=45, convexity = 9) translate ([30,11.5,-2.75]) circle (r=2);
}
translate ([0,0,-3])cylinder(18,17,17);
}

}

If Anyone wants a master to mould tyres from then I can produce one at £5 a shot plus postage
The dimensions are:
OD 67.5mm
ID 33.5mm (designed for use with the hub designed by Wibbly with a minor mod which I will happily pass on to anyone interested
Width 17.6mm - This is the reason for producing the tyres as I need to have a double rear tyre and there's nothing out there this size.

Cheers
Alwyn

Can you print in rubber?

Hi, unfortunately not, there are flexible PLA filaments, for example Ninjaflex, and there are a host of new suppliers for flexible PLA popping up. I'm going to try a couple and report back. Just to note, these filaments have to be printed at higher temoerature (e.g. 220C to 240C) and have to be printed S L O W L Y, which means this tyre will take about 4 hours to print. One option is to print in PLA, make a mould, and cast using some rubber like compounds that are out there - but my knowledge of moulding/casting is non-existent. To anyone who is a wiz at casting I will gladly supply a couple of free masters if I can then get some moulded copies at a reasonable rate.

Alwyn

Hi Alwyn ,now you have done the tyre , maybe you could convert it to a two part mould with fill hole and vent hole, then bolt together and inject it with some kind of RTV (black if possible) leave to cure probably at least 24 hrs need to wipe Vaseline around the inside first. Making a RTV mould of tyre wouldn't work RTV would tend to stick to a RTV mould.

regards pete

As I lay awake this morning coughing and spluttering with man flu, I suddenly realised how thick I was being! I don't need to make a mould, I can print one by subtracting the wheel from a block in two halves and making a couple of holes to pour in the rubber DOH! Anyway after this revelation I ordered some black rubber and when it gets here I'll give it a shot.

Alwyn

Looking forward to your experiments, flexible filament presents all sorts of problems to solve.

Hi Alwyn don't forget to put mould release on or it could be messy ,both faces of the mould .

regards pete

Thanks Pete for the moulding advice, much appreciated. I printed the mould halves (nine hours of printing!) and here they are




Just waiting for the RTV components to arrive. I had major problems with Openscad as eventually there were so many elements to resolve that it took forever. In the confusion of it all my changes to put locating tabs and holes on the two halves got lost so I will have to put in some brass pins to ensure proper location before moulding.

Meanwhile the 10 metre sample of flexible PLA arrived so that will be today's job to test that.



Looking at various bits of advice on the net there are a number of small tweaks to do such as disabling retraction on the filament, so this is going to be a learning experience.

Alwyn

The only issue I can see is that the RTV isn't being pressure injected. I know zero about all of this, but you may find air bubbles being a problem. There are a few vids on You Tube that I watched a while back, and it seemed like the theory was rather easier than the practice.

If you can pull this off then at least we will all know whether it works or not. 3D printing tyres seemed appealing but looking at the results that some have got with different filaments, that too seemed a bit hit and miss.

I actually had solid PLA wheels and tyres on my Long Tom, surprisingly it ran very nicely. My current challenge is wheels and tyres for the 25pdr and limber to go with my Morris Quad. The Lego truck ones are too big, and their motorcycle tyres are too big and too narrow.

Hi Rob, re the limber and gun, this may be useful or may be too small
https://www.ebay.co.uk/itm/Lego-4-Large ... SwGUBZ7ky7

Re the moulding I have ordered some large disposable syringes so hopefully they will enable pressure injection
https://www.ebay.co.uk/itm/2-x-50ML-DIS ... 2749.l2649
I am hoping that if I very slightly slope the mould and inject at the lowest hole it will push all the air out. I was careful to make the vent holes at the highest part of the component. In case of blemishes then the vent/fill side will be on the inside of the vehicle.

Alwyn